FOOD AND DRUG ADMINISTRATION

	CENTER FOR BIOLOGICS EVALUATION AND RESEARCH

	TWENTY-SEVENTH MEETING OF THE

	BIOLOGICAL RESPONSE MODIFIERS ADVISORY COMMITTEE

	8:43 a.m.

	Friday, July 14, 2000

	Hilton Hotel
	620 Perry Parkway
	Gaithersburg, Maryland  20877

	ATTENDEES

COMMITTEE MEMBERS:

DANIEL R. SALOMON, M.D., Chairman
Associate Professor
Department of Molecular and Experimental Medicine
The Scripps Research Institute
10550 N. Torrey Pines Road, MEM 55
La Jolla, California  92037

GAIL DAPOLITO, Executive Secretary
Scientific Advisors & Consultants Staff
Center for Biologics Evaluation and Research
Food and Drug Administration
1401 Rockville Pike
Rockville, Maryland  20852-1448

RICHARD E. CHAMPLIN, M.D.
Professor of Medicine
Department of Blood and Marrow Transplantation
University of Texas M.D. Anderson Cancer Center
1515 Holcombe Boulevard, Box 24
Houston, Texas  77030

JOANNE KURTZBERG, M.D.
Professor of Pediatrics
Department of Pediatrics
Duke University Medical Center
Box 3350, Suite 1400 North Pavilion
Durham, North Carolina  27710

W. MICHAEL O'FALLON, PH.D.
Professor of Biostatistics
Department of Health Sciences Research
Mayo Clinic
Harwick Building, Room 766-A
Rochester, Minnesota  55905

EDWARD A. SAUSVILLE, M.D., PH.D.
Associate Director
Developmental Therapeutics Program
National Cancer Institute
National Institutes of Health
6116 Executive Boulevard, Suite 500
Rockville, Maryland  20892

	ATTENDEES  (Continued)

COMMITTEE MEMBERS:  (Continued)

ALICE WOLFSON, J.D.
Bourhis, Wolfson and Schlichtmann
1050 Battery Street
San Francisco, California  94111

TEMPORARY VOTING MEMBER:

HUGH AUCHINCLOSS, JR., M.D.
Professor of Surgery
Department of Surgery
Harvard Medical School
Massachusetts General Hospital
GRB504, 55 Fruit Street
Boston, Massachusetts   02144-2696

CONSULTANTS:

DAVID A. DRACHMAN, M.D.
Professor and Chair
Department of Neurology
University of Massachusetts Medical School
55 Lake Avenue N., Room S5-753
Worcester, Massachusetts  01655

THOMAS B. FREEMAN, M.D.
Professor
Department of Neurosurgery
University of South Florida College of Medicine
#4 Columbia Drive, Suite 730
Tampa, Florida  33606

STEVEN A. GOLDMAN, M.D., PH.D.
Professor of Neurology and Neuroscience
Department of Neurology and Neuroscience
Cornell University Medical College
1300 York Avenue
New York, New York  10021

	ATTENDEES  (Continued)

CONSULTANTS:  (Continued)

JEFFREY H. KORDOWER, PH.D.
Professor of Neurological Sciences
Department of Neurological Sciences
Rush Presbyterian-St. Luke's Medical Center
2242 W. Harrison Street
Chicago, Illinois  60612

VASSILIS E. KOLIATSOS, M.D.
Associate Professor
Department of Pathology
The Johns Hopkins University School of Medicine
Ross 558 Research Building
720 Rutland Avenue
Baltimore, Maryland  21205-2196

JEFFREY D. MACKLIS, M.D.
Associate Professor of Neurology
Department of Neurology
Harvard Medical School
Children's Hospital
354 Enders Building
320 Longwood Avenue
Boston, Massachusetts  02115

MAHENDRA S. RAO, M.D., PH.D.
Associate Professor
Department of Neurobiology and Anatomy
University of Utah Medical School
531 Wintrobe Building
50 North Medical Drive
Salt Lake City, Utah  84132

EVAN Y. SNYDER, M.D., PH.D.
Assistant Professor in Neurology
Department of Pediatrics
Harvard Medical School
248 Enders Building
300 Longwood Avenue
Boston, Massachusetts  02115

	ATTENDEES  (Continued)

CONSULTANTS:  (Continued)

JEREMY SUGARMAN, M.D., M.P.H., M.A.
Associate Professor of Medicine
Center for Study of Medical Ethics and Humanities
Duke University Medical Center
Box 3040, Trent Drive
Durham, North Carolina  27710

MICHAEL D. WALKER, M.D.
National Institute of Neurological Disorders and Stroke
National Institutes of Health
Neuroscience Center, Room 2223
6001 Executive Boulevard
Bethesda, Maryland  208892-2581

GUESTS:

FRED H. GAGE, PH.D.
Professor
Laboratory of Genetics
The Salk Institute
10010 N. Torrey Pines Road
La Jolla, California  92037

RICHARD C. MULLIGAN, M.D.
Mallinckrodt Professor of Genetics
Department of Genetics
Harvard Medical School
Children's Hospital
861 Enders Building
320 Longwood Avenue
Boston, Massachusetts  02115

MARK NOBLE, PH.D.
Professor
Department of Oncological Sciences
Huntsman Cancer Institute
University of Utah
2000 Circle of Hope, Room 4280
Salt Lake City, Utah  84112

	ATTENDEES  (Continued)

GUESTS:  (Continued)

JOHN Q. TOJANOWSKI, M.D., PH.D.
Professor
Department of Pathology and Laboratory Medicine
University of Pennsylvania School of Medicine
3rd Floor Maloney Building
3600 Spruce Street
Philadelphia, Pennsylvania  19104-4283

NIH PARTICIPANT:

ARLENE CHIU, PH.D.
Project Director
National Institute of Neurological Disorders and Stroke
National Institutes of Health
6001 Executive Boulevard, Room 2205
Bethesda, Maryland  20892

FOOD AND DRUG ADMINISTRATION PARTICIPANTS:

DONALD W. FINK, JR., PH.D.
Biologist
Division of Cellular and Gene Therapies
Office of Therapeutics Research and Review
Center for Biologics Evaluation and Research
1401 Rockville Pike (HFM-527)
Rockville, Maryland  20852

MALCOLM MOOS, JR., M.D., PH.D.
Medical Officer
Division of Cellular and Gene Therapies
Office of Therapeutics Research and Review
Center for Biologics Evaluation and Research
1401 Rockville Pike (HFM-524)
Rockville, Maryland  20852

PHILLIP D. NOGUCHI, M.D.
Director
Division of Cellular and Gene Therapies
Office of Therapeutics Research and Review
Center for Biologics Evaluation and Research
1401 Rockville Pike (HFM-515)
Rockville, Maryland  20852

	ATTENDEES  (Continued)

FOOD AND DRUG ADMINISTRATION PARTICIPANTS:  (Continued)

MERCEDES SERABIAN, M.S.
Division of Cellular and Gene Therapies
Office of Therapeutics Research and Review
Center for Biologics Evaluation and Research
1401 Rockville Pike (HFM-579)
Rockville, Maryland  20852

JAY P. SIEGEL, M.D.
Director
Office of Therapeutics Research and Review
Center for Biologics Evaluation and Research
1401 Rockville Pike (HFM-500)
Rockville, Maryland  20852

BARBARA WILCOX, PH.D
Biologist
Division of Therapeutic Proteins
Office of Therapeutics Research and Review
Center for Biologics Evaluation and Research
1401 Rockville Pike (HFM-524)
Rockville, Maryland  20852

KATHRYN C. ZOON, PH.D.
Director
Center for Biologics Evaluation and Research
1401 Rockville Pike (HFM-1)
Rockville, Maryland  20852

ALSO PRESENT:

JONATHAN DINSMORE, PH.D.
Diacrin

VALERIE ESTESS
Project ALS

CURT FREED, M.D.
University of Colorado

RICHARD GARR
NeuralSTEM Biopharmaceuticals

	ATTENDEES  (Continued)

ALSO PRESENT:  (Continued)

DR. KARL JOHE
NeuralSTEM Biopharmaceuticals

DR. HELENE KARLIN
Canavan Research Foundation

CAROL MEYERS
NeuralSTEM Biopharmaceuticals

DARWIN PROCKOP, M.D., PH.D.
MCP Hahnemann University

LOLA M. REID, PH.D.
Renaissance Cell Technologies

	C O N T E N T S

AGENDA ITEM	PAGE

PRESENTATION OF CERTIFICATES
	by Dr. Kathryn Zoon	11
	by Dr. Jay Siegel	13
	by Dr. Phil Noguchi	14

FDA INTRODUCTION
	by Dr. Donald Fink	15

REMARKS REGARDING NIH
	by Dr. Arlene Chiu	25

OPEN PUBLIC HEARING
	by Valerie Estess	28
	by Dr. Darwin Prockop	30
	by Richard Garr	38
	by Dr. Curt Freed	43
	by Dr. Helene Karlin	74

FDA PERSPECTIVE - QUESTIONS RELATED TO 
PRODUCT DEVELOPMENT
	by Dr. Malcolm Moos	78

COMMITTEE DISCUSSION OF QUESTIONS - 
PRODUCT DEVELOPMENT	85

FDA PERSPECTIVE - QUESTIONS RELATED TO 
PRECLINICAL MODELS
	by Mercedes Serabian	169

COMMITTEE DISCUSSION OF QUESTIONS - 
PRECLINICAL MODELS	174

	P R O C E E D I N G S
	(8:43 a.m.)
		DR. SALOMON:  Good morning to the second of this two-day meeting, the Biological Response Modifiers Advisory Committee.  I guess that means if you're here for another Response Modifiers Advisory Committee meeting, this isn't the right one. 
		(Laughter.)
		DR. SALOMON:  I don't have a whole lot of introductory comments.  I think that today is the opportunity now to get into the questions that the stage was set for yesterday.  Again, I want to thank the speakers for really a tremendous contribution.  I certainly learned a lot and I think there's a lot to build on today in the discussions.  We will get a little bit more into kind of the ground rules for the discussions in a few moments.  
		There is one thing that is actually not a pleasure at all to do this morning, and that is to introduce the presentation of a certificate for one of the people on the BRMAC that is going off.  It's not a pleasure because Dr. Auchincloss has been my evil twin on the BRMAC and on the Xenogeneic Advisory committee.
		(Laughter.)
		DR. SALOMON:  We usually are worried if we agree on anything, and I think I stated once in advisory committee, yes, I totally agree with Dr. Auchincloss, and went on about what it was I thought I totally agreed with him.  He immediately responded, you have got me totally wrong.  That's not what I meant at all.  
		(Laughter.)
		DR. SALOMON:  So, we are 100 percent.
		But I think he knows the depth of my respect for him.  He is one of the most intelligent, well-thought, articulate people.  I say as a joke that I am just an Auchincloss wannabe as a chairman.  I don't think there is anyone who chairs a meeting with more style and competence than Dr. Auchincloss.  Anyway, neither the Xeno Advisory Committee or the BRMAC is going to be the same without him.
		MS. DAPOLITO:  He's still on the Xeno.
		DR. SALOMON:  Oh, he's still on the Xeno.  Excellent.  
		(Laughter.)
		DR. SALOMON:  This isn't quite as bittersweet then as I thought.  That's really good.  But you know, the loss to the BRMAC is really major here so it really isn't a pleasure, except to say what I have said.  I really respect you.  You're really a tremendous contributor to all this.
		Phil, Jay, and Kathy?
		DR. ZOON:  Well, I just wanted to take a few minutes.  I know we have a busy schedule.  But when somebody contributes so much to CBER through the Biological Response Modifiers Committee, and helping us with xeno on so many tough issues over the past several years, I think it's just appropriate, right, and a pleasure to thank you for your service. 
		In many cases being on our advisory committees, as many of you know, is often met with many challenges.  It takes a lot of time.  The pay isn't very good, and the issues are always tough, complicated, and often highly political.  It takes a real dedication to purpose, a real excellence in science and knowledge, and what they call good common sense to deal with these complex issues so that we move science forward, that we don't become handicapped by our inability to deal with new challenges and new issues, but we have the sense and purpose of making sure that it goes forward with the health and safety of the individual subjects in the trials that these patients will participate in.
		I think all those qualities have been contributed by you.  We are pleased as punch that you could still be on Xeno.  I think that is wonderful.  
		And I would just like to take a moment to give you a small certificate of appreciation, Hugh, and thank you very much for all your contribution.  And just to say, Dan, that he always told me you were the evil twin.
		(Applause.)
		DR. AUCHINCLOSS:  The first thing to say is that it doesn't seem like it ever comes to an end because, in fact, I retired at the end of last meeting and here I am back again for this one.  And then I learned that, in fact, I do remain on the FDA Subcommittee for Xenotransplantation.  
		But I do want to thank a number of people, three of them right here and two of them over here.  Gail and Rosanna have been terrific.  You've really been a great help.  Thank you very much.
		(Applause.)
		DR. AUCHINCLOSS:  But let me just conclude by saying that the most important thing that I've learned over the course of the past several years is the extraordinary contribution that I think that the people who work for the FDA are making on behalf of all of us.  I really do believe that the dedication that they bring to their job is everything that I would like to think a public servant brings to his service to the country.  And I think this is an extraordinary group of people, not only the three people here, but others further back behind the table.  Thank you.
		(Applause.)
		DR. SIEGEL:  I will keep it quick.  Just to say, first of all, it's not bittersweet for me at all because, as you know, when someone does as good a job as you do, you don't get off the hook so easily.  You are back.  You will be back I am sure in the future, as well as in our Xeno committee, and we much appreciate that.  You're now in the core of distinguished alumni.
		I also would like to quickly note a couple of things that some folks may not appreciate.  One is the amount of time Hugh has spent not just on the topics in these meetings but reviewing our scientific programs and asking the same penetrating questions of our researchers and providing the same insight and advice and help in that setting that he has in dealing with both the sponsors and the FDA through advisory committees.
		A second and important issue, Hugh, also is that, regarding those last remarks, I have heard indirectly that you have spoken among colleagues similarly about the importance of this advisory committee and those like it and what the agency does, and that has, I know through the grapevine, significantly facilitated our ability to assemble the types of scientists that we have here today.  For that as well, we really appreciate it.
		(Applause.)
		DR. NOGUCHI:  I will keep my remarks really short.  I think, Hugh, you have brought to the committee exactly the type of discussion, courage, and debate that we look for.  All of us never agree on anything all the time, but that's what we have advisory committees for.  In the old days we used to say, I'm from the FDA and I'm here to help you.  But I think today the FDA is on the opposite end, to say really, we are from the FDA, and Hugh, thank you very much.
		(Applause.)
		DR. SALOMON:  So, to start this morning's meeting off, I'd like to introduce Dr. Donald Fink from CBER to give us an introduction.
		DR. FINK:  Well, as chair of the planning committee for this meeting, on behalf of my colleagues in CBER, and including folks from NIH, we have an interesting group in which we have shared resource to help in the planning of this meeting, which has been going on for about four months.  I'd like to welcome you to round two. 
		As a scientist in training, and for those in the audience who are both scientists and clinical investigators, I think yesterday was almost exhilarating in terms of what we heard and the breadth of the information that was made available, and we just appreciate that opportunity.  I think in the audience for those who are not of the scientific community, I think you can get a clear vision for how fast this field is going, how complex it is, and just how fascinating.  And I am sure the promise out there is almost hard to resist.
		Now, yesterday was the fun day.  Today is the brass tacks day, or the FDA day, in which we'll get about to a little more business at hand in addressing questions that have been crafted by the committee.  So, having done that, I would like to also thank the audience for their participation and remind you that, as certainly our most important constituent and consumer, this is your direct access.  You can cut out the middle man today, come to the microphone, and share your thoughts.  It's a wonderful and dynamic interaction that you can have in addition to these well qualified folks here who we are grateful have been able to participate and share of their talents.
		I was contemplating, when I went home last night, a title for today, and I want to borrow my title from a picture that Dr. Mahendra Rao showed, and I'm calling it Bridging the Gap from Thursday to Friday.  If you remember that classical picture of things that didn't quite fit together.  But I think today hopefully our architecture and our energy and certainly our engineering will be a little bit better.  So, I am going to try to use my remarks this morning to bridge the gap from Thursday to Friday and lead us into what I hope we will accomplish.		
		I was thinking about how should I best do this, and I thought, well, I was sitting at the table and said, I know, for tomorrow what I'll do is kind of give a reprise of the take-home messages.  As I started to collect those take-home messages, I realized it was going to take me two trips to do that, so I changed from that.  What I am going to do is just give you some reflections or I think kernels that I can remember that seem to be highlights from all of the talks that went on yesterday and try to bring them to the guise of what hope to get to.
		I think we all can recognize the fact that stem cells are complicated.  I mean, it was just clear as a bell in its complexity.  There are many issues and facts and novel discoveries that need to be considered and addressed as we begin this process together collectively of building a strategy for oversight of this product area.  
		Single markers, a single identity factor.  Not enough.  Can't do that.  We're going to have to look at a variety of characterizations, establish linkage with donor source perhaps, but certainly keep track of where this material comes from, the cell sourcing.  And we need to know not only its lineage but its function.  It just isn't enough to know that they have a certain phenotypic expression, that they look like something.  They have to do something and perform in a certain way.  So, that's going to be also part of the considerations.
		We know that now in transplanting these cells, it may not be that the function we envision for them, based on their phenotype, whether they be neuronal or glial, is perhaps how they are going to actually work.  The cells, simply by virtue of being there, may elicit responses or secrete reparative factors that can do the trick.  I mean, it may simply be as elegantly simple as that.  Perhaps not, but it is certainly something to be considered when we go about our contemplating the regulation and oversight of this product and looking at the preclinical testing.
		Location, location, location, particularly in the D.C. area, is extremely important.  The influence of the microenvironments may be critical.  Putting a cell derived from a certain source into different areas can have a completely different outcome, and so it is clear that we need to be considering the importance of those elements.
		And finally, I do remember outcome measures was a conversation we spent some length on in terms of being measurable and meaningful.  What is the data that we have, how are we monitoring it, what is it telling us.  So, those are things that I think that most struck me as being important that I can recall and would bring back to your attention.
		Thank you to Dr. Mahendra Rao for his FDA perspective yesterday.  It was quite elegant actually.  And we appreciate, I think, the fact that a genesis has come from outside with this group, with the people who are involved in the research and the characterization and the understanding of these cells, that somebody would be bold enough to go forward and put up a straw figure on which we can all sink our teeth into.  That's a great starting point and a great place because it tells us not only what you are thinking but how people that are actively involved on a day-to-day basis with these cells and their possibilities, what are some of the most important aspects to what you would like to see a product be.
		But I am not going to just let it go at that, of course.  What I am going to do is add around that structure, and we will go through just a brief thing of what it is that the questions that we're going to ask later today, we hope to get at in terms of getting some information, input from our advisory committee through its panel of experts as bringing in additional insights.
		Source controls.  By source controls we are talking about the cell source itself, be it embryonic, be it fetal, be adult, be it autologous, be it allogeneic.  We need to know how to best characterize and qualify the source of that material that is going to be used for the product.  
		Then once we have done that, we have to manufacture them.  They have to be made.  They have to be made consistently, over and over again in a way that people can have confidence in.  So, we are going to have some issues that are related to manufacturing of stem cells or derivatives thereof, or neuroprogenitors, if you will, that are going to be used eventually in the clinical setting.
		Perhaps one of the more critical aspects will be characterizing your preparations.  Once you have made them, you have taken them from the source, you have made them, are they what you want them to be and how do you know what they want to be?  What we used to establish that we call specifications or setting specifications.  These are criteria whereby you perform your qualification tests and you look at your outcomes, and if in fact you meet your outcomes that you have specified in advance, you say, yes, I have the product I want, this is what I am willing to use.  And if not, you need to be willing to discard that and start again.  It's as simple as that.   So, we're going to talk about how to best characterize them, and a little bit start thinking about ideas for setting what would be appropriate specifications for them.
		A real critical aspect using biological materials are what we call potency assays.  It's a way to say, we know now what we have, we know where we got it from, we know what it looks like, we know what it sounds like, what it feels like, does it do what we want it to do.  We have to have some functional assessment of that.
		Now, these can be broad in their scope.  I do not want you to think of it as just simply having to go back into an animal or a model that has a condition.  We can talk about surrogates or indices of activity.  It can be an association between a marker and a known function that we know the marker shows up as a functional correlate and that can be used to tell us with certitude that, in fact, these cells will perform biologically once we have stuck them into the patient.  Now, that may not have an intended effect, or the outcome may be negative, but at least we know that when we put them in, they have an activity.  So, it's part of describing the quality of what it is that we are trying to use in the clinic.
		I think we also heard that animal models in preclinical testing are important, and they are also very variable.  We have bandied about the term "gold standards" for asking whether or not there may be models that are already in place, that are already well characterized.  We don't have to reinvent the wheel, that we can rely on in certain disease indications or conditions that will give us the information we want in a preclinical setting.  
		But it also appears that there are many levels of these models.  Some of them may not necessarily be in whole animals.  Some of them may be in a different activity type of paradigm.  It may not be a genetic animal.  It may be something that's done with a chemical to create a lesion.  So, there is modeling, and it is an important preclinical assessment in terms of providing safety information before we enter into the clinic in order to begin those initial trials.
		I think a big question that always comes out that I have heard is tumorigenicity, or maybe not tumorigenicity, but the ability to form clustered masses of size in places where you don't want them and to exert influences that aren't desirable.  I think we heard that in several points, in several different places, and it may be variable depending on your source of cells, whether they were embryonic in origin or adult in origin.  Certainly in number.  How compact were they put in, do they coalesce.  And I think it's an important aspect with the stem cells with pluripotency and potentiality, and we know the ability to proliferate in order to get a handle on whether or not this is an issue that is going to be of importance and may have an adverse outcome.
		And finally then, there's consideration of what we call the post-implantation cellular fate.  We have seen, I think, just some outstanding abilities to track cells, to visualize them, to identify cells that have been put into a recipient, be it a model or eventually into a patient, as to where those cells are, what are they doing, how are they behaving, do they survive, what is their fate.  Integration is a word that we've talked about.  We've heard that once you put in stem cells they seem to integrate seamlessly, they migrate and locate.  What does that mean?  How is that established, and is that integration simply structural or is it functional, and are there actually contacts being formed and interactions within the host environment that function in a way that is something that we might be able to predict and assess.
		So, these are the lists of things that we'll try to bring out in the questions, and we want you to begin thinking about this morning as we go forward.
		To wind up this little presentation, again, I am bridging the gap.  Hearing from the public.  I think I raised that earlier, is important.  We listen with ears wide open when you stand at the microphone.  The statements that people make from the public, be they from patients, be they from interested individuals, be they from people in regulated industry, are profound at this point.  It's the beginning of a process, a strategy, development, a blueprint formulation of a plan to hopefully, efficiently, as well as effectively, regulate this really dynamic area of a novel biologic therapeutic for the clinic.
		Finally, on to the questions.  Now, I know that the community members are saying, but wait, didn't Dr. Gage answer our questions yesterday in his presentation?  Well, yes and no.  The questions that Dr. Gage answered actually, for those in the audience, was a list of questions that was provided by the working group to help the presenters formulate their ideas around how best to structure their talks, and he did a remarkable job.  I can tell you, Dr. Gage, people came clamoring afterwards from the agency and say, oh, my gosh, we've got to get those slides, we have got to have those.  So, they were really relevant and very important.
		But now for the committee we have their questions, which we hope to delve into deeper detail on the issues that I highlighted in the previous slide.  
		Finally, so that they can't escape anonymity, I know that they were listed in your program, but this is public acknowledgment of all my collaborators that served with me over the last several months to put together this program, and who suggested the names of these people who have been here today and yesterday, who have made such marvelous presentations and for our participants.  And I can tell you from sitting and listening to the depth and the breadth and just the enthused responsiveness of our participants, their expertise is without question of the highest level.
		Again, Dr. Salomon, your management of the chemistry here has been excellent and we've had a wonderful debate, even though somebody said it looked like we were setting up the Hatfields and McCoys across-the-river shots here.  But you've done an excellent job in addressing issues and in speaking to them.  
		As I close now, I am going to invite one of our committee members from the NIH, and that is Dr. Arlene Chiu.  She, along with Christina Borror from the Office of the Director at NIH, but Arlene herself is from the NINDS, to make a few remarks regarding NIH, its interest in stem cells, and its interest in funding research in this area.  With that, Arlene, you may go ahead.
		DR. CHIU:  Thanks, Don.  
		Obviously, everybody thinks this is a tremendously exciting meeting.  I just want to take a few minutes to, first of all, personally thank Don and the FDA for allowing me the privilege of serving on this committee.  It is a great example from you of how different government agencies can come together and cooperate and be productive, as well as having a very enjoyable experience.  
		Although the responsibilities of these different agencies are very different, we share areas of common interest, and stem cells is clearly one of them.
		The mission of NINDS, just to bring this up to the front, is specifically to reduce the burden of neurological disease and stroke.  Stem cells, those that produce neurons and glia, as well as those that can in any way promote the restoration of function, is clearly of the highest interest to us.  Our support in this area of research has been strong, and continues to be strong, and will be even stronger in the future as more data, more results come out that could lead to preclinical and clinical trials.
		But we also want to remind you that we fund both basic research, the biology of stem cells, all the way to clinical trials, and this is a huge umbrella.  And as a member of the panel pointed out yesterday, we need advice of how to spend the money, how to allocate resources.  We have been blessed by Congress giving us increases in the last few years, but it is still not enough to fund everything.  So, I hope in today's meeting, with the discussions, you will help us identify areas of highest priority so that we can go back to the institutes and then work with you to bring stem cells, the most promising ones, to preclinical and clinical trials.
		Just to conclude, I'd like to end with two thoughts.  The first is that everybody mentions the important link of preclinical testing.  However, I have noticed personally that when these grants go to study section, they die, and they die because they may be minimally hypothesis testing and they may not be the most creative in terms of approach.  I also want to remind people at the table that many of you are the reviewers, and when you put on the reviewers hats, please remember what you have heard at this meeting, that you have very strong impact on what gets funded.
		So, when you talk about models and you talk about comparing cell types, those are by themselves maybe not terribly interesting studies to bring to study section, but nevertheless of enormous importance.
		The last thought is that in moving toward our common goal, no single agency can do all that needs to be done.  So, I want to extend a personal welcome to the possibility of greater interaction.  That's even partnerships between the NIH, other government agencies, private patient advocacy groups, and industry so that we can do this together, that we can share information, what we do know, share ideas, and maybe split the task and come back together again.  
		Thank you very much.
		(Applause.)
		DR. SALOMON:  Thank you very much, Arlene.  That was great. 
		What we are going to do now is go to the open public hearing portion.  There are several people who have asked to speak and I will call them in the order I was given, and no particular order of priority, however, is implied by the order I am going to call people in.  I am going to keep it to the point.  Five minutes or less, unless there's some compellingly important reason to go longer.  The first person would be Valerie Estess, from Project ALS.
		MS. ESTESS:  Thank you, members of the advisory committee for inviting me to speak to you this morning.  My name is Valerie Estess.  
		On March 26, 1997, a neurologist told my sister Jennifer, who was 35 years old, that she had ALS.  He told her that her motor neurons were dying and would never be replaced.  He told Jenifer that she would die from ALS, because it is always fatal, probably within two to five years.  He told her that ALS is a neurodegenerative disease for which there exists not one effective treatment, not one medicine, not one intervention.
		Three years later Project ALS, the nonprofit organization founded by Jenifer, my sister Meredith, and our friend Julianne, has funded research that is yielding exciting pilot data.  What the data suggests is the stem cells may indeed replace motor neurons and other support cells destroyed in the ALS disease process.  Today Project ALS is riding herd -- and I mean that -- on a true working partnership between stem cell biologists, experts in motor neuron generation, motor axon biologists, and ALS researchers-clinicians.
		On the strength of Project ALS funding, the laboratories of Evan Snyder, Jeffrey Rothstein, Robert Brown, Thomas Jessell, John Gearhart, Marc Tessier-Lavigne, and Steven Goldman comprise a collaboration designed to identify any and all possible roles for stem cells in ALS.  Project ALS has launched rigorous investigations at all levels in these laboratories and will not rest until we have thoroughly tested the safety and viability of stem cell replacement in ALS.
		It is the ultimate aim of Project ALS to deliver the best stem cells to people who are dying.  To that end we will continue to exact best efforts from our scientists, recruit new talent from the research community, and seek a constructive relationship with FDA.  
		There is no disease more lethal than ALS.  It is torture without interruption, a prison camp.  It is nature at its worst.  
		Given their apparently limitless potential to heal, stem cells may represent nature at its best.  We urge that the FDA, NIH, Congress, the world's gifted scientists, and all Americans who have been or will be touched by brain disease and injury work together to free the world from prison.  
		I believe, Project ALS believes, that ours is a nation of wisdom and compassion.  Starting now, let us carry the flag forward with a new dedication, for there will be no help for the sick and dying until we work together to bring the best basic science home. 
		Thank you.
		(Applause.)
		DR. SALOMON:  Well spoken.  
		The next person is Dr. Darwin Prockop from Hahnemann University.
		DR. PROCKOP:  Dr. Ausim Azizi and I came here with several rather specific questions about moving from laboratory experiments to clinical trials.  It really kind of addresses several specific problems which I think are of general interest in terms of the very nice discussions we had yesterday about the whole topic of stem cells. 
		So, just to quickly review what Catherine Verfaillie said yesterday, we're dealing with cells, which the name is a little bit still ambiguous because of the history of them.  The cells are isolated in most laboratories by a very simple technique of putting whole bone marrow in a tissue culture flask and washing out the hematopoietic precursors.  After one or two passages, these cells are quite pure, they're free of hematopoietic cells, and they have this potential to differentiate into a wide variety of tissues.  This is not new.  These data are over 20 years old and repeated in many, many laboratories over the years.
		Our own approaches were to look at these cells injected into animals.  In one series of experiments, we introduced them intravenously, with two different markers indicated there, and we found in mice 1 to 3 months later, somewhere between 1 and 20 percent of the cells in a variety of tissues were derived from these injected cells.  Some of these cells took on the phenotype of the tissues.
		Now it's an old concept.  A beautiful treatise in 1867 by a German pathologist Cohnheim suggested in wound healing, this is what happens.  A subset of cells are mobilized in the marrow and become fibroblasts in wounds.  So, we think of it as kind of a vestigial pathway that's been there a long time, of course, but only detectable by the latest techniques.
		The second series of experiments prompted by Dr. Ausim Azizi, who is here, we infused the cells in the brain.  We have several different markers indicated here.  We are certain that some of the cells become astrocytes, and yes, we said here perhaps neurons.  We are now more certain some become neurons.  So, in response to some of the questions raised yesterday, this is kind of result that's difficult to believe unless one looks at the data.  We've repeated these experiments now for about 3 years and totally convinced ourselves.
		In a third series of experiments, we have tried to take these cells and create an animal model for Parkinsonism.  We introduced two genes that produce L-dopa using a retrovirus in a standard model for Parkinsonism, a rotational model.  We got a good response.  We could show synthesis of dopamine in the brain.  We can also rescue the phenotype of rotation.  We had a flaw in our experiments in that we used a retrovirus that since has been known to call inactivation because of methylation of those sequences.
		In pursuing a solution to these problems, in fact two of them, one is to use a self-inactivating retrovirus, and the other is to introduce the genes by electroporation.  It turns out the inefficient technique of electroporation is now open to us because we can amplify these cells at an absolutely unbelievable rate.  Simply putting these cells in very low density, not 1,000 or 5,000 cells per centimeter squared, but 3 cells per centimeter squared, we can make them grow at arrays indicated here.  In 2 months, we readily reach 50 population doublings.
		The key here is that by plating at low density, we retain the cells you see on the left here at two different magnifications.  Extremely small cells, 7 microns in diameter, almost no cytoplasm.  But as those cells deposit in culture, they give rise to clones where you have the larger cells you see on the right.  In a way these cells make their own feeder layers, is what we're seeing.  They make the large cells to which small cells then grow.  
		The number of the cells we can make I still find staggering.  Three passages over 6 to 8 weeks, from 20 ml of bone marrow aspirate, we can make a total of 10 to the 13th cells, and the key measure here, surrogate measure of multipotentiality stays there.  So, we can make 10 to the 13th multipotential cells in these cultures. 
		So, for those reasons we're optimistic in pursuing these cells with two general strategies.  Cells from bone marrow aspirate, expanded, engineered in the laboratory, systemically infused for systemic diseases, particularly diseases of the skeleton, into the central nervous system for diseases of the central nervous system.
		Now, I have an updated obsolete technology here I'd like to use.  
		The advantage of these cells are simple.  We can get cells from the same patient.  They are multipotential.  Our laboratory, Catherine's laboratory, other laboratories are convinced they can differentiate even into astrocytes and some neurons.  We can't say all neurons, we can't say they make connections in the central nervous system, but clearly you see some neurons.  And we can rapidly expand them so we can manipulate these cells without the need of a virus.
		Now, specific questions that we've come here with.  We need the help of the FDA, the panel, and I think the whole scientific community.  We tried to say how are we going to go from these results to therapy of disease like Parkinsonism.  So, how much do we need to characterize these cells?  We certainly don't know all about the nature of these stem-like cells, and we certainly could spend a long time further characterizing them by microchip techniques, a whole bunch of things.  We don't know how exactly to differentiate them in many cases.  And again, we could spend a long on time on that.  How much time?  I think we're talking years, many years.
		But the real question is whether, from what has been learned about these cells over a 20, almost 30-year period, can we go ahead?  Can we do the kinds of procedures I have said to make the cells produce L-dopa, which becomes dopamine in the brain, and then can we go on to toxicity studies and efficacy studies?  
		As Rusty brought out in his presentation, right here is the major question:  Do you use human cells in incomplete or difficult animal situations, or do you use, say, in rat rat cells and in monkeys monkey cells?
		Ausim Azizi has shown that human cells in rat brain do survive, but they obviously don't do as well as rat cells.  So, we have a question of how to sort that out.
		Toxicity in rats and dogs is reasonable.  How much do we need in the way of more elaborate, costly toxicity studies in monkeys?  Don't know.  
		And again, questions from yesterday.  What are the assays?  There is no indication that these cells make tumors, but maybe what we need to do is extended, many-month, and maybe many-year studies to see if we do get to tumors.  No indication of it, but how do you really rule it out?
		Then the efficacy.  The rat model is a well-accepted model, working well in our hands.  Do we go to the monkey models?  Well, they have many problems.  Extremely.  Jeff here knows a great deal about that, in setting up the monkey model.  We have had experts give us answers on both sides of that question.  Yes, you need extensive monkey model testing, others say no.  If it's a serious disease, you don't really need that.
		In the end here we are convinced -- certainly I am convinced -- we don't want to deal with mildly affected patients in early stages of the disease.  I am very much committed to the idea that you look at the very severe patient before you try something as new as even this.  
		In terms of Dr. Sugarman's presentation, we would love to have a consensus on this, how to go about this, and the help of the FDA and the whole scientific community.  But I must say I am pessimistic about a consensus because of an experience we have had in using these cells there are different clinical problems.  I would like to just take a couple of minutes to tell you that history.
		In 1966, we presented data in mice with these cells, showing they were nontoxic and there was some efficacy in a mouse model for brittle bone disease, osteogenesis imperfecta.  We made the model of a mutated collagen gene, which we and others had shown produces severe brittle bones in children.  Based on those data, Malcolm Brenner at St. Jude's in Memphis suggested we go ahead with this therapy, take a patient with severe OI -- or rather he and his colleague go ahead -- do marrow ablation, and then transfer whole marrow to a matched sibling.  Standard bone marrow transplant.
		I was sort of involved in providing initial data.  I felt very uncomfortable about this because marrow ablation, of course, is a very serious procedure.  I called a meeting in Philadelphia, attended by over 100 people, experts in this field.  It was the most tumultuous scientific meeting I've ever attended.  Words like "outrageous," "unethical" were bandied about in the air.  I could not get a consensus.  People from the bone marrow transplant field were on one side of the room, microbiologists were on the other side of the room.  
		Malcolm Brenner and Ed Horwitz, who began work on this project, went ahead with it anyway.  They did 5 patients.  They reported last year that all 5 showed a decrease in fractures, increase in growth, and increase in bone mineral.  These were extremely severe patients.  They had to be propped up in bed with pillows because they would break bones just rolling over in bed.  These results were encouraging, but Malcolm presented it at a meeting on OI last summer, and again he was criticized very heavily.  
		But just at a meeting held two months ago, he presented another series of results.  He took the same patients, the same donors, and gave expanded cultures of these cells.  So, the patients now had the immune system of the donor.  He reported that in 4of 4 patients there were no toxicities.  The patients at this stage are 4 to 6 years old.  3 of them stood for the first time, a very rare event in this serious form of this disease, and 2 took their first steps.
		I'm not sure that even those data are going to convince everybody in the field and give us a consensus, but we think they set the basis for this kind of plan, taking cells from the patient, gene-correcting them with the techniques I've talked about briefly, and bringing them back to the same patient, this time without marrow ablation.  But it's in that context that we invite help and discussion from the whole community to see if we can reach a consensus as to what's the wise thing to do.  
		Thank you.
		(Applause.)
		DR. SALOMON:  Thank you, Dr. Prockop.  Just one quick question.  In addition to representing yourself and your lab at Hahnemann, are you also representing a company when you repeatedly use the word "we"?
		DR. PROCKOP:  No, I am not representing a company.  We have been approached by several companies.  I have started a company in a different area, I should say, totally unrelated to this, but I have found it's a very strange, complicated game to deal with companies on these issues.
		DR. SALOMON:  We're just sensitive.  Just wanted to know.
		The next person is Richard Garr, from NeuralSTEM Biopharmaceutical.
		MR. GARR:  Good morning.  Thank you for this opportunity to address the committee exploring the status of stem cell research as it applies to neurological indications.  My name is Richard Garr and I am the President and CEO of NeuralSTEM Biopharmaceuticals.  
		As our name implies, we are a CNS stem cell company and we are in fact the owners of the U.S. patent on the isolation, expansion and culture and differentiation into functional neurons of human CNS stem cells.  Obviously, we have a great deal of interest in your topic today.
		Briefly I will tell you that our cells are different in many ways than the cells you have been hearing about.  Whether or not they are stem cells or progenitors or precursors, while of academic interest, is irrelevant, I think, to the important questions that you are learning about.  What our cells do is they turn into functional human neurons all the time, every time, and we can do it in vitro as well as in vivo.  We can grow all different types, all different phenotypes, dopaminergic neurons, cholinergic neurons, spinal motor cord neurons, and we do this without inducing the phenotype.  This is constituitive from the cells.  That technology is also the subject of an issued U.S. patent. 
		The doubling capacity of our cells without genetic manipulation is roughly about a billion-fold, and we can completely control the expansion phase, as well as the differentiation phase.  The cells are extremely well characterized.  We do know all about these cells.  We do know how to control the differentiation of these cells.		
		And I bring this to your attention because I think that in this area, in particular, there is a great deal of expertise and knowledge in the private sector and that you need to reach beyond the usual suspects in academia to really educate yourself as to where this is.  In one of your introductory remarks, the gentleman talked about how fast this field is moving.  Well, I can assure you it's moving much faster than any of you are aware of.
		We have in the past year licensed our technology to major genomics and drug discovery companies.  We have chosen not to publish, outside of the patents that have been published, for business reasons.  However, several of your presenters here are very familiar with our work.  And as the patents are now published, and even as some of the data you saw the other day suggest, there are probably a great number of labs that are actually working with the cells.
		Because of the unique focus of our company, and because of the commercial resources that we have had access to because of our genomics and drug discovery deals -- and in fact, I believe we will probably announce the major global transplantation partner, pharmaceutical company, this summer -- we have already spent a great deal of time and effort on many of the preclinical and product development issues that you all are beginning to consider.
		Clearly, the technical questions about models and product efficacy and safety are crucial to even thinking about moving this technology forward into human clinical trials.  But I think it's also obvious that the expertise and experience exists to evaluate and create standards which will adequately protect the public's interest.  Dr. Gage's insightful and direct consideration of these questions the other day is itself an excellent starting point.  
		There was also no question that the science will be there.  Clearly, within the next 12 to 18 months, in addition to ourselves, there will be companies that will be coming before the FDA that have in their minds worked out the manufacturing GMP issues, worked out the model issues, worked out the efficacy and safety issues, and in their own minds feel that they have compelling evidence to move forward into human clinical trials, at least in the CNS stem cell area.
		I think that the most difficult areas for us have been addressing issues of donor privacy, donor consent, and other tissue sourcing issues.  There is an extremely fragmented regulatory, legislative, and ethical framework that exists out there right now with respect to these issues.  I think that I would urge you to accelerate a robust public education on and debate about the ethical issues involved in tissue sourcing, and particularly donor privacy.  This needs to happen sooner rather than later because again, I think as you're going to find out as you move through this process, as you expand your educational reach out into the private sector, this is much more imminent with respect to CNS stem cells than perhaps your first glimpse is showing you.
		I want to thank you again for the opportunity to address the committee.
		(Applause.)
		DR. SALOMON:  Thank you very much.  
		I guess this is a personal comment, not a comment as the chair of the committee, so please take it as that.  My response to that is, if we're calling for a public education, an acceleration of the process toward clinical trials in this area -- and I think most of us would be okay with that process -- the fact that companies are making supposedly major strides in this area but not publishing anything -- again, I provide you my personal comment and not in any way a comment from the chair.  But there is some contradiction in that.  So, I would urge companies to really step up and do their part of this whole process, which is critical, I think.
		DR. KOLIATSOS:  I think we should all say I support you fully in that sentiment.
		DR. NOGUCHI:  Dr. Salomon, I'd also say that the FDA is always open to interactions with everyone at any stage of the product development cycle.  We, in fact, would urge you to come in earlier rather than later, especially as we're talking about issues of product characterization and preclinical studies.  
		I would say that the FDA does have expertise in the use of autologous and other cellular therapies.  We have licensed an autologous therapy.  We have a full CMC section for advice on how to do that.  It's the details of the more complicated neural stem cells that we're talking about.  But rest assured, should anybody have proposals, we're ready to entertain them, but we also want to get as much advice as we can at the very edges of the cutting edge of the science.
		DR. SALOMON:  The next speaker is Dr. Curt Freed from the University of Colorado.  Dr. Freed I have given 10 minutes to because I think he has some really important clinical experience doing cell transplants in patients that I think is important.
		DR. FREED:  Dr. Salomon, thank you very much for giving me the chance to talk to this committee.  I have enjoyed the discussions and also the individual scientific interactions that I have had with committee members.  It is a tight group of folks that do this kind of work, and it's a pleasure to see so many of the people here.
		I'm going to talk to you about this double-blind fetal cell transplant trial which we have just completed with Stanley Fahn of Columbia University in New York and Dave Eidelberg because I think it illustrates -- while not stem cells, it illustrates the use of a cell substitute or alternative to drug therapy.  I think you will see the interplay between drugs and cells in this presentation.
		We are transplanting embryonic dopamine neurons from week 7 to 8 post-conception abortuses which we recover from elective abortions.  In order to put tissue into the brain, you have to have it in a form that can actually be put into a needle.  We have chosen to make strands of tissue, and you see this tissue strand being expressed from a glass cannula.  This has proven to be a method that provides reliable delivery of tissue.
		This is the second patient to receive such a transplant.  This was back in 1994, before we actually started doing the NIH protocol, and he actually has four small incisions in his forehead that represent four needle passes into his brain.  Parenthetically, I'd like to say that this man is the first man that we have had get off all medications for Parkinson's.  That was a year and a half after transplant.  He has been off all medications for 4 and a half years.  He received tissue from two embryos, one on each side of the brain, each subdivided in half.
		This shows the MR scan with the traces of his needle passes through his frontal lobes, one, two, three, four. 
		Based on these studies and other work, we proposed a double-blind placebo controlled trial with 40 patients aged 20 to 75.  The youngest was actually 34 but the oldest was 75.  You had Parkinson's for more than 7 years' duration.  As we talk about animal models that mimic human Parkinson's, I don't think anyone would have kept an animal around for 7 years prior to transplant.  The typical patient had almost 14 years of Parkinson's.  
		All patients had to be L-dopa responsive, with fluctuations, namely being frozen and then having excess movements.
		20 patients received implants, 20 placebo.  In addition, we divided the recruitment roughly equally to patients under age 60 and over age 60, and then we also paid attention to disease severity, age, and sex in distributing the patients.  
		The patients were evaluated at Columbia and had fluorodopa PET scans done by Dr. Eidelberg on Long Island.
		There were lots of results but I am going to just highlight a couple.  Motor UPDRS off scores, a standard measure of Parkinson's; high is bad and low is good.  When we looked at the sham patients, we saw no evidence of a placebo effect over the 12 months of this trial.  It was a baseline period, then people looked at 4, 8, and 12 months after surgery.  For the transplant group, there was a highly significant difference compared to placebo, and I believe that is at about the .01 level.
		Very interestingly, when we subdivided the groups into the preassigned under age 60/over age 60, the improvement occurred in the under age 60 group.  The over age 60 group as a whole did not improve.  7 out of 10 of these patients improved; 1 out of 10 of these patients did.
		We had as a primary endpoint a very subjective variable.  It said at 12 months, how do you feel?  Are you better than you were before?  And much better was plus 3, and much worse was minus 3, with 0 being the same.  What we found in this distribution was that, in fact, the young transplant group had the largest change in this value.  However, you see all patients on average felt that they had improved.  So, this is the only demonstration that we have that there is a placebo effect when you ask a very global, subjective question as opposed to an objective measure of neurologic condition.
		I might add, those data were not significant.  However, when we looked at these data at 4, 8, and 12 months after surgery, as you saw the other data, there was a significant difference between the transplant group and the sham group.  But again, our decision prior to breaking the blind was to look only at the 12-month data.
		What happens in the long run?  This is 36 months after transplant.  Same scale that you saw before.  What some of us had observed almost for a decade is that patients improve over time who have transplants.  Transplants are a dynamic process, with fiber outgrowth continuing over a period of years.  
		So, if we look at the average transplant patient, shown in green, this was the blind phase you saw before, and then by 18 months after transplant, you see a dip here.  You say, why is there a sudden dip?  Is this a placebo effect with people catching up?  Well, there was another important effect.  Some of these patients had become dyskinetic, and yet their drugs were kept constant. 
		At this point drug reduction was allowed, and then, as you'll see in the next slide, drugs were reduced and the overall motor UPDRS off value has improved.  Younger patients have done better than older patients, although now as we have more patients -- this is a year-old graft -- as we have more patients out here at 36 months, we're finding that there's been progressive improvement in the older group as well as the younger group.
		The total daily drug doses are shown on this slide.  The typical dose is about 1,000 milligrams of L-dopa or equivalent drugs, and by 36 months after transplant, that drug dose has been cut in half.  While the drug dose reduction is interesting, it still complicates the use of neurotransplant therapy in that we have drugs playing together with the cell therapy, and it makes juggling the two therapies simultaneously difficult.
		Will the transplant survive?  This is a fluorodopa PET scan.  The red shows the normal dopamine uptake in the striatum, caudate, and putamen.  Typical Parkinson's patients have fluorodopa uptake in the caudate but much less in the putamen.  Here is a transplanted patient with fluorodopa uptake very closely resembling normal.  Sham surgery patients had no change in that signal.  85 percent of transplant patients showed detectable transplant growth by a blinded rater.  There was only 1 out of 20 false positives.
		This just quantitates that PET scan data, and the point of showing you this is that the implant group had this change, the sham group had, if anything, a reduction.  In the sham young patients, that reduction was significant.  So, this is rising.  The ability to store L-dopa in the brain is rising and the natural tendency through the natural disease tends to be falling.
		Well, you saw that only young patients responded.  How did the transplants grow in the elderly?  These are the under age 60 group, change in PET scan, significant.  Old implant group, change in PET scan, significant.  So, the transplants grew equally well regardless of age.  This was a striking finding.  Namely, the aged Parkinson brain can support fetal dopamine neurons and their outgrowth, a remarkable result of this study, and one that we were perhaps somewhat surprised but still delighted to see.
		So, the failure of transplant effects in older patients must have something to do with other kinds of brain disease or downstream events from the transplant.
		When we correlated the change, in this case improvement in UPDRS score, with the change in how well the transplant grew -- this is in younger patients -- we saw a significant relationship between the growth of the transplant and the change in neurologic score.
		We've had 2 patients who have died of causes unrelated to transplant in the year since surgery.  I am going to show you a pathology from a man who died 3 years after a transplant of a heart attack at age 71, one of the older patients.  This is a glial scar in his transplant tract.  Here's the caudate, here's the putamen, our only target.  No patient was immunosuppressed in this study, so the growth that you're going to see of the transplant is without immunosuppression.
		So, this is the transplant that you saw glial scar with.  You notice you're not really seeing a central line here, even though this is where all the cells are.  But the fiber outgrowth from the transplant is so extensive that you lose the transplant tract, and in fact this man has filled his posterior putamen -- well, his putamen up to here with fiber outgrowth.
		The caudate, interestingly, the untransplanted structure, has only a thin rim of tyrosine hydroxylase fibers.  He has lost nearly all of his intrinsic nerve terminals.  Ordinarily this is preserved and this is lost.  So, all he has is the transplant.
		Adverse events during the course of the study.  We had no surgical complications that required breaking of the blind.  There was one asymptomatic hemorrhage.  We defined serious adverse events as events that required hospitalization or cause death.  There were 8 such events in the real implant group, 1 in the placebo group.  Other adverse events, including development of dyskinesia, were not regarded as serious adverse events during the course of the study, and they were equally distributed between placebo and implant patients, although dyskinesias themselves, excess abnormal movements, were more common in the implant patients but for the most part responded to drugs.
		And then this slide just summarizes the specific adverse events to show you what they were.  We felt that they were usually not related to surgery.  So, the needle track hemorrhage was clearly related to surgery but did not produce symptoms and, thence, was actually not called a serious adverse event in our definition.  
		There was a subdural hematoma that appeared as confusion 2 months after transplant surgery, and again, in that patient the confusion responded to reductions in drug therapy.  A woman died in a motor vehicle accident.  A cerebral infarct, myocardial infarction happened in two people within the first year.  Wrist fracture from a fall, so forth.  The sham patient, only 1 patient, was admitted in that case for a hysterectomy.
		There is an elective shoulder surgery here which was made possible by the fact that the transplant produced a reduction in Parkinson dyskinesias, which made it possible for this woman to undergo shoulder surgery.  She has since had dyskinesias develop that were at least as bad as before surgery, and she's 1 of 2 patients with severe late dyskinesias despite elimination of drug doses.  There are another 2 patients who have had some dyskinesias following substantial reduction of drug doses.  So, 4 of the 34 transplant patients have had long-term development of dyskinesias.  
		Thank you very much.
		(Applause.)
		DR. SALOMON:  I have one quick question.  The graphs that you showed with a significant decrease in drug dose, for example.  You didn't show the sham, the placebo control there.  
		DR. FREED:  And the issue was, did the sham patients reduce the drug doses?  No.
		DR. SAUSVILLE:  Also a question related to this, any selection criteria for donors, particularly with respect to matching for transplantation antigens?
		DR. FREED:  We are transplanting tissue from four embryos per patients.  It is still very difficult to acquire human fetal tissue now.  When we started doing transplants, we did ABO matches, and then we also inventoried results from HLA matches.  In the first patients which we did, the first dozen patients which we did, when we looked at HLA mismatches, there was no relationship between the apparent clinical success of a transplant and the degree of HLA mismatch.  We have now had the opportunity to see 2 patients' brains with randomly ABO matched tissue.  There does not seem to be a difference in survival based on ABO mismatch in the transplant tracts that we've looked at.
		The immunology of transplants is really a beginning field.  The fact that we decided to go ahead without immunosuppression was based on animal studies, and so allogeneic transplants in rats and in monkeys showed generally no transplant rejection.  It was based on the monkey data that we decided to go to humans without immunosuppression.
		DR. GAGE:  Related to the charge of this committee, what did you use to standardize the cell preparations in terms of dopamine content or whatever, between patients and between groups?  What were the variables that were used to assess equivalency of each batch, as it were?
		DR. FREED:  There are several issues with preparing fetal tissue.  First of all is the standard for dissection, how big a piece of tissue, what age tissue are you going to work with.  So, those are the first issues that were standardized.  Namely, you have to be confident that you have an intact mesencephalon to dissect.  Embryos are always fragmented, so you have to have someone very skillful actually doing the initial dissection.
		I think we’re the only group that's actually looking at dopamine production of each tissue fragment prior to transplant, and we're doing that via the measurement of the dopamine metabolite HVA, and so we measure HVA production per day with twice weekly testing.  We actually put these strands into tissue culture as strands, and we transplant out of tissue culture from 1 to 4 weeks after these cells go into culture.
		Actually over a period of time, namely after 4 weeks, we can see a fall-off in the rate of HVA production.  So, HVA production within a window is our measure that we're dealing with a dopamine-producing tissue.  It also confirms that our dissection was correct, that we don't have something other than dopamine-producing tissue.
		We also screen for fungus, bacterial and viral infections.  Herpes simplex and cytomegalovirus are both specifically cultured, and tissues only transplanted if those cultures are negative.
		DR. GAGE:  This is a serum-free medium that you put them in before this week period of time?
		DR. FREED:  Oh, no.  As a matter of fact, this might be helpful to other people working with human tissue that is going to go into humans.  We use human placental serum.  We found that human placental serum from cord blood is better than fetal calf serum, is better than horse serum for keeping dopamine neurons alive, and of course has the advantage of being compatible with human use.
		DR. TROJANOWSKI:  Curt, could I ask you -- and I'll just say that Curt and I collaborate, so I am asking a question that I couldn't have asked last night.  We had dinner together and I just want to ask him if he thought, having heard the questions that have been posed by Dr. Fink this morning, which I think are very, very good issues to target -- are we in the right ballpark?  
		I sometimes worry that if Adam and Eve had to provide all the pallet data to go forward with producing their children, we might not be here today because you can't really foresee everything in the future, which doesn't mean you shouldn't, of course, try to be as safe as possible.
		Are we in the right ballpark with our questions, having brought something to human trial from animal studies?
		DR. FREED:  The question that we used, when we decided in 1988 to do a transplant in a person, was would we change anything about the way we are going to do this in the next year based on anything we could discover in a year.  And what was the basis for proceeding?  The basis for proceeding was about 8 years of successful research in the rat.  
		Then we had done some studies in monkeys for the issues of scale, what was it like to transplant a bigger brain.  That was largely a scale issue rather than a principle issue.  
		So, the rats have provided essentially all the principles.  What I think is exciting is that the rat model, even though not Parkinson's, has predicted accurately what has happened in all other species after transplant.  So, I would say that the monkey is not a necessary model.  The rat data is explicitly important, and every time we consider a change, we say, what has the rat told us?  And the rat has been right all the time.
		DR. SALOMON:  I am going to allow the discussion to continue because this is so on point, I believe.  I know there are some people over here who want to talk.  Tom?
		DR. FREEMAN:  I think the field of fetal transplants has brought up several salient features for this meeting in particular.  The first is from the immunologic point of view, as you have pointed out.  Your data, as well as the work that Jeff Kordower and I have done, have shown that now about 20 different allografts have survived in the absence of immunosuppression in four different unrelated recipients immunologically.  Then there's also PET data on over 20 patients with long-term survival without immunosuppression.  So, the immunologic aspect of neural allografts is looking very favorable from a clinical point of view.
		Secondly, the long-term survival on PET data is looking very, very good, as I mentioned.
		Thirdly, these cells are dynamic in nature.  For example, at autopsy at 18 months, they have synapses on the shafts but not the dendrites, which is more of an embryonic form.  So, therefore, when one looks at efficacy results, the clinical outcome in a month when you start to see benefit may be via a mechanism of dopamine storage, and then the secondary improvement that occurs at 18 months may be related to drug manipulation.  There are tertiary changes down the road at 3 years that may be related to synaptic morphologic changes and development to a more adult nature.  So, therefore, it is a very dynamic pharmaceutical in comparison to drugs, which are static.
		Therefore, when one looks at the late onset of dyskinesias in some of these patients -- and this has also been reported from Sweden, and we have seen this in our group of our open label patients from early on as well -- this suggests that from a regulatory point of view these cells are not static and it is a very dynamic process that evolves over time, and therefore the long-term follow-up of any patient receiving a cellular therapy will be necessary.
		DR. SALOMON:  I would just like to capsulize that, then, that that's a critical thing for us to think about later in terms of outcome parameters, this time frame, and I think that was well articulated, actually by both of you.
		David, and then you.
		DR. DRACHMAN:  These data, these results are very important.  This is really one of the few human observations, but I think it would be very important to get it all right out on the table.  Would you describe for us the very worst dyskinetic consequences so that we might think a little more about whether the benefits are worth the risk?  As we discussed, one of the negative results came my way and Stan Fahn has spoken highly, widely then.  Fill us in.
		DR. FREED:  Yes, there are 2 patients, as Dr. Drachman was alluding to, that actually had a spectacular initial response to transplant.  I will describe a man -- not this patient -- I will describe this gentleman first, a man about 43 years of age who had had bad Parkinson's for more than a decade.  When he was off, he had dystonic posturing that was quite uncomfortable, so his hands would be strangely postured.  He had difficulty walking as well.
		Following transplant, I was at a meeting at National Institutes of Health and this man had been presented at NIH -- we were unaware of that, it was certainly not a part of our program -- during the blind phase.  And two senior NIH neurologists, Tom Chase and Mark Hallett, said, we saw your patient presented and he is on no drugs and he looks normal.  I said, isn't that terrific.  Maybe this is a placebo patient.  They said, if that's a placebo, that is a miracle.
		So, here we have a person with an extraordinary response to transplant, off drugs and looking normal.  Of course, if we could do that in every patient and capture that moment, we would have finished with transplant evolution.  
		That lasted for a period of about a year and then he began having abnormal movements of his head.  At rest, I might add.  When he walked, his ability to walk was better than before surgery, but these abnormal movements of his head made it difficult for him to eat.  That required a lot of working with drugs.  Amantidine seems to be helpful in that situation.
		So, that's that gentleman.  His weight has been maintained.  He continues to walk three miles a day, but the abnormal movements of the head have continued.
		The second is a woman in her late 40s, who was wheelchair-bound prior to transplant, largely from her bradykinetic state because when she took drugs, she became extremely dyskinetic.  So, this woman, several months after surgery, got up in the middle of the night and walked to the bathroom.  Then she came back and she woke up her husband and said, I walked.  I can walk now.  I don't want to make this excessively melodramatic because I am also telling you the down side of these things.  So, for about 1 year this woman was able to progressively reduce her drugs and come off drugs.  Again, a very remarkable response.  
		Beginning somewhat after the 1-year point, the lady began having generalized dyskinesias of her limbs, and again, more at rest than when she walked.  She actually can still walk and her dyskinesias are somewhat less when she walks than when she is at rest.  
		What can you do about that?  The lady is off drugs, she's dyskinetic.  In fact, Paul Green, the neurologist who's doing primary care on these folks, actually went so far as to start her on a dopa synthesis inhibitor, alpha methyl paratyrosine.  In fact, the alpha methyl paratyrosine was able to shut off the transplant.  But then she became very slow again.  
		Now, it would be possible to pull the transplant out of the picture by giving a drug that inhibits dopa formation by the brain and then give back moderate doses of dopa.  In fact, in her, because there is a surgical strategy that seems quite effective for eliminating the dyskinetic state, namely stimulators into the pallidum, this lady had last week bilateral pallidal stimulators put into the brain, and we hope that in fact the combination of the transplants, plus an operation that will inhibit dyskinesias, will in fact give her a better control of her Parkinson's disease.
		I add to this discussion, all of the patients that we have considered for operation are candidates for a surgical intervention.  They have failed conventional drug therapy.  So, even with the 2 patients who might be candidates for an additional surgery, not only they but the rest of the patients would have been candidates for some sort of surgical procedure.
		Now, if we did not want to see any chance of having an excess transplant effect, we could transplant less tissue.  We are now modifying, looking at the total results and modifying our thinking about transplants.  One of the things that we're going to do is to transplant only tissue from two embryos into the brain instead of four, and it will be in the dorsal rather than the ventral position.  The ventral aspects of the putamen are less denervated than the dorsal aspects. 
		We're also going to start transplanting the substantia nigra as well as the putamen.  Why would we do that?  Because rat studies said that combination is better.  We are being led by results in rats dating back to 1989.
		So, I see the development of transplants as having been made necessary by the lack of good drug therapy for advanced Parkinson patients, and the implementation of transplantation absolutely tracking what we have learned from animals.
		DR. DRACHMAN:  That I think clinically really does describe well what happened.  What I've got to say, though, is something a little bit different.  That is, one must be fully aware that cells when transplanted no longer are under our control.  The expression "sorcerer's apprentice" and "Frankenstein monster" have been used by people viewing videos of these cases.  Those are very dramatic terms.  The point is not to raise that specter, but merely to say that some degree of control, some way of shutting down, may be part of what we really want to think of whenever we put in totipotential, pluripotential, multipotential cells whose growth, whose reconnection, whose secretion may not be what we want because the intrinsic regulatory environment may no longer work in this setting.  So, it's not whether this lady or these two or four people did well, but what is the principle we want to propound.
		DR. FREED:  I'd like to add just to your comment because obviously that's a critical one.  With stem cells, where there is the possibility of a malignant cell, or at least a mass growing, I think it could be very important to have a suicide gene or an immunotherapy.  Namely, there is value in having a cell be a foreign cell because you could have a pre-existing kit for immunizing a patient and rejecting the cells.
		What I described with our patients is that it's possible to use an anti-dopamine synthesis inhibitor to actually shut down the transplant.  We have known from the beginning, we published in 1992 that transplants evolve over a period of years.  So, that isn't a surprise. 
		A surprise and, in fact, a result of doing tens of patients instead of a few patients has been that we can now see 10 percent probability events, whereas when people were reporting 2s, 3s, and 4s for patients, you didn't have enough patients to make it likely that you could see the extremes of response as opposed to a more average response.  So, the issue of control is important, but I think it has to be in the context of the biology.
		The other issue in the transplant patients is we don't see excess absolute dopamine production on PET scan.  That's why I think the issue that we don't have balance in the brain, that we need innervation of the region of the substantia nigra is as likely as not to be a participant in this.  It could be the persistent denervation in the nigra as opposed to excess production in the putamen.  We have no evidence for excess production in the putamen.
		DR. KURTZBERG:  I just had a quick question.  Did the engrafting tissue express HLA markers?
		DR. FREED:  We have seen, in different transplant tracts postmortem, HLA class 2 antigens and lymphocytes in some tracts, even though we see lots of surviving dopamine neurons.  That's at 7 months after transplant and 36 months after transplant.  There was no apparent relationship between the amount of HLA class 2 antigen expressed or the number of lymphocytes and the number of dopamine neurons that survived.  My transplant friends have called this minimal inflammation, and it's in the absence of immunosuppression.
		DR. AUCHINCLOSS:  Somewhere in the introduction to your talk, and I can't remember whether it even came from you -- I thought I heard that we were going to learn about embryonal stem cell treatment for Parkinson's disease, but what I thought I heard actually was about a fetal cell transplant for Parkinson's disease.  Where in that sort of spectrum would you actually place this?
		DR. FREED:  Well, these are embryonic dopamine neurons.  At the time that they are transplanted, they are terminally differentiated.  The time for transplant is selected, as shown in rats, at the time that the dopamine neurons have declared themselves, have differentiated, but before they have reached out axons to their targets.  So, they are in the embryonic period as opposed to the fetal period, but they are differentiated cells.
		DR. MOOS:  One of the things that sounds very impressive from listening to you would be how difficult it must have been to design that clinical trial.  You are talking about a treatment that changes over a period of time that we don't even understand.  What about the non-treated arm of the study?  How long could you leave them untreated?
		DR. FREED:  The contract with the patients, namely the initial consent form, said that the people who have been in the sham arm could have their transplant not at the end of the study but after their 1-year participation followed by unblinding.  
		Now, there was some disagreement with the performance safety monitoring board, saying, well, wouldn't it be better to wait till the end?  The patients insisted that the contract and the consent be lived up to.
		So, 34 of the 40 patients have had transplant operation; namely, 14 of the prior shams have had transplant.  That was up to the breaking of the blind in January of '99, and at that time the older patients were advised this may not be such a great idea for them.  The younger patients said, well, maybe this is not a cure for Parkinson's.  Maybe we will wait to see what happens in the long run before we decide what to do.
		DR. MOOS:  So, in essence the original study was a 1-year --
		DR. FREED:  1-year follow-up.
		DR. RAO:  A real quick question.  Presumably even though it was enriched for dopamine cells, it must have been a mixed population.  When you see the dyskinesia, how convinced are you that that can be attributed really to a loss of dopaminergic cells, or not some other aspect of the fetal tissue that was transplanted?
		DR. FREED:  Well, the general assumption is that dyskinesias are caused by an excessive dopamine effect, as they are with drugs.  It could be some other neurologic regulatory event, though, in that you could say that dyskinesias are allowed to appear when dopamine is present.  You see that there could be a difference between those two.
		The transplants that have been done in rats, on which all of this is developed, has been the whole ventral mesencephalon.  This is a fragment of tissue from human brain that's perhaps 4 milligrams in volume.  It's a small transplant.  Each of those 4 milligram individual embryo fragments was put into each of four separate holes.  It is simply following the technique.  Efforts to isolate dopamine neurons and transplant pure dopamine neurons have failed.  There is no way to isolate dopamine neurons without losing the tissue.  So, you are transplanting the tissue as it existed in ventral mesencephalon.
		There are also studies of survival, of which tissue elements survive.  The dopamine neurons do a very good job of surviving in striatum, as do serotonergic neurons.  There are a few serotonergic neurons that survive as well.  If you transplant cells that would not ordinarily innervate the striatum, they tend to die off, at least the neuronal populations do.
		DR. SNYDER:  I just briefly wanted to reiterate Tom's point about how important it's going to be for us to really understand the immunobiology of transplantation.  Particularly for us in the stem cell field, it's an issue we haven't talked a lot about.  But whether or not stem cells are well tolerated may very well influence how we decide to harness this biology for therapy.  It will be important for deciding, do we need to do autologous transplants, in other words, adults donating their own cells for reimplantation, or can we really have universal donor cells prepared under GMP.
		Much of that issue rests on our understanding of whether cells will or will not be rejected, which gets down to the immunobiology.  	The work that Curt and Tom and Jeff have talked about suggests that grafts may be better tolerated, at least if they're young, than we ever might have imagined.  Some very early pilot work that we have suggests that immature stem cells, in the state in which we do the transplantation, do not express MHC class 2, and can be tolerated without immunosuppression across strains, at least in rodent recipients.
		So, this is a very, very important point that I think will need to be explored very, very carefully and hasn't been as explored in the stem cell field as much as it's going to need to be.
		DR. KORDOWER:  Unlike a drug trial where you can get uniform delivery of a compound across centers, transplantation trials are dramatically different in terms of parameters chosen, techniques used from one center to another.  I spoke with Olle Lindvall recently about dyskinesias in his patients.  He said to me that he doesn't see them in his patients.  I know he does suspension grafts while you do solid grafts and Tom and our group does solid grafts.
		I was wondering whether there are any parameters that you can think of in, let's say, Olle's trial than your trial or Tom's trial that might explain why you see what Stan is calling runaway dyskinesias.  
		I think it's also important, when we evaluate stem cell trials, that we understand that it's likely that it's going to be done very differently in very different centers.  We've got to think about that as we proceed toward clinical trials.
		DR. FREED:  Starting with our first graft, our first report in 1990 in Archives of Neurology and continuing to a New England Journal paper in 1992, we said that all patients, or 6 out of 7 patients, developed increased abnormal movements in the months after transplant.  Now, that was with transplant of tissue from a single embryo initially on one side of brain, so roughly half the dose that we used in the double-blind study.  That responded to reductions in drug dose.
		  What I think is going on here is the number of patients that we have transplanted.  In the double-blind study, there are 34 patients.  I think with Lindvall, the total number of patients he's transplanted over the years has only been 10 or 12.  So, if you have something with an incidence of about 10 percent, you may not see that with 10 or 12 patients, although I think everyone has seen the tendency for increased abnormal movements if drug doses are kept the same.  Some people say those go away if you keep the drug doses constant.  We have found generally the drugs have to be reduced.
		But you're absolutely right that there are a variety of techniques.  I think that the variety of techniques is helpful to the field because it gives us a range of looks at this physiology without saying this is the way.  If we had a doctrinaire philosophy that said this is the only way to do transplants, we would have a much less rich understanding of this field.
		DR. KORDOWER:  Let me just respond.  I agree with you for the most part, although I think the people who are not in this field, they see a paper on transplants and they say, this is what happens when you get a transplant, not appreciating the differences in technique across different trials, which may dramatically impact upon both the positive and the negative aspects that follow the graft.
		DR. AUCHINCLOSS:  Sorry.  The question that I had, I wanted to talk more with Don Fink about the original FDA perspective on this.  I think we ought to come back to that. 
		DR. REID:  This is a general question to the panel and to the speakers.  Obviously the issue that keeps coming up again and again and is of concern to all of us in the stem cell field is the sourcing issue.  What I'm curious about -- certainly we've been facing a lot in the liver stem cell field, but I am curious about what you imagine being your source in the future for the patient.  Is it all going to be fetal brains, or do you have some hope for being able to isolate out the relevant cells from either cadavers or from pediatric or adult sources?
		DR. SALOMON:  When we come back from break, we will take that up at that time.
		Jay, and then Tom.
		DR. SIEGEL:  Yes, I just wanted to comment on the point of two or three speakers ago, that I would agree both that there is a lot of value in diversity of approaches, but also point out that when you reach the point of doing multi-center trials, there is significant value to come into consensus approaches.  We have seen a number in the field of hematopoietic stem cells.  There are people who can speak better to that than I can, but suffice it to say, in some of them where there was less investigator consensus, not just about how to handle the cells but how to use platelets, how to use antibiotics, whatever, it's a lot harder to make sense and interpret the results than where there is more consensus.
		DR. FREEMAN:  A response to a few of the comments that have been made.  First of all, the dyskinesias.  Olle Lindvall has reported 2 patients, in writing, actually, that have developed increased dyskinesias.  So, it's something that I think everybody has seen in a subset of their patients. 
		Secondly, it can be related to anatomic issues such as uniformity of distribution throughout the putamen.  For example, in Huntington's disease, chorea is not present early, then it develops, and then as there is more burn-out of the putamen, it disappears.  So, non-uniform anatomic issues can be involved, such as transplants in the post-commissural putamen rather than the anterior putamen.
		Finally, it raises the issues of dosing being critically important for the cells.  And for example, our prospective randomized trial has a dose escalation arm.  It is these types of systematic base hits I guess has been the analogy du jour.  I think we have to look for incremental changes in the field before the therapy is optimized. 
		I think the paradigm that is relevant is the kidney transplants that were incrementally improved over a 30-year period.  And even if you look at success rates around the era of cyclosporine introduction, there was no giant 20 or 30 percent increment.  It was still a 2 or 3 percent increment every year over a 30-year period.  So, I don't think we should look for these types of home runs right off the bat.
		Secondly, from the evidence point of view, from the allograft versus isograft point of view, obviously if allografts are beneficial there are tremendous advantages from the corporate point of view and the production point of view and the safety point of view.  You can use good manufacturing practices on large batches of tissue rather than having individually produced cells.  
		Secondly, as many of these neurodegenerative diseases are genetic in nature.  If you can obviously have a cell source without the aberrant gene expressed, or without the need to do gene therapy with the cells, that is tremendously important.
		For example, in our transplants with Parkinson's disease, there was no evidence of Lewy bodies in any of the transplants in our autopsies studied.  In a patient with Huntington's disease there was no abnormal expression of the aberrant Huntington protein in any of the grafts as well.  So, that would be another important issue.
		Finally, from the trial design point of view with the crossover, that is actually not a trivial point.  In our study, I think if I was to point to a flaw, we had a crossover at two years, but when you take into account also the time to actually perform the study with recruitment, it is not a simple recruitment.  It's a surgical trial, it's not a drug trial.  It does not tend to progress as quickly.  Particularly in early studies, that can be a burden on patients.  I think alternative trial designs need to be considered earlier on, such as delayed start trial designs so the burden on patients is not as high.
		DR. SALOMON:  Last two questions.
		DR. KARLIN:  My name is Dr. Helene Karlin.  I'm the President of the Canavan Research Foundation, which was originally started with my husband, Dr. Roger Karlin, after my daughter Lindsey was diagnosed at 3 months of age with a leukodystrophy called Canavan disease.  We're a nonprofit foundation.  We currently fund research in gene transfer and stem cell approaches to be used clinically.
		I would like to thank the FDA and all the scientists for their wonderful presentations and the education it provided me about the current state of stem cell research.  Now I do understand that stem cells are not simple.  Clearly there is much research that needs to be done in order to completely understand stem cells and their therapeutic possibilities.  
		I would, however, urge the scientists here in considering regulations to keep avenues open for clinical applications to develop in tandem with basic research.  My daughter Lindsey has the distinction of being the first person in the world to be treated with gene transfer.  This, amidst a scientific controversy over whether gene transfer was ready to be used in the clinic, in spite of the fact that safety had been demonstrated and efficacy was a real possibility.  Lindsey, who was then 2 years old, improved dramatically on clinical measures, as well as objective measures such as MRI.  Eight months after the gene transfer she developed new myelin, which children with Canavan disease do not do.
		In spite of this clear improvement, we needed to wait 2 years for a virtually identical trial to be approved in this country.  During this time, we had to watch our daughter decline, when we knew that she had already received something that had helped her.  When she received gene transfer again in this country at age 4 and 4 and a half, she again improved.  
		We have now waited over 2 years waiting for a new technology in gene transfer to be approved.  Once again, we have watched our daughter decline to the point where the window of opportunity, in terms of the degenerative route of this disease, is just about closed.  We've basically stabilized her, we've improved her, but it's a degenerative course, and after 2 years of not having the gene, she's starting to deteriorate again.
		As Dr. Noble mentioned yesterday, some patients resort to crazy treatments in nonregulated environments.  We're not interested in this.  We're interested in good research with safety as our foremost concern.  However, we're also interested in the recognition that people with devastating fatal illnesses have the ethical right to potential clinical treatments in a timely manner.  The safety and efficacy guidelines for devastating diseases may not be the same as the guidelines for non-life-threatening disease.  In addition, science for the clinic cannot tolerate bureaucratic delays that have to do with such things as people's vacations and the intermittent scheduling of review meetings.  
		Valerie Estess mentioned the collaborative scientific efforts that private funding is encouraging.  We believe that privately funded research, such as the research that we were also funding, can only expand on the science and present opportunities that limited public funding cannot offer.  I will mention that Canavan research has received no public funding.  Zero.  It's all coming from families, and it's quite a lot of money.
		I urge scientists to consider the notion that not all the patients out there are dummies.  We are educated.  We are informed consumers.  We know what is going on.  We are looking for good research.  We are not looking for snake oil, as Jordana mentioned yesterday.  I hope that people will consider that in considering regulations and review.  I thank you very much.
		(Applause.)
		DR. SALOMON:  That was a little off track, not that it wasn't perfectly appreciated.  I thought it was a question for Dr. Freed.
		I think at this point we'll end Dr. Freed's presentation.  I really appreciate that you brought another dimension and very on point to the discussion this morning, Dr. Freed.  Thank you.
		DR. FREED:  Thank you, Dr. Salomon.
		(Applause.)
		DR. SALOMON:  I'd like to bring this part of the open public hearing to a close and go to a break.  However, I do offer, is there anyone else in the audience who'd like to get up and make a brief comment? 
		(No response.)
		DR. SALOMON:  No?  Then I certainly invite the audience to participate the rest of the day as we have before, and see you in 10 minutes.
		(Recess.)
		DR. SALOMON:  What I'd like to do now is begin now the most serious working part of the meeting.  We've divided the questions that the FDA wants us to address specifically into two parts.  The first question is related to product development, and that will be introduced now by Malcolm.  Then we won't break for lunch at 1 o'clock.  We have got to be done by 3:00 because there is one direct flight out of Washington Dulles a day to San Diego and I am not going via Chicago.  
		(Laughter.)
		DR. SALOMON:  I think I have tried very hard to be very freewheeling in terms of the discussions up until now, but now we have to really focus.  I apologize to everyone in advance if I cut you off or move ahead.  I only feel like the whole reason that we are here, and tremendous amounts of effort on anybody's part, not to diminish the investment on the part of the government to get us here as well -- they have some questions and we do need to address them.  I promise to be fair, and it is nothing personal.
		For that particularly, if we can keep our answers on point and ask yourself while you are giving answers.  There are lots of fascinating biological and scientific questions that the experts here would want to discuss, and all I am asking is that in the midst of thinking about them, if they are not on point any longer to the questions, it does not mean they are not interesting, it just means that we probably should not be wasting time discussing them now.
		With that introduction, Malcolm.
		DR. MOOS:  Thanks, Dan.
		Those of you who have long memories may perceive that I have redrawn this slide slightly and there may be a perceptible alteration in the proportions between the upper two and the lower two quadrants, based on the discussions yesterday.  Notwithstanding this, as Don has pointed out, we now have to get down to brass tacks.  Basically when somebody comes to us with a proposal, we have 30 days to make a determination as to whether it represents an unreasonable risk to human subjects or not.  And the default position is that the IND goes into effect.
		One ground upon which we can place something on hold is what we call insufficient information.  So, I would like to enjoin as many of you as possible not to throw up your hands in despair, but to try to come to some considered suggestions that we can use.  
		Parenthetically, since it was touched on earlier this morning, I'd like to just mention the quadrant that is not really shown up here, which is the quadrant of secret competence.  Now, the Founding Fathers considered the protection of intellectual property so important, that it's actually framed in the Constitution.  The establishment of the Patent and Trademark Office is there, not in statute or regulation.  I didn't really realize this until just a couple of years ago, but we also consider proprietary secrets very seriously indeed.
		On the other hand, there are certain matters which are often kept confidential by companies for which an ethical and even a legal argument that they should be is difficult to maintain.  I would like to simply make the statement here that it has been our experience that fields where information is exchanged relatively freely advance more quickly.  The old phrase about a rising tide floating all boats definitely obtains here.  We not only see everyone's successes, which become public, but we see everyone's failures, which do not.  At least not immediately.
		If the FDA suddenly starts asking for a particular type of experiment and you can't figure out why, you might start to put two and two together.  There are constraints upon what we can say and what we cannot say, but nevertheless there is an eventual percolation of private data into the public domain at various paces, especially as they relate to data involving safety.  In certain particular fields -- and perhaps Dr. Siegel and Noguchi can speak to this at greater length -- there are different considerations about what is confidential and what is not.
		With that out of the way, I would like to return to the point that Dr. Drachman made with a slightly different analogy yesterday, in talking about the confidence that we have of things being represented as clay, molding themselves however they want.  The paradigm I like is that articulated by that a brilliant American cartoonist, Al Capp, a half century ago.  These are the schmoo.  These were organisms that were so delighted that anybody might find them of utility, that they would turn into whatever you wanted to eat, like magic, and in unlimited, self-renewing supply. 
		(Laughter.)
		DR. MOOS:  So, I think the analogy and the whole concept here is exactly on point. 
		We need to establish how far we can take this, and more importantly, what we can use to place limits on our confidence or lack of confidence.  That brings us to some of the basics, which Don alluded to and I am going to focus on in just a little bit more detail, of how we regulate biologics.  And these were the basics that Don mentioned.  Source control, process control, and specifications.  I am simplifying a little bit too much here, but I want to get through this quite quickly so that we can start addressing the questions.  
		Source control involves things like who, how old, history and habits if we are talking allogeneic donors.  There was some discussion, and we will have more of it, I think, about whether or not there should be constraints on who can donate and whether there might need to be genetic testing of them.  Various types of testing, not just the standard microbiology screening that we have talked about, but HLA matching, other types of tissue matching.  And most importantly of all, things that didn't make it to our list that we should be thinking about that didn't occur to us.
		Next is process control.  For those of you not familiar with our paradigm, this is perhaps one of the most unfamiliar ideas.  But really it relates to a very common experience.  The analogy I like is candy-making in the mid-19th century, where you could use qualitative tests called hard ball stage, soft ball stage, hard crack stage, depending on whether you were making brownies or peanut brittle, and you would not have to understand chemistry or carbohydrates and caramelization to make use of these tests, but if you followed a consistent recipe, if you were an experienced confectioner, if you knew what your raw materials were, who they came from, you trusted your suppliers, you qualified your supplies, and you used these sorts of what we call in-process tests appropriately, you could generate a consistent product.  If you became the sort of a confectioner that everybody might want to emulate, eventually you kept careful records and you might have even made an extra buck by publishing them.
		And finally, there are elements of process control that we're beginning to hear about.  For example, Dr. Gearhart has mentioned magic lots of fetal serum that work for some things and not for other things and variability in starting materials.  And how you qualify the starting materials?  Maybe the tests that you use to qualify the starting materials have their own problems.  Or alternatively, what are strategies for getting away from starting materials that are difficult to control.  I think this is a technically quite knotty issue that we'd like to hear as much advice about as possible.
		Finally, what we call specifications.  Some things are very basic.  We need things to be sterile.  We need the endotoxin levels to be low.  We don't like them to be growing mycoplasma and so forth.  We know all about that.  But beyond that there are some special difficulties with these products that we often don't have as much trouble with with other classes of biologics.
		One of the most nettlesome that confronts us I think in this arena is how do you identify your product.  It's continuing to evolve in culture with time.  It may be heterogeneous.  The characteristics which define it unambiguously I submit we probably do not know.  Certainly we have been thinking about gene profiling and microarray technology and FACS scanning with as many different antibodies as we can find, and looking at function and so forth, but this is just a start.  We heard the number of three markers yesterday, and I am willing to bet a large portion of my personal assets that it will only be in rare cases that that will suffice to define the identity of a product.  I know other examples where 18 markers is not enough, as judged by evaluation and stringent in vivo models.
		So, the idea that some people think that you can identify something just by its morphology, even when there are fairly good characteristics, this structure here usually identifies a witch, but it's important to determine whether or not what you're looking at is artifactual as just one example, is really quite premature and inadequate.
		We heard about functional testing, which I think is a very interesting and difficult area.  One could imagine doing patch-clamp electrophysiology, but then if you are looking at a dish or a lot of cells, what is your sampling paradigm?  How many, what kind of standard deviations, what actually is your number, what is your specification?  Do you say plus-minus, action potentials, yes-no?  Do you place a number on it?  Calvin told us that science is measurement.  Was it Rutherford who said if you can't reduce it to numbers, I am not interested?  I think that is a terrible paraphrase.  But nevertheless, that issue needs to confronted.
		Dr. Gage mentioned a very interesting idea, that there may be windows of competence during which, or states of competence during which a product may adopt its eventual fate, or not, depending on what you have done to the cells, how they have been treated, how old they are, how many passages, and who knows what.  The importance of this may depend on where you're intending to implant them.  Could one envision functional tests to evaluate competence, whether in vivo, or perhaps maybe one could figure out some magic growth factor or combination or sequence of growth factors, and then look at immediate early response genes.  One kind of idea.
		And finally, the most difficult issue which, like Dr. Salomon, I will refrain from going too far overboard with.  I guess I've kind of talked about this already, but then the thought of developing surrogates for potency is something that we'd like to hear a lot about if, indeed, there are rational ways for doing it. 
		So, with that I will yield the floor to you folks so that we can hear as much as we can about what we need to know.
		DR. SALOMON:  Thank you, Malcolm. 
		I know you had wanted to make a set of questions.
		DR. AUCHINCLOSS:  I guess it's a question for both Malcolm and for Don Fink.  It's really a generic issue.  This is a generic discussion.  The question that I think you are asking us today is what special regulatory issues are associated with stem cell therapy.  But when you put up your list of considerations, both your list, Don, and what we just heard there from Malcolm, they're precisely the same issues that you address in any other form of cell transplantation, or indeed, precisely the same issues that you would address if you were approving a new cytokine or monoclonal antibody, et cetera.  There is nothing unique in any of the questions at least in the broad categories of any of the questions that you put to us, and you know how to do that kind of regulation.
		So, my first question for you is, what do you feel is really special about "stem cell therapy" that you want us to try and help you with?
		DR. FINK:  Well, let me take a first shot, and Malcolm, you can follow up if you need.  I think probably the one point that we focused in on as a group or a committee is the rather unique and intrinsic capacity of these cells, presumably stem cells with pluripotentiality, to actually become perhaps something different, or maturate following placement within a patient, whereas in many contexts when we're evaluating cells for therapy and characterizing them, we know what they are prior to implantation.  We probably have a fairly good idea what they are going to do.  
		But in this context what we're interested in finding out as much as we can about what we might anticipate, either positively or negatively, to be the case following placement of the cells within the patient, that we cannot perhaps necessarily get a handle on up front, although we can use tests to qualify or characterize them as derived from the source to get some indication that at least this primordial or this prior to implanting formulation will lead to, in fact, what it is we hope to find.  I think that's probably the difference or the intrinsically different nature of this product compared to other cellular therapies.
		DR. AUCHINCLOSS:  Well, I don't think so, if I can comment further on that.  It seems to me that it's fully apparent to you that you have been regulating adult stem cell therapy for a long time in the form of bone marrow transplantation.  In bone marrow transplantation, you put in cells that are going to differentiate into other cells than the ones you put in, and you're perfectly comfortable with that at this point.  Indeed, as I go through bone marrow transplantation, it seems to me -- and I guess I am now going to put this as a question to everybody -- why isn't bone marrow transplantation a paradigm for all of the issues that you are dealing with?
		Bone marrow transplantation brings up the immunogenicity of stem cells.  There is no question that outside of the CNS they are exquisitely sensitive to rejection.  Bone marrow transplantation involves adult stem cells at least at the multipotent level, probably at the pluripotent level, and yet we don't talk about teratomas in bone marrow transplantation.  We don't worry about over-doing it.  We don't worry about too much bone marrow production when we do bone marrow transplantation.  We have recognized, when we do bone marrow transplantation, that there are different recipient populations, some of which can respond to stem cell therapy, some of which can't.  We recognize, when we do bone marrow transplantation, that the population that we're putting in is heterogeneous and inherently so.
		So, many of the issues that have popped up in the questions that we're going to be supposedly addressing are ones that you're perfectly comfortable with at this point.  So, my question, I guess, would come down to, what's different between the stem cell therapy that you've been regulating for a long time, bone marrow transplantation, and your worry about stem cell therapy in a larger context?
		DR. MOOS:  Well, there continue to be, I think, both some scientific and historical differences.  For quite some time, there was a lot of activity with bone marrow transplantation, before it occurred to anybody that the practice should be regulated, and there was a sort of a grandfather effect -- go ahead.
		DR. SIEGEL:  Just as a quick technicality.  Bone marrow transplantation per se is not under FDA regulation.  With peripheral stem cell regulation, transplantation is, and many other devices and growth factors that are used with bone marrow transplants are.  So, from a scientific perspective --
		DR. AUCHINCLOSS:  You're very comfortable with regulating bone marrow transplantation, is all I am suggesting.
		DR. MOOS:  Well, with technologies that grew directly from bone marrow transplantation and have many analogies to it.  It's also worth noting that even stem cells derived from bone marrow or peripheral blood are naturally occurring, and in only a few cases is it contemplated to manipulate them extensively, and if they are manipulated extensively, that triggers some of our concerns.
		There are, I think, to expound on what Don has said, significant technical differences.  While we grant that there is substantial overlap between some of the difficulties with other types of cellular therapies, we think that they are enhanced here.  
		One is that they have a biology that we don't have a lot of experience with.  For example, there is a lot of experience with blood-derived cells, which suggests that tumorigenicity is not a serious safety concern, or at least is a manageable one.  There is experimental evidence, some of which we heard about yesterday, that suggests that this is an issue that needs to be studied more carefully.
		The other one that Don mentioned is that in more than one aspect, therapies based on stem cells represent sort of a moving target.  Often with other types of cellular therapies what we are putting into the patient is very similar, perhaps all the way differentiated to what is going to be there, that we can test the terminal function, if you will.  Whereas with many types of stem cell-based therapies, varying levels of further differentiation are anticipated, up to the level suggested by Evan Snyder, where you might use extensively manipulated stem cells rather than stem cell-derived products as tumoricidal killer bees.
		The other issue is that there are behaviors of some of these cells that, although there is some precedent in other types of cell therapies, perhaps are more dramatic here.  One thing that makes us very nervous is the issue of migration of cells, which especially with relatively immature cells seems to be quite extensive.  We don't know yet if this is a problem or if it's just a concern.  This is something that we need advice to deal with intelligently.
		DR. AUCHINCLOSS:  I wrote down what is unique about stem cells on my list yesterday, and I was putting down different things.  I had cell migration down there at one point, and I had differentiation down there at another point.  And I don't think those are actually the fundamental features that make this a subject for special concern to the FDA.  
		We know perfectly well that hepatocytes and islets actually migrate all over the place to different places.  Migration in and of itself, and indeed differentiation in and of itself, is not a unique feature of stem cells or a unique concern from a regulatory point of view.
		To me -- to answer now my own question, what is unique -- what is unique is your concern of unlimited proliferative capacity.  I think that's what's unique in the stem cell therapy.
		Now, here I am going to now split between embryonal stem cells, where I think we have heard lots about how the unlimited proliferative capacity is a major potential problem, and adult stem cell therapy, where I haven't heard so far any evidence of overdoing it with adult stem cell therapy.  
		But then you say to me, as you did yesterday at lunch, well, that is not the point.  The point is that what really makes these stem cell therapies different is they're going to take them out and culture them, and they're going to leave them there for 6 months, and a transformation event might take place.  Then we might take an adult stem cell and turn it back into a cell with unlimited proliferative capacity.   And I think that's exactly the right concern
		But my suggestion to you would be that that is equally true if you take islet cells and put them in culture for 6 months, as people may eventually do.  There is the potential for a transformation event that becomes a special regulatory concern to the FDA. 
		My point in all of this conversation is that I think the FDA wants to try and struggle to say, what's special about stem cells?  The conclusion I come to is, what's special about embryonal stem cells is a good topic, but what's special about adult stem cells isn't about adult stem cells.  It's about any tissue in which you do something that potentially gives it unlimited proliferative potential.
		DR. SIEGEL:  I think here you're not addressing the question we need to answer.  Because the question is not what is unique.  That is a straw man.  It is how to regulate these cells.  These cells are not bone marrow cells.  They are not pancreas cells.  We have experience with cells.  We need to know what are the right specifications.  You're not going to tell us, like some people told us 3 months ago, that insulin secretion is the right specification for this type of cell --
		DR. AUCHINCLOSS:  Jay, but you know we can't answer that question in a generic form.
		DR. SIEGEL:  Well, absolutely.   
		DR. AUCHINCLOSS:  How can we possibly sit here and tell you how to regulate these cells when there are going to be 150 different --
		DR. SIEGEL:  Well, that is right, and that is why we've been talking about what the various issues are for various types of cells.  That's what here for, but we're not here just to focus on what is absolutely unique or different.
		DR. AUCHINCLOSS:  Yes, I think you basically asked us to talk to you about what's inherently different, what's generically different about the regulatory issues associated with stem cells.  I don't know how to have a generic conversation any other way.
		DR. SALOMON:  This is typical of Hugh and I not agreeing.  I totally disagree.
		(Laughter.)
		DR. SALOMON:  And that is fine.  This is a dynamic we're used to.  
		I agree actually with what you just said now, but I do not agree that that is what we are supposed to be doing this morning.  What I see us doing this morning is focusing in on what is unique about neural diseases and neural stem cells and neural models that the FDA should be aware of in regulation.  I think if we find ourselves discussing something that is generically cell regulation, like measuring endotoxin levels at 3 weeks in culture, I am perfectly happy to give that short shrift.
		But if we are talking about going in and taking adult stem cells by taking a piece of brain and dissolving it, or we are talking about taking fetal stem cells or embryonic stem cells and using specific growth factors that are not common to any other field to differentiate, and then come up with an assay and put that into a specific disease, then we're talking about something unique to neural stem cell transplantation, or neural cells transplantation.  It doesn't always have to be a stem cell.  So, I think that is where I would like to see us focus.
		DR. DINSMORE:  If I could just make a comment from the floor.  John Dinsmore from Diacrin.  I just wanted to speak to Dr. Auchincloss' comment about what is unique about these stem cells.  
		I would agree with him, the one defining feature is they're expanded in vitro extensively prior to their utilization, and there are events that could occur during that expansion.  So, therefore, it is a very useful area, unique area, that isn't normally regulated because other types of cell therapies deal with transplantation into the central nervous system, or putting cells to replace insulin function or liver function.  So, in some ways it does come down to an issue of the uniqueness of the stem cell.  One of the things is that they're expanded extensively.
		DR. SALOMON:  Well, that point is taken, but Dr. Auchincloss made the point that other fields are talking about longer-term culture, and so I think that that is not -- I do not think the FDA is hung up on this unique thing anyway.
		I know there are some questions.  Dick had asked me initially, and then we'll go on.
		DR. CHAMPLIN:  Just reflecting again on the paradigm of hematopoietic transplants, there is a possibility, at least, of overdoing the requirements for characterization, potency, et cetera because right now we cannot characterize hematopoietic stem cells.  There's no assay for potency.  So, some of these things are impossible to achieve, at least at our current level of understanding, yet we have been doing hematopoietic transplants for 30 years and curing a lot of patients.  
		There is sort of a happy middle ground here where one has a body of information that is sufficient to go forward with human experimentation with clinical trials that isn't necessarily the desired set of knowledge that we all would like to have in terms of fully understanding the biology of these cells.
		I think the general principles that apply to other forms of cell therapy apply here as well.  We have heard a range of types of cell transplants.  The Parkinson's disease study really was a tissue transplant of fetal, dopaminergic tissue into an adult brain without much manipulation.  They just take it out and put it in, sort of a minimally manipulated transplant in the vernacular. 
		Then we've heard about extensively manipulated cells that are grown for long periods of time in vitro, and potentially even genetically modified.  That is another category that obviously wouldn't need much more critical characterization of the cell populations involved.
		In some cases it's probably a good idea not to have purified cell populations.  In hematopoietic transplants, for example, there is a range of things that we have put in the stem cell or progenitor cell category, some that have short-term proliferative potential, that give rise to cells very quickly and rapid engraftment for the patient, but that can't be sustained forever.  Then there are probably true stem cells that may take 6 months to show progeny.  If you just gave those cells, the patients would die before they'd recover.  So, basically it is a mixture of cells that we actually give to the patients is probably optimal, so that one can't sort of pre-judge necessarily -- at least I couldn't foresee pre-judging in the neural sense -- which nerve cell a priori would be what you would want to be transplanting in any given situation.
		So, I could envision being able to go forward, in a spinal cord injury, for example, with a poorly characterized population as was described yesterday, without necessarily needing to have extensive characterization data.  On the other hand, if one is genetically modifying and expanding cells in vitro, then that's a totally different situation that would call for a much more stringent description of the source material.
		DR. SALOMON:  I know there's a number of people who want to make comments.  Again, just trying to do my chair's job here.  We've got about an hour and in that period of time I need to get through these questions.  So, if you could think about what comments you want to make, if it will get us toward talking about human stem cell sources, then I'm happy to yield you the floor.  If not, then can we just keep the comment and bring it in at the right moment?  I know there were some comments here.  Go ahead.
		DR. MACKLIS:  I'll try to take 30 second and then you can decide as the chair whether they're on point.  But just to give very short answers from a very neurocentric point of view to Dr. Auchincloss' questions, and these may sound exceptionally naive because I do not know that much about hematologic system anymore.  
		But two central differences may be that when one replaces blood cells, there's a whole range on a CBC with DIF of what's normal.  In the nervous system, at least we believe that there are very, very, very perfect, careful controls during setting up of the circuitry of the exact complement.  So, that's one.
		The second is that we as a field, I think, in general believe that, with the exception of the olfactory bulb in the dentate gyrus of the hippocampus that we heard about yesterday, that the developmental signals to guide proliferation, control, stopping, differentiation, and integration are gone in the adult CNS, and that microenvironment is so important that what we're really talking about in this field is releasing cells from those controls and making them do something on their own or reactivating those.  
		And I don't know, those might be two ways in which it's different from the hematologic system.
		DR. SALOMON:  David and then Tom.
		DR. DRACHMAN:  Very simply stated, the brain is not a liver.  That's very important to remember.  Because of that, it is protected by the skull.  The cells you put in you may never get back.  That's the first thing. 
		The second thing is that stem cells are not drugs.  We give cumadin and we check the INR every other day until we get it right.  Once we put the stem cells in, they're gone.  These are the two things that to me make this very different. 
		 The gypsy moth issue is another one that you will always worry about, or kudzu.  These were things that were brought into this country with the idea that we would have tons of silk as a result of the gypsy moth.  It started right there in Massachusetts.  Kudzu is going to be a way of solving our problems of eating.  It grew a little more than one would want.  
		This is probably not generally the issue, but rather the brain is not a liver, one, and two, these cells are not drugs and we can't regulate them once they get into the brain.
		DR. AUCHINCLOSS:  Well, I do not think the brain is the liver, and that is a very important point, that all of these trials need ordinary regulations specific to their particular cells.  Nobody has any doubt about that.  The issue is, in a generic conversation about stem cells, what do we really want to concentrate on about stem cells.
		Secondly, islets are not drugs either.  The FDA is very used to regulating cellular transplantation, and this is cellular transplantation.  About 80 percent of what I heard yesterday was cellular transplantation.  I didn't hear a stem cell component to it.
		DR. FREEMAN:  Very quickly, I think there are cellular biologic issues and then there are neurologic issues.  First of all, with, for example, bone marrow transplants or pancreas, you're dealing with systemic effects versus local effects in the brain.  
		Secondly, there's no way to biopsy these cells, and we're relying completely on surrogate, noninvasive markers for monitoring effectiveness.
		From the neurologic perspective, also what's unique is that the cells do not do what they are primarily designed to do.  They are transplanted heterotemporally, and heterotopically.  You don't complete the normal neural circuit.  You don't have the same objectives.  You have a much more limited set of objectives than you do with pancreas or bone marrow, for example.  
		The immunologic issues are different.  The host milieu issues are different with advanced diseases.  And the mechanisms of functions are completely uncharacterized in many cases or may be a moving target and multifactorial.  So, I really do think there are a lot of differences from that point of view.
		DR. SALOMON:  John, on point, and then Jay.
		DR. TROJANOWSKI:  After listening to yesterday's discussions and then the questions today, all of which I think have been very valuable to air, I think what we're talking about is a road map for how to proceed in the future.  
		I would suggest that we may already have a rudimentary road map in the studies that Curt Freed presented, that Tom Freeman and Jeff Kordower presented.  I mean, they have gone forward and done studies that are not unmitigated disasters.  In fact, I would say the positive effects outweigh the negative.  If we could use their guidelines for going into clinical trials as benchmarks for other clinical trials, we would be able to move ahead more quickly with guidelines.
		I am aware that the FDA has approved clinical trials for laboratory-grown cells.  I don't know all of what they have allowed to go forward, but if you were able to tell us, without naming names and so forth, where problems arose because you didn't have specific data sets, that too would help I think shape and focus what may be a very, very good rudimentary road map.
		The only thing I would finally add is that, remember, we're not talking about treating headaches.  We're talking about treating diseases that have no therapies, and individuals who have no life to look forward to.  It doesn't mean we should be cavalier, but I think there is a sense of urgency that we all should feel in our bones.
		DR. SALOMON:  Jay.
		DR. SIEGEL:  I am pleased to see Don is ready to get on to the specifics.  I think that is what will help us the most.  I am going to make three very short comments that I think will help set the stage for that.
		One is, the agency has shared through guidance documents quite a bit regarding our experience with cell therapies in general, and those are available through our web site.  
		Secondly, I do agree with Hugh's point about this issue of what you can accomplish in the general and in the specific.  So, as we move ahead I hope we'll talk about general principles, but clearly many things will be different for different cell types.  To the extent that time permits and that there is enough known about those differences, it would be nice to bring those out and talk about specific issues regarding specific cell types.
		Thirdly and finally, another nonscientific perspective on the difference between this and bone marrow transplantation, or only partially scientific and somewhat more regulatory, to think about is that for many of the products we are talking about here, unlike typically for, say, bone marrow transplant or many of the other cellular products that we've dealt with over the years, including blood products, there is the potential for there to be a single allogeneic donor and tremendous expansion in commercialization, in a sense, of large numbers of like vials of virtually the same product going into the same patients.  
		And I think Dr. Champlin spoke to the issues in controls in bone marrow transplantation, and if you've obliterated somebody's marrow and you thaw allogeneic cells and they're not quite the quality you want, you think twice before you throw them out, but the issues may be different simply because of the directions of the ability to expand the use of allogeneic cells and the commercialization.  That will come to bear in thinking about what are appropriate product and process controls.  
		In those settings at least, there's more flexibility to say, this lot isn't quite right.  Let's grow up another lot because this one has lower viability than the last three or four.  There's more flexibility, for example.
		DR. SALOMON:  Michael.
		DR. WALKER:  Yesterday was an extraordinary day, I think, of remarkable science.  That science is going to keep investigators going for at least the next decade.  I don't think the clinical things can wait.  Nor should clinical things necessarily yet be overly influenced by the concerns and the important scientific questions that we pose to the laboratory.  
		To that end, I think really what we're speaking about is the incredibly complex issue, with the vast unknown that we have to deal with.  But we have to deal with it right now, and it really comes down to, what would the prudent investigator want to know at this juncture, with the available data at this juncture in order to proceed forward.
		DR. SALOMON:  In neurological disease.
		DR. WALKER:  In neurological diseases.  And I think the discussion as to whether the brain is different or not, we really shouldn't be discussing because it is at least perceived by a lot of people as being different.
		(Laughter.)
		DR. WALKER:  
		DR. SALOMON:  I think we'll warrant that it is different.
		Rusty, okay.
		DR. GAGE:  I'd just like to reiterate the point that we're talking about stem cells, and it's an essential component of the transplantation in bone marrow, that you have a stem cell.  We do not know whether or not stem cells are a requirement for the transplant procedures of anything that we've talked about.  Stem cells have a property that may be useful in the propagation of the cells, but we have no idea whether or not a stem cell is a requirement for the actual transplantation of the cells and for its viability and its function.  I hope that we can keep that in mind in perhaps the separation of the manufacturing and propagation of the cells as perhaps stem cell quality and the actual product that goes into the patient, which may be something required, very different from that which you're actually manufacturing.
		DR. SALOMON:  I was hoping you would make that point.  So, that's a good lead-in right now into where I want to go here.  So, just to set some parameters here, we are going to go till 12:30.  That is one hour on this.  If we can get done before that, which I can't imagine, but if we can, that would be great.  But at 12:30 it ends and we will go on to the second part in the afternoon.
		So, the first question is on human stem cell sources.  I understand that Dr. Fink is going to put the bullet points up here.  I am not that hung up on these bullet points, but they are discussion points. 
		So, the first question is, I think, obvious to everyone, and that is, what sources are going to be appropriate for these early trials?  How far afield are you going to go with, let's say, some of the first studies versus how far afield are you willing to go as the field evolves?  I think the latter isn't that important right now because I think without some proof of efficacy it's really sort of a non-issue.		
		So, I think what we ought to do is just take a minute to consider, in the expertise of the group here, what's practical.  I heard somebody say they were going to go up and actually take a piece of brain from somebody and process cells out of it.  I mean, I need a reality check on that from my field.  That's a hell of a something to do.  But this person was very serious about that, and I am not in any way trying to make light of that.  It may be something that in neurobiology is okay.  So, you guys have got to give us some framework here.
		Fetal tissues, embryonic stem cells, et cetera.  So, can we start with that, comments along that line?  Short.
		DR. KOLIATSOS:  An obvious thing that comes to mind is that most of those tissues come from sick brains.  So, although they come in the neighborhood of illness, they have epilepsy, which propagates beyond the site of origin, and I would be very much concerned about the pathology inherent in these tissues.  So, in my mind, I think there's not a way to go about it by going to embryos.
		DR. SALOMON:  So, you would take the position that in the first phase of trials, which is the only thing that we really can advise the FDA to do because the shape of things change anyway as things go on, you can't see allowing someone to go and take a piece of adult brain in a diseased state.  
		How about anyone else on that comment?
		DR. MULLIGAN:  I would take the completely different point of view that it's fruitless to actually begin to pick a particular cell line or primary cell culture.  I think the point was made yesterday that everyone has their own favorite source of tissue.  There's never going to be any good comparison, which there ought to be, but there will never be such a thing.  And so, I think even to kind of move ahead quickly, I would almost say we should defer that issue.  I don't think we're ever going to come to any consensus about whether one person's source is more appropriate than another's because it depends completely on the application.  There may be cases where, using epileptic derived stem cells, someone will show that that has a better effect in terms of growth in some tissue.
		I would put it, if I can jump just a second to the issue of purity of these cells, that one thing the FDA definitely wants to know is how do we define purity.  This is what I think is the most key issue, what is different about these cells.  Just to stir up some things, I would say that it's impossible that you'll ever be able to find a pure population of these because biologically, certainly one way it may work is that these cells are undergoing amazingly sophisticated transitions, even in culture.  So, people that think, like Evan, that because he has cloned out cells and amplified them that they are more pure than cultures of RSP cells, I think that that's going to be the difficulty.
		So, we have to think practically, that when we think of purity, that we can't be thinking in a way that people think about a compound.
		DR. SALOMON:  Okay, I wanted to clarify one thing, Richard.  There is no desire, certainly on my part, to achieve consensus on anything today.  If we naturally fall into consensus, that's fine.  We're not taking any votes.  We can't take any votes, not even spirit of the committee votes.  
		So, what I want on this topic is merely what you did initially, and that was to say you don't think that you can do this.  I mean, just everyone should have a right to pick whatever brain source, come forward with their data and defend it.  That's your opinion and that is fine.
		So, I just want from the experts these kind of statements, and don't worry about.  We're not going to argue about consensus, but I wanted to give the FDA as broad a sense of at least the experts on this committee of where you're willing to go and what you're willing to consider.
		DR. RAO:  I agree that we cannot say which source of cell you use or what is your favorite choice.  But what we should try and emphasize is consistency, and that is that if you are using a source, you should know something about your source and you should be able to type it in some manner or profile it in some manner that you can say, this is  --
		DR. SALOMON:  We'll get to that next, source control.  What I need are comments specifically on sources.
		DR. SIEGEL:  I guess, if you would look at the questions, what we're trying to get here is not, you know, whether one should use live human donor or embryonic, gonadal.  But is the issues, you know, well, I think there would probably be consensus here you shouldn't use and HIV-infected source.  What are the other, you know -- whether it's Parkinson's or not.  But what are the other issues here?  Should there be genetic screening for, say, prion, TSE risk or other -- I'm not a neurologist.  I'm not even sure there are others here who could word the question better.
		DR. SALOMON:  Jay, we'll get to that.
		DR. SIEGEL:  I thought that's where we were.
		DR. SALOMON:  I'm taking a little latitude on the part of the chairman just to get a quick sense because yesterday there were sources mentioned from such a wide variety, I was just curious what the response to this question would be.  It doesn't have to take too much longer.
		DR. SNYDER:  Well, whatever the source is, it should probably be well-suited for what the clinical trial is going to be for the particular disease.  So, knowing perhaps what you are trying to achieve will then dictate what the logical source would be.  
		Then the second point, whatever the source is, it should at least be very well understood what its biology is.  I am not talking about safety concerns about that.  Just understanding what you would expect these cells to do, what your knowledge of the cells is.  It should be well understood.  Which may mean not just for the first time pulling out cells, putting them in a dish and saying, this is what we are going to use.  It should be well studied before going into a clinical trial.
		DR. SALOMON:  Are there any other comments on that?
		DR. WALKER:  I'd agree with Evan, and I'd put one other point in on that, that since we don't know how to fully characterize them.  We should also, in some fashion, bank some of that source as future questions come up, that we can then go back and address those issues.   
		DR. SALOMON:  So, what I'm hearing at this point is fine, is that there isn't a sense that there is anything off the table at this early point in stem cells and neural cell transplantation.  I think that's fine.  That's the question that I was asking.  To the extent that there's nothing off the table, it's also a message to scientists and companies in the field, that if they've got a sensible path to defend a specific source, then they will fulfill some of the issues we're going to talk about next.
		DR. GOLDMAN:  To put something on the table with respect to Dr. Koliatsos' question or remark.  I don't know that it's fair at this point to rule out any given source, including the adult ventricular zone, even from an epileptic, given our absence of evidence that there's anything different about that stem cell population or defined progenitor cell population.
		Secondly, I can envisage clinical scenarios where autograft would be reasonable, thinking in terms of nondominant hemispheric biopsy for extraction and implantation into small dominant hemispheric subcortical infarcts, by way of example.  So, I don't know that I would rule out clinical scenarios either.  
		But again, by way of putting something on the table, we discussed yesterday adult sources, we discussed early fetal sources, but mid-gestational or late gestational fetal sources are actually much richer and much more abundant sources of the same types of multipotential progenitors that we've all been talking about in terms of cell therapy.  That's something that was not addressed in the course of these two days.
		The same types of cells that we see in the adult ventricular zone we can get many, many-fold greater numbers out of late second trimester embryos.  That's something that's out of NIH jurisdiction but it's something that may well be an appropriate consideration here.
		DR. SALOMON:  Again, I think one of the things that we are not going to get into is the ethical issues, just because it's not our purview.  I didn't think you were posing an ethical issue.  I am just saying --
		DR. GOLDMAN:  I am trying to divorce it from the ethics.
		DR. SALOMON:  So, as long as we, again, in general, are sending the message that if a source is well-characterized and fulfills the rest of the things that we'll get into hopefully now, then a specific source isn't off the table.
		DR. KOLIATSOS:  Can I respond to that, Dr. Salomon?  
		DR. SALOMON:  Yes.
		DR. KOLIATSOS:  The way that the chair addressed the question was not ruling in or out.  It was a chance of coming up with what we all think of as a homogeneous source.  It seems to me that upon the complexity of this cellular sample, you add the complexity of disease.  You do know that growth factors are in very different arrangement, including BDNF, FGF perhaps, or the neurotrophins in the epileptic brains, especially in the temporal lobe.  So, these tissues have a different trophic profile to begin with.
		It seems to me, talking about probabilities of coming up with a homogeneous source of cells, this would be second in my order of priority.  It's not ruling in or out.  It's just my sense of what would probably give you a more homogeneous and well-controlled, propagated over time cell line.
		DR. SALOMON:  Good point. 
		Hugh?
		DR. AUCHINCLOSS:  I was going to suggest we come to the questions.
		DR. SALOMON:  Thank you for your suggestion.
		DR. AUCHINCLOSS:  So, I was going to address the first four.
		DR. RAO:  Just one point, and that's just simply that this deposition of a reference aliquot that Dr. Walker made to of keeping cells is really quite critical, and that we do have an opportunity to do that, which we haven't done with other cells.  We should consider that as a generalized requirement.
		DR. SALOMON:  Now I'm happy, so let's go to the questions.
		DR. AUCHINCLOSS:  I wanted to address A, B, C, D, with two questions.  I started with the question when I read A, B, C, D by saying to myself, why wouldn't you assume that what we do for blood donors is perfectly for what you would do for "stem cell donors."  So, that's a question.  
		Then the second question came about as a result of what you just said, Jay, when you said, well, you know, it is a matter of scale.  One blood transfusion from one donor, but this is going to be a pot of a million vials that could treat, you know, the whole population. 
		But it seems to me that a special question enters in, so here is the second question.  How much of the kind of testing that you mentioned here, say for HIV, or for the genetic defects that might be there from the donor, can you actually do on the sample that you have, rather than needing to go back to the potential donor?  Can you solve that problem with the tissue at hand rather than by the source?
		DR. SIEGEL:  I think for both of your questions, including, why shouldn't it be the same for bone marrow, I would rather hear from the committee than try to answer those myself.
		DR. SALOMON:  So, why don't we get the committee to start.  The first issue is, are existing standards for blood banking and/or organ transplantation appropriate for this new field of neural cell, neural stem cell transplantation? 
		I'm trying to think about how to frame this.  So, there are going to be cell lines.  There's going to be fresh tissue, that isn't really a cell line, and then there's going to be some sort of gray area where there will be cell lines that are cultured for maybe even several weeks but not particularly manipulated.  And then there will be cell lines that are heavily manipulated by specific growth factors, along the line that several mentioned yesterday, including Dr. Gage.
		So, in those settings, existing standards get a little bit confusing.  But the initial thing would be HIV testing of the donor, hepatitis C testing, Epstein-Barr viral testing, CMV.  My personal opinion at this point is ‑‑ and I think that was what Hugh was saying -- I don't see anything that the blood banking and organ transplantation and stem cell transplantation groups haven't covered.  But here is a chance to think about it.  Is there anything unique in your area?  And there may be, like prions.
		DR. NOBLE:  It may be that as there are a number of mutations that have been identified that represent relatively later onset neurologic disease, that if one is going to harvest from fetal specimens, one might think of introducing that screen.  
		DR. KOLIATSOS:  That's a wonderful point.  I think all we know about genetic predisposition factors for neurologic disease should be out of the pool that we're going to use.
		DR. AUCHINCLOSS:  Can you test that on the tissue at hand?  Do you have to go to the donor?
		DR. NOBLE:  Most of the mutations, I guess, can be screened.  I think they could be screened on the tissue.  I don't think you have to go to the donor.
		DR. KOLIATSOS:  Yes, absolutely.
		DR. AUCHINCLOSS:  So, now take it to the next part of this question.  Supposing you do the screen on the donor tissue, which you have got there and you are developing as your pot of stem cells for therapy, and you find there is a genetic defect there that has hideous consequences.  Do you go back to your donor and tell him?
		DR. KURTZBERG:  I don't think we know what these mutations mean, or what the denominator is that people who have them and what the expression of the disease is, and it gets very difficult.  We face the same thing in the cord blood program of not knowing exactly what it means.  I think it is easier to say that for mutations definitely associated with neurologic disease, those should be eliminated from the pool and those tissues shouldn't be used.  But in terms of what does it mean in the context of fetal tissue, I don't think we know.
		DR. SALOMON:  That's a really well-put point.  So, the question back to the neurology experts here is, is there a short list of genes today -- obviously, we hope they will grow -- that if you see them in a source tissue of any sort, means the disease is going to happen in such a high proportion that you'd all feel comfortable not allowing that to go forward?
		DR. TROJANOWSKI:  You can screen for 70 PS-1 mutations, 6 PS-2, if I got that right.  There are 20 tau mutations.  I mean, you can screen for lots of mutations.
		DR. SALOMON:  If they are positive, John, does that mean that you would not allow transplantation?  That's the question because there are things like BRACA II which you could screen for that has some association with breast and ovarian cancer, but not -- what is it?  20 percent? 
		DR. TROJANOWSKI:  There are mutations that we don't know.  Fully half the FAD mutations have not yet been identified.  But it is important, I think, to consider this in the context of a specific disease and even perhaps an individual's age.  A 60-year-old gets a transplant but may have an FAD mutation, presumably it will take another 40 years for that to manifest itself in that graft.  So, it's not, I think, an absolute negative.  It has to be seen in the context of the disease mutation.
		DR. CHAMPLIN:  I think the obvious thing is that if you're talking about autologous applications, then you have a much shorter list of things you have to check.  Just sterility really if you're giving it back to the same patient.  If it's a one-donor/one-patient type transplant, then again it's a different category of risk than if it's one donor now who is going to give a million transplants, with expanded cells.  Under those circumstances I would look for prions and everything else I could think of if you're exposing large fractions of the population.  Whereas if it's a single transplant from a relative, then a much more limited list would probably be appropriate.
		Also, the sort of timing issues might be appropriate to think about.  Say you're going to try to do a related donor transplant for spinal cord injury.  You're going to have to do that fast.  You're not going to have 6 months to do your infectious disease testing, whereas if you're talking about Alzheimer's disease, where it's not an emergency to do the transplant within 2 weeks, there's a different time frame that could allow more complete testing.  So, I think to some extent this has to be common sense for the application and the cell source.
		DR. SALOMON:  I know there are a couple of comments.  Evan, Rusty, Vassilis.
		DR. SNYDER:  I would just think that if you have the option to screen for genes that even theoretically could be time bombs, at least at the early stages of talking about first approaches for clinical trials, you would take that option to use the best source material possible.  Obviously, the universal donor cell approach allows that more than the autologous donor cell approach, but I think one should screen not only for all the genes that we understand now, even those that subsequently may turn out to be problems as our knowledge unfolds.  We can screen for a lot of neurogenetic diseases of childhood, like the lysosomal storage diseases, which are now routinely screened in prenatal testing anyway.
		We might even want to screen for deletions of tumor suppressor genes, for instance, or loss of p53, or things that we think may be down the line, if this cell is sitting in the brain of somebody for 10 years, could become a problem later on.  So, I would screen as much as possible.
		DR. GAGE:  I think this could get out of hand in terms of screening for everything, and there would not be any cells available.  
		One could approach it empirically, and that is, the way it's being done just as an experimental question, and that is, is a gene mutation dependent on the environment for its phenotypic expression, so you can mutate cells, over-express CAGs, for example, and then transplant the CAG repeat cell, transgenic cell, into a normal host animal to see whether or not the expression of that transgene in a normal host results in a deleterious manifestation in that graft itself.
		I think we need more empirical evidence supporting the fact that these gene mutations are really damaging to the cell itself autonomously, and whether or not in the context of a normal brain they're going to be bad.  If you eliminate all tau mutations and all amyloid mutations because of their potential, or anything else we are talking about, I think that maybe these are all just issues to bring up, but maybe empirical evidence supporting the fact that that mutation in a cell graft situation has some deleterious effect would be a good reason for excluding it.  There are obviously other ones that we have talked about that we already know are bad, and those can be excluded for some reason, but it seems to me that you need to have some empirical evidence that the expression of that gene in that cell is deleterious in a graft context, not just that it is a potential for some genetic abnormality down the road in a normal context.
		DR. KOLIATSOS:  Actually, Rusty, you know, you take some of those genes that cause familial Alzheimer's, familial ALS, and Huntington's disease and stick them in mice and produce the disease.  I wouldn't like those cells in any of the initial transplants.  Period.  And it's not that many.  It is 1 to 2 percent.  Those familial forms of neurodegenerative disease are not very common.  This would hardly eliminate your basic pool of donors.  You certainly have to take out the heterodegenerative diseases that involve childhood neurology and other things.  I don't think that would severely limit your pool.  
		And the other concern I have is, remember, you put those cells in sick brains.  It may very well mean nothing, but at the same time I could argue that it could mean much more than the mutation itself in a normal host.  So, I think that we could eliminate those things which we know in transgenic animals can produce the same disease without losing the necessary pool that we need to do our clinical job.
		DR. MACKLIS:  To reinforce what Rusty Gage just said, putting on my clinical neurologist's hat, in addition to all of the research-based mutations that John Trojanowski told us, and the ones that we may all agree would exclude, there's an increasing list, 50, 70, 100 clinically available tests for polyglutamine repeats, peripheral, central, spinal cord, and I think what Rusty pointed out, that we need to take into account where and how would such a mutation be limiting because I think every month I get a new mailing from Athena Neurosciences with four new tests, and we are going to be chasing our tails if we rule out all of these on every bit of tissue.
		DR. SALOMON:  That's the kind of input I think the FDA needs to hear.
		DR. NOBLE:  On a practical note, one of the ways in which one might approach this is with a mutational chip analysis.  Maybe, Arelene, with your being here, there'is value in thinking about whether there's value in assigning a contract for someone to actually develop a kind of chip that everyone would be able to use in these approaches in order to actually turn this into something that's feasible.
		DR. SALOMON:  Standardization is good.
		DR. CHIU:  That's a very good idea, Mark.  Thank you.
		DR. FREEMAN:  One other practical issue is, is the hurdle going to be different for phase I trials versus multi-center trials?
		DR. SALOMON:  They don't need any help from us with that.  The hurdles are always different for phase I versus phase II and phase III.  I think that is a fair statement?
		DR. SIEGEL:  Well, they change as a function of phase.  The amount of manufacturing controls typically do in terms of the validation.  But the level of safety still needs to be there in all phases.  When something becomes a safety issue, the amount of validation is what varies more.  Of course, knowledge will change by the time a trial is in phase II.  This is a field that's rapidly evolving.
		DR. SALOMON:  John?
		DR. TROJANOWSKI:  I think we should take disease mutations very seriously.  Rusty's comment about empirical data is very important.  I think Vassilis knows that, much to the chagrin of many of us trying to make models of disease, merely putting a transgene in a mouse doesn't guarantee disease.  In fact, you have to over-express the protein at a whopping level to see the disease in the 2-year life span of an experimental animal.  
		From our work with the N-Tera-2 cells, which have an abnormal chromosomal profile including, as I recall, three copies of chromosome 21, and a number of small -- I forget what they're called.  We just haven't seen disease in the basic science studies within the 2-year life span of the animals that we've transplanted, and those chromosomes have been stable for a decade.  So, I think merely an abnormal chromosomal profile, with other data mitigating the potential side effects of that, shouldn't be discarded.  The cells shouldn't be discarded.
		DR. SALOMON:  I'd like to go on to the next question.  I think just summarizing what I've heard, not trying to say any kind of consensus, but the flavor has been that the idea of general use of guidelines already in place for organ, blood banking, sperm, and hematopoietic stem cells is perfectly reasonable to apply to this new field.  However, there are some unique features and things like prion, infection, certain specific genetic malformations that could be screened right now.  
		I thought then things get gray about what would be the criteria that would allow you to add new genetic malformations to the list.  I think that maybe falls into the area we don't know and perhaps further research should be done in that area.  
		I thought John's last point, in contrast to Dr. Gage's, is just to be careful about, again, the models.  I think if you put the disease in and you absolutely got a disease in the animal model, that would probably influence the committee.  If you put an abnormal gene in an animal and you didn't get disease in a given time frame, that might not be as easy to interpret.
		That's not meant to cover everything, but is that generally okay with everybody?  Hugh?
		DR. AUCHINCLOSS:  I wanted to say a couple of things.  There is a danger in a generic conversation that we start acting like academics.  I don't know.  We were up to about 100 genes that I think we wanted to be looking at.  And the notion that we should be using those 100 genes to exclude tissue is, I think, ludicrous.  That decision is a matter of individual disease and individual nature of recipient populations, so you can't answer that question.
		From a research point of view, the chip I think makes a lot of sense.  But that brings you back now to this other question that we haven't addressed on here.  When you have a chip and you have all that information, do you go back to the donor and tell them about it?
		DR. SALOMON:  Great.  I like that.  Let's go on to that question.  Maybe, Joanne, given your experience with cord blood donation, do you want to start by making a comment?  So, what do we do when the donor sources are fetal?  How do you feel about that in terms of confidentiality, keeping records of the person?  How far do you go?  And then we will turn it back to the group here.
		DR. KURTZBERG:  There are two levels of answering in cord blood.  One is what the specific groups that I am involved with have decided to do, and the other is what the whole community has sort of accepted as a consensus.  That still is sort of up in the air. 
		I think our general approach has been that we've screened for infectious diseases that could pose a risk to the recipient but use the blood donor rules for informing the mother and her physician if an infectious disease was found, like HIV or hepatitis, that had an impact on the health of the mother or baby.  
		In fact, in our consent form, we require that the mother allows us to tell her and her physician that she has HIV or she has a positive test for syphilis or hepatitis screen so that the baby's interests can be prioritized because some mothers have refused consent on that basis.  They let you test as long as they don't have to know, but they don't want to know.
		DR. SALOMON:  Have you done any genetic testing?
		DR. KURTZBERG:  The genetic testing is limited to screening for trisomy 21 and 18 in mothers over 35 who didn't have amnios -- and the baby's cells -- and screening for the leukodystrophies.  If the recipient of a unit has a leukodystrophy, then the unit is screened.  What the consent form says is that should one of those diseases be diagnosed, and if there is therapy for the disease, the family will be informed.  
		DR. SALOMON:  Do you screen for things like Gaucher's disease, or Niemann-Pick or any of these other things that are hematopoietic stem cell significant?
		DR. KURTZBERG:  We are screening for globoid leukodystrophy, metachromatic leukodystrophy, adrenal leukodystrophy, but not in all units.  Only in a unit that would be selected for transplantation of a patient with that disease.  So, if a unit is selected for a patient with leukemia, it's not screened for ALD, but if it's selected for a patient with ALD, then it is screened, both because we don't want to use a carrier, and because we obviously don't want to use an infected unit.
		Now, we have really waffled on whether or not to have look forward.  Look forward makes sense intellectually but it is very expensive.  It is administratively a nightmare, and it’s just not feasible in all cases because it is easy to lose track of these people.
		DR. SALOMON:  Look forward you define --
		DR. KURTZBERG:  Look forward means following the baby who was the donor of the tissue for some period of time to see if they have a disease that's not expressed at birth or at the time you harvest the tissue, but that could be important to a recipient of the tissue.  The easiest example to give you in our field would be a baby could be born perfectly healthy but at the age of 2 develop ALL, and would that be important to the recipient of that baby's cells.  Honestly, we don't know the answer to that, but that's the kind of thing that you wouldn't be able, right now at least, to pick up at birth.
		A baby could have an immunodeficiency syndrome and that could be missed at birth.  That would certainly be important to the recipient of those cells in the context of marrow transplantation.  
		So, some of the groups banking cord blood have elected not to have look forward just because of the administrative issues and the confidentiality issues.  Others have elected to go forward with it, but it is very expensive, and it's an administrative nightmare to some extent. 
		 It depends what community you are collecting your tissue in.  If you have one donor that is going to supply a whole bank of tissues, then it makes a lot of sense.  But if you have thousands of donors that supply individual tissues to individual patients and you are in an urban center, it can be impossible, really, to follow all of those babies.  And no one knows how long it makes sense to follow those babies.
		Here you're talking about diseases there may be no screens for, that may not present until somebody is 60, 70 years of age.  Intellectually that might be interesting to do, but I don't see how it is going to be feasible right now.
		Our biggest issues have been, I guess, focused on diseases that are either important in real time to the recipient or to the donor of the tissue.  We have the added obligation to protect the baby donor, who is a minor and doesn't really have any ability to protect themselves.
		DR. SALOMON:  I think that is an excellent start from a field that has really definitely done its homework in the last couple of years, so I appreciate that.
		How about now taking that area and commenting on it with respect to neural stem cells or neural cell transplants?
		DR. WALKER:  I'm hearing a principle coming out of what was articulated, fundamentally that if we have a genetic test, using it as broadly as we want to in definition, that pertains to the specific disease we are trying to treat, maybe that is the very appropriate test to use very specifically in those patients.  That is, if we're going to treat a Parkinson's patient, we've got to test for Parkinson's.  You surely don't want to be transplanting it in that patient with those cells.  That sounds like a good fundamental, straightforward principle.
		DR. AUCHINCLOSS:  I still haven't heard the principle for what you tell the donor.
		DR. SALOMON:  Joanne talked about that.
		DR. AUCHINCLOSS:  Do we tell them about genes that we are not sure whether they -- do we talk about genes that have a 10 percent association with the development of --
		DR. NOBLE:  What is wrong with saying that the donor has the option, when they are agreeing to be a donor, that they tell you whether they want to know?
		DR. KURTZBERG:  I agree with that.  I think you inform them in advance that if there's a disease you can identify for which there's therapy, you're going to tell them if they have it, and you can list the diseases you're testing for, and then they have the option of deciding whether or not they want that information.
		DR. WALKER:  I think this is a critical issue that you raise about the donor.  On the other hand, that is a generic question that applies to all of these kinds of things which we can't necessarily or shouldn't necessarily solve solely for the central nervous system.
		DR. AUCHINCLOSS:  I couldn't agree with you more, but it is a question on the FDA’s list, what do you tell the donor.  But it's a question that is very big, way beyond neural stem cells.
		DR. KURTZBERG:  There's one more question.  There are a lot of diseases we don't have tests for now and we will have tests for later, and how do we handle that.  How do you get permission for that testing that you know you're going to want to do but you don't have right now?  What we did was put in this generic line that says we plan to do future tests, when they become available, for diseases that are important in this setting.  But I don't know if that really covers us or not.
		DR. AUCHINCLOSS:  Just to comment that when I jump to A, B, C, D in this group here and said blood bank rules apply, at least I would start with that assumption.  That includes the assumption that there always is a link between the stem cell product and the original donor, that there are records maintained.  And that is the standard in blood banking, is it not?  So, is there any reason why that wouldn't be the case here?
		DR. MACKLIS:  Two quick comments again from the clinical neurology side.  This idea of look forward is very interesting.  Many of the degenerative neurologic diseases are anticipated by older members of the family one or two generations ahead, and that comes out in a family history.  Would one include that in the look forward kind of procedures?
		And the second, if I understand, is only some states have insurance controls that would defend patients from this broad array of genetic tests that we are considering linking to the donors and their families.
		DR. KURTZBERG:  Well, the linkage can be confidential.  So, you can handle that.  But instead of calling what you just said look forward, that's really part of the donor screening.  		
		DR. MACKLIS:  I was thinking of following them along, the donor and/or members of their family.   You could broaden it that much to think we'll look two generations ahead for spinal cerebellar atrophy.
		DR. KURTZBERG:  Well, you could also use the family history of -- I mean, we define the family history as such and such and such and such in a first degree or second degree relative as an exclusion.  So, you would have to think about, for each of these diseases, what makes sense.
		DR. SALOMON:  I think we have to realize those are great research questions, but we're not going to be like Sweden who has got every patient who has ever been born in Sweden's health care for the last 100 years.  Which would be wonderful, and I am not saying wouldn't be great for public health research.  
		From the back, and then to Tom.
		MS. MEYERS:  I just wanted to make two comments specifically having to do with fetal tissue.  Many of the issues with fetal tissue are similar to things like blood donation or bone marrow transplants.  But when you're talking about women who are donating fetal tissue, they may be themselves women having abortions and may have risks that are not pertinent to people who are doing blood donation.  So, the whole ethical issue of abortion I think is very relevant to this.  There may be real risks to women if it's found out that they did donate their tissues.  So, I would urge you to consider those risks.
		The other thing is that if you're talking about genetic mutations or any kind of potential markers in using fetal tissue, you need to test the cells or the tissue because you are interested also in the mutations that could be in the father, and not just in the donor who might be available.  So, I just would remind you about genetics includes both parents, not just the donor, in this case for fetal tissue.
		DR. SALOMON:  Can you please identify yourself?
		MS. MEYERS:  Carol Meyers, from NeuralSTEM Biopharmaceuticals.
		DR. SALOMON:  Tom?  And then I think we need to go on.
		DR. FREEMAN:  In terms of blood bank differences, I'd like to amplify that one point, that when the FDA audits records, for example, they do generally go back to the sources.  It directly conflicts with confidentiality issues for women that have had abortions.  So, that is a special consideration, how to protect that confidentiality, if that is part of the protocol, which from an ethical point of view it should.
		Secondly, source sterility is obviously very important for any type of organ donation.  Yet, federal guidelines specifically prohibit changing any abortion techniques if fetal tissue as a source is used.  So, then you have mutually conflicting regulations, and that has to be taken into consideration.  
		On the other hand, there are precedents for biologic products where source sterility is not enforced.  For example, bovine pericardium, which is used clinically.  Obviously, after-the-fact testing of sterility issues is suboptimal, but may be necessary to be considered in this situation.
		DR. SALOMON:  So, I think that in general what we've discussed is that the groundwork that has been laid carefully by the groups in doing cord blood banking is fairly applicable to this field, that there are some unique gene markers unique to neural disease, and those could be handled by making it optional in the consent form to the mother.  There are some confidentiality issues in maintaining the identity of the mother, the history of the mother, and now we've added the mother's family including, I think quite appropriately from the floor, also the father's family.  I think that, however, is relevant, particularly in this sort of cell transplantation, maybe even more than in cord blood stem cell banking.  But I don't know.  Joanne, you might comment on that last point.
		DR. KURTZBERG:  I have two comments.   One, I would say roughly 10 percent of the time Dad is not Dad.  You can't just rely on the history for that.  
		And two, I think the longevity in some of these diseases is going to make this a little bit different than cord blood.
		DR. SALOMON:  I agree.  I was just saying that in this case there probably should be a provenance, if you will, that the grandfather of the mother had ALS, or had a degenerative disease.  That is all I meant.  And that would be unique to this, is what I was trying to articulate.
		DR. CHAMPLIN:  There is a precedent in bone marrow transplants from unrelated donors in terms of donor confidentiality and issues that result from that.  In the early days where that was not foreseen as a problem, there were issues of donors or recipients finding out about each other and undue influence or coercion occurred in one or the other direction.  
		So, it's actually a federal law that the donor identity needs to be maintained confidentially from the recipient until at least a year after the transplant, and then if there's mutual consent, that they get to know who the donor was.  But that has avoided the coercion aspects to a large extent.
		DR. KURTZBERG:  I just wanted to say one thing.  In cord blood we decided not to allow that to happen because the donor is really a minor and can't consent for themselves.  Just in the few transplants we've done, we get questions all the time from recipients about can't they know who their donor is, can't they meet their donor.  But we've decided no because the donor is a minor, and I think the same should be true of fetal tissue.
		DR. KOLIATSOS:  I think that the family history is not mutually exclusive.  In fact, it's complementary to testing the embryo itself because, for one, you may have a family pedigree without having the gene and then there's all kinds of unknown genetic causes.  We can envision a complementarity here in taking a history, at the same time testing directly the embryo.
		DR. SALOMON:  That is what I'm saying.  I think in this particular case one unique feature of it is that you'll want to know the paternal and maternal histories.
		DR. REID:  Yes.  Lola Reid, UNC.
		A suggestion that at least alleviates to some extent what you're describing.  It is neonatal tissue.  With the help of the neonatal intensive care unit and the surgeons, we've been learning about the postmortem collection of neonatal tissue.  That tissue is not used by any transplantation program because the tissue is too fragile for most transplantation procedures.  But those tissues are quite replete with progenitor populations, and they are very easy to handle for most of the processing, the studies that most of us do.  
		Moreover, the parents of those infants who die are usually quite willing to participate in whatever analyses might be necessary for this because in the tragedy, they actually have some degree of comfort in thinking that they may be helping out some other group of people.  So, it's just a wholly different situation than fetal tissue where you're dealing with abortuses.
		DR. SALOMON:  Thank you.
		I think we've covered that. 
		The next question is, are there intrinsic safety concerns for stem cells based on their source of derivation?  I think we've kind of talked about that already.  I think that it's quite clear that there are.
		And if there are differences, describe them.  I think then we would deteriorate into a 20-minute discussion of step by step, which didn't go very well at the beginning anyway.
		DR. AUCHINCLOSS:  Whoa, whoa.  This is the fundamental question in the entire two days, it seems to me.  
		I would have said, listening to you yesterday, that embryonal stem cells are a dangerous product, given the information that we have available right now.  Indeed, I was going to ask the committee would it be appropriate to say that embryonal stem cells -- not embryonal tissue transplants, such as we just heard about -- should not be transplanted into humans at this moment, but that there is no intrinsic danger to adult stem cells that I've been able to identify.
		DR. SALOMON:  Yes.  Hugh, in this case we're not far off.  I was thinking in terms of infectious disease and genetic screening was what I thought was in this section, and I was going to go on to that issue under characterizing of a stem cell, in which case your point is well taken.  So, if we agree, then I'd like to go on.  I certainly think that that is critical and I agree with you on that.
		I think I'd like to go on, just in terms of time, to the next major category, which is manufacturing of stem cells.  Well, we've got manufacturing and we have characterization.  I'm now just thinking about the way things have gone.  I'm going to go to characterization because I think that's the issue that Hugh brought up, and that is if we have these different sources, which I tried to get a sense whether were off the table and the sense was none are off the table, so let's go back and think about the characterization of stem cell preparations.  
		So, if someone wants to come forward to do a clinical trial, what is it you think should be given in terms of characterization of the cell for transplantation?  And then we can talk about manufacturing next.
		DR. SAUSVILLE:  I think this question is inextricably tied up with model considerations because we're in the position that in contrast to, for example, marrow preparations, which you can define in terms of BFUs and CFUs and things that you can do in a laboratory, we really can't do that here, at least I think.
		DR. SALOMON:  Well, that's a good question.  So, you guys yesterday, though, showing all these beautiful confocal pictures, you know, these are oligodendrocytes and these are dendrocytes and these are astrocytes and these are glial cells -- can you guys comment on that?  Do you guys go with what Ed is saying, that you can't distinguish these things, or can you?
		DR. MULLIGAN:  I think that there are two things.  One is the engraftment efficiency.  I think there would be great merit to looking at the potency of these cells and their functional purity by looking at, in cases where that's possible, some quantitative measurement of engraftment.  Evan and I have been talking about this and I'm not convinced from what I've seen that that is so simple.  But when you're talking about purity and the inherent impossibility of looking at real physical purity, functional purity would be the closest you'd come to.  So, as you march towards what's functional purity, certainly transplantation, seeing how many cells you get per number of cells that you introduce is a measure of transplantation purity or a specific activity.
		But I think the slippery slope is that in all these animal models, the actual issues of what accounts for the therapeutic effect is so questionable and not pinned down that you don't have any important measure of kind of the potency of the drug in the most important type of context.  So, for instance, is it making neuronal connections or is it releasing cytokines?  If you knew it was releasing cytokines, then you can measure the ability of these cells, when implanted, to deliver a certain amount of cytokines.  But I think that in so many cases we're not going to even have that luxury.  
		So, I would just come back to if there is a quantitation, a way to really see whether a given number of these cells consistently gives a certain amount of cells being transplanted or persisting, that might be very, very helpful.
		DR. SAUSVILLE:  Right, although that remains an argument from analogy, unless you actually have the human cells function in the animal environment, which I think is a little dicey.
		DR. CHAMPLIN:  Well, the fundamental problem with stem cells is that they're defined by what they're not and not usually what they are.  At least even in the discussions we've had here today, these are undifferentiated cells that don't have the mature differentiation markers of the end product.  So, as much as in hematology we've been searching for the markers of the true stem cell forever and thought we had it in CD34, but now know that that's not the case in terms of identifying the most primitive stem cells, it's a very difficult matter to quantify the number of stem cells that you have.  The readout is in fact engraftment in vivo and reconstituting hematopoiesis or, in this context, neural function.  You can obviously look at that preclinically in animals, but how do you know you've got it in a human transplant before you transplant?
		DR. SALOMON:  Well, we do SCID repopulating cells.
		DR. CHAMPLIN:  Right, but that's not a quantitative assay and we can't say now this is an adequate bone marrow transplant because it produces so many cells in the SCID mouse.
		DR. MULLIGAN:  I agree with you, but I'm saying that we do competitive repopulations for bone marrow transplants in mice, and you can definitely get a quantitation of the functional host that you introduce.
		DR. CHAMPLIN:  I think there are two parts to this question.  One is showing that the cells in principle can mediate neuronal function, but the other practical thing is you've got your cells that you're planning to transplant.  Is that an adequate graft?
		DR. NOBLE:  I think that there are two points that are being confused here.  One is that in respect to asking what is the repopulation potential of any of the neural stem cells, we really don't have any limiting dilution assays that have any meaning at this point.  You can't do the kinds of things that are being done in the most sophisticated hematological experiments.  
		What we can ask, however -- particularly Mehandra is being very quiet about this, but I want to give him credit for being really important in this.  There are markers that we know distinguish between the totipotent cell and the lineage-restricted cells.  And there are not many of these markers.  There are things like A2B5 antibody and antibodies against polysialated NCAM that Mehandra and his colleague Dr. Mayer-Proschel have described well as delineating these populations.  
		It would certainly be nice to know, because we are aware in the community that as these stem cells are grown in culture, a certain proportion of them do become lineage-restricted.  It would be nice to know what people are transplanting in that respect.  So, similar principles as in mapping the hematopoietic cells, run a few antibodies, so at least we have that information.
		DR. SALOMON:  Rusty and then John.
		DR. GAGE:  So, blood reconstitution is one system.  It's one objective.  And all the neurological diseases we have are uniquely different.  So, there's Parkinson's, Alzheimer's.  Like you were saying, these are inextricably linked to the model.  So, once you establish a model, then you establish your assay based on that model, and then you can do the reconstitution assay and justify it.  Whoever is going to come to the FDA has to justify their model.  
		Now, 15 years ago, when we were grafting fetal tissue into rats, we tried to establish basically a reconstitution assay, and the question was what is the minimal number of dopaminergic neurons surviving in the striatum that was adequate to drop the rotation behavior in a rat from 7 cycles per minute to below 2.  We came up with you have to have a minimum of 300 surviving dopaminergic neurons.  Independently of what all the other cells were, there was this threshold, obviously with some variance around that.  And you had to get tissue, we found out, between 14 and 16 embryonic day of a certain type of rat, and if you did that, it becomes a high school experiment.  You can do that over and over and over again.
		DR. SALOMON:  So, I think that's excellent.  The feedback that you're giving us is that, at least in some animal models, you can be quantitative.  That's what we were asking.
		DR. GAGE:  Now, the question was how does that then translate to the human condition.
		DR. KURTZBERG:  I think what's important here is to have a working group of the people who are going to be doing the transplants to come to consensus about what they're going to measure so they can compare their different techniques.  I don't think people who don't know the field should be the ones telling them what to measure.  I think that's a mistake or something that came late in bone marrow transplantation.  Everybody kind of did their own thing and some things matched and some things didn't.
		But I think there should be a formal arrangement where there's a group designated who's doing these trials and who decides on the kinds of collective data and even has workshops to make sure you can get the same results in the same assays in your own laboratory, or else have standardized reference laboratories.
		DR. TROJANOWSKI:  And I think with that in mind, we've come very close to having some guidelines.  Again, I would refer to the work of Freed and Freeman and Kordower.  There are some numbers that you can go with that are scaled for humans and not rats and that we should benefit from the success I think of their schemes.  They're different in each laboratory we've heard, and they inject different sites and so forth.  But still I think we can benefit enormously from what's already on the table, published or in applications, to proceed with some of these studies.
		DR. KOLIATSOS:  It seems to me that we can come up with a consensus in principle here.  I refer to Rusty's wonderful non-definition of a stem cell.  It's not going to be a pure preparation.  It's going to be something enriched in something, and we have to accept impurity as a matter of principle in these procedures.  
		To add to this, you have impurity in terms of side effects.  That's why the hematopoietic precedent is not extremely useful in the nervous system.  When I've tried to put the cells in brains, you can see one effect in one side of the cortex and a total different effect in another side of the cortex.  
		So, I propose that the unit of treatment is not only particular cell preparation but a cell preparation in a particular engraftment paradigm.  So, this together should be used as a, so to speak, modular kind of treatment as dose to guide any human experimentation.  It's not only the impurity of the population of cells.  It's also a site-specific effect you see in the nervous system all over the place.  In one side, tumor; in another side, integration into the cortex.
		DR. SALOMON:  So, I think trying to come to sense of what I'm hearing is that, first of all, we all seem to agree that every disease is going to have to be taken -- now, there are going to be groups that are going to say I have a stem cell preparation that can treat all diseases.  We've already heard that today.  Fine.  Prove it. 
		Basically, what I'm hearing from everybody is that you're going to have to start with some sort of a model, with all its limitations.  And I think it's important, the idea that these models should be discussed and validated in some sort of working group of experts in your field, not by outside people, including myself.  
		And there should be some way of quantifying it, albeit the day you step forward for the first clinical trial, we won't be able to answer Dr. Gage's question, so what does that mean in humans.  But that's a problem in all translational research.  I think all of us have dealt with it in our own areas.  So, I think that that works.
		What I would like, before we break for lunch in a minute or two, are there any specific markers from the neural experts that are like CD34 and CD45 and CD3, that if you can nail that one, that's really, really useful?
		DR. SIEGEL:  Can I ask a question about your summary and about the last conversation?  In a later set of questions, we're talking about what models are good for safety testing or for proof of concept in efficacy.  Here we're talking about cellular characterization to ensure lot-to-lot consistency and perhaps some investigators are interested in, I think appropriately, also comparing results across centers, a less direct regulatory issue but an important one. 
		So, in that context, this discussion of models is what I'm hearing, in fact, that in terms of characterizing cells, that the best answers to ensure lot-to-lot consistency, for example, may not just be in surface markers or in vitro functional tests, but actually plugging them into models to look at implantation viability, developing specs --
		DR. SALOMON:  I think that's exactly what they're saying.  My thinking here is that we'll get back to these discussions as we talk about the animal models, Jay, this afternoon.  But, again, input if you don't agree with what I'm saying.  I'm just trying to capture the threads that came out, and we'll get back to it again in the afternoon.  But, yes, that's exactly what I have heard everybody say.
		I still wanted some response from you guys.  Dick Champlin and I went out to dinner last night.  We were saying, oh, it's like a parallel universe.  He comes to me and says, we've got these CD34 negatives, Thy 1, and I go, yeah, yeah, yeah, and blah, blah, blah.  You guys are talking about a completely different set of markers.  So, can you kind of enlighten us?  Are there ones like that that you guys are comfortable with that would be important?
		DR. RAO:  Like with a lot of stem cells, you have negative markers which are present on differentiated cells but are not present on stem cells.  So, you can do a depletion selection and there's a wide variety of markers which people will agree as a consensus. 
		In terms of a cell surface marker which is specific to stem cells, the data is very weak except for one molecule which was recently described at a meeting, and that is this antibody which is used, recently characterized in stem cells in the hematopoietic system.  And that, in our hands and in other people's hands, seems to recognize a subset of stem cells present in the nervous system. 
		Unfortunately -- and that's the problem I guess in terms of looking at human versus animal models -- antibodies are only human specific.  The mouse homologue of the gene has just recently been cloned, and it's not clear that that expression of that antigen in mouse is the same as that in humans.  So, it's not perfect.
		DR. SALOMON:  How about Stro-1?  Dr. Verfaillie brought that up as one marker for a mesenchymal stem cell.  Have you guys looked at Stro-1, what you'd define more narrowly as a neural stem cell?  Darwin, do you have information on that?
		DR. PROCKOP:  I can speak to that.  No, it hasn't held up.  Even Paul Simmons doesn't say it holds up.  It was a nice early start. 
		But as we're studying these cells more and more, the primitive cells -- what Dr. Rao says -- they're pretty negative for almost anything we can look for.  A few clues but not many.  They're mostly negative.  We look in the cultures.  We see mature cells which are late progenitors and really don't differentiate well.  They do light up with a number of markers, but if we look at the small cells, the real precursors, very few things stain them.  Stro-1 is negative.  Everyone agrees on that now.
		DR. GOLDMAN:  I think it's important to remember that the stem cell population, quote/unquote, of the ventricular zone, even in the earliest stages of embryogeny is very heterogeneous itself.  So, we're left with requiring many markers in combination to define as accurately as possible progenitor populations.  I think in retrospect it hasn't turned out to be very different from the hematopoietic system.
		DR. SALOMON:  One advantage we have in the hematopoietic system -- Dr. Champlin mentioned that it's incomplete, but CD34.  If you purify CD34 cells and transplant them, a population within that heterogenous group reconstitutes the bone marrow and the hematopoietic system.  So, at least we have that.  
		So, if you came to an hematopoietic stem cell group and said, I've got this stem cell, the first thing everyone would want to know is what the CD34 status is, as a general rule.  I was just asking if there was something similar to that in neural.  I think you've answered it.  There isn't.
		DR. RAO:  Not a marker, but there are mechanical ways of separating cells.  I think Rusty alluded to it where you can use density gradients.  And then Evan alluded to the fact that you have some kind of transporter which pumps out the bis-benzamide so that you can use absence of bis-benzamide staining -- oxidized staining to select a population of cells, and you can, relatively with reasonable certainty, guarantee that you have a high population of progenitors in those two populations.  You can use a combination.
		DR. SAUSVILLE:  So, the way this would play, if you were going to make some minimalist product description, would be I have a bis-benzamide negative population of cells that, in an immunodeficient animal that's been appropriately lesioned, gives at least 300 dopaminergic neurons per something or other.
		DR. MULLIGAN:  But this belies the whole concept of the fact that everyone is going to have different favorite cell populations.  Just on the hematopoietic front, what you said is very funny because there are now a lot of people that think that CD34 deficient cells are just as good if not better. 
		DR. SALOMON:  But at least there has been a general experience up until now purifying CD34, injecting them into patients clinically, and using them.  
		Again, I'm not trying to fight a battle that doesn't need to be fought.  If someone came tomorrow and we were all sitting here, a sponsor, and said, I want to do a clinical trial in disease "fill in the blank," and I have a population of stem cells, is there anything that these sponsors should tell you about markers or behavior, Hoechst dye exclusion, that you'd say, yes, I'm on board with you.
		DR. TROJANOWSKI:  Are you focusing on the right issue?  You can differentiate the stem cells in vitro, and we transplant postmitotic neurons and they survive and they engraft.  I think a note of optimism here is we may not need to use stem cells.  In fact, for many of the diseases that we've heard about in the model systems, we want oligos, we want neurons, we want, in fact, not just generic neurons, we want dopaminergic neurons.  I think we have lots of markers for those.  And you can very effectively transplant postmitotic neurons into the brains of animals and people and they will survive.
		DR. CHAMPLIN:  But those aren't stem cells, which is fine.  Maybe that's what you want to do.
		DR. TROJANOWSKI:  But they can come from stem cells and be differentiated in vitro and then you can transplant them.  So, I just would offer this note of optimism that we're not hopelessly lost.  We can go for the immature derivatives that go on to become fully mature neurons, oligos, myelinate, what have you.
		DR. CHAMPLIN:  Getting back to the stem cell issue, one thing is even when you get into these highly enriched populations, when you look by limiting dilution how many of them actually are reconstituting are reconstituting or form colonies, what have you, it's 1 in 1,000 or 1 in 100 if you're in a highly enriched population.  So, the word "pure" is not correct here.  This is enriched populations and to have a truly pure, uniform population is both technically impossible and it's probably premature to even try to identify such a population.
		DR. SNYDER:  So, basically when we all sit around in the field and somebody presents cells, we ask, as Steve mentioned, for a battery of proof that these are very immature cells, a Musashi or Hu or nestin or SP or something of that sort, and then as Mehandra mentioned, functionally do they behave like a stem cell should behave?
		But ultimately, to reiterate John and Rusty's point, if somebody was going to come to you with a population and then say it is Musashi positive and all of that, and I want to do it for Parkinson's disease, you would not say, fine, it's Musashi positive, go ahead.  You would say, are you now from your population getting at least 300 dopaminergic neurons?  And if he says, yes, you would say, okay. 
		If he then came back and said, now I want to use my exact, same cells to treat Krabbe's disease, look, I have 300 dopaminergic neurons, you would say, well, that's not relevant now, even if it's the same population.
		DR. RAO:  Can I just add one?  I think it's most of the case that since there are so many cells, that somebody is going to come to you and say, I have this cell, and you have to tell him, prove it to me that this is the cell you're saying it is and this is the population that you're going to use.  In that sense, we have markers and we can do it.  So, the criteria that you use will depend on what the guy says he's coming with and what he wants to do with them.
		DR. MULLIGAN:  To get back to Jay's question, I think that the surface phenotypic characterization is definitely a reasonable thing, but for like hematopoietic stem cells, there will be maybe 8 or 10 markers, and you'd want to know that every time you use this population, you'll have the same distribution.  That's a totally separate question about whether any of those markers are important to the functional --
		DR. SIEGEL:  In some sense, so that's the one more critical to us in terms of product control.  The science is very important and we'll be reviewing the science.  Obviously, people are going to have a rationale to justify experimentation.
		But one of the issues that's right on the table -- even if science isn't ready to answer it, we're going to have to answer it in the near future -- is what is your product.  One of the critical things in product development is to know that if you make batch after batch and you experiment with a few people and you start modifying things, you know what you had and you know how it changed.  That's kind of where at least this set of the questions is focused.  How do we know what it is that's going in so we can interpret the results?
		DR. KOLIATSOS:  It is exactly because we don't have all these wonderful markers that we need more in vitro and in vivo descriptive validation.  They used to make mandragora and say it's mandragora because they made it from this and this extract and it puts people to sleep.  So, this is why you need to include your animal model together with the preparation.  
		So, to extend Evan's point, yes, it makes so many dopaminergic neurons and I stuck it in the nigra of this type of rat and it worked and it functioned and it did this and this.  You need more descriptive validation in the absence of specific molecular markers if you are going to start with this as a clinical potential.
		DR. SALOMON:  I just remind you what Jay is saying to you is part of the frustration from the regulatory side.  I don't know if you're quite getting it.  What you're saying is really sensible in the sense that I have a population, I want to use it in this disease, and the justification of it is this sort of a validation scheme.  I think that really makes a lot of sense to all of us.
		What Jay is saying, though, is when we get past the position of saying, yes, you can do your trial, then what the FDA has to do is say -- there are three centers, let's say, in your trial.  Is the stuff you're going to give in centers A, B, and C the same?  It's not that you didn't 6 months ago in the lead-up data to justifying your trial do all the right stuff, but now is the preparation that centers A, B, and C have the same as the preparation you made.  That's what Jay is trying to get at, this idea of product testing.
		DR. KOLIATSOS:  But you need a model with it.  That's what I'm saying.  I agree.  But it's not enough to say I give the same cell origin.  I also give the same cell origin that has proven to work in a certain model. 
		DR. SIEGEL:  I would just add, by the way, to that explanation.  I understand what you're saying and appreciate that.  The most critical issue we face in human experimentation in phase I in terms of product consistency is not usually the multi-center issue, but the dose escalation issue.  So, once you've established that 10 to the 6th cells is safe, then you're going to say, I want to give 10 to the 6th and a half cells.  I'm going to want to know is that really three times as many of the same cells or might they be tenfold more potent because if they're tenfold more potent, that may be unsafe.  Or is it a different type of cell, so there's really 30 times more stem cells or dedifferentiated cells there.  That's where the critical issue of knowing what you have most commonly comes into play in early clinical studies of cells. 
		DR. SALOMON:  Tom and then Rusty had his hand up.
		DR. FREEMAN:  Just following up on this dose escalation thing, it's even more problematic with stem cells.  First of all, we can't biopsy.  Secondly, they migrate.  So, if you want to eliminate them, say, by making some lesion where your graft is, you can't do that as opposed to a differentiated cell that doesn't migrate.  And that brings up the need for careful autopsy studies being put into protocols because very often that's missing from a lot of clinical trials at this stage.
		It also brings up the point of having ways to eliminate excess cells because with pharmaceutical dose escalation trials, if there's toxicity, you can generally stop your drug.  In this case, that won't be possible particularly if cells mature with time, which raises the spectrum of not only suicide genes but also methods of inducing second-set rejection, which is a possibility if you have a purified allogeneic cell line.  Can you have a parallel isogeneic cell line of fibroblasts that you bank with each cell line for inducing second-set rejection?  There's evidence that an isogeneic skin graft, for example, can make a second-set rejection of a purified cell line.  So, these are other considerations.
		DR. SALOMON:  That would get complicated.
		Rusty?
		DR. GAGE:  I was trying to separate out the manufacturing of the individual cells and the propagation.  Then we can talk about stem cells or really any cell that propagates that you can do good blood banking strategies on.  Then that doesn't tell you anything about the function of the cell.  What you really want is the assay.  We've talked about animal models. 
		But I was just thinking about there is really an intermediate phase, and that is, what are the conditions that you are going to apply to your propagated, well-characterized, GMP quality cell to get them into a state that they're now ready to transplant that's going to give rise to it to assess in your functional assay?  Because unlike in the blood system, we're not going to just graft the propagated cell.  In many cases, I would argue, if not in most cases, we're going to do something to the cell that's going to take it out of that rapidly propagating state and put it into another state.  We're going to do differentiation factors.  People use retinoic acid.  And we probably need to separate those things out between how you assess the manufacture or the propagation or the cell storage and that next stage where you actually do something to the cell to put into a state that it's now ready to put into the patient.  And that's a point of standardization too, it strikes me. 
		DR. TROJANOWSKI:  But I think we're there, though, Rusty.  I haven't heard of anyone citing a model that they wanted to use pluripotent -- most of what we want is a specific type of neuron or glial cell or what have you.  And I think we have the markers to know after we've proliferated and got a handful of neurons or astrocytes or what have you.  We have everything we need, I think, to characterize, to say those cells are 99 percent neurons or glia at what level of maturity.
		DR. GAGE:  I couldn't disagree with you more.
		(Laughter.)
		DR. TROJANOWSKI:  Well, I'd like to hear the details.
		DR. SALOMON:  And that's a good relationship actually.
		Evan, I think you were one of these people who actually, I think, would use pluripotential cells, wouldn't you?  Or multipotential cells in a --
		DR. SNYDER:  No.  I feel very comfortable using multipotent cells. 
		In answer to your question to go back to what you were asking, probably what you're asking for is not a stem cell marker.  What you want is a surrogate marker that shows efficacy and safety in a particular use.  Regardless of how you're going to define the cells that give you that, you're not going to get agreement on a stem cell marker.  But that's probably not what you're asking for anyway.  You want a marker that they can assay from lot to lot over time that's a surrogate marker that says lot number 1 and lot number 300 both have this marker which is associated with efficacy in this model or this disease and also safety.
		DR. SAUSVILLE:  But the important point, one way that this conversation is going is that this field should evolve and the FDA should make that aspect part of what they require people to come to the fore with.
		DR. SNYDER:  Absolutely, and our job is to come forward with a surrogate marker.
		DR. MACKLIS:  Well, I think it's very unlikely.  I think many of us would agree that there will be a marker.  It will, rather, be a big panel, maybe in one or two or three dimensions, of presence and absence of various markers.
		DR. SNYDER:  Right, but it's going to be markers not defining stem cells.  It will be markers defining safety and efficacy for the particular use.
		DR. MACKLIS:  Agreed.
		DR. SNYDER:  I agree, yes.
		DR. MOOS:  I'd like to follow up on that.  I think, yes, it's a dream to find a marker or two or three markers.  And especially in the interim, it could be a reasonable goal to come up with some kind of -- Dr. Koliatsos used the word "descriptive validation" -- a pattern, perhaps 5,000 randomly arrayed plasmas on a chip that is characteristic -- I'm just throwing that out as a straw man -- okay, 10,000 -- of this differentiated cell type or this type of pluripotential stem cell from this source that is associated reliably in an animal model with the desired effect and which is not associated with adverse effects.  
		I would go one step past that.  It may be worth considering looking carefully at lots of cells that fail in the validated preclinical model or stress lots of products which can be manipulated in such a way that they do fail and then make careful comparisons using the tools that genomics has given us.  We may not quite understand in a reductionist way what that plasmid at position at XY is really doing versus something else, but at least in much the way that anatomic pathologists were doing 150 years ago, we would have some kind of a way to assess consistency of manufacture.  
		It's perhaps not too fanciful -- maybe a little bit fanciful -- to even envision that one could address not just identity, but purity and impurities profile to the extent that if you have a heterogeneous population, there might be some things on your microarray that are characteristic of certain cell subpopulations and some characteristic of others but could be maintained.
		DR. SALOMON:  I think we have to be very careful here.  Again, this is just discussion.  I realize we're not making any sort of regulatory advice to you. 
		The gene chip thing is great.  My lab is working on custom DNA arrays and I love the technology, but I'm waiting to see what it really gives.  I don't think we should get carried away here with gene chip profiling at this point. 
		DR. MOOS:  Please don't misunderstand.  It's a paradigm, and I'm just throwing that out as an example that has been touched on.  We do not want to foreclose any other very ingenious, multi-dimensional set of -- in fact, we changed all of our wording before because we had carelessly used the term "markers" and replaced it with characteristics.
		DR. SALOMON:  Right.  I just think, speaking for myself -- and I'm pretty sure I would speak for the group here -- I don't think the FDA should get the idea that anyone here is suggesting to you that today there's any data that suggests that you should use gene chip profiling here.  It's a lovely idea.  In California, we get to use the word "cool" once a day.  It's a very cool idea.  That's it for the day for me. 
		DR. MULLIGAN:  I was going to say that I would agree about the gene chip.
		But the other twist to the surface phenotype is that there is clearly in hematopoiesis great precedent for a reasonably well defined surface phenotype that, depending upon how you generate the cells, will either not have the activity or have the function activity.  This is Sca plus lineage-deficient, cKit positive.  That has been work people have done.  If you mobilize cells in a recipient in a different fashion, you get those exact same cells which at one time were the pure cell for transplantation, and they had no long-term potential.  So, it's not to say we shouldn't do this, but you really need the surrogate marker.  You need to push for trying to associate even a simple marker phenotype with a consistency of function.
		DR. CHAMPLIN:  We actually use CD34 in that way in that the time to engraftment correlates with CD34 cell numbers, and we all have a sort of minimum CD34 number that we would feel comfortable in a blood stem cell transplant would be adequate then for an individual patient.  So, we're not fooling ourselves saying these are all stem cells and we're measuring stem cells, but it's a surrogate marker that correlates with adequacy of the transplant for engraftment.
		DR. SALOMON:  Yes, and I would add it has been very useful in things like purification strategies and otherwise, including device development.
		We need to wrap this up and go to lunch.  Is there anybody who has something that just has to be said right now?  
		(Laughter.)
		DR. KURTZBERG:  One sentence.  I think the FDA has to realize a lot of this is going to evolve in these phase I clinical trials.  I don't think you can demand all of these answers to start the phase I trials.  I think you have to come up with some minimum set of requirements but then know that it's going to change and it will be a work in progress.
		DR. CHAMPLIN:  In the field of hematopoiesis again, a minimal sort of understanding in correlate markers has evolved over 20 years.  In the beginning, we were just using cell numbers.  We learned from experience in large numbers of cases how to refine that.
		DR. SIEGEL:  In regard to those last comments, I'd like to second the comment of one of our speakers -- I'm not sure who -- about, where feasible, storing specimens.  I think that from the perspective of genomics but also surface antibody or whatever, we may know a lot more 3 years from now, and if we have the specimens to go back, ultimately we're looking for what are the markers, as I think Dr. Snyder pointed out, that predict safety and efficacy.  But, of course, until we have clinical data, all we can look for are what are the markers that can ensure consistency and hopefully predict that.  We'll measure some, but others, if we have the specimens, we may be glad, as we go back, that they're there.
		DR. SALOMON:  I think trying to summarize sort of where we are, so we can go to lunch --
		DR. NOGUCHI:  Excuse me.  I don't think we can let this close.  We are very cognizant of the fact that every new technology carries its own price, but tomorrow's technology is yesterday's CD34.  Ten years ago, nobody would do that.  So, it's incumbent upon people to recognize that, no, we won't require these fancy techniques now, but you've already heard from industry.  The claim is they already know how to do everything, which we would find to be very interesting.  But it is true that there are going to be large corporate dollars going into this, and if they can characterize something in a way that gives us a better, safer product that's more efficacious, we're likely to be moving toward that in terms of requirements.  
		So, it's up to the people here, not only to advance the field, but to get down to brass tacks on what can you agree on right now and to evolve that on a continual basis.  That way you can control the future of the standards we require rather than have someone who has more money put the standards in place for you.
		DR. SALOMON:  That's my summary.  I like it.
		(Laughter.)
		DR. SALOMON:  I think that's great. 
		See you guys at, let's say, 1:25.
		(Whereupon, at 12:55 p.m., the committee was recessed, to reconvene at 1:25 p.m., this same day.)

	AFTERNOON SESSION
	(1:48 p.m.)
		DR. SALOMON:  So, I'd like to welcome everybody back to the last session of the meeting. 
		I want to just make one point and that is that nothing from this morning is necessarily off the table this afternoon.  It's just that we'll start with the afternoon's questions.  My objective is to be done and summarized by 3:00.
		Yes?
		DR. AUCHINCLOSS:  I didn't hear us come back to the source of the cells question from the morning discussion.
		DR. SALOMON:  But you guys abused the hell out of me over this source of the cells question.
		(Laughter.)
		DR. AUCHINCLOSS:  I'm not going to let that one rest.  I really think that's a fundamental question.
		DR. SALOMON:  Okay, that's fine.  I thought it was too.  I thought you guys told me it wasn't a fundamental question.
		DR. AUCHINCLOSS:  I didn't hear that.
		Let me explain what's on my mind.  This meeting of the FDA is called by the Stem Cell Working Group.  It means the FDA has put stem cells in a special box.  There's something particularly important about them.  Their regulation might be different.  If I were working with stem cells or some variation on stem cells, that would bother me because I'd sit there and I'd say, now I'm going to get special attention.  I'm going to get labeled as a stem cell.  I'm going to get public headlines to say I'm a stem cell.
		So, I've been listening over the course of particularly yesterday about what's different about stem cells compared to other forms of cellular transplantation.  What I hear -- what I think I'm hearing -- but it's a question that I wanted to put to the rest of the committee -- is that embryonal stem cells do have a special feature attached to them, an inherent increased risk, that I would put them in a box, separate from other kinds of cellular transplants.  But I haven't heard one thing about adult stem cells or variants of adult stem cells or progenitor cells that warrants their being put in a special box, and I think we ought to make clear that that distinction is very, very important.
		DR. SALOMON:  Actually I like that.  Let's try to figure out a strategy then to go at this afternoon.  That's a really well-taken point. 
		I know Mercedes wanted to introduce the topic.
		MS. SERABIAN:  Yes.  I'll be as quick as possible.  Just a couple of minutes, but I just feel a little more comfortable introducing it.
		DR. SALOMON:  Why don't we do this?  Mercedes, why don't you give us your introduction?  When she's done, let's start with that point.  It's kind of what I was trying to do earlier, but let's see if we can do it better.
		MS. SERABIAN:  Now, I wrote out some notes, so I won't ramble.  I'll stick to what I have.
		I just want to introduce myself again very briefly.  My name is Mercedes Serabian.  I am a toxicologist with the Office of Therapeutics.  So, when you submit an IND, there is a large section that, as you have been referring to, is preclinical safety as well as efficacy.
		Not to be outdone by Malcolm, I found this when I went home.  To me, from listening to everything that went on yesterday, I feel we're not quite ready for prime time yet, getting there, but not quite.
		Just in general, to give you a background, because I'm not sure from yesterday, it seemed like a lot from the research aspect.  Just exactly when someone is at the point where they feel they need to submit an IND, they can submit an IND, they do, what preclinically from our aspect do we tend to look for?
		Well, obviously from this, my main point is that the preclinical study program is driven by what you want to do clinically.  I think that's very important.  It's a backward arrow, if you will, from clinically to preclinically.
		Obviously, the clinical indication and patient population determines what you're going to do preclinically for your safety studies, and we've been discussing that for a day and a half now.  That's quite obvious.
		For traditional biotherapeutics, if you will, the duration of therapy has been an issue, whether it's an acute or a chronic therapy.  In this case, it's obviously intended to be chronic because of the implantation of cells.  So, that brings with it a certain set of issues and concerns. 
		And then dosing procedures I put down, which is important for such things as route of administration, how many times you're going to be giving an agent in terms of number of injections, et cetera.  That may determine at times the species that you use also.
		This is kind of a standard slide that I've put up in other talks.  Again, it's for traditional therapeutics, just to set the scene.  You notice I highlighted the word "safe" because I think that's very important.  We've been talking about animal models, proof of concept, but the terminology "safe, safety, toxicology" we haven't heard too much of.  
		So, I just made a general list of what we tend to look at in an IND review in the toxicology aspect to get into phase I/phase II trials.  Obviously, you want the animal studies to be able to support the recommendation of an initial safe dose and dose escalation scheme in humans, to be able to attempt to determine an acceptable risk/benefit ratio in humans, to identify any potential target organs or tissues of toxicity or activity, as well as to identify parameters to monitor clinically.  We've been talking about that as various endpoints, surrogate or otherwise.  Identification of inclusion/exclusion "criteria" that should have read.  I left a word out, which again is important as to who you're going to enter on the trial.  Last but not least, which we've been talking about also, is to be able to discern the mechanism of action.  You may have obviously desired pharmacological effects that you want to see, but you may also have some undesired toxicities that you either haven't anticipated, obviously, or crop up either in the clinical trial or earlier.
		One last slide.  The bottom line then.  Toxicology data derived from preclinical models can provide information for the clinical management of potential toxicities.  To be able to identify preclinically certain toxicities will, hopefully, be helpful and a requirement for clinical monitoring as to what kind of a parameters are going to be monitoring and what you're going to be looking for in the clinic. 
		The predictiveness -- we've been talking about this -- of the toxicology data now, as well as the preclinical efficacy data of the human response from the animal studies to the human response, as well as the potential impact on clinical development.  If you see some type of toxicity in these models, what effect will it have on preclinical development?  Will it stop it altogether?  Will it simply slow it down?  Will it affect cohort dosing between patients, patient cohorts, it's a dose escalation, this type of thing?
		So, again, the point of preclinical toxicology studies is to be able to address all these issues.
		There are three main areas of questions that we have in the package.  One is with respect to animal models.  This is not just animal models for efficacy but safety.  Number two, tumorigenicity, which appears to be cropping up quite a bit.  That issue, as well as third which I think in our group we consider probably the most important is the fate of the cells post-implantation as to toxicology studies, what to do, how to do it, how to interpret the data.  So, those are the three main.  
		I guess, depending on how the conversation goes, it's up to Dr. Salomon in what order he wants to discuss them, but it would be very helpful to get through them all in the hour.
		So, I'm just going to leave the first slide, which has some of the bullet points, and then I think Don will help me.  We'll go through it as we advance.
		Thank you.
		DR. SALOMON:  What I'd like to do now is go back to what you asked at the beginning and perhaps accomplish what I didn't do a good job of at the beginning.  So, let me try and articulate a question out of this, and then you guys help me make sure I've got the right question. 
		My thinking, from what I've heard in the last two days and what I've read in this area, is that under the rubric of the word "stem cell" for this field, there seem to be several different things.  The first kind is either what's been called an embryonic stem cell, which is coming from the inner cell mass of the trophoblast, and a similar, albeit it not identical, cell coming from the gonadal ridge, which they called a gonadal stem cell -- germ line cell.  So, there are those, I think for the points of discussion, I personally sort of put together, albeit I accept as a scientist that they're not identical.
		Then there are what I would call stem cells such as those that Catherine Verfaillie explained to us but others not here at the meeting have, for example, found them in muscle cells.  So, these sort of noncompartmental stem cells that may have multipotentiality and that could be harvested from adults as well as fetal and your point was even different gestation fetus.  So, that would be another one to the mesenchymal stem cell or mature stem cells. 
		Then there seem to be compartment stem cells.  I didn't use the word compartment-specific stem cells because just because they're found in a specific compartment doesn't mean that they didn't derive from bone marrow or from a circulating source in the right arm, but they're in the brain.  Those could be induced, as we've heard some people talk about, or they could be harvested, developed in vitro, and put back in.
		Then the last group would be products that started with any of these stem cells and then, through in vitro purposeful manipulations, could be driven down a lineage commitment pathway that would be useful for a specific disease.
		Does that sort of cover the spectrum now? 
		DR. GAGE:  The latter case is a subcase to all the three prior ones.  It's not a fourth category.
		DR. SALOMON:  Okay, it's not a fourth category.  I agree.  It could be thought of as a fourth category in that a clinical trial using that kind of a strategy would be intrinsically different than a clinical trial that would use the other three.  So, yes, I think that's fine.
		DR. AUCHINCLOSS:  That's not what we heard yesterday.  What we heard was that even the in vitro derivatives of embryonal stem cells had tumorigenicity.  I think it's important to keep the in vitro derivatives of subcategories of each of the other. 
		DR. SALOMON:  That's fine.  I wasn't trying to imply anything now.  I was just trying to make sure that we all agreed that I wasn't leaving some major group of cells out.  
		A really interesting question Hugh has asked -- and I agree with it.  I was trying to get at it too -- is if clinical trials are going to go forward in this area, is it -- well, maybe back up.  That's the way I went at it and it didn't work. 
		The way you put it was?  Hugh, can you help me formulate this question so I do a better job than I did this morning?
		DR. AUCHINCLOSS:  Well, I would ask the committee two things.  Can they imagine circumstances in which it would be okay to proceed with a clinical trial of embryonal stem cell therapy for any disease given what we currently know about the risks associated with tumorigenicity?
		On the other side, I would ask them the question, is there any evidence that an adult stem cell therapy, including in vitro derivatives, is any more risky than any other form of cellular therapy?
		DR. SALOMON:  Comment on it, either way.  More risky, less risky.
		DR. SAUSVILLE:  I have a question pertaining to that actually to members of the panel.  Although there is the -- I'll use the word -- theoretical risk from the embryonal stem cells, is it within anybody's experience who has used these cells in any animal system in which it would be either likely or even possible that such a tumor has manifest itself?
		DR. SALOMON:  Well, they gave us data yesterday that embryonal stem cells produce teratocarcinomas.
		DR. SAUSVILLE:  But the point is you have to select for that.  My question is putting it in the milieu of the animals that you're going to use them in.
		DR. SNYDER:  John was talking about cells that he had not pre-differentiated, that he had taken as ES cells and put in there.
		DR. SALOMON:  Let's start with embryonic stem cells.
		DR. AUCHINCLOSS:  John showed us an experiment in which he induced the differentiation, selected on the basis of markers -- 
		DR. SNYDER:  Well, he selected for markers.
		DR. AUCHINCLOSS:  Selected on markers of differentiation, put those cells in, and said, oh, my God, I've still got three tumors.
		DR. SNYDER:  But most people working with the ES cells will predifferentiate or precommit them, and the risk of putting in undifferentiated ES cells is not just teratocarcinomas, but for instance, Oliver Brustle has taken ES cells, put them into the brain, and has not gotten a tumor, but has gotten an autonomous neural tube growing within the brain.  That doesn't seem to happen if they do these precommitment steps ex vivo.
		DR. SALOMON:  What I want then is first embryonal stem cells, not embryonal stem cells and this and this and this.  Let's start with embryonal stem cells and try and work through these different groups to identify the risk.  Like I said, I was trying to do that this morning. 
		Before Mehandra, Evan, can you just address the embryonic stem cell?  If I want to do a clinical trial with an embryonal stem cell, yes or no?  I'm not holding you --
		DR. SIEGEL:  Dan, could I interrupt to broaden out the question you and Hugh ask?  We really need a different answer from that question.  The question is framed as do we know enough now to go there.  But what will happen to us is that three months from now someone will present a proposal and in that proposal may well be a lot of data that are not before this committee.  So, really the type of questions that we're getting into here are not yes or no, do we know enough now, but what do we need to know.  Is tumorigenicity an issue that we can define?  What tests need to be done to rule it out?  So, that's the advice that we could use here.
		DR. AUCHINCLOSS:  I think that's an excellent way of putting it because I can't imagine that one would ever want to say we'd never want to use ES cells.  Presumably we do.  But there needs to be more information than I heard today, presumably, before you would go ahead with a trial.  I don't know what that information is, but somebody would need to address head on the tumorigenicity problems.
		DR. SALOMON:  My point only is that there is some information here.
		All right.  Answer the question the way Jay asked it.  What would you want to know about a cell population of any of these stem cell populations that would say no way I'm going to do it?
		DR. SNYDER:  It's no different than what we were talking about this morning.  You still need to prove that the cell population you're using is efficacious in your model and safe by whatever marker.  So, ES cells, yes, can be safe but you need to prepare them ex vivo, probably commit them or predifferentiate them and put them in under the right circumstances.  And there are ways of doing that.
		Conversely, when you don't do that, for instance, Jonas Frisen has recently demonstrated that you can take adult neural stem cells -- now, we can debate whether we believe the data or not, but what he has published is adult cells, neural cells supposedly committed to the neural lineage can be processed in such a way that he can put them into the embryo where they behave just like ES cells.  So, there's at least there the theoretical risk that if they behave like ES cells, can they also give rise to teratocarcinomas and give rise to autonomous organ systems?
		DR. SALOMON:  So, let's stop there for a second.  What everybody is saying is that if they had a cancer-producing potential, it would be bad, but we didn't need to come to Washington to tell the FDA that.  So, what we need to tell the FDA is what is evidence, what is a way of determining the cancer-producing potential of any given cell for these kind of transplants. 
		Mehandra and then Jeff and then John.
		DR. RAO:  So, I think to answer your question specifically, I think we should make a distinction between ES cells themselves in a naive undifferentiated state and derivatives of ES cells because derivatives of ES cells have the same risk in some ways of getting tumors as any dividing cell population which is maintained in culture for a certain time period.  You get spontaneous immortalization, all of those.  That risk is probably about the same, at least until there's clear-cut data to the contrary. 
		In terms of undifferentiated ES cells which have been maintained, I think the data is quite strong because that's a definition that every time you put them in any part of the brain, you're going to get tumors.  So, in that sense, if you had to have an absolute answer, I'd say that unless there's data to the contrary, you would not put in ES cells in an undifferentiated way into the brain because there's data clearly saying it. 
		In terms of differentiated cells which are derived from ES cells or from any other cell type, you use standard criteria to say are you going to get a tumor.  Since we're growing them in culture, we have standard sort of ways of looking at things like p53, looking at the levels of telomerase, looking at cell division rates, and alteration of cell division rates, which would be criteria you would use for looking at frequency, soft agar assays, those sort of things.
		DR. MACKLIS:  It seems like we already heard part of the answer to your question yesterday.  John Gearhart told us that he worked hard, predifferentiated the ES cells for many weeks to make them pure -- they were supposed to be pure oligos?  I can't remember, but to purity.  Then he did a great experiment.  He transplanted them into 150 animals and 2 of them got tumors.  It would seem like that's exactly what one would want to insist upon.
		DR. SNYDER:  He was selecting for hematopoietic lineage.
		DR. MACKLIS:  That's correct.  
		This might be the only time that I'll disagree with something Mehandra said over these two days, but it's not clear that we have the data to say that ES cell-derived proliferating cells have more or less or the same risk as other proliferating cells unless somebody does a head-to-head experiment.
		DR. SALOMON:  Well, again, I'm following sort of the idea of it's not really important to get hung up on whether we think embryonic stem cells, this or that.  But I think we need to still give specific things.  Now, Mehandra has responded to say, okay, do karyotyping, do p53, do gel assays.  Fine, that's what I want to hear.
		DR. MACKLIS:  How about transplantation into animals in large numbers.
		DR. SALOMON:  That was good. 
		John, Michael, and Vassilis.
		DR. TROJANOWSKI:  Virginia Lee and I in Philadelphia have eight years' experience with the N-Tera-2 cells in animal models on normal nude mice.  These, as I mentioned, have an abnormal karyotype.  They are differentiated.  We have never seen a tumor with the postmitotic neurons beyond 1 year. 
		In a parallel life, I've worked for 15 years on medulloblastomas.  These are stem cell-like tumors, and I've tried very diligently to create animal models of tumors.  I've looked side by side at the N-Tera-2 cells.  I know of no precedent for a cell sitting in the brain for over a year transplanted and suddenly becoming a tumor cell.  It has not happened.  It may be formally possible.
		DR. SALOMON:  John, you're making a key point, that in my listing of stem cells, I apologize I left those out.  That would be some sort of a transformed or accidentally naturally immortalized cell line.  That should be on the list.
		DR. TROJANOWSKI:  Right.  I think it applies to stem cells. 
		So, you do 100 animals, you leave them for a year, if they don't make tumors -- and in fact, I would say we've taken the retinoic acid-naive N-Tera-2 cells, which are considered to be neuronal progenitor cells, not stem cells, and depending upon where you inject them in the brain, they will or will not form tumors.  If you confine them to the caudate, we have shown they will differentiate.  There's some retinoic acid-like factor there.  And those animals too survive for over a year and a half without erupting into malignant tumors.  
		So, I think we have very good screens for tumorigenicity, and it ain't mysterious and it ain't problematic.  I'm just telling you that. 
		DR. SALOMON:  What you're talking about are rodent studies.
		DR. TROJANOWSKI:  These are human cells -- human cells I would emphasize -- into mouse brains.  I would challenge you to show me a model in monkeys, squirrels, zebras, whatever.  Everything is formally possible.  We have to talk about what is realistically possible, and there just is no precedent in brain.  Maybe in marrow, maybe somewhere else, but not in brain.
		DR. SALOMON:  We're going to keep going.  I just want to point out already there's one inconsistency here.  We like the idea that we would take cells and look at karyotyping and p53 expression, and the implication there, Mehandra, was that if we found these changes, those would be arguments against going forward with that as a trial.  Rusty yesterday showed us data in which 1 of 2 that had karyotypic changes, 1 of 7 total that he characterized did form tumors.  However, what John is saying is that here's a cell line that has a karyotypic change, and he's saying that it's safe.  So simply finding a karyotypic change is not necessarily saying that it's not safe.
		DR. TROJANOWSKI:  The data is king, and I would listen to empirical evidence for or against some of these things.  And be mindful of formal possibilities and really seriously consider practical problems.  But if there's data to the contrary, I think you're going to pass.
		DR. SNYDER:  There are functional assays that you guys probably even know better than we do for transformation, which is growth in soft agar and lack of contact inhibition, producing a tumor in the brain or in the muscle of a nude mouse.  So, we would subject these cells to exactly what you would do to define transformation.
		DR. SALOMON:  Michael and then Vassilis.
		DR. WALKER:  We're talking about what, in essence, is a very low incidence phenomenon.  Therefore, we're always going to be approaching it from the null point of view, namely that we haven't found anything but we might find something in the future.  So, from that point of view, any cell that to me has the potential for unlimited and uncontrolled replication is of concern.  That doesn't mean we don't do it.  It just is of concern.
		Second of all, we're used to considering the brain as fully and irreversibly differentiated, and now we're finding out that it clearly is not and that there are cells that you can get out of there that have all sorts of wonderful potentials.  If they were pushed back to acting like ES cells, I wonder what might happen. 
		That being the case, I think we have to start thinking about simply the kinds of things that John was talking about, that when a model is set up, for example, that's going to be showing whether this particular treatment has in that particular model efficacy, I'd like to have an aliquot of those models totally set aside for long-term follow-up simply to find out if there is an incidence that we could find or not.  It doesn't prove there isn't any, but I think we need to set some of those kinds of things up.  I think to try and break it up into each individual cell, each individual cell type, each individual cell source, and sort of say for each one of those, we're going to have a different parameter, that's too difficult. 
		DR. SALOMON:  Vassilis and then Rusty.
		DR. KOLIATSOS:  Actually I feel obliged at this point to release some published information from my lab.  I really want to make a plea that John Gearhart's deposition is not misinterpreted.  These things were not tried in the nervous system.  
		We tried in my laboratory some of these ES-derived cells, not human but mouse, and the person who did it was trained with Ron McKay and did exactly what Ron McKay does to get neural precursors from ES cells.  We had a 90 percent UN positive population before we put the juice in the brain.  In some parts of the cortex, we saw some nice integration, and in some other parts of the cortex, we saw something that I don't call it a cancer, but I will send to John the slide, if you want, John.  It's clearly unintegrated.  It's round.  It pushes.  And it doesn't look like nervous tissue to me, so clearly not cortex.
		This is not to say that this is going to happen all the time.  It is to say that even when, Mehandra, we do all these steps to differentiate, even one or two cells can remain that can do a job not necessarily to form tumors, but unintegrated globs of tissue, which are not going to be of any functional relevance and may be deleterious.  The potential will be there and the picture is very complicated.
		DR. GAGE:  In our case, they were cells that had been passaged for long periods of time and karyotyped.  In one of the two aneuploidy cells showed tumors sometimes.  I should point out that they didn't tumor all the time.  Probably 1 out of 30 animals had a tumor, but that was marked in the protocol saying that there was a tumor found in that animal that received that cell type.
		The other point about using rats or small animals as an index for safety of tumorigenicity concerns me, that generally our graft sizes are about 200,000 cells per microliter.  You might be putting in 3 or 4 microliters, and that's not comparable to the number of cells that you'd actually be putting into the human. 
		So, if you come to a point where you have a question of aneuploidy, p53, you've done your first-pass screen and there's something that is highlighted and you begin to do your tumor assay to see in 100 animals what percentage of them give tumors where, I think the number of cells that you put in should at least be taken into consideration.  It may not be that a mouse or a rat with 100,000 of those cells is adequate to determine whether or not that cell has tumor cells in it.  Because it's not that every cell is going to be tumorigenic, but some small fraction.  
		Certainly in cancer studies, even with gliomas, if you take a mouse glioma or a rat glioma and put it into a rat at 200,000 cells, you're not going to get a tumor.  You need to get up to a certain number of cells before you get that kind of growth.
		So, at least in the consideration of things and then the assays are being developed to determine whether or not the cells that reach a certain stage that they need to be evaluated -- we've got to make sure we're looking at enough cells and enough animals to feel comfortable that it has passed some sort of criteria.
		DR. TROJANOWSKI:  So, I think we have to distinguish between tumors and whatever is going on in Curt Freed's poor patient.  I don't think that's a tumor.  That may be exuberant growth or overproduction or what have you.  I'm talking about tumors that kill people and not hamartomas, not benign growths, not aberrant differentiation.  You can do bromodeoxyuridine labeling and if you do that, as we have done, it's negative in animals that survive beyond a year, the postmitotic neurons, when they put them in there.  I would again challenge anyone in this room to show me a tumor that you can get after you put a million cells of whatever your favorite benign -- and let them survive a year without a death.  That I have not heard of.
		DR. KOLIATSOS:  John, this is a very important point.  I'm afraid that the less BrdU I see, the more I get concerned because it tells me that the cell has gone through several generations in the brain.  In fact, I see much better BrdU in well-integrated, graft-derived cells than in the ones that I'm afraid of. 
		DR. TROJANOWSKI:  I'm not saying one or the other.  I'm saying do both.  Bromodeoxyuridine, pulse them several times.
		DR. SALOMON:  Phil?
		DR. NOGUCHI:  In this conversation, I think we must be very careful to distinguish between rodent cell lines and human cell lines and embryonal human cell lines.  These are all new things.  
		But in terms of classical cell biology, there is, as far as I know, no documented case of a human cell line, normal cell line in culture being transformed by any means, shape, or form into a malignant line.  Now, you have malignant lines who start that way and you have normal lines who start that way.  But people have been trying by many means.  Human cell lines are clearly different than mouse cell lines.  We lost about 20 years in using any kind of continuous cell lines because of the concern that we had for mouse. 
		The same goes I think for testing for tumorigenicity.  What we can say is if it forms a tumor in nude mice, you probably don't want to use that as it is, putting it into the brain, but it could be differentiated like the N-Tera-2.  
		So, there is a fundamental difference of human cell lines, and I think what we really don't know at this time is for an embryonal stem cell or any other kind of human stem cell, other than hematopoietic, does that kind of transformation ever really occur in vitro or not.  I would posit that so far we haven't seen it, even when people tried desperately to do that.
		DR. SALOMON:  So, Phil, just as a point of clarification, because this came up in a conversation, is it then what you just said, that mouse cell lines may have a much higher potential of malignant transformation in culture than human cell lines?
		DR. NOGUCHI:  I would say that the common factor is a mouse cell line carried long enough will become tumorigenic.  That's how all the original lines were derived.  It's not the same for humans.  You cannot really transform them in vitro.
		DR. SALOMON:  Darwin?
		DR. PROCKOP:  I'd just like to make a couple comments. 
		I think a lot of interesting points of view have been raised here, but I keep coming back to Dr. Auchincloss' point.  How is this different than what we've been doing for 50 or 100 years in developing therapy for patients?  There are some differences, but I don't see very many.  
		So, yes, in the beginning, we'd like to thoroughly characterize what we start with.  It would be great to have a single crystal organic compound whose structure we know. We're not going to get that out of these cells.  I think it's more like Premarin, pregnant mare's urine, which is still used in place of estrogen.  It has compounds in it; we don't know what they are.  So, we're going to get an approximation of what the cells are, but it's only going to be an approximation.  
		Our experience fits with the hematopoietic stem cell line.  We can see two cells divide.  They look the same but they're already committed down different routes.  Our data fit with that kind of paradigm.  We're going to wind up with mixtures of cells no matter what we do, so we can give plus or minus what the percentages are, define them.  We have to do that for dosage and all the rest.  But beyond that, we're going to do standard pharmacology in effect.  We're going to do as much as we can in isolated cells, look for karyotypic changes.  And, oh, yes, that all helps, but you've got to go from there to the animal and you've got to give doses to the animal.  You've got to look for toxicity.  Yes, if you've seen changes of changes in the karyotype ahead of time, you've got to do much more studies for tumors.  But it's all the same thing.  As John was saying, it's an empirical game which is not so different than we've been doing for nearly 100 years.  I really don't see a difference.
		DR. SALOMON:  The only point, Darwin, is that if this field came forth to successful clinical trials, having done all of that, that would actually not have been done for any of the things that you're talking about.  It hasn't been for islet transplantation.  It hasn't been done with hematopoietic stem cell transplantation.  So, the fact is if this is done, it certainly builds on the shoulders of all the hard work that's been done in those other areas.  But it's not been done before, so it is unique. 
		DR. PROCKOP:  The other step is this.  The lung transplant field is one lesson.  You can do as much as you can in animals.  You go to the patient, you see something different.  I think you have to go to the patient who's extremely ill, be very attentive to what's happening, and get an idea how you might go back again and improve things.
		It's part of the story I was telling about osteogenesis imperfecta.  We got ahead in the clinical trials of what the animal trials are about.  It's not the way I would have liked to have done it.  That's the way it happened.  
		Bone marrow transplants went the same way.  As I understand the field, before you answered basic fundamental questions in mice, you went on to humans.  And you still can't make that transition very cleanly.  
		So, it's going to be a whole game that way, but I don't think it's that different than we and scientists in the past have faced before developing therapies.  I don't see the big differences.
		DR. SALOMON:  I understand the point.  As a clinical investigator myself, I'm always concerned that we regulate things out of business.  If that's Darwin's point, I agree with that. 
		Ed?
		DR. SAUSVILLE:  I just had one follow-up to the point may be Phil.  Recent work by Bob Weinberg has actually shown that humans differ from mouse cells in the telomerase regulation, and if you control for that, you can actually transform human cells.  So, I just would point that out. 
		I guess I'd turn it back to Hugh.  You asked two questions.  Do you feel like this conversation has clarified things?  
		DR. AUCHINCLOSS:  For question number 1, I think I got an answer.  The group thinks that an undifferentiated ES cell has an intrinsic capacity to form tumors and would be an unlikely candidate for a source of tissue at this point.  Maybe somebody can put in a suicide gene or a regulatory gene, et cetera.  I can imagine lots of things that could change that, but right now an undifferentiated ES cell has an intrinsic difference. 
		But what I think I heard is a differentiated ES cell puts you into the world of empiricism where you do lots of tests that you people have talked about, both in vitro and in vivo, and it may well be that you can come up with sufficient numbers of indicators to say I think this is safe based on what we've seen so far.  You may turn out to be wrong, but there are assays that you can do. 
		Then I thought that you made the correct point that the real intrinsic property that we're looking for is the capacity for uncontrolled proliferation and that you might get there in vitro with any cell line, an islet cell or hepatocyte, that is in culture long enough to transform, if in fact that were to happen in humans, and that would put you into the special box category. 
		So, now back to the second question.  So, that's what I had gotten on question number, but now there's question number 2.  What I thought I heard yesterday or what I didn't hear yesterday was any evidence that an adult stem cell is any more risky than any other form of cell transplantation.
		DR. SALOMON:  Mercedes?
		MS. SERABIAN:  I just want to make a comment that if you have a tumor in the brain, you can't remove the brain.  There is a difference that and the other organs, other tissues.
		The gold standard is in vivo testing.  We can talk back and forth here about what cell type, what would be required, what not.  But if an IND gets plopped on my desk and it's a certain cell type and someone has or has not done tumorigenicity, then we have to make a call as to whether it's appropriate or not, what animal species, what's the study duration?  Is it an immunosuppressed animal and we watch it for a year?  I've seen some they claim after 6 weeks no tumorigenicity.  You think that convinces me?
		DR. SIEGEL:  Let me follow up actually on that question and on your remark, Hugh, on this area of adult-derived cells.  Somebody commented that at least if you put adult-derived cells in a certain environment -- but we've talked a lot about environment, so I'm not sure where in the brain you want to inject these cells for tumorigenicity, but that's another issue.  Or do you want to inject them in the brain?  But probably you'll get different results based on all we've heard about microenvironments. 
		But somebody pointed out you could put them in the embryo and unlike, I would guess, a pancreas cell, you can get dedifferentiation of these adult stem cells to totipotential stem cells, which presumably at least we're concerned do have some risk of tumorigenicity.  So, that raises the question is that risk or concern high enough that there ought to be similar types of -- your question.  Should the similar types of safety testing be done regarding tumorigenicity and dedifferentiation if the cells are from an adult neurological source?
		DR. AUCHINCLOSS:  I think your question is just right.  That's the first I know of that data and it seemed to me it began to move the adult stem cell back into a more risky category again.  How do you interpret that data?
		DR. SNYDER:  Even the cells that Rusty was talking about were adult neural progenitors passaged many, many times.  So, simply being adult or not adult is not the decision. 
		DR. AUCHINCLOSS:  Passaged many, many times puts me back into the category of in vitro potential for transformation.  It's taking the adult stem cell out and putting it into the patient that I so far haven't heard any indication that was a risky procedure.
		DR. SNYDER:  I think the distinction maybe is not so much whether it's adult or not.  There are many steps in between.  Perhaps organ-committed, organ-specific, or lineage-committed.  And the ES cell clearly has the intrinsic potential to give rise to many lineages by definition.  Shortly after that, under normal circumstances, there may be stem cells that are at least organ-committed or organ-specific that under normal circumstances do not seem to give rise to inappropriate cells in the respective organ.  Those can be brought out.  They need to be expanded, and you would subject them to same kind of safety and efficacy studies. 
		Now, we're not certain, however -- and it's still an open question -- whether a neural stem cell from a fetus, let's say, which is beyond the embryo but certainly not an adult, is better or worse than an adult stem cell.  There's a division now and it's going to be an empiric decision.  There's some evidence that maybe an adult stem cell doesn't have quite all of the potential that a fetal neural stem cell does.  Others believe that they're completely synonymous and that a stem cell is a stem cell.
		DR. SALOMON:  We're going to need to move on in a minute because there's too much to do and it's almost 2:30.  So, if there are a couple really pithy comments on this, I'd like to close this and move on.
		DR. CHAMPLIN:  I have a pithy comment.
		DR. TROJANOWSKI:  I would just like to say I think we have the data that Dr. Auchincloss is looking at.  We've had 40 mesencephalic transplants.  I was just looking at a fetal mesencephalon last week, a section thereof, in my laboratory where I'm study alpha-synuclein expression in the fetal mesencephalon.  And I saw dopaminergic TH positive cells in the fetal nigra, but I also saw them moving -- or at least what could be interpreted -- away from the central canal.  I don't know if you guys, Jeff, have done marker studies, but I can't imagine that there aren't fetal neural progenitor cells in those mesencephalons that we've already done the experiment to show that they don't form tumors by virtue of doing fetal mesencephalic transplants in 40, 50 patients, however many.
		DR. SALOMON:  Well, just maybe to jump forward here, I think that what I'm hearing -- I just can't imagine you guys would disagree with it -- is that if you have a stem cell, wherever you get it, as defined by its ability to differentiate in a very plastic way in many different directions, i.e., multipotent, whether it's for adults or whatever, even if you manage to keep it in that primitive state in culture rather than differentiating down a specific lineage, that cell will have to be tested by the same standards of tumorigenicity as any other cell you want to use that's a stem cell.  Right?  I think everyone agrees with that. 
		DR. RAO:  Yes, but it shouldn't be held to the same standard that you're trying to hold the embryonal stem cell to.  That's all.  Despite the data around the --
		DR. SALOMON:  I think you're going to find it very difficult to get the FDA to set too many different standards.  I think that Mercedes is going to have a standard for tumorigenicity.  Jay Siegel and Phil Noguchi are going to have a standard for tumorigenicity.  Meet that standard, you can use the cells.  Don't meet that standard, get back to work.  I think that's how it's going to be.  You can't say, well, let's see this, and then you'll argue, but it really fits into this standard.  I don't think that kind of thing works in a regulatory environment.
		DR. RAO:  I thought in the big thing of this conversation we agreed that embryonal stem cells formed a special class.  Right?  I just don't want every cell to be held to that standard.  It's okay to hold embryonal stem cells to whatever standard you're holding all the other cells to, but --
		DR. SALOMON:  I think this is something that the FDA should respond to.  My comment is that they're going to hold you to the same standard.  But, Mercedes, tell me I'm wrong. 
		MS. SERABIAN:  I don't know what the standard is.  That's part of the question.
		DR. WILCOX:  We've already heard somebody suggest that it would be 100 animals for a year.  Is that going to be long enough?
		DR. TROJANOWSKI:  100 animals for a year, yes.  Show me data to the contrary.  100 animals surviving a year with cells injected, a million, 2 million, 4 million, and do bromodeoxyuridine labeling at various times in between for further backup.  But as someone who has worked on tumors for 15 years of the brain, I don't see any animal models of tumorigenesis beyond 365 days when the cells are there, and they're alive of course.  They can't be dead cells.
		DR. WILCOX:  Are you referring to the nude mouse models?
		DR. TROJANOWSKI:  I'm referring to nude mice, yes.
		DR. SALOMON:  Dick, Tom, and Mark.
		DR. CHAMPLIN:  I think biologically there may be a difference between these ES cells and other cells in a steady state.  The embryonal cells are programmed to make an embryo.  So, they're going to proliferate and make a mass naturally.  Whereas, cells that are collected in the steady state situation from even the fetus or an adult are quiescent because of natural controls on their growth.  I'm not aware of any precedent for those cells making tumors in any system.  So, I would be very suspicious of ES cells in terms of their tumorigenicity, but I would think it's going to be the exception rather than the rule for these other cells, and I wouldn't make a giant requirement there when there doesn't appear to be a rational need.
		DR. FREEMAN:  Just to support this number of 100 animals, if you're looking for landmarks, if you use a stem cell that is partially committed such as Evan's and they can migrate all over the brain, including to the contralateral side, and you can deliver them with one needle track, as opposed to cells that are differentiated and stay where they're put -- for example, in our program we're using 16 needle tracks.  What's the relative risk surgically?  You're talking probably about a one-half to 1 percent risk surgically for all those needle tracks, not to mention cognitive difficulties from multiple tracks through the frontal projections.  So, therefore, that gets weighed into the formula, and I think that 1 percent number is probably reasonable.
		DR. NOBLE:  I'm just a little concerned about the focus on tumorigenicity.  We know that the most mutagenic components of the brain are myelin, and in the brain you have lipidic haptene that people worked on for so many years and that you always got an immune response to is galactocerebroside, the major myelin in glycolipid.
		So, I think there's a certain concern that I have that if you are going to do a nonautologous transplant into a patient in situations where you were going to generate oligodendrocytes, that perhaps there is a need to at least be looking for changes in the percentage of T-cells or immunoglobulins that are reactive against the myelin antigens so that we are aware of the potential of these autoimmune disorders. 
		DR. SALOMON:  So, that's actually raising another issue.  That may allow us to move on.
		In a year or two, when they get rid of me, I still want them to get up and give me a plaque or something.
		(Laughter.)
		DR. SALOMON:  So, I think we've done tumorigenicity.  I don't know that anyone wants to tell you it's 100 animals, though we've had an argument for that. But I think in general we agree that there should be information available on any cell line for a clinical trial that includes but doesn't exclude anything specifically, but includes karyotyping, p53 expression, contact inhibition in in vitro growth assays, but certainly also includes data in animal models.  Maybe we'll get back to that a little bit about immunodeficient animal models versus primates.  I think that's kind of where I'm wanting to have a little bit of time to talk about next.  But it should be both animal tumorigenicity data and in vitro tumorigenicity data.  I think that's probably where we ought to hold there.  And I'll resist the gene chip comment at this point. 
		Yes?
		DR. JOHE:  I'm Karl Johe from NeuralSTEM Biopharmaceuticals. 
		In terms of tumorigenicity, the nervous system disease does present two unique differences which I would like the committee to consider.  One is the lesioned environment, whether the tumorigenicity test should be done in lesioned nude mice or not.  Second is the site of the injection.  There are different neurogenic sites in the adult brain and I would like the committee to make specific recommendations.
		DR. SALOMON:  I think certainly with respect to the latter, the committee has already repeated on multiple occasions from multiple people here.  So, I think I can speak for the committee, unless you guys disagree, that site is important and lesion is important in terms of the environmental signals.  I think everybody agreed with that.
		Some of that will come back down to models.  I think at some point along the line, if you want to do a disease X study, you're going to have to provide animal information in a model of it.  The intrinsic quality of that model is something that is not easy to predict because there are so many different possible models. 
		Well, immunogenicity.  I don't want to forget that one because that's certainly not irrelevant at all.  It's certainly relevant in a number of different things that we do in terms of transplantation and sensitization.  In gene therapy, the idea of immune responses altering therapeutic responses and certainly in cell transplantation like islet transplantation and autoimmune disease destroying the islet.  So, that was quite an argument between us last time.  So, anyway, I think this immunogenicity issue is very important, Mark.  I'm glad you brought that up. 
		Let's talk a little bit about, in the context of animal models, post-implantation cellular fate.  Again, I'm cognizant of the time.  So, here I might get a little heavy-handed.  Please forgive me. 
		There are two or three really important things I think we should talk about.  One is markers.  If you do these studies, it would be a big advance if the cells survived and functioned after transplant even if you might not meet the absolute ideal clinical profile, and a lot of that could then spur further research.  I think we'd all agree.
		So, what ways do you guys suggest we have available now to follow cells after transplantation in animal models or in the human situation that would be important to think about now?
		DR. RAO:  It's pretty much all the standard ways, and you saw some of the evidence.  You can use noninvasive radiographic methods to follow cells at least in humans, and at least in specialized cases where you have MRI scans, you do this with mice.  
		I think a couple of things that we should be considering in creative ways that you can use paramagnetic labels, and we may want to see whether we can use those.  We can use labeled antibodies with specialized uptake.  Especially if you're doing human cells into mice or rats, we have species-specific antibodies which can bind on the cell surface and one can use them to actually follow cells.  And all of those are possible.
		DR. SALOMON:  So, can I get a little bit more?  You guys did some neat PET scanning.  Stuff was shown yesterday.  Now, can those PET positive markers -- you loaded the cells pretransplant with them.  You don't get special uptake if you give them IV to the patient after you do the transplant.  Right?
		DR. RAO:  No.
		DR. SALOMON:  How long will they last?  Usually those kind of things we're talking 48, 72, 96 hours.  BrdU may be a few days.
		DR. RAO:  A short time. 
		DR. SALOMON:  So, in terms of a clinical trial, these are not going to be very satisfactory.  Right?
		DR. GAGE:  One of the clinicians explained what's going on with the PET markers in the fetal tissue grafts.  That's what you're talking about.  This is bottom line rather than the details.  
		After the graft is in there, you can give something to the patient and mark the functionality of different aspects of the graft.
		DR. KORDOWER:  You can give like agonists, give amphetamine and have the graft be activated, and you can see function that way.
		DR. GAGE:  And you can do it repeatedly.  So, there are ways of assessing specific functional aspects of the graft.  It's debatable, is that the host or the graft that's doing it?
		DR. KOLIATSOS:  But this is the product of the graft.  The question is if you can use neutral markers to trace the origin of the cells.  If there are neutral markers and there are markers of differentiation and fate, I think we need both because you need to show that fates come from your implant and they're not just an independent event. 
		DR. GAGE:  I was just responding to what his question was.
		But what we don't have are what we're looking at.  What we'd like to have is some sort of tag that you can put onto a cell that could be read out in vivo repeatedly over time, independently of the fate of the cell, just to know where all the cells went.  That would be a terrific thing.
		DR. SNYDER:  That actually does exist.  Ralph Wielander up in Boston with us has actually FDA-approved now ferromagnetic tags that can go into cells such that the transplant itself can be imaged by MRI over time in mice and presumably in primates and humans.  So, that kind of technology does exist. 
		There's some emerging technology on actually being able to image lacZ expressing cells equally as well.
		So, the technology exists, but hopefully we would be using in clinical trials if we did transplants to follow in vivo in a living person by MRI the cells that we put in there.  Again, it wouldn't tell us what --
		DR. KOLIATSOS:  Have they used the cells and have they MRIed these brains, Evan?
		DR. SNYDER:  Yes.
		DR. KOLIATSOS:  Because there's one issue of feeding them ferromagnetic stuff and the other is for the MRI machine to have the resolution to pick up small collections of neurons.  There are two different things. 
		DR. SNYDER:  Yes.  There is a resolution, but the resolution it's not bad.
		DR. GAGE:  But I think we need to be careful about what we're thinking about we want to have in the future and what is standard practice in the field at present.  And what is not standard practice in the field at present is being able to track individual cells that are grafted now.  There may be a hope for something like that in the future, but that is not standard practice in the field.  
		So, what we know right now is not where all the cells go in all of the different models that we are dealing with, much less the fates.  That information is at best derived postmortem in our sections when we look at the animals, and if you label every cell, you hope that the label stays on long enough so that you can then double-label that marked cell with enough phenotypic markers to determine what they turn into.  
		But that's the state of it, and it's not bad.  Actually that part of it is coming along pretty well.  But I think it would be wonderful if we had magnetic markers or something like that for clinical applications where you actually could track the cells in situ, independently of knowing what they are.  Just knowing where they are would be a relief I think to experimenters and clinicians alike.
		DR. KOLIATSOS:  The problem I see here is that because of the extensive migratory properties of those cells, they're going to disperse themselves quite a bit.  It's not like the traditional grafts where you put a big chunk of cells inside of the brain and the machine, the magnet can pick it up.  They're going to go all over the place, and they're going to dilute the signal.  So, this is a significant technological problem which is ahead of us.
		DR. SALOMON:  One of the things I think about the migration is that if you have an injury somewhere, they may migrate out, but if the injury is in the site where you just injected the cells, there may not be a specific reason for these cells to migrate.  I think it's an important question in each of these models, how much, if any, migration will occur.  Of course, it will have to do with the cell type.  I don't want to get into that.  That's obvious.  But also just the situation around it. 
		Tom?
		DR. FREEMAN:  In terms of radiologic surrogate markers, obviously with dopamine neurons it's our best characterized surrogate marker using the fluorodopa PET scan where the test/retest variability is available.  But even that even in the best of situations is limited because region of interest is 2 centimeters or a centimeter and a half even in the best of hands for test/retest variability, and many will say it's even larger than that.  So, to expect a pharmacologic surrogate marker is just not practical even in the best of situations.  
		Then once you get into other diseases, what's the pharmacologic outcome you're measuring?  Are you looking for GABAergic function or whatever?  The markers and the methods for looking for that are just not available. 
		On the other hand, if one is looking from a safety point of view, just a plain old MRI scan a year and a half out is good, regardless of therapy, for tumorigenicity purposes.  That's really what we're looking for primarily, and that's available. 
		DR. SIEGEL:  Tumorigenicity may be a primary concern, but we are interested in, as noted in the bullets in this question, what animal models might tell us about migration, differentiation, phenotype, integration, and survival. 
		DR. SALOMON:  Great.  We've got 15 minutes to do all of that. 
		(Laughter.)
		DR. GAGE:  Well, I think that there are some answers.  Again, in the short time, trying to give some advice or some recommendations, cells can be labeled either with dyes or with bromodeoxyuridine prior to grafting so you can track them, or with viruses in some way so that you can see where their fate is.  And then after grafting, in the appropriate model, use that graft-identified marker to determine what the cell fates of all those cells are. 
		To go back to what we were saying, not just how many tyrosine hydroxylase positive cells develop reliably as a function of the number of cells that you put in, but also how many of the cells that you put in survive -- get some quantitation on it -- and then how many of those cells differentiate into the phenotype that you've determined in your experimental model is causally responsible for the functional recovery that you've seen.  You can set that barrier and say, okay, look, we need to get, based on our experiments, this many cells surviving.  We've put in this many cells, this percentage of our cells, differentiating the fate, and we get that in some sort of ratio.  
		I don't think it's unreasonable to ask for those parameters in any experimental model to say what percentage of your cells differentiated in the phenotype that you believe is causally responsible for the function that you have in vitro and in vivo.  And that is a percentage of the total number of cells that you put in.
		DR. SALOMON:  In the back.
		DR. WILCOX:  I agree with that, but I think one of the other problems that we face as reviewers is that we're also concerned with what else they may become.  If the intention or the desired phenotype is tyrosine hydroxylase positive, what are the risks that the cells might, or a portion of the implanted cells, may assume other phenotypes?  And does that matter?  Is it going to be clinically relevant?  When we ask sponsors for preclinical data at this point, it's often not clear what kind of clinical relevance it's going to have, and it's very difficult sometimes to convince sponsors that we want to know what else these might do.  
		My feeling is that we should have that information in case there are adverse events which we then can use those data to perhaps evaluate the adverse events.  But is it realistic to ask sponsors to put resources into these large preclinical studies where we don't really know even what we're looking for at this point?
		DR. GAGE:  Well, if you have markers in the cells and you've used one marker to identify what the fate is that you're searching to, you use other markers to determine the percentage of cells that have gone into other fates.  You wouldn't just use a single marker, but you have to at least get the cells down the lineage that you want or that you're targeting.  Then as a corollary, you want to find out as many of the other fates as you can within the cell type.  But I wouldn't be satisfied just knowing all the other ones.  I'd want to make sure that you've got the fate that you want.
		DR. SALOMON:  Tom, Jeff, and Vassilis.
		DR. FREEMAN:  So far with, for example, fetal transplants, no one has had more than, say, 5 to 10 percent of the neurons that are going in being dopaminergic because that's standard within the mesencephalic dissection.  So, by definition, our experience has been with the heterogeneous population not with the homogenous population.  
		There is evidence suggesting that that may actually be good.  Say you have your dopamine neurons surrounded by mesencephalic glia.  That may not only affect survival rate in vivo, but also the type of outgrowth versus branching is directly related to the surrounding glial milieu around the dopamine neurons. 
		So, the bottom line is I think that, from my point of view at least, all that matters is that what's going to go into patients is tested from a safety perspective in animals.  I think we tacitly have to admit that it may not be possible to characterize to the last cell exactly what's going on, at least at this stage.  That may take 20 years to achieve.  But as long as the safety profile for the way it's going to be used clinically is evaluated, I think that should be paramount from the practical point of view.
		DR. MACKLIS:  A comment to follow up on what Rusty said about markers and prelabels.  I don't think this committee can decide, but I think there would be some agreement in the field that there's some prelabeling markers that are not dependable, that can be transferred to endogenous cells by cell lysis, and one would want to use one or multiple markers that are going to be dependable and also ones that are going to show all the cells you put in so you can look at these alternative fate decisions.
		DR. KOLIATSOS:  I would also vote that we do these experiments with neutral markers and with fate-specific markers both in normals at different ages and in a variety of lesion models, try as many different scenarios as possible.  I could envision five or six, and I don't want to lay them out.  Because, again, let's remember that in an acute stroke model, the behavior may be different than in a familial ALS transgenic mouse than in a control mouse than in a control rat.  So, we may want to have observations along a number of models in terms of fates and differentiation.
		DR. SIEGEL:  For the most part, I haven't found the issue of uniqueness too important.  Every class has its own issues.  Every product has its own issues.  And we're here to discuss this class and this product whether they're unique or not. 
		But one thing that has struck me as unique about this that hasn't come up yet, which is that this is the only class I can think of cellular products where we've talked about long-term animal safety studies.  We don't put human blood products or pancreas in animals for a year and see what happens.  
		DR. SALOMON:  That was my point to Dr. Prockop.
		DR. SIEGEL:  Right, and that gets to a particular question.  The reason, obviously, that we can talk about that is the immunological barriers presumably.  But that raises an important inferential question because the cells exist.  They live in animals.  They sometimes differentiate.  They do things in animals, but we know that all the neurokines and cytokines and different factors and their receptors are not all identical across species.  So, then part of the question in animals then is are we likely to learn more by putting human cells into animals or by putting animal homologous cells prepared the same way into a homologous species?  Where are we likely to get our important information on these questions? 
		Do we know, for example, if you do rat into rat versus rat into mouse or dog into mouse with these embryonic cells, that you see major cross-species behavioral differences?  Are our findings quite similar when you use homologous species?
		DR. SALOMON:  Yes.  That's actually exactly what I wanted to finish with, so that was perfect.
		What we've talked about here have been rodent models, but obviously we're using human cells of various sorts so that one issue here is putting human cells into immunocompetent animals or human cells into immunoincompetent animals like SCIDs or nudes, and then we haven't talked yet about rodent models versus primate models.  And now Jay has put one last thing on the table and that is going backwards, I think, to start to model rat cells into rats and then come here and say, well, now I want to put human cells into humans just after Phil got done telling us that the tumorigenicity question just starting from scratch is different.
		Ed?
		DR. SAUSVILLE:  Although I think that highlights that I think you can't make a one-size-fits-all thing.  I think you have to be driven ultimately by the biology of the process that you're trying to model.   The cytokine experience has shown us that in some cases there's a very good correspondence between cytokine to cytokine. 
		In other cases, there aren't.  Really they are two sort of different questions.  Right?  In one case, the tumorigenicity is looking at sort of a gross, space-filling complication that might be addressed best in an immunosuppressed rodent receiving human cells.  
		As far as the efficacy issue and whether there are long-term toxicities associated with these cells operating in their normal milieu, I could imagine that you'd want to see supporting data of the species to species.  But you have to look at each situation in and of itself.
		DR. REID:  One technical issue.  At least of the data that I've heard from some of the investigators here and elsewhere, I think the lowest efficiency I've heard about in any kind of transplantation phenomenon has been in the neural stem cell field.  That is, when they're injecting cells, at least from human cells, into the brains, they're having to use, I think, extraordinary amounts of starting material in order to get some type of efficacy.  
		So, one of the things in the inoculation procedure, which you have on your list to be concerned with, is the implanted cell survival.  So, I think you're getting exceedingly low cell survival based on some of that data, and at least some of the known conditions that might improve that might, in fact, dramatically improve not only your model systems, but even some of the effects that you're worrying about in studies of transplants into one species into another.
		DR. SALOMON:  The problem here, though, is that cell transplantation per se is troubled by the number of cells surviving.  In islet transplantation, everybody was jumping around with press releases yesterday about a tremendous step forward in islet transplantation, but it's two whole pancreata worth of islets to cure a patient, realizing that we can probably take out two-thirds of a pancreas from any one of us and have a normal glucose.  And I can give other examples.  Cell survival in any cell transplantation experiment is a big issue.
		In the few minutes that we have left here, where do you feel in your field are primate model experiments?  How far are you willing to go on rodent experiments?
		DR. KORDOWER:  Are you talking in terms of safety or in terms of efficacy?
		DR. SALOMON:  I think just in general.  In terms of efficacy perhaps is better put, but safety too.
		DR. KORDOWER:  I'm going to kind of limit my remarks, because we don't have much time, to Parkinson's disease.  My opinion is that we need to do more nonhuman primate studies.  
		Now, I think, first of all, the rodent studies are too much dependent upon rotational behavior alone, so people who do rodent Parkinsonian studies I want to encourage to do more complex motor tasks because there are lots of things that will reduce rotation. 
		Curt Freed said that fetal grafts in rodents were totally predictive of the human studies, and that's true.  But there are a lot of other manipulations where that's not true.  You can reduce rotations in rats with adrenal cell transplants, or the success that Marty Bohn has had with the adenovirus GDNF in rats she has not been able to replicate in nonhuman primates. 
		I think with regard to stem cells, there have been reports from Ron McKay's group and Tim Collier and Paul Carvey from our group have demonstrated you can put dopaminergic progeny from stem cells into rodent models and get reductions in rotation, but that's because the striatum is so small.  What happens, though, if you look at these grafts, is they don't innervate.  They don't send out processes like our primary cells do, and if you had those grafts in a monkey, I doubt that you'd see efficacy.
		DR. SALOMON:  How about safety?  I got a dirty look from the back table when I said efficacy, which just reflects my bias.  I apologize.
		(Laughter.)
		DR. KORDOWER:  With regard to safety, I think you have a problem in that you're going to be doing a xenograft.  Now, there is some evidence that dopaminergic cells can be grafted into monkeys without cyclosporine.  If stem cells can similarly survive under those conditions, I think you can learn a lot.  But if you have to immunosuppress just to get the cells to survive, then the rules change, and I'm not sure that that's going to be particularly beneficial.
		DR. SALOMON:  So then, let me just broaden it a little bit.  Whereas I tease Jay about the idea that I thought it was going backwards to start doing rat to rat to prove what you'd want to do in a human, I might put out on the table for discussion the idea that I don't think you'd be moving backwards if you had to do primate to primate as a model for humans.
		DR. SNYDER:  Or even human to primate.
		DR. SALOMON:  No, no.  The human to primate was fine.  I was sliding that by.  That would be the best.  But I'm just saying that if you felt that there was an issue of xeno that you could do primate to primate if you have pretty good models.  I'm suggesting.
		DR. FREEMAN:  A few things.  As a clinician that went from rat to humans, there are a few issues wrapped up in this.
		Clearly volumetric issues are better answered in primates.  So, therefore, degree of outgrowth, if outgrowth is an issue, degree of migration, or Rusty's point which I think was very important, if the dose is much larger than what can be tested in a rat and if the differentiation of the cell is dependent on the environment, then really that needs to be looked at in the species that is quite close.  These volumetric issues clearly need to be addressed in primates. 
		On the other hand, a lot of basic biological issues like reproducibility, dosing, cell-cell interactions in terms of pathways where migration occurs.  Where does neuritic outgrowth stop?  Does it stop at appropriate somatotopic targets?  Those answers can be addressed very safely and appropriately in a rodent.  
		On the other hand, one doesn't want to slow research to the point where it's inappropriate.  If we had waited for the primate data for nigral transplants, we still would not have started our programs after 13 years or 14 years of waiting for primate data. 
		DR. KORDOWER:  I don't agree with that at all.
		DR. FREEMAN:  There are many issues that the primate programs have not answered in the fetal arena.  The human data was literally 5 to 8 years ahead of any primate experiment.  Almost every primate experiment followed a clinical experiment, and they were happy to be able to reproduce what was done clinically.
		DR. SALOMON:  We are near done here, but I don't want to leave it on that.  To what extent is that an historical truth based on the way people moved forward in those days, which was let's just go do it, as opposed to some fundamental barrier raised for primate research?
		DR. KORDOWER:  Well, what's the down side to doing primate research?  I wouldn't say that it was difficult.  It's not difficult.  What it is is uncommon, so people can't set up their own infrastructure.  But if someone has a real good cell that makes dopamine and they get it to function in rats, I guarantee you we'll be lined up to try and get the cells to try them in our primate model. 
		They're expensive, but they're not as expensive as a failed clinical trial. 
		DR. GAGE:  Can I say one more thing about the rat-to-rat stuff?  Because I agree with you about the importance of primates.
		DR. SALOMON:  Are you done with your comment?
		DR. KORDOWER:  I think where people are hesitating going to primate trials, it kind of slowed them down in getting to be first or close to being first into the clinic.  I think we have to realize with Parkinson's patients, these patients have a lot of options.  They can get DBS, they can get pallidotomies, they can get transplants.  We don't need to rush with a technology that has an excellent clinical model for use.  It's an excellent model and it should be used in that regard.
		DR. SALOMON:  Two more comments.  Rusty and then Tom wanted to follow up.
		DR. GAGE:  I wanted to disagree or bring in the idea of this intraspecies evaluation as being an adequate approach towards clinical applications.  So, a rat-rat or monkey-monkey.  I think that I personally would feel much safer if you used the cell that you're going to use in patients.  That strikes me that that has to be the -- and how you grow it, how you ever plan to use that cell in the patient is exactly how you ought to test it in your animal model.  Now, you may use other cells to get to the point where you're testing yourself, but ultimately it strikes me that you really have to look at that particular cell in the best model that you can.  And if you don't have a model that can test your cell, you should find one to test your model in and not make assumptions based on how rat cells function or how monkey cells function in some other model.
		DR. SALOMON:  I agree with that, but you have to accept the fact then that taking human cells into any model but a human adds another layer of confusion.  I know you're well aware of that.  In mouse models, for example, there are endogenous and exogenous retroviruses that can enhance the whole tumorigenicity thing.  That's one point that hasn't been made yet. 
		DR. KOLIATSOS:  It's not only immunological.  If you stick human cells into rats, it's not only the immunological compatibility, it's the cell cycle, the differentiation, the time encoded factors, which are totally different.
		DR. SALOMON:  Again, I don't think that we are going to answer anything, but I think that your point is well taken, that if you're going to do a clinical trial, as much as possible you want to do your studies with the final product.  So, we totally agree.
		Of course, there are methodologic questions, so I'm suggesting that in some cases if you have this whole methodology, I'm going to do this, this, this, and this, and after that set of steps, put it into a human patient, I could say to you, you should probably be able to go to a nonhuman primate and do this exact set of steps and get it to work.  And if you can't, it's possible I could still get my head around that, but it would worry me at least.  If you had a process that was biologically relevant and well-described, it would bother me that you could tell me, oh, it works great in humans, let me do it, but I can't reproduce it in a primate.  But that would have to be discussed. 
		Tom?
		DR. FREEMAN:  I don't want to give the impression that I'm saying primate research should not be done.  It absolutely does have to be done, particularly right before you have your final formulation, your final protocol, and go into patients.  Clearly it's relevant. 
		The issue is that many of the scientific questions can be adequately answered in rodents and to require that every question be addressed in a primate would be an unnecessary burden that would slow the progress of research.
		DR. SALOMON:  I don't think any of us who have rodent models and primate models, including myself, would bother that one.  That's a good point. 
		I don't think we answered every question, but I'd like to think that we answered quite a few questions.  At this point before absolutely closing, I'd like to ask the FDA if there are any comments, last minute, we just can't leave without answering this question kind of thing.
		MS. SERABIAN:  The only other question I have ‑‑ and again, it opens another a whole can of worms -- is behavioral data.  Again, we are talking functional, meaningful, measurable observations.  Well, you can get cell migration, you can have an aberrant phenotype expression, but behaviorally what do you see?  Do you see changes?  Again, like I said, it's whole other can of worms because there are numerous different behavioral testing and controls, and some of that was mentioned yesterday. 
		DR. SALOMON:  Particularly the dirty looks I got when I went "efficacy" and drifted back to safety, so now you want efficacy.  
		MS. SERABIAN:  Not efficacy.  For safety.  If there's aberrant behavior -- 
		DR. SALOMON:  Oh, you're talking about behavioral.  I'm sorry.  Excuse me. 
		MS. SERABIAN:  -- some motor dysfunction or something.
		DR. SALOMON:  Well, I think that point is well taken, and I think also, as Ed just whispered, some of that is going to also be more relevant when we get down to specific diseases.  Someone wants to do a trial in this and that. 
		MS. SERABIAN:  Right, and again the question from that is talking with sponsors, they're extensive, expensive, time consuming tests.  So, you don't want to just say FDA says you have to do this and there's really not an appropriate reason for doing it or it's not the appropriate test.
		DR. SAUSVILLE:  Well, that I would underscore.  Just watching how well they withdraw a paw or do something doesn't have a clear tie to the pathophysiology that you're trying to fix, I think I would agree.  I don't see any particular reason to do that and would discourage sponsors from doing that. 
		DR. SALOMON:  I think one of the things that came out in today's discussion that I think has a lot of merit is that there are, as we admitted early on -- Mehandra got a lot of grief about his Harrison list, but then Rusty saved him by having a worst list.
		(Laughter.)
		DR. SALOMON:  I think that there are a lot of interest groups here that are coming together that are interested in this area, and I think that working groups probably should go out from here and begin to address some of these issues and deal with the FDA early.  I think that's one of the points Phil and Jay were making.  This idea that all of a sudden, after everything is all done and everything is settled and it's perfectly done and there's nothing else left to do and we all get to go home, now we're going to come to the FDA and we're going to have a clinical trial, and then the sponsor gets frustrated.  I don't think that's the model that we're trying to communicate.  
		I think what we're trying to say is that the sponsor shouldn't be frustrated, Mercedes.  The sponsor should be talking to you very early in the developmental process.  I just don't have a whole lot of sympathy anymore for sponsors on that score.
		Anyway, again I'd turn to Jay and Phil, Malcom.  Are there any last comments you want to make?  And then I'll close.
		DR. SIEGEL:  Just not more questions, but as a comment, I for one have learned a tremendous amount over the last couple of days.  I've learned, based on Malcom's model, that there's a great deal that I don't know, but I feel a lot better knowing I don't know it than not knowing what I didn't know. 
		(Laughter.)
		DR. SIEGEL:  Those of you who have worked with us, hopefully when we're at our best, we appreciate how much we don't know and what is and isn't possible and try to work and try to work and try to expect you to work within the realm of the possible.  This field is moving quickly, and I'm sure that we'll have many future discussions.  But I think this has been a great foundation for moving ahead. 
		I would like to second your remark, Dan, and other remarks we've heard about the scientific community getting together and developing consensus when that's helpful and when we've reached those stages, whether it's about use of reagents, use of animal models, whatever.  The agency is very interested in those areas and will find it very helpful.  
		I just ask everyone to remember that even though we're dealing with a science that isn't -- as many have pointed out, we don't have all the answers yet.  We don't know all the things we need to know.  We don't know the best ways to test.  We're also dealing with an area which is, as suggested by some, rapidly approaching a time for human experimentation.  So, we do need to make the best decisions based on what we know now of the right ways to proceed.  In that regard, I think this has been a very useful meeting for us.
		DR. SALOMON:  Then I'd like to close the meeting.  
		I'd like to thank Gail Dapolito and Rosanna Harvey, Bill Freas, and the rest of the FDA staff for all the kindness and organization.  I don't know how I ever get here and back without these guys, but I do.  I appreciate it.  Thank you.
		(Applause.)
		DR. SALOMON:  Thanks to all the speakers and to the audience that actively participated and see you at the next meeting.
		(Whereupon, at 3:10 p.m., the committee was adjourned.)