DEPARTMENT OF HEALTH AND HUMAN SERVICES

PUBLIC HEALTH SERVICE

FOOD AND DRUG ADMINISTRATION

CENTER FOR BIOLOGICS EVALUATION AND RESEARCH

BIOLOGICAL RESPONSE MODIFIERS ADVISORY COMMITTEE

Twenty-eighth Meeting

Friday, November 17, 2000

8:34 a.m.

Holiday Inn

Bethesda, Maryland

P A R T I C I P A N T S

Committee Members:

	Daniel R. Salomon, M.D., Chairman
	Gail Dapolito, Executive Secretary

	Richard E. Champlin, M.D.
	Richard C. Mulligan, Ph.D.
	W. Michael O'Fallon, Ph.D.
	Edward A. Sausville, M.D., Ph.D.
	Esperanza B. Papadopoulous, M.D.

Consultants

	W. French Anderson, M.D.
	Xandra O. Breakefield, Ph.D.
	Jeffrey S. Chamberlain, Ph.D.
	Jon W. Gordon, M.D., Ph.D.
	Carole B. Miller, M.D.
	Bruce E. Torbett, Ph.D.

Guests/Guest Speakers:

	Dale G. Ando, M.D.
	Katherine A. High, M.D.
	Donald Gay
	Deborah Hurst, M.D.
	John Levy
	Louis Zumstein, Ph.D.
	Richard J. Whitley, M.D.
	Amy Patterson, M.D., NIH Participant

FDA Participants:

	Kathryn C. Zoon, Ph.D.
	Philip D. Noguchi, M.D.
	Steven Bauer, Ph.D.
	Carolyn Wilson, Ph.D.
	Jay P. Siegel, M.D.
	Karen D. Weiss, M.D.
	Philippe Bishop, M.D.
	Anne Pilaro, Ph.D.
	Estella Z. Jones, D.V.M.
	Mercedes Serabian, M.S.

C O N T E N T S

AGENDA ITEM	PAGE

Call to Order - Daniel Salomon, M.D., Chair	4

Open Public Hearing	4

Session III

FDA Introduction - Vector Classes with Potential for
Long-Term Risks - Carolyn Wilson, Ph.D., CBER	15

Long-Term Follow-up of Subjects in Gene Transfer
Clinical Trials - Philippe Bishop, M.D., CBER	24

Committee Discussion of FDA Questions	35

Session IV

FDA Introduction - Preclinical Considerations for
Gene Transfer Clinical Trials:  Vector Biodistribution - Mercedes Serabian, M.S., CBER	xx

Risk of Germ Line Transduction After Direct Injection
of Retroviral Vectors - Deborah Hurst, M.D., Chiron Corporation	xx

Questions from the Committee	xx

Committee Discussion of FDA Questions	xx

Adjournment	xx

P R O C E E D I N G S
	CHAIRMAN SALOMON:  Karen, is Jay here?  We can't start if Jay's not sitting down, by the usual rules of order.  If Phil is sitting down, we can do it.  Phil's surrogate for Jay.  Phil, I said the usual rules of order is I have to get Jay to sit down before we can start the meeting.  No, I'm teasing.
	Okay.  Well, welcome to the second day of the BRMAC Advisory Committee.  I think today is very interesting since some of these issues now of long-term follow-up that we're going to deal with I think have potentially very important implications for the design of trials and their conduct, and I think it's a potentially extremely interesting set of issues to deal with.
	I have two things I want to do this morning.  The first is our consumer representative, Abbey Meyers, who also has an organization called the National Organization for Rare Disorders, Inc., she was unable to attend the meeting today because of a previous commitment.  But she feels very, very strongly about the issues of long-term follow-up, which is Session III's main topic.
	So as there were no official public speakers that stepped forward, the first of two things I'd like to do is read just sort of an excerpt or two from the letter she sent as a way of showing respect for Abbey's position and at least allowing her in some way to have contributed to the meeting today.
	The second thing I'd like to do while I'm reading that is if there's anyone in the public who would like to step up and address the committee this morning before we get started, please, if you would come up and identify yourself when I'm done with the letter, you're more than welcome to contribute now before we get started.  And as I said yesterday, let me reiterate you're more than welcome to participate at any stage along the way.  Just come to the microphone, identify yourself, and help out.
	So to do the first of the two things, in sum, Abbey writes:  I want to explain that my involvement in the emergence of gene therapy has spanned more than a decade.
	And she then goes on to point out that she's served on the NIH Human Gene Therapy Subcommittee from 1989 to 1992, and then the NIH Recombinant DNA Advisory Committee from '93 to '96 as a consumer representative.  She has advocated from the beginning, her point is, that there should require--and she underlines the word "require"--long-term follow-up of research subjects.  Unfortunately, neither the government nor sponsors have done this, so we still have many unanswered scientific questions.
	NIH is not a regulatory agency and, therefore, could not and did not enforce the monitoring of patients.  NIH gene therapy rules in the points to consider required long-term follow-up.  But investigators didn't submit data, and the NIH did nothing about it.
	Therefore, my first recommendation is that the FDA and NIH formulate a joint task force to develop uniform rules and regulations that both agencies will abide by and monitor and enforce, and they should share data with each other and with the scientific community so that precious resources will not be wasted.
	One of the greatest flaws of the current system is that once sponsor information reached the FDA, it automatically becomes a trade secret and cannot be shared with other scientists who need this information to formulate their own scientific decisions.  In fact, in the case of the tragic OTC experiment in Philadelphia, the protocol was changed after it left the RAC and the RAC was never told.  That at least is her writing.
	I believe that gene therapy technology will not mature towards commercialization unless there's a determination to share information quickly, completely, et cetera.
	Secondly, she's absolutely convinced that long-term follow-up of research subjects is critically important, that testing for gonadal dissemination, annual physical evaluations, and particularly autopsies are essential if we're to avert possible future public health calamities.  And she says this is why the patient community lobbied for gene therapy database which was supposed to track gene therapy research subjects throughout their lives.
	Of course, she points out then in the following paragraphs that these were not instituted.  There is no gene therapy database at the current time.
	Finally, she's convinced that the most important element of long-term follow-up is the gene therapy database which Congress directed FDA to develop several years ago.  It's my understanding that the FDA ceded responsibility for the database to the NIH and the Office of Biotechnology.  She feels that one of the things that we ought to come up with today is some sort of recommendation that this whole issue be revisited in a practical way to see whether or not a database can't be instituted and brought forward efficiently.
	I think I've given a general sense of where Abbey was coming from, and I'm going to stop reading from her letter.
	But, again, you know, I promised her that I would represent her general sense that her feeling as consumer representative is that there is an assumption with the American public that, in going forward with these new technologies, we are saying, okay, fine, the public's giving us some flexibility to go forward, but the quid pro quo, if you will, is that we are responsible about the potential long-term risks of this that might in the end affect the public, and that in the absence of really demonstrating honestly an acceptance of that responsibility, I think Abbey--and I'm raising the point now for the whole committee to consider this morning, you know, at what point are we actually not doing the right thing by the public.  If we're really, you know, saying give us a break here, we're going forward with this new technology, but we really aren't doing the job that we've committed to following what the impact is on the public and on the long-term health of the patients.  So I think that covers that.
	The second thing, is there any public discussion?  Is there anyone from the public who wanted to join in the discussion at the beginning that was not allowed to yesterday?  No.  Okay.
	Yes, I'm sorry  Please, Amy?
	DR. PATTERSON:  Yes, I thought it was important to respond to some of Ms. Meyers' very important concerns.
	First of all, I think I'd like to note for the record that NIH feels that long-term follow-up is extremely important.  We also feel, however, that it's important that long-term follow-up be done in a manner that generates data that is both scientifically and medically useful and valid.  And we also feel that long-term follow-up does impose a burden on patients to bring them back at regular intervals.  And so the design of these studies, both from a patient's perspective, a caregiver's perspective, and the field's perspective, needs to be given a lot of thought.  And we are planning a policy conference on this in the upcoming year about how to best design these studies.
	At the upcoming safety conference on cardiovascular gene transfer research in December, on December 14th, we'll begin to explore long-term follow-up for both cardiovascular safety sequelae as well as non-cardiovascular safety sequelae in that particular context.
	I'd also like to mention that we are also going forward with a database and we'll have a Web presence on--December 20th is the target date this year.  This is purely a pilot.  It's a beta type but we invite public comment on it.
	We are going also toward working with FDA in these months to develop a more fully fleshed out Web presence with the database next year that will use the controlled medical vocabulary and allow comparisons across trials of clinical outcomes and adverse events.
	I just wanted to go on the record that we endorse Ms. Meyers' concerns.  We also recognize, however, that long-term follow-up can't be done randomly.  It needs to be done thoughtfully to generate useful data, and we also recognize that there may be some regulatory constraints for how long one can compel long-term follow-up and what is the authority at the hands of the Federal Government to compel long-term follow-up.  These are very practical and real issues.
	Thank you.
	CHAIRMAN SALOMON:  Yes, thank you, Amy.  It's obvious that some of those issues we're going to kick around the table in a few minutes, but that was great.
	French?
	DR. ANDERSON:  Yes, I just wanted to make a comment after Amy's.  I guess it was Fred Lederle (ph) and I who were the first to push for a database back about 1990, I guess, and, in fact, I maintained a database in human gene therapy for a number of years, and then it got to be too big for one person to handle.
	And one can be critical, as Abbey quite correctly is, about the fact it still doesn't exist.  But let me say on behalf of both NIH RAC and the FDA that there has been a real effort to do this and to do it properly, both on the part of Amy Patterson at the RAC and Phil Noguchi at the FDA.
	It hasn't been forgotten, but there are real logistic problems.  There are real budget problems.  Within the constraints, I think they have done as superb a job as possible, and as sort of the originator of this idea, I appreciate the fact you two are still slugging away at this.
	CHAIRMAN SALOMON:  I guess if--I'm trying to think what Abbey would say right now.
	DR. ANDERSON:  She'd say, Why isn't it here?
	CHAIRMAN SALOMON:  I think what Abbey would--Abbey would start with that.  Thank you.  That was good.  And I think what everyone should understand is that, you know, Abbey has served for many years as a conscience to all the medical and other expertise on this panel, and, therefore, I hope that no one's misinterpreting the seriousness with which I'm trying to represent Abbey's viewpoint here, because it's not just a personal thing of Abbey, who I have a lot of respect and personal care for, but it really is her role on this committee.  And I feel like it's just not here today, and this is probably the one thing that she would really be the person to be passionate about.
	So I think one of the things she would say is that it's not--it's rather--we talked about what was great about government working yesterday.  This is actually what's bad about government working yesterday, where there are, you know, public concerns, congressional mandates, no funding, frustrated federal workers at the FDA and the NIH who--let's face it, you know, it's not rocket science to make a database and, to be honest, there's really very little else to say about that.
	Okay.  So I'd like to introduce--is there further discussion?  Please.
	DR. GORDON:  I just wanted to make a comment.  I think, first of all, I understand her position as saying that she wants a database from the point of view of the well-being of those who participate in the study.  But there are other good reasons as well for a usable database, not the least of which is identifying promising trends in the area of gene therapy.  That's a scientific reason as well as a patient protection reason.
	I disagree, respectfully, that it is not a rocket scientist's job, unless the rocket scientists have an easy job, because this is, in my view, a very challenging job to develop a database that can be accessed easily, where correlative data can be obtained with facility.  And I've pushed as a member of the RAC, which I'm not here as at the moment, for very great care to be taken as this database is designed in terms of those issues.
	There's another point and, that is, of course, I've never seen a research study involving human subjects where the human subject was not told you may withdraw from the study at any time.  If a person is undergoing long-term follow-up, having received gene transfer at the age of eight, they may choose at the time they get married at the age of 38, or whatever, to withdraw from the study.  There's not much one can do about that.  It would not surprise me if a significant number of people did that.  And so there are these human issues, and I must say I have a lot of sympathy for those feelings, not that I necessarily would do the same myself, but I can certainly understand them.
	CHAIRMAN SALOMON:  I appreciate the comment.  Part of what we'll do is return to all of this and those kind of discussions I think should probably be better saved for a few minutes.  But I think the comments stand well, and there are a lot of different things that we need to talk about.  For example, it will be a good debate about what's so hard about making a database.
	DR. SIEGEL:  It's easy to make a database.  It's just extremely difficult to make a useful database.
	[Laughter.]
	CHAIRMAN SALOMON:  Amy?
	DR. PATTERSON:  You have the Chairman's prerogative to tell me if this point needs to wait until later, but I just wanted to also note that in designing a database, as we are doing, it's important to keep in mind who the users are.  And in the context of a gene transfer database, the users are quite a heterogeneous group.  They're patients, patients' families, groups like Abbey's National Organization for Rare Diseases.  There's certainly the media and the press.  But there are also investigators, there are federal advisory committees, there are colleagues at FDA, and there are NIH investigators and the RAC.
	And all of those groups have very different informational needs, and one of the things that we're going to be doing over the next several months is setting up user groups with representatives from those various communities to tell us what is it--when you sit in front of your computer, what is the type of query you would like to be able to do with this data.  That's an important issue to keep in mind.  Unlike many databases, this is a database with a very heterogeneous user group.
	The second and last point that I'll raise, it's also very important to consider whether the data that is put up is validated or not.  And I think that NIH is very sensitive about putting up data from investigators and how does one express amply the caveat if this has not been peer-reviewed data and outcomes.
	These are very sensitive and important issues.
	CHAIRMAN SALOMON:  Well, as I've pushed the Chairman's prerogative this morning quite beyond the usual pale, I'm not going to interrupt anyone else who wants to comment now.  But I think we will get back to some of these things.
	Okay.  Well, it's my pleasure to ask Carolyn Wilson to give us an FDA introduction to vector classes with potential long-term risks.  Carolyn?
	DR. WILSON:  As has already been introduced quite well, there is concern in the community that at least certain types, if not many types, of clinical trials in the gene transfer field carry with them the potential for long-term risks to patients participating in those trials.
	What I'd like to do this morning is outline in part some of the scientific rationale for why we believe that there are long-term risks in gene transfer clinical trials.  I'd like to distinguish a little bit between patient follow-up in that some of these long-term risks may require long-term patient follow-up; others may be able to be determined through short-term patient follow-up, and I'll explain that a little bit more later.
	I'll be discussing what properties of gene transfer vectors are most likely to carry long-term risks and determine which of those vectors and methods that are currently in use share these properties.
	I've focused on three main areas that are likely to cause concern about long-term risks, and the first is integration into host genomic DNA and somatic cells.  I'll be discussing that in more detail in the next few minutes.   Then I'll do in the second half of my talk integration into host genomic DNA in germ cells, and actually, Dr. Philippe Bishop of our Division of Clinical Trial Design and Analysis will be discussing in a talk to follow mine the third risk, which is if a gene transfer vector is contaminated with a replication-competent virus that is capable also of integrating, that this would add an additional long-term risk.
	When we talk about integration into host genomic DNA and somatic cells, the biological effects that could result from that are a spectrum.  The hoped-for effect, of course, is expression of the transgene product with no other genetic alterations.  And this in and of itself hopefully would not have a long-term effect, but as we heard about, for example, yesterday in hemophilia, you could develop antibodies and have, you know, with other diseases, autoimmune responses and so on.  So even that in and of itself isn't trivial.
	In addition, upon integration, depending upon the site and how it's done, a gene transfer vector may cause chromosomal rearrangement, such as translocations.  If it carries strong viral promoters or enhancer elements, there's the possibility to activate gene expression at quite distal sites, up to 100 kilobases.  And, again, depending on the site of integration, you could also disrupt the transcriptional or translational control agents of cellular genes.  And so these last three, in particular, the outcome could be just regulated gene expression.
	Now, this in and of itself may have no clinical consequence, and as I'm sure many of you know, we have a diploid genome, there are two copies.  So, in particular, if you're silencing a gene, hopefully the other allele could kick in and compensate for that.
	Alternatively, you could also have a phenotypic effect in the individual cell that has the dysregulated gene expression without necessarily having a pathogenic effect on the organism.
	However, in the case where you're activating a gene that may be controlled in regulation of cell cycle, this is an area that would cause--has the potential to cause tumor formation.  And to try to give you some sense of what is the likelihood of that event, it's now considered that there are approximately 80,000 genes in the human genome.  Of those, at least as of last week, on the Cancer Genome Anatomy Project website, approximately 130 loci have been identified as oncogenes or proto-oncogenes, those genes that would cause dysregulation of cell cycle.
	But even should a gene transfer vector integrate into one of these types of loci, the risk of tumor formation still is not absolute in that tumorigenesis is still going to be a multi-step process with insertional mutagenesis only being the first.  And we can make that statement based on data that has come out of really two to three decades' worth of study on murine retroviruses, a particular type of murine retrovirus that is actually very closely related to those retroviruses that are used in clinical trials today, where it's known from those studies that in mice tumorigenesis is associated with high levels of virus replication, and that even past the provirus insertion event, additional steps, such as recombination with endogenous retroviral sequences in the genome, are also involved, and that because of these two points, tumor formation really only occurs after relatively long latencies.  So we feel that this data allows us to suggest that in gene transfer vector integration that the risk of tumorigenesis is most likely low and that the effect wouldn't manifest itself until sometime after the treatment period.
	This is the same graph that was shown yesterday by Dr. Bauer, just a breakdown of what gene transfer INDs we currently have, again, most of them being retrovirus, adenovirus, and plasmid, but we also have poxvirus, adeno-associated virus, and herpes.
	One point I want to make on this slide is you can see there's a breakdown also of ex vivo versus in vivo, and I think it's important to realize this risk of somatic cell integration and potential long-term risks of tumorigenesis would be the same, regardless of whether it's ex vivo or in vivo.
	In terms of the potential for integration, retroviral vectors, of course, have high rates of integration.  This is one of the reasons that they're so attractive for gene transfer clinical trials, is that they do allow for long-term expression because they do integrate into the genome.
	With the other vector classes, it's not so clear-cut.  Adeno-associated virus vector, while the wild-type virus from which that vector is derived certainly is known to integrate and, in fact, does so in a very site-specific fashion on chromosome 19, the properties of the vectors seem to be a little different in that it may depend upon the tissue type that you inject it in and so on.  It doesn't seem to reliably integrate the way the parent virus does.
	Plasmid DNA, at least in vitro, is known to integrate at much lower rates, certainly, than something like a retroviral vector, and also from in vitro data, we know that you can manipulate the method of introduction.  For example, a report using an inhibitor of topoisomerase has shown that you can get about a 30-fold increase in integration frequency.
	Adenovirus vector is traditionally considered a non-integrating vector, but, again, in vitro it's been measured that these vectors can integrate themselves about 1 in 1,000, 1 in 100,000 is the rate, so it's very low.  A recent report in Nature Biotechnology demonstrated that genetic modification, introduction of actually retroviral sequences, increased this integration, so that now 10 to 15 percent of the cells exposed to that vector had integrated sequences.
	Herpes and poxvirus vectors don't carry--or at least data to date doesn't suggest that these integrate.  But they may have other long-term effects, for example, concerns about latency with herpesvirus could not--may not manifest itself for decades.
	So based on data that we have about the vector classes that are currently in use and thinking forward about modifications that are certainly going to happen in the future, we can recognize that there's a range of integration frequencies and that depending on what modifications or methods of introduction are used, even for one particular vector class, integration frequency may vary.
	And so that really sets up the questions that we're asking the committee to focus on today, which are we don't really want to have an answer of, well, can you tell us what class a vector needs long-term follow-up; but, rather, we'd like to think about what properties of vectors need long-term follow-up.  What would be the characteristics of the particular gene transfer method and what are, for example, some minimum frequency of integration events that would give you greater concern?
	Now I'd like to spend the last few minutes on the other long-term risk, which is integration into host genomic DNA and germ cells, and this is the one where I wanted to distinguish between where the effect of germ line integration would certainly be long term, the patient follow-up to assess the risk of this event could be achieved in the short term.
	The risk of integration in terms of biological effects, again, would be a spectrum, depending on where a gene transfer vector were to integrate.  Again, the hope would be that there would be no biological effect, but you could have genetic disorders, birth defects, lethality to a developing fetus depending on the site of integration.  And, of course, there's the larger societal issues where it's been deemed unacceptable to do deliberate germ line alterations with unknown public acceptance of inadvertent germ line alterations.
	Now, again, trying to make this a little bit of a data-driven discussion, we can go back to studies with murine retroviruses in model organisms like zebrafish and mice where these have actually been used as insertional mutagens to study key genes in the developmental program.  And what we've learned from those studies is that in order to see a phenotypic effect from provirus insertion, you really needed to breed these animals to homozygosity.  So, again, our diploid genome can protect us from provirus insertion.
	However, on the other hand, studies from H. Kazazian on line elements, which are transposable elements in the human genome, have identified that certain retrotranspositions or novel insertions into the human genome can result in human disease.  But even this information should be taken in the background rate of retrotransposition, which is about 1 in every 50 to 100 germ cells.  So, clearly, our genome can tolerate a fair amount of novel insertions, but, again, depending on the site of integration, disease may result.
	When we talk about the potential for integration into germ cell DNA, now we need to think about not only the characteristics of the particular vector system that's being used, but also equally important is the route of administration.  In this case, unlike somatic cells, ex vivo gene transfer would carry little to no risk.  Localized injections, such as intra-tumoral, sub-cu, IM, again would likely carry low risk of germ cell integration.  However, if you're doing localized injections into the gonadal regions or system injections, the risk may be higher.  And we feel these last two are more than just theoretical postulates because there have been two recent reports in the literature from preclinical studies suggesting that these types of routes of administration could cause germ line alteration.
	The report by Sato et al. demonstrated that liposome-encapsulated plasmid DNA, when injected directly into the testes of mice, these animals were then bred within a two- to five-day period, and their progeny were shown to carry the transgene.
	The second report where a retroviral vector was used to inject into rats by the intra-cardiac route, they were able to demonstrate that the hypertensive phenotype in these rats could be corrected not only in the recipient animals but in their progeny as well.  So there are at least some data suggesting that germ line alteration can result from these types of injections.
	Then, to summarize, the factors that influence long-term risks in our opinion would be, foremost, the ability of a gene transfer vector to integrate, and really as correlates of that are the dose of the gene transfer vector or presence of replicating integrating virus, as these would increase the likelihood of integration into a potentially oncogenic locus.  The route of administration is going to be key for germ cell integration and really interplayed in all of these are other issues such as immune status of the recipient.
	The long-term adverse events data that's available that predict could occur in these patients are things like malignancies in the case of somatic cell integration, in the case of germ cell integration, genetic disorders, birth defects, embryonic lethalities.
	And so really the broad question before the committee today is to ask whether we can achieve through long-term follow-up of patients whether or not--really, as Dr. Patterson was saying, whether we can use this to provide scientific data to assess the long-term risks of gene transfer research, and if so, how can this best be achieved.
	I'd like to now turn the podium over to Dr. Philippe Bishop.  We're going to take questions after both of our talks.  He'll be discussing our experience and guidance on this issue in the case of retroviral vectors.
	DR. BISHOP:  Good morning.  On March 6th of this year, we issued from the FDA a letter to sponsors of gene therapy trials asking them to describe for us their clinical monitoring programs.  We wanted to know what it is that they had established for their protocols and the INDs.
	In reviewing the responses, it became apparent that some of the sponsors had difficulty following the published recommendations, and we were especially interested in the feasibility and practical issues that pertained to lifelong monitoring.  Later in the latter portion of my talk, I will discuss some of those comments, and I hope that you will find what we have learned to be useful in your discussion later this morning.  But before doing so, I would like to revisit the event that led the FDA to initially ask for lifelong monitoring, and then also review the current guidance documents.
	Rooted in the initial request for lifelong monitoring was an event that occurred in 1992, a report by Donahue that described three of ten monkeys that had developed rapidly progressive T-cell lymphomas following autologous bone marrow transplantation using progenitor cells that were transduced ex vivo.  These cells were exposed to replication-competent retroviruses.  The monkeys were severely immunosuppressed following total body irradiation.
	The pathologic analysis of these lymphoma cells was significant and demonstrated that numerous copies of replication-competent retroviruses were present.  A direct correlation to the lymphoma cannot be overlooked, and at that time we had limited clinical experience with retroviral vectors, and a letter to sponsors was issued in 1993.  For the first time, clinical monitoring programs were required for all clinical trials using retroviral vectors.
	A key principle rooted in the--and prevailing over time relates to a major clinical concern, and that is that clinical exposure to integrating vectors may pose risks to subjects that may not become apparent until years later.  De novo cancers can occur following the activation or suppression of cellular genes.  Autoimmune diseases may result from unwanted immune responses, and hematologic and neurologic disorders could occur subsequent to unanticipated replication events.
	These long-term risks to patients serve as a basis for the current requirement in the newly updated guidance document.  This document was originally posted in draft form in November 1999 and was just recently finalized and posted on our website in October of this year.  It is available at the website that I have listed below there.
	So what is in the current guidance document?  What is it that the FDA is currently seeking?
	Well, there are two assay that are mentioned for monitoring patients for evidence of replication-competent retroviruses.  The first is an antibody assay.  The second, which is more commonly used, I think, by sponsors, is a PCR assay looking for RCR-specific sequences in peripheral blood mononuclear cells.  Sponsors only need to perform one of these assays, not both.
	We recognize at the FDA that there are limitations to these assays, and as an alternative, if a sponsor feels that a different testing method is more appropriate for their study, this should be actually discussed with the FDA, and we would be willing to consider alternative methods to implement for the monitoring of replication-competent retroviral vectors in patients.
	There are five time points that are suggested for RCR testing:  pre-treatment, at three months, at six months, one year after treatment, and yearly thereafter.
	However, testing is no longer required beyond the first year if all samples are negative for RCR at three months, six months, and 12 months.  In these cases, yearly blood samples should still be gathered, but archival would be sufficient.
	If there are clinical concerns or if there are at any point positive results for RCR, additional testing and more extensive patient follow-up may be required.  In these cases CBER should be contacted.
	Upon completion of the intensive monitoring period, which is usually up to a year following the initiation of treatment, yearly clinical follow-up is required.  A clinical history that includes questioning for the interval appearance of symptoms or diagnosis of de novo cancers, neurologic and hematologic disorders should be obtained.  Any suspected clinical outcomes that could remotely be associated to the integrating--or to an integrating or replicating event should trigger a phone call to CBER, and it is likely that this will result in additional testing or archived samples, in addition to obtaining new samples.
	If a study participant develops a new cancer, it is recommended that a biopsy be performed and that the tumor be tested for RCR.  When a study participant expires, an autopsy and tissue sampling for RCR testing is recommended.
	Positive results that are neither positive--I mean, positive results, either positive laboratory or clinical findings, should be reported to us in an expedited fashion.  All other outcomes should be reported in an annual report.  These reports should be as complete as possible and should include a summary of all the laboratory results, including the negative findings, clinical updates, and autopsy findings.
	If the goal of lifelong monitoring is for us to be able to acquire actual data to assess the true risk to study participants, then I think it is very important that we get good information with these annual reports.
	Now, as I mentioned at the beginning of this presentation, when we began reviewing responses to the March 6th letter, it became apparent that many of our sponsors had difficulty following the lifelong monitoring guidelines.  Consequently, we contacted sponsors and we asked them to comment on their experience implementing the lifelong monitoring protocols that they had established for their INDs.  Sixty-six percent of our sponsors that are currently involved in retroviral vector studies were contacted.  This represented the majority of INDs and approximately three-quarters of all clinical trials under evaluation.
	We confirmed that 89 percent of INDs, of all the retroviral vector INDs had an established lifelong monitoring of protocol for their studies.  Almost all of the sponsors, however, noted difficulty meeting all of the requirements in the guidance document.
	In an open-ended fashion, sponsors were asked to identify the barriers that were most problematic in conducting and evaluating patients for long-term follow-up.  What I would like to do now is to review and to present a brief summary of this survey, and I would like to bring to this committee the concerns that were most frequently, at times universally articulated by the sponsors.
	First, issues pertaining to cost.  This was a nearly universal concern by sponsor investigators at academic institutions and also of commercial sponsors with limited resources.  This was especially true for sponsors of trials in which the participants' life expectancy was measured in years, sometimes in decades, rather than months.  Some sponsors volunteered their cost estimates for ongoing trials, and these estimates range from $1,500 to $5,000 per patient per year.
	Included in these estimates were costs relating to the yearly clinic visits, including the physician's billing, laboratory testing, sample collection, shipping, preparation, and testing for RCR in the first year, simple archival and storage, the equipment supplies and maintenance, the personnel required for data management, the clinical quality assurance, and adverse event reporting.  It also included provisions for periodic auditing and monitoring costs.
	Some of the sponsor investigators at academic centers were very concerned with the lack of resources, citing that most grants will only fund a study for up to five years and that alternative sources for lifelong monitoring are rarely identified a priori.  In addition, many of our sponsors noted that third-party reimbursement is usually sub-optimal.  It is unlikely to get an insurance company to pay for RCR testing for these patients.
	Another almost universal barrier to lifelong monitoring is that yearly clinical follow-up is not always feasible for all patients.  Some patients may move or may be lost to follow-up.  There may be geographic barriers with some patients having to travel across the country to return to the research centers.  Others may be from other continents, such as Europe, Africa, and South America.
	The patients or the referring physicians may lose interest in the clinical trial.  This was commonly observed by sponsors of clinical trials that involve children.  Now, these kids usually grow up to adulthood and typically would prefer not to come back to the research center.  Their priorities just have changed.
	Another issue that was raised by some of our sponsors and by sponsor investigators is the inability to consistently obtain adequately reports either from a referring physician to a principal investigator or a principal investigator to a sponsor.
	Another almost universal concern relates to the unusual level of commitment that lifelong monitoring requires.  Many ask:  Who is responsible for monitoring if a sponsor--or if a principal investigator moves to another institution?  What happens if that principal investigator leaves academia to the private sector or goes to industry?  What happens if a business goes bankrupt and no one assumes responsibility for the long-term monitoring?
	Commercial sponsors and academic institutions are reluctant to devote indefinite resources.  In one estimate, in a large trial that was going to involve participants whose live expectancy is measured in decades, budgeting for lifelong monitoring requirements required a half a million dollars per year per 100 patients.
	I think it is fair to say that for most studies autopsies are just not being obtained, even if our sponsors are well intended and motivated.  Most patients die away from the research centers at home or under the care of a hospice service or under the care of a treating physician.  When the patient dies or is near death, it is unusual that the sponsor will be notified in time, and usually an opportunity to request an autopsy has been lost.
	The hospice nurses or the local physicians are unlikely to ask the next of kin for autopsies, and if they do ask, families can decline that request, even in instances in which the participant had previously consented to an autopsy in a living directive.
	When autopsies are obtained, unless this occurred at the research center, it is unlikely that the tissue sampling for RCR testing will be performed.  If it is performed at those remote sites, it is unlikely that the specimen collection will be adequate or optimal for RCR testing.
	Another commonly raised concern by the sponsors is that the assays that are used for RCR testing lack standardization.  Some sponsors had asked for a central laboratory and archival center, essentially the equivalent of a core facility for which autopsies--for which the samples are to be sent and tested and archived.
	Sponsors are concerned about the sensitivity and the validity of these assays.  Are these assays providing reliable information that pertains to the integration or replication events?  Are the negative results reliable?  How is this information going to be used to guide us in the future?
	Some of the sponsors questioned the utility of RCR testing and the lifelong monitoring in studies in which retroviral vectors were used to transduce cells ex vivo, for example, the cellular vaccine administered intradermally after the cell had been irradiated.  Some investigators view these studies as different from in vivo gene therapy studies and may not feel as committed to the lifelong requirements that are in the guidance document, and they may not work as hard at getting that information for us.
	Since the March 6th letter, the FDA has received several requests to inactivate or withdraw retroviral gene transfer INDs, representing approximately about 15 percent of these INDs.  In instances in which surviving patients were documented, the sponsors were asked--and I have to say have agreed--to continue following these patients annually.  The FDA will continue to accept expedited and annual reports for all inactivated or withdrawn retroviral INDs until we have been informed that there are no surviving participants remaining.
	Now, to ensure monitoring will go on, the agency has limited enforcement options, and if it is the goal of lifelong monitoring to obtain quality information pertaining to the risks associated with the use of integrating and potentially replicating gene transfer vectors, it is unlikely that any of our enforcement options will get us better data.  It is unlikely that our enforcement options will solve the problems that are associated with long-term monitoring of patients.
	So, in summary, I have reviewed the current guidance documents and presented an overview of common barriers that are associated with lifelong monitoring of patients as articulated by the sponsors of retroviral gene vector studies.  Significant issues that were raised pertain to the logistics of long-term follow-up, the costs, and sponsors' commitment to doing lifelong monitoring of patients.  If it is our goal to obtain quality information that pertains to lifetime risk to participants, our strategy for monitoring must take into consideration the limitations that were presented here.  Finally, it is unlikely that the problems associated with lifelong monitoring could be solved by the FDA's enforcement options.
	Before I entertain questions, I want to thank everyone at the FDA who helped me with this survey, and I also wanted to thank all of the sponsors who have actually volunteered this information.
	Thank you.
	[Applause.]
	CHAIRMAN SALOMON:  I'd like to thank both the speakers this morning for a really excellent and pragmatic review of the situation.  And I think it clearly is a task for the committee to deal with, to maybe outline a series of reasonable principles upon which to do long-term follow-up that's more pragmatic than the current guidelines for all the reasons that were just outlined, which is going to be an interesting process.
	Ed?
	DR. SAUSVILLE:  But a pragmatic question is:  Where's the money going to come from for that?  I mean, because we can make recommendations, but should it be required of sponsors to fund this ultimately?  Should it be required of funding agencies?
	CHAIRMAN SALOMON:  I guess I have mixed feelings about whether that's something we ought to be discussing, or, you know, maybe I'll look to Jay and Phil and Amy to comment on it.  Do you think that we should be discussing where the funding options should be, or should we not get caught up in that right now and stick with the main topic?
	DR. SIEGEL:  I'm not a--we don't fund clinical trials, and perhaps Amy can comment more cogently.  I would say this, though:  If we're recommending that the protocol call for something, then it's somewhat duplicitous to have the protocol call for something to commit--in a protocol to commit to follow that protocol and to have that protocol call for something that costs millions of dollars that you don't have.  So, I mean, it's hard to avoid that question.  Should people be submitting protocols committing to do something that they can't afford to do?  I just don't know.
	DR. SAUSVILLE:  Yes, but to follow on what we heard from Dr. Anderson yesterday--and perhaps you could go where I think you would go with this--if you're worried about sequencing a few kilobases of DNA in terms of what physician investigators would react to this requirement, I think that pales by comparison to the potential implications of a sweeping generalization in this mode.
	DR. SIEGEL:  Oh, absolutely.  And that's why it's on the agenda.  I mean, the current status, as you've heard, is that we've asked for this commitment.  There is potentially some perception in the public domain, until an hour ago, that maybe even this data were in some sense being reliably collected.
	So I think we move to move forward from here with an honest--either saying we don't need the data, we need the data but we're not going to get it, or come up with a solution to ensure that we get.
	DR. SAUSVILLE:  But the biology is obvious.  I mean, from any of these vectors we clearly need it if this is going to be widespread.  I mean, you know, everything ranging from the particular patient to the larger societal concerns of people who might be treated at an early point in life, as you pointed out or someone pointed out, with a vector and then these people have long-term reproductive potential.  So, I mean, it would seem to me that from a biological standpoint the answer is pretty clear.
	But, you know, there's a discordance between biology and practicality that is really, you know, coming up now.
	CHAIRMAN SALOMON:  Well, I mean, a couple other people want to make comments, but so far what I'm thinking as a strategy here is I think that we should start by going through sort of what we consider based on solid biology, science, and some consideration of what is reasonably practical, what should be a monitoring scheme, and then come back to this sort of funding issue.  Because the real problem I have with the funding issue is that my NIH grant is for five years and then I'm done.  So if that's really true, then there's no long-term monitoring or I can't do any gene therapy trials, period, end of story.
	So, I mean, can't--if we make it that simple, we might as well all go home.  The sponsors then can worry about it, you know, because they're the only ones who've got any kind of money that goes longer than five years.
	DR. SIEGEL:  Let me respond to that to say I think that's correct, because I think that both the practicality and the costs associated with long-term follow-up depend greatly on what is long-term follow-up.  If you want to simply determine if somebody's alive or not, you know, you can do that through serial postcards, phone calls, and maybe get a pretty high reliability.  If you want them to answer a question or two, you know, you're going to get less data and more expense.  If they need to come in to draw specimens or to do physical examinations and have that reported into a center, that's going to require a lot more resources and have a lot more missing data.
	Whatever we do, I think if we focus it on what's most important, we're more likely to see it done better.  So I think you're right in suggesting first we need to figure out what it is we want and then how to get it.
	CHAIRMAN SALOMON:  I know French had a comment and Dick Champlin wanted to, and then Dr. O'Fallon and Amy.
	DR. ANDERSON:  The first time FDA brought this up was about four years ago, and I was sitting about where Xandra is and, Jay, you were sitting about where Phil is, and I violently disagreed for lifelong follow-up--not long-term follow-up.  I agree with long-term follow-up.  Lifelong follow-up for many of these reasons.  And at the end of that session, it was sort of left vague as to whether it would be lifelong or not.
	Afterwards, I contacted a number of people who run programs and their bosses, the deans, vice presidents of medical affairs and so on, and I posed them the question:  If the FDA requires lifelong follow-up, what would your reaction be?  And I basically had to first ask the question, well, what's the value of lifelong follow-up?  And in trying to answer that in terms of this sort of, well, what if this happened, what if that happened, the usual response I got was:  Well, if people start having cancer based on their gene therapy, then everybody would look for it, so why do you have to spend a lot of money to do a really long, detailed follow-up for something that might never happen.  But when we got past that, they said, well, what if it's required, the response was we will not commit to that.  If we have to commit to a lifelong follow-up, we will not allow gene therapy trials at this institution.  That's what I got across the board from a number of major institutions.
	Therefore--I mean, this is deja-vu.  We're now bringing up the issue again, and I don't have to say what I said yesterday because people know what I would say, and that is, you have to balance, and to budget a half million dollars a year to follow up patients for life on the grounds that you might find something, it doesn't make sense.
	CHAIRMAN SALOMON:  I think what we have to be careful now is that we don't take--I mean, I appreciate your comments, but what we've done now is gone to the end of the discussion and we haven't had the beginning of it.  I mean, I think what we owe the FDA--and really, if we are taking this one, we owe the field--is an intelligent discussion of what follow-up should be and why you should do follow-up.  And the politics of that follow-up and the funding of that follow-up and sponsors versus academic institutions, albeit all extremely important issues, shouldn't be the first thing we talk about, I think.
	You know, you could take a different view, but that's the view I'd like to take in the committee.
	DR. PATTERSON:  I'd like to say something, not about cost, actually, but I think an even more fundamental question or equally fundamental, what the biology is, what is the regulatory authority that FDA has to compel follow-up.  We can talk about a grant being over, but it's also important to consider if an IND is withdrawn by a sponsor.  What is--I think the committee, before we go down talking about the biology and giving recommendations, I think you need to understand what the FDA can and cannot do in this arena.  So that's the comment that I--I think if FDA--
	CHAIRMAN SALOMON:  I guess that's what I don't want to do right now.  In other words--
	[Laughter.]
	CHAIRMAN SALOMON:  Now, you can override me, Jay and Phil.  But, I mean, we have a choice here that I think has a lot to do with what we do this morning.
	If you want to talk about--before you decide what follow-up should be, you want to jump ahead--this is the way I'm putting it:  that we're jumping ahead to talking about what the FDA can then insist based on no recommendations yet on what it is they're supposed to be insisting on or regulating, then I think that's premature.  But if you guys disagree, then override me and we'll put this--
	DR. SIEGEL:  Yeah, I'll override you.  I think you can't--thank you for empowering me to do that.  I would simply say it's hard to tease apart the two issues, that you can't discuss--what we don't want is a discussion of what should be done in the ideal.  That's what we've had in the past.  And then to go on doing what we're doing, which is fooling somebody, ourselves, industry, the public, into thinking that we're getting what we all said we should get knowing that we can't get it.  So that said, it's hard to tease them apart.  I think when you discuss what we should get, you need to discuss it pragmatically both because of costs but also because I think it's very much a fact that the more things we try to get, the less good a job we'll be able to do at getting any of them.  I think that's a practical issue in terms of how you follow up patients.
	I think it would be worthwhile to give a little bit of clarification on that issue.  Our lawyers believe that a withdrawn IND, if the protocol calls for continued patient follow-up, the sponsor and investigator retain all their obligations for that follow-up and for reporting of adverse events.  To date, when we've received requests to withdraw, in that case we've asked just to avoid any confusion that instead they be inactivated, which means they can't enroll, but with clarification that they would still follow up.  And every sponsor has agreed to do that.  If they were to insist on withdrawing, it would not make too much difference from a legal point of view, but I think Philippe made a point at the end, which is that they're still required to do so but it's very hard to tell how much commitment and effort is going on.  You know, if we don't see data, we don't know what to make of that.  There's not a lot we can do.  We put trials on clinical hold, but if they're finished, that's not going to matter.
	We can send an inspectional team out and try to determine whether they're making good enough efforts to follow up patients, and if they're not making good enough efforts to follow up patients, you know, we could--there's not a heck of a lot we could do.  We could try to disqualify that investigator from doing FDA-sponsored clinical trials.  Then we'd get into an argument as to whether, in fact, their failure to follow up was because of lack of diligence or because, in fact, as we all know, it's very hard to follow up.  And I'm not sure--you know, none of those avenues look particularly promising as a way of making it happen.  But, yes, you are--you do need to continue to do that.
	CHAIRMAN SALOMON:  I promised Dr. Champlin and then I know Dr. O'Fallon would like to talk.
	DR. CHAMPLIN:  In other fields, of course, we try to do long-term follow-up for late events in hematopoietic transplants.  We've been trying to do this for many years.  And my observation is that as time passes, it becomes exponentially more difficult to get the patients back and to get good follow-up information.  And so as a practical matter, beyond five years, it's really--it's just a major problem getting even compliant patients to return, and all the problems that were raised--investigators leaving, companies closing down, et cetera--come into play.
	The other issue is that, particularly in blood tests, it's hard to envision that something that you haven't seen in the first few years is going to pop up 20 years later.  So even though there is a risk of cancer perhaps 25 years down the road, as it is with radiation exposure--you see solid tumors peaking at 25 years after exposure--so you do need long-term follow-up, at least in terms of the history of those events.  I'm not sure getting blood samples for that long is going to help you.  And so one might have a strategy of sort of intense initial follow-up with sampling of blood and tissue samples as appropriate and then some longer-term postcards and/or registry function that might contact people for the core information about birth defects, unusual diseases and/or malignancies.  And you're going to be looking for increases above the expected levels, of course, and so you're going to see birth defects and you're going to see cancer in patients as they live long enough, and the important thing is it's not going to be above what you'd expect in the background.
	The other issue is that you may not need to follow every patient.  If you would construct a study, you know, to look at a sample of patients for a given outcome over a period of time, you might avoid the need of 100 percent sampling of every patient for the duration of their life.
	DR. O'FALLON:  I might be expected to know more about this process than most of the others in the room, but I certainly don't know anything about it in the context of this particular category of patients.  Jay just said it perfectly.  The more you ask to collect, the more you try to collect on these patients, the less likely your study will be successful and the whole thing will die because of the weight of the process.
	Earlier, you used the term this isn't rocket science.  They're making it into rocket science because they're trying to shoot a rocket at a very precise target.  And if you have to do that, you have to treat it as rocket science.  If, on the other hand, you're perfectly willing to lob a rock in the general direction of the moon and are happy if it encounters some of the moon's gravitational pull, you might be able to pull that off.
	We have a horrible history in this country of doing things to patients and having no knowledge of what it is that's going on because we're not even keeping track of where the patients are because we don't even have a way of finding out who has had these materials inserted or this whatever we're talking about.  And the legal profession is stepping in and taking all sorts of actions and making all sorts of determinations that somebody is or isn't responsible for all of this.  And, of course, it's never possible for us to do a study to find out what's going on because we can't even identify the people who have had these insertions, or whatever.
	I have been involved heavily in the breast implant controversy, and we could not find women who had had their breasts implanted because nobody was following them up, nobody was keeping a record.
	If we didn't do anything other than try to keep an annual postcard follow-up on where these people were so that when people began to observe adverse events we can mount a scientific study, that I think is possible.  But if we insist that every protocol carry with it the extra burden that we've just been talking about of samples and follow-up and whether the samples are archived for 20 years or 30 years or studied immediately, that will ultimately spell the death of any program that you try to put in place for all the reasons that we've just heard, because of the financial aspects, the financial weight.
	But I think we owe it to the patients and we owe it to ourselves and we owe it to society to try to find some way to just keep track of where they are and who they are.
	CHAIRMAN SALOMON:  Okay.  I know Carole wanted to...
	DR. MILLER:  Again, from the bone marrow transplant standpoint, we know that it is important to follow these patients long term, and we've had major publications in the last couple years out of the International Bone Marrow Transplant--the Autologous Bone Marrow Transplant Registry, on 10- or 20-year follow-up of patients looking at the risk of secondary malignancies, et cetera, which really move--which really help us when we talk to the patients, you know, who are starting out now.  So I think as a scientific community, much less a legalistic community, we should be doing everything we can, I think, to collect as much long-term information on these patients as possible.  And it's possible through, you know, the national registries that are scientific in nature to follow up, you know, transplant patients, which are a volunteer organization, but are funded through a group of committed researchers who know that this is a life-threatening complication and there's long term--they've got together 20 years, 25 years ago now for the IBMTR and says we're going to follow these patients long term.  I think that that should be--that that type of rigor is really benefiting us, and so from a scientific standpoint, I think that that's what should be strived for.
	From a practical standpoint, I'm understanding of the risks and the difficulty, but this is--you know, I think that the minimum amount that we should be able to--that we should do is at least very aggressive follow-up for the first five years.  It works very well in bone marrow--I think reasonably well in bone marrow transplant, that you tell the person when they come to begin with that you need to be followed up for five years.  All these people getting gene therapy studies have a disease that, you know, unless gene therapy cures it, is going to need follow-up anyway, just like bone marrow transplant, you know, you need to follow up their leukemia, you need to follow up--I mean, and we have experience with genetic diseases where we transplanted people 20 years ago and we follow them out.  This can be done and most bone marrow transplant programs don't have a sponsor, except for the Federal Government and their academic institutions.
	So I really strongly think--support that we need to obligate people who are doing very exciting protocols to commit to long-term follow-up.
	On the other hand, I agree with Dr. O'Fallon that the easier you make it--and the archiving samples for 20 years is probably not necessary, if you put a finite in, you need to archive samples for five years, because that's the expectation that they're going to come back, and for the next 20 years you follow them up, year after that, and after 20 years, you know, we hope that by that time we'll all know what the answer is and not worry about that, and then you'll commit to lifetime, which scares people, but you commit to 20 years, which is four granting cycles, and we've had our BMT program project for 25 years, it can happen.  So that's from the transplant standpoint.
	CHAIRMAN SALOMON:  I wanted to amplify from the organ transplant standpoint, there's already very well established precedents, and in the U.S., our renal disease database has tracked patients through HRSA, through dialysis, all the way through to transplantation, and there's follow-up now available that's over 20 years.  It's accessible through the Web.  It's accessible to the press.  It's accessible to investigators.  There's United Network of Organ Sharing, which follows all kidney transplant, liver transplant, heart transplant, pancreas transplant patients.  There's another--a series--there's North American Pediatric Transplant Registry.  There's the ESOT Registry for transplantation, and I can list two or three others, Tarisoki's (ph) Registry, some of which have 20-year follow-up.  We all voluntarily--they're Web-based access.  I mean, there's a lot of things that can be done.  This is plenty of precedents for very functional, long-term databases in other disease states and therapies, and we just, you know, heard about the International Bone Marrow Transplant--
	DR. CHAMPLIN:  I think the common feature of all this is that you need an infrastructure.  You need an organization whose job it is to collect these data, and there needs to be a funding mechanism, and you have to have a nurse, a research nurse or a data manager that calls the people.  And it's going to become an increasing burden when you've got thousands of patients that you're following and not just a handful.  And so gene therapy programs over time, assuming the growth--expected growth of the field, this is going to become an enormous burden.  So there has to really be an organization whose job it is to do this function, and it's a big cost.
	And so it always comes down to, you know, on the grand priority scale, should we be putting millions of dollars into this function or should we be putting millions of dollars into fundamental research in cancer therapy or gene therapy or whatever?  And it's a big cost for possibly a small return, but we all agree it's an important question.
	DR. SIEGEL:  One other point that adds to the complexity here is that for most of those registries that you've mentioned, most of the patients are getting essentially the same treatment by essentially the same route for more or less the same disease, although the etiology--well, you're shaking your head, and I know there are lots of reasons your kidney can fail.  But let me assure you that when you start collecting--if you start doing something like that for gene therapy, are you going to start--you know, in determining cancer incidence against background, are you going to, you know, compare a topical therapy, a local injection of an adenovirus with an intracerebral injection of a retrovirus, or that with a three order of magnitude higher dose of a totally different retrovirus that's been engineered to avoid some of the problems of the first one?  It's like there's so much variability that it's hard to know even how or where to group the data when you think about that, which is--
	CHAIRMAN SALOMON:  The reason--
	DR. SIEGEL:  --exactly on point for long-term follow-up but is on point as to the ease with which simply creating a registry is a solution.
	CHAIRMAN SALOMON:  Well, the reason I was shaking my head is that if you go to the website right now at UNOS, you can follow kidney, heart, lung, liver, pancreas, small bowel.  In other words, they're all different.  They're all--over the last ten years there have been at least ten different immunosuppressive regimens.  So, I mean, all I'm saying is that you can collect data.  That's all I was shaking my head at.  If you want to talk about how to evaluate the significance of data in gene therapy, all your points are well taken.  I have no quick answers for any of that.
	DR. PAPADOPOULOUS:  I just wanted to make the point that, you know, this whole concept of collecting data is really the same--this is the clinical version of the sequencing issue that we had yesterday.  In the ideal world, we would want to collect data forever, clinical data forever, and that's just not feasible.
	There is also the other issue that there's the public perception of what we're doing and what we need to do, and perhaps what would be an intermediate step is to demand, request information be collected and samples be collected for a certain period of time, and then make the public comfortable that beyond that period of time, through extensive patient education--and that's not cheap, either--that the patients are fully aware that--and as Carole said, these patients usually have an illness which requires ongoing medical follow-up.  It's not as if the majority of these patients are going to be lost from any medical follow-up.  But to have patient education of the importance of follow-up and through just yearly postcards and surveys and things like that, that information be collected.  The key thing is that there has to be, as Dan mentioned before, an infrastructure, there has to be some organization to receive that information, like the IBMTR, ASBMT, et cetera, et cetera.  But perhaps putting some of the burden on the patient that they have to be educated early on in the process, those that are going to be long-term survivors, obviously, may leave an out for the public awareness that we're doing something for the patients who are alive 10, 15, 20 years down the line.
	DR. SAUSVILLE:  I was going to pursue a point that may be a corollary of an issue that Jay raised and actually does want to point to a potential difference in comparison to what we'll say, the organ registries.  I mean, you know, you don't have pancreas version 1.1, 1.2, pancreas with a different promoter.  I mean, you know, there are numerous technological issues that come into differences between different trials, and in a sense, you're making a requirement of sponsors that is going to be perceived as treating them differently, for example, than other drugs.  These things are sort of on the interface between an organism or an organ and a drug.
	So I think that we should consider, again, with an eye toward promoting the many possibilities of this field, to consider how sponsors would react to requiring them to put in some sort of quasi-public database what ultimately are, shall we say, strategies in formation.  And I think that's an additional difference in comparison to the transplant-related issues.
	CHAIRMAN SALOMON:  Well, I think, you know, I mean, there's an obvious danger here I'm going to try and step aside from, and that is, you know, get into this ridiculous, well, no, but pancreas transplant, you know, you could do with steroids and without steroids and with cyclosporin and with FK506 and with micro-fanolay (ph) mofitil and with rapamycin and in all different combinations--
	DR. SAUSVILLE:  That actually illustrates the fact because all of those immunosuppressive regimens after the fact become legally defined treatments that we can all talk about.  But in the anterior case, when you're developing the agents, I mean, I'm sure we don't have the detailed, shall we say, dossiers, the registration dossiers, for those agents in anything that approaches the public domain.  So there is a difference.
	CHAIRMAN SALOMON:  So Ed makes a couple of interesting points here that I actually have a note to bring up, and so this is a good time to bring it up.  That is, who is the target for a database?  And who are we designing a database for?  Are we designing it for scientists?  Are we designing it for a regulatory agency, specifically the FDA, or for government agencies like the NIH and the CDC, et cetera?  Is it for sponsors?  Is it for the press?  For the public?  And for the patients?  Who is it for?
	DR. SIEGEL:  Well, I think Amy spoke very well to the fact that there are many potential consumers of a database, and they're all quite valid.  But I would like to focus today's discussion not so much on who to build a database for but on what information FDA should be requesting and requiring, because that's a question that we need an immediate answer to, independently of how the database is structured or whatever.  Hopefully there will be a database that will be populated with information, but it's likely to be populated only with that information that protocols call to be collected and that we--and that is feasible for people to collect in an efficient way.  And those decisions are the decisions that we really need to be making now as we're reviewing the protocols.  What information will be collected, how, and by whom?
	CHAIRMAN SALOMON:  Well, you could narrow this conversation to a database for the FDA, which, of course, is a big narrowing of the conversation of this morning--
	DR. SIEGEL:  Fair enough.  Which isn't to say that we're by any means the only or not necessarily even the primary consumer.  But it is our current interest, what information we're going to ask for people to collect and ultimately submit to us and presumably--
	CHAIRMAN SALOMON:  So I guess my response to that, in a question form, is:  In one way, of course, it satisfies Ed's issue because if it's to the FDA, it's all confidential and we don't have to worry about all this stuff being in the public domain.  I don't know if that's a good answer, but that would certainly satisfy that problem.
	But the other question really is:  Is that the best advice that this committee can give the field at this point?  I mean, I think we've not succeeded because every time we get at these issues, we become divisive.  So we're talking about a database that the public wants, but now we're talking about only the database that the FDA wants, but not the database that the RAC wants or the database that the Congress wants or the database the sponsors want.  And then, of course, nobody has any money to do any of it.
	DR. SIEGEL:  First you have to collect the data or you can build all the databases you want and you won't have data to put into it.  It is our hope--it is our intent, as we've publicly stated in the past, in the last year in the FDA, that a significant amount of gene therapy information that's submitted to the FDA will be releasable into the public domain, but the rules--you know, there's a limited amount that one can discuss rules that are under development.  Suffice to say we have stated publicly and committed publicly to promulgate rules that would allow substantial additional release of information into the public domain.  So it would be our hope that if more information were submitted, whether to the FDA or elsewhere, that could be used to populate a database whether it's at the NIH or elsewhere, or that would be--or directly from the FDA that would be publicly accessible.
	But, again, the issue is what information to collect, and I might--you know, as we've moved along and talked about the types of information and the pragmatic implications, I think, you know, the wisdom of your earlier remark is growing in my mind, not surprisingly, and I'm thinking that maybe--
	CHAIRMAN SALOMON:  I was going to point it out in a second.
	DR. SIEGEL:  Right.  But I didn't want to divorce the science from the pragmatism, and I think we need to address the pragmatism, but we need to address the science, and the first question goes to that, because we're talking about gene therapy as a group, for one thing, and as we all know there's a great deal of diversity in gene therapy, and to date, as highlighted in the talks, our policies have focused on retroviral gene therapy because of--largely because of concerns about insertion, but then, again, there are--there's a variation among retroviruses and how much insertion there is.  There are other vectors that insert and there are long-term risks besides insertion, and we would like to focus on where--how to determine when and how much long-term data is necessary.
	DR. CHAMPLIN:  One other side of that is, you know, who's going to look at the data, how is it going to be presented.  It would, of course, in the public interest to know what the cumulative risk of malignancies related to retroviral systemic treatment would be, just as it's been published what the risk of secondary malignancies is after an autologous bone marrow transplant.  So you're pooling thousands of cases, you know, from different centers here.  One would be potentially looking across many companies for protocols, but someone would need to access that data, analyze it, and then present it publicly, and with all of the, you know, considerations for proprietary information.  But, still, this is what Amy and others are calling for.  Somebody wants to look at the public safety of the overall strategy of gene therapy.
	CHAIRMAN SALOMON:  Dr. Noguchi, and then Dr. Torbett.
	DR. NOGUCHI:  Yeah, I'd like to try to just address Dr. Sausville's very cogent point, and this is a very unusual field.  Actually, in terms of the proprietary nature or what we would term commercial confidential typical FDA submission, that's much less of an issue in this particular field because of the presence of the RAC and the public review process.  Whether or not a protocol is discussed publicly, information that is sufficient to really distinguish between promoters and retroviral--within retroviral vectors as an example is available.  And I think that we should not try to distinguish this as an FDA requirement or public requirement, but the fact of the matter is that FDA is charged with the regulation of this field, and as such, information is submitted to us.  But we certainly do feel that the scientific information has pretty much a public domain aspect to it by its history and the continued public exposure through the RAC.
	We too often get into that if it goes to FDA it's all private.  That's not totally true, and especially in gene therapy it is not true.  Much of it is public.  Some of it is not.
	DR. CHAMBERLAIN:  I guess some of us at this end of the table are a little confused, because when you set up a database, you know what you're going to use that database for, and you have to have inclusion of that, what particular--who you're going to--what audience you're going to address, how that information is going to be assessed.  And I guess I haven't heard--at least, I think all of us have an idea of what database internally means, but I think it's clear from each individual here that we all have a different idea what that database should be and who the database is for.  And I don't think that's clear to some of us down here at this end of the table.
	DR. GORDON:  Yeah, I think I'm quite impressed by the differences drawn between procedures such as bone marrow transplantation and organ transplantation as global field and gene therapy.  I really think one thing that could help the FDA would be to advise them that a blanket protocol for follow-up is not suitable here, that what we need to do is look at what the protocol is, make some assessment of what kind of information would be important in long-term follow-up, and gear the follow-up protocol to what's actually been done to the patient.
	I mean, on RAC, we've seen normal people get subcutaneous replication-defective adenoviruses to see what kind of antibodies they develop.  Well, it's still going to be very difficult to give that person a lifelong follow-up or do Southern blots on all their children if they're not going to cooperate with that.  So, you know, in the cases where people are seriously ill, the follow-up won't be as difficult.  They're going to have to be followed for their illness.  So I think one thing at least we might be able to do is advise FDA that follow-up needs to be tailored and the data collected would then be tailored.
	DR. SIEGEL:  But wouldn't that lead to only seeking long-term follow-up on people who aren't going to live for a long time?
	DR. GORDON:  No, no.  Not at all.  You could easily have a person born with an enzyme deficiency who receives a retrovirus, and they could live a very long time, but that could be tailored as a long-term follow-up protocol.
	Now, again, I'm not typically thought of by people other than patients as a patient advocate, but here I have to say that to tell a person--I mean, sure, it's a burden on the sponsors to follow people up.  But what about the burden on the patient to be followed up?  It's a big burden, and they may not cooperate.  But I think FDA can't control that.  They can just say, look, if you're seven years old and you're getting an enzyme deficiency correction by gene therapy, we recommend the following follow-up protocol, and that would be different from a person with a melanoma getting an intratumoral injection.
	DR. BREAKEFIELD:  Yeah, I mean, I think the more scientific information we can gain and the more hands it is in to be analyzed is going to be beneficial.  But I guess the thing I worry about most is just kind of a real epidemiologic disaster.  You know, some of these replicating vectors that could have altered tropism and could be shed into the population or trials where, you know, they're putting BEGF in to cause angiogenesis in the heart, but actually it could cause tumor formation even in a relatively--you know, five-year period.  I think we have to target our questions as much as we can.  What are our concerns, our wildest concerns?  And we have to make sure that we get that information.  We don't want--you know, these are amplifying drugs, as somebody once phrased it, and we have to at least make sure that we capture anything that is going to be a real public--you know, major public problem, whether it's that you do induce cancer in somebody within five years based on a certain type of therapy or that you generate a novel vector, a novel virus that's going to cause--whether it causes warts or whatever else it does, people are not going to be happy.
	DR. ANDERSON:  Well, in the first place, let me say that this discussion is infinitely superior to what we did four years ago, and it's getting me thinking, particularly some things Carole said in terms of we already follow up many of these patients because they have a long-term illness.  And so I was just thinking about my own personal compliance if this were a requirement.  Some protocols, like our ADA protocol, Ashi DaSilva (ph) doesn't have an illness that I'm not on the phone with either the family or the doctor.  It's been ten years.  That will go on--well, she'll live longer than I do, but certainly my lifetime.  A lot of the protocols that have been associated with it didn't work.  I don't know.  There's no way we'll get a follow-up on these for 20 years.
	So I guess what I'm trying to think of is what is something practical.  I mean, that's what we're here for.  What's the practical--and so I'm going to make a proposal simply as a start, and it's going to be exactly what Dr. O'Fallon said, because I think that is right on, and that is, clearly for five years, every one of us agree five years is perfectly appropriate, intense follow-up, exactly as the FDA says.
	But after that point, there are going to be specific protocols like replicating adenovirus where one can have a feeling that one would like to know where those patients are.  And my feeling is, having listened to everybody, thinking about it, that what is enforceable, what investigators and sponsors will do--and, you know, in the last analysis, if investigators don't think it makes sense, you know, it's going to die.  I mean, you can pound and you can shout and so on, and you can say we'll send an inspection team.  You don't have the resources to send an inspection team.  Even when there are--not big problems, you certainly do when there are big problems, but even when you know there's a little problem.
	So I guess if it's five-year follow-up and then there is a clear agreement to maintain contact with the patient, whether it's a yearly postcard--you can give your list to a secretary to simply call once a year to get a follow-up, get a current phone number and who the physician is, and that's doable.  But as soon as you talk about bringing the patient back, come back from Cleveland to get a blood study and the patient or the family says, Why are you doing this?  Well, because the FDA demands it.  That's--
	DR. SIEGEL:  Are there--you know, Question 1, which asks:  FDA currently asks that gene transfer trials using vectors with demonstrated potential for genome integration would include plans for long-term follow-up.  What characteristics of gene transfer methods should trigger the need for long-term follow-up?  Well, you've suggested that there might be certain types of vectors where you want more.  Are there not somewhere, in addition to knowing where they are, you'd want to seek information about, say, malignancies, congenital anomalies, maybe neurologic, hematologic disorders in the case of retrovirus?
	CHAIRMAN SALOMON:  Jay, before French answers that specifically, what I wanted to do is do exactly what you started to do.
	DR. SIEGEL:  I'm sorry.
	CHAIRMAN SALOMON:  No, no, no.  That was perfect.  So you just did what I was going to do, is read Question 1, because I think we need to get on with specific questions, because I think that the conversation has devolved back around to it, is let's be practical, but what it is that--you know, what protocols, what principles for long-term follow-up can we come up with that are reasonable now, and then we can vet it against the discussion we already had about practicality.  And I'm not giving up so easy on the idea of--I can't advise the committee at this point to restrict it to just what we think the FDA wants.  I'd like to just see it in general and then we can maybe ferret out--if there's something unique that the FDA wants that the RAC doesn't want or the public doesn't want.
	DR. SIEGEL:  I don't think that's a real or a significant distinction in any case.  I think we're all interested in learning what we need to learn about the safety and efficacy and long-term effects of this environment.  It's hard to imagine--you know, different people have different opinions, but it's hard to imagine information that's of interest to the RAC or the NIH and not the FDA or vice-versa.
	CHAIRMAN SALOMON:  I'm more comfortable with that then the idea that this is just about the FDA.
	So let's pick up these things that we've sort of come to logically, and that is, we've got--like we spoke yesterday, there's a universe of different sorts of vectors, retroviral vectors, adenoviral vectors.  Actually, we've discussed these.  Let's have some discussion about by vector--I mean, there's a whole bunch of different issues, but let's just say by vector type first.  I'm just trying to start somewhere, with the different kinds of follow-up.  So integration, does everyone agree that an integrating vector is a dividing line for, you know, a follow-up issue?
	DR. BREAKEFIELD:  Well, I would say integrating vector and certainly any vector that has potential replication competence needs to be tracked.
	CHAIRMAN SALOMON:  That's two things:  an integrating vector and a replication-competent vector.  Does anyone want to add--is that a dividing line?  So if you approach a gene therapy--any gene therapy trial at any point, would a general principle be is it integrating or replicating, and that would be an important thing to consider.  I'm not saying there aren't five other things, but does everyone agree those would be two important things?
	DR. GORDON:  Yeah, I think that overlaid on that is the issue of whether they're put into a cell with the potential of replication.  In other words, I would make a distinction between irradiated cells that receive integrating vectors ex vivo and are put back from integrating vectors injected directly into meiotically competent cells in the person.  So I think if you generalize to say replicate--vectors with the potential of replication, whether it because they're integrated and the cell's replicating its DNA, or whether they're replication-competent is a class of vectors that requires special attention.
	CHAIRMAN SALOMON:  Okay.  So if a gene therapy protocol would involve a cell that's irradiated, so that there's no reasonable expectation that any of those cells would survive, that wouldn't fall--that wouldn't cross the line, let's say, into this group of--but if it otherwise would be some--there'd be long-term survival or at least a reasonable expectation, we should say, because we don't really know what the efficacy of a given trial is before it's done, but if there's reasonable expectation if the trial is successful that the cell line carrying an integrated vector will survive, so that now covers an ex vivo treatment and transplantation of some sort or in vivo treatment with the design to get integration.  Or if we have replication-competent virus--
	DR. SIEGEL:  That's an important issue.  I think Philippe noted that a number of investigators have proposed that ex vivo transduction not be followed the same way.  I just want to make sure we've explored that because you potentially can create 1012 insertional events, right, ex vivo in non-replicating cells and put them into the body to exist long term.  Are we, in fact, saying that because that's limited, those cells aren't going to reproduce, there's not going to be more virus, and it's not going to get any more exposure than just 1012 cells that we don't need the same sort of follow-up?
	CHAIRMAN SALOMON:  I guess the purpose of trying to articulate these principles is to deal with that; in other words, to--if a principle is fulfilled by ex vivo therapy, then it's fulfilled.  And if it's not, then it's not.  But the idea is that there are any living cells that are not replicating is just not biologically very valid any longer.  I mean, any cell that's living can replicate.  We even know that neuronal cells, which for many years the paradigm was couldn't replicate, we even know they're replicating.
	So, you know, certainly any cell that there is a reasonable anticipate is going to survive function in a dynamic tissue environment, to me fulfills the principle of a cell that--you know, of a therapy that should be followed in a different way than, let's say, an irradiated cell or a cell that doesn't survive.
	DR. BREAKEFIELD:  Even a cell that isn't going to--even if it wasn't going to propagate and is infected with, let's say, a retrovirus vector that was contaminated with RCR, so we have to decide whether our level of contamination could go on to produce those on-site.  So--
	CHAIRMAN SALOMON:  Right.  So that would fulfill the principle of replicating vector.
	DR. BREAKEFIELD:  But I think it's less of a chance than if you flood the body systemically with a retrovirus vector, for sure.
	CHAIRMAN SALOMON:  I was saying that that's a good example of the principle working.  So there the principle was that there was a replicating viral vector that was put in, even if the cell itself was irradiated, we know that an irradiated cell can replicate--you know, can do gene transcription and replicate viral vectors.  In fact, we all know that radiation actually can enhance retroviral gene transcription, for example.  So I don't think the irradiation has anything to do with anything if you've got a replicating vector being transplanted.
	DR. NOGUCHI:  But isn't it also--if you're talking about a replicating cell or living or not living, I think for many of us at FDA when we review something, irradiation is not killing the cell.  It's inactivating the component of it, but it's still metabolically active and may be secreting cytokines.  So I think we need a little clarification, Jon, really, on what you meant.
	CHAIRMAN SALOMON:  Well, let's--I mean, the question here is, if you irradiate cell, so Phil is saying if I irradiate a cell and transplant it, would that cross a line into a long-term follow-up by the principle?  Now, my argument would be that that cell wouldn't survive, that it would last a couple weeks, at least in vitro, I've never had any irradiated cell survive in any of my cultures for more than a week or two, though some stable epithelial cell lines maybe longer, but, I mean, essentially no.  So I think you could still argue that those wouldn't cross the line by the principle to long-term follow-up.  But, you know, other comments from others, including Phil?  You don't agree?
	DR. SIEGEL:  So is the issue cell survival or cell replication?  Because I'm confused about the scientific importance of cell replication.  If a virus replicates, well, as we saw in Neenhouse's (ph) animals, you have the opportunity for many new insertional events at different loci.  What particularly is the relevant risk factor of whether the cell replicates, or is it really whether the cell survives?  That's the concern.
	CHAIRMAN SALOMON:  I wasn't making a distinction.  If the cell survives--I was just pointing out to you that any transplanted cell that's not irradiated and survives replicates.
	DR. NOGUCHI:  I guess we're still a little confused here because what happens in vitro is by no means the same as in vivo.  We really don't have a whole lot of information of how long irradiated cells would last implanted in any given site.  So what we're looking for is, I guess, a brighter line.  Are we talking about cells that we expect to survive beyond a certain time when implanted?  That would be very useful to know.
	CHAIRMAN SALOMON:  Well, that's excellent.  So we could say, then, as a--you know, to the list of the principles, if you don't have confidence that an irradiated--that irradiation per se doesn't necessarily guarantee that the cell will only live transiently or survive transiently--and I'm not going to argue with you because I don't have any in vivo data--then the response to you would be that a protocol involving an irradiated cell with gene therapy, with integration, right, that was transplanted, that either the sponsor or the investigator would have to show very clearly evidence that convinced the FDA review that it wasn't surviving, or that it would cross the line into a category that would require long-term follow-up.  Does everyone agree with that?  I have no problem with that.  Carole?
	DR. MILLER:  There's two reasons--I mean, there's many different reasons, but, I mean, you can separate cells that are used to be--are gene altered in order to provoke an immune response--we're talking about vaccines--versus alterations that are either ex vivo or in vivo intended to survive and replace something that is missing, correct?  Isn't that the two major--if you're doing it simplistic--
	CHAIRMAN SALOMON:  Well, if you get a vaccine and the--I would just--following the--again, I'm trying to test the principle with these different examples, but if you did a vaccine that irreversibly modified a cell and that cell survived, even if your strategy was rather a short-term interaction with the immune system, if the integrated cell survived and/or propagated, it still would fulfill the principle and require long-term follow-up.  Just because you decided that it only had its impact for the first three weeks, if the cell survives and has an integrant, it would still fall under the principle for long-term follow-up.
	DR. ANDERSON:  Well, using your principle of hypothesis-driven science here, a non-replicating cell is not going to pick up the additional hits to end up with a cancer--I mean, all we're really concerned here is are you going to get cancer, are you going to get in the germ line, are you going to affect some other gene so that it messes up the immune system or the neurologic system or something else.
	So what are the chances?  Well, yes, you could argue, well, there might be one chance in 108 that a non-replicating cell might turn on a gene that might turn on a fact that might be next to something in the--but, you know, now you're going way out.
	If you've got an integrated gene into a blood stem cell, I'd say that this is long term.  But just because you're in a cell that survives but seldom divides, you're not going to pick up the multiple hits to really have an effect.  So I think we're pushing people--what you--what you're trying to get at, and I agree with, is where's the percentages of seeing a problem, because what this field cannot survive is another unexplained death--much less an explained death, which is something worse.  And what we want to avoid is that suddenly there's a rash of hundreds or thousands of patients that develop a lymphoma or leukemia because of a gene transfer ten years before.
	But, of course, if that happens, it won't be stopped or detected because of a database.  It'll happen because hematologists look at this and say, great, you know, this person got gene transfer, let's look and see what we find here.
	So I guess--I was trying not to say anything, but it sounded like we were starting to push too much and including too many things, and I'd rather stick with Occam's razor and just say what are the most likely things where you need a special long-term follow-up, and a replicating virus or integrated virus in a dividing cell fits that, and I'm not sure if anything else does.
	DR. NOGUCHI:  Just to argue a little bit on that, French, the fact that if a cell survives that has an integrated virus, that you can guarantee would never replicate is one thing, but this is biology, you can never guarantee that.  Certainly there are multiple cases of things coming from a non-dividing cell can cross to another cell, thereby lending it--and I would say that the experience with cold culture as a more sensitive method of detecting replicating-competent retroviruses would just suggest that the chance of something happening with a long-living but not dividing cell with an integrated virus would not be terribly different than with a growing cell.  I mean, you could still get those things.
	The question, I guess, we're just trying to articulate is, based on the science that we know right at the moment, is the distinction between dividing cell and non-dividing cell sufficient for us to make that distinction at this point or not.  And I think we're getting very good discussion on trying to hone in on that, so I wouldn't--
	DR. CHAMPLIN:  What do you consider a non-dividing cell?
	DR. NOGUCHI:  Non-dividing living cell is what we're talking about here, specifically because irradiation may or may not render that cell capable of long-term survival.
	DR. CHAMPLIN:  If it's irradiated--and so I guess I would just think of three sort of simple categories.  You have that example, say the example of a transduced endritic cell or immunotherapy protocol where you've irradiated the cell, it's expected to survive only a short time, and it's a non-replicating integrating virus, you would not expect, logically, at least, in that situation, late events to occur, assuming you don't--you can't demonstrate replication.  So that would be perhaps one setting that you wouldn't need long-term follow-up.
	On the other hand, if you are having a non-replicating virus in a long-term surviving cell, say, for example, a lymphocyte, is transduced with PK or another vector, those cells might become lymphomatous presumably over a long period of time and you would need long-term follow-up for such a trial.  Or if you transduced liver cells, you know, that could develop hepatoma over a period of time.
	And then any time that you had a replicating virus, of course, then you'd need long-term follow-up.  So the one situation where I would envision you might not need long-term follow-up is an irradiated short-term cell with a non-replicating virus.
	CHAIRMAN SALOMON:  Xandra?
	DR. BREAKEFIELD:  Yeah, I just wanted to add, I think I actually agree with everything that French and Richard have said.  I think it depends on how you put the gene in though.  You know, if you just use DNA transvection to put a gene in and the cell can't divide, I mean, I don't think there's much of a risk.  But, you know, if you put it in with a retrovirus vector, then you do have to worry about the recombinant replication-competent vectors.  So in a way, it's how you alter the genome that determines if it succumbs to the potential risk to generate a virus in the future.
	CHAIRMAN SALOMON:  But can I just make one point as a cell biologist?  There is no such thing as a non-replicating living cell.
	Okay.  Now you're playing rate, but I'm just telling you that it's replicating.
	DR. SIEGEL:  Next somebody will probably say that there's no such thing as a non-integrating virus, it's just a matter of frequency, right?
	CHAIRMAN SALOMON:  Now, one thing that--so I think you've got a set of principles out of us that we, you know, touched on a couple examples and they, you know, created a little controversy, but nothing that we couldn't handle.  So maybe that's, you know, a step in the right direction.
	The question I now have is:  Retroviruses definitely integrate.  Now, but we can't--that's the easy one.  Let's talk about viruses that create these episomal DNA, such as the herpesviruses, EB virus, poxvirus, and then I'd like to go to the really hard one, which is the adenoviruses, which apparently can catamarize and that they can detect DNA later and there's a possibility of recombination in the genome.  So let's deal first with, you know, these different forms of episomal DNAs.  Are those--they're not integrated, so what do we think of that?
	DR. SIEGEL:  Let's also put on that list plasmid-vectored gene therapy because we're--it's a significant class that we need--
	CHAIRMAN SALOMON:  Okay, okay.  Fine.  Let's start with just the herpesviruses because I brought that up first.  Then we'll do plasmid and then we'll do the adeno, because I find the adeno is not my area of expertise.  I'll look to others for that.
	DR. BREAKEFIELD:  So if we just take EBV and herpes as examples of episomal states, EBV is in a replicating episomal state.  It replicates along with the cells.  So I would say that although normally it doesn't integrate, its chances of integration are probably higher than certainly something like an adenovirus, I would think, a non-replicating adenovirus.  So it's--I think you have to--people haven't actually, you know, quantitated that in great detail.  I think you need to know that.  But it's there.  It's replicating along with--it's associated with the chromosomes.  Its chance of integration is relatively high.
	With herpesvirus, when it's in the episomal state, it's a very condensed nucleosomal configuration.  It doesn't even express genes very well.  And so I don't think it's a problem of integration when it's in that state.  The problem, of course, with herpes is reactivation.  You know, that you can't--is it going to at some point reactivate and especially if it's replication-competent, cause, you know, additional problems.  So it has its own problems about integration, but it's a different type.
	But the other issue is that, you know, the new trend in vectors is hybrid vectors.  So people take mixed and--many people in gene therapy want to integrate, so they take elements from retroviruses and put them in the context, so they're trying to get integration.  So I would say discuss the common viruses now that people use is just very early stages now, we're going to--
	CHAIRMAN SALOMON:  Just so that we kind of go back into these principles, again, if we put in a replication-competent vector, then that fulfills the principle that we go on and follow it, right?  So in the sense that a herpesvirus, let's say, can be reactivated, we should say that that's interpreted as therapy involved being transplantation of a cell with a replication-competent vector, it fulfills the principle and needs long-term follow-up.  Right?
	DR. BREAKEFIELD:  Right, and I would say any genome, even if it's non-replicating herpes, that's in there, that's in there for a long time, and when it--when it reactivates, it doesn't have to make new virus.  It could reactivate and then make itself available integration.  So there is always a chance that that DNA is staying in the cell long term that's integrated.  It's just what is the relative frequency of that and at what point should we be concerned.  We need to know the relative frequency, and then we can say this level of frequency we're going to live with, you know, and what those levels would be, I'm not sure, actually, right offhand, but I would say there's probably some--the relative rates will be so low we won't be concerned about it.
	CHAIRMAN SALOMON:  Okay.  So I would say by the principles of caution, given what we know now, it would be reasonable not to exclude the herpesvirus vectors from any of this, in other words, it's not just retroviral.
	Dr. Gordon?
	DR. GORDON:  I just wanted to say the same, that I think if vectors are replication-competent, even if it's only a potential competence, then I personally have the intuition that the risk of integration is commensurately increased and, therefore, I think that's the major categorical division in my own mind, is if they're replication-competent, a different level of attention needs to be paid to them.
	DR. ANDERSON:  I think Xandra has made a superb point.  I suddenly feel like the old thing about generals are always planning how to win the next war based on the previous war, and it never works that way.  And I was thinking about the main things that we're doing, we're developing hybrid vectors, adeno-retroviral, adeno-linthy(?) virus, replicating this, adenovirus with a replicating retrovirus inside of it.  And I've been thinking, looking at the tables in here, as we have adenovirus--that's not where we're going.  So we've got to do it based on function and what happens, not is it a herpes or is it an adeno or is it a something, because that's not where we're going.
	DR. SIEGEL:  You'll note our question, in fact, for that very reason doesn't ask which classes of virus.  It says what characteristics of gene transfer methods should trigger.
	CHAIRMAN SALOMON:  I think that--I'm hoping that's what we're doing here.  So how about plasmids?
	DR. NOGUCHI:  Before we go there, Jon, could I ask a little more detail there?  You said replication-competent or potentially replication-competent.
	DR. GORDON:  Well, if you have a latent virus, it may not be regarded at the moment as being replication-competent, but it could make itself available for integration, which would make it replication-competent, because the cell can replicate.  All non-replicating vectors that we know about will have some possibility of replication-competent contaminant.  So how does that--does that make any difference to you?
	CHAIRMAN SALOMON:  Phil, I think the principle here that we're saying is it's not that there might be a small contamination of replication-competent retroviruses.  That you have to figure out up front, and if we can't satisfy--I think if a sponsor or an investigator doesn't satisfy you that they've--that that's enough, then it--you could use the same principle and say I'm not satisfied, there may be contamination by RCR, and that would be--that would fulfill the principle.
	I think what we're talking about here is the distinction of latent virus, that a lot of these vector types are latent, and so they may--they're not really correctly replication-competent, so we were amending the principle to say replication-competent virus or latent virus that could become replication-competent given stress or immunosuppression or something else.  Is that fair?
	DR. GORDON:  Yeah.  I just wanted also to make a brief comment about the tenor of the discussion.  I remember when the guys went to the moon and they came back, and they were sitting there on the runway or whatever, and there was some question as to about when they should be let out because they could have picked up some infectious organism on the moon, for which we have no resistance.  So should they still be quarantined today?  I mean, I don't know.  But I'd say that an appropriately defensive person might have done that, then I think at some point we have to figure out what is our best guess about what is the greatest risk.  We can't do everything in every situation.
	DR. ANDERSON:  But, Jon, you remember what happened when that happened.  Lyndon Johnson just broke the quarantine, walked over and shook their hand in front of television.
	DR. GORDON:  Well, whatever happened there--
	DR. ANDERSON:  And nobody died and so they forgot the quarantine.
	DR. GORDON:  What I'm trying to say--
	CHAIRMAN SALOMON:  That's great TV, French, but I don't know if that's public health.  But my point is--
	DR. SAUSVILLE:  Actually, I think Lyndon is dead, but--
	[Laughter.]
	DR. GORDON:  Well, what I'm trying to say is I think if you have criteria for a level of contamination, I don't think you should then get paralyzed because you're never going to eliminate all of it.  And I--
	CHAIRMAN SALOMON:  My strategy would be--no, I think that's fine, and my strategy here is enunciate a series of principles that would require some type of long-term follow-up without any implications yet from the committee on what that long-term follow-up is, and then deal with that issue directly.  So you're just one step ahead of where I was trying to go.
	Carole?
	DR. MILLER:  Since French got to make a little statement yesterday and I'm the other retiring person, I just wanted to comment on this.  I was a little concerned about what French said about whether the field can withstand another death or unexpected death.  And as an oncologist, somebody who in general understands in a bone marrow transplant that unless you--5 to 10 percent of the patients die, you're not giving enough chemotherapy, and attempt to cure a disease which cannot be otherwise cured.  So I just wanted to bring it to the public domain that in general gene therapy--in general, the risk has to be worth the benefit.  And, therefore, in an attempt to cure diseases which cannot otherwise be cured, we're likely to get deaths.  And what the public wants us to do is to make sure that patients are adequately informed of the risks and benefits so they can make an informed decision, and that's our role to advise you how to do that.  And, secondly, that rules are made that can be reasonably followed and, therefore, with some expectation in that.
	So, I mean, I heartily expect that at some point more people will die related to gene therapy, but I even better expect that there will be more people potentially cured or long-term disease.  And so you have to expect some potential deaths.  And what I'm hoping, that 20 years down the road that we'll understand what the risk of lymphoma will be after this, expecting that there will be some lymphomas, and as hard as it is as an oncologist to see a patient die of a secondary lymphoma after treatment of Hodgkin's disease, you have to understand that this patient is alive 20 years later from MOP(?), which at a time 20 years ago was fatal.
	So that's less than three minutes, but I just wanted to put that into the demand, and so when we're talking about this, we have to think about what it isn't.
	CHAIRMAN SALOMON:  Can we go back to plasmids?
	DR. ANDERSON:  I just want to say, Rick Weiss is sitting in the second row.  Did you hear that, Rick?  Did you get all that written down, get that in your notes?  Thanks a lot.
	DR. GORDON:  I think plasmids deserve attention as long-term follow-up potential because of their potential for integration.
	CHAIRMAN SALOMON:  So plasmids can integrate even though they're classically a transient, everybody agree with that?  Okay.  So, again, as we go vector by vector, it seems that no one's convinced, based on what we know today in the field, which is fine--that's what we're here to tell you--that any of these vector classes are particularly devoid of the potential of integration in some way.  Ed?
	DR. SAUSVILLE:  Yeah, I mean, well, DNA, I mean, it's well-known DNA  (?)  is a mutagen, basically.  And so with that I think all this has to be on the table.
	CHAIRMAN SALOMON:  So somewhere here, my sympathy with one of French's earlier comments comes back, and that is, at some point here, though, maybe we're getting a little too gray.  In other words, plasmid might integrate and now we're getting into the principle of any time there's DNA in a cell, it might integrate; but we're not now putting--and so that would by our principle trigger a long-term follow-up.  I'm wondering at some point whether we ought to put a brake on it.  In other words--based on what we know now.  Are there--would you accept that there are some things that could be done before a trial got initiated that might satisfy the FDA that you were below the level of concern, you know--
	DR. BREAKEFIELD:  Yeah, I don't know what that should be set at, but I think if investigators, whatever they use, plasmid or whatever vector, there was some kind of assay they did to look at just integration.  You know, it's harder to look sometimes at low levels of replication-competent virus.  But--and gave a number of what that relative frequency was in, you know, a couple of standard cell type, and then--like we said, because I agree, I think the chance of plasmid DNA integrating is very low.  And, you know--
	CHAIRMAN SALOMON:  Ed, go ahead.  Do you have a follow-up?
	DR. SAUSVILLE:  Well, that--I mean, building on that way of starting to think about it, I mean, one thing that's been sort of missing from our conversation this morning is something that has come up in other meetings of this group, and that is the reliance on the preclinical model that you're trying to emulate in the clinical trial to help guide one's sense of risk.  And in thinking about the way we've been discussing this, I really think that many gene therapy trials are actually going to come to the fore based on somebody doing something in a model.  In fact, we've actually taken the position in other fields of requiring such a thing or strongly advising that such a thing be required.
	So I guess--so to frame the question, is there any way that we can delimit the nature of the follow-up based on how things behave in a model and have that make it more tailored, actually, to address the point that was just raised.
	CHAIRMAN SALOMON:  Okay.  So that's a really interesting point.  So up until now, we've come up with a set of principles that really are triggered by the nature of what we know about the vector and are independent basically of depending on any preclinical model to modify it.  So, in other words, if I had a retroviral vector that integrated and I had a non-human primate model for it and showed that I didn't get cancer in a three-year follow-up or whatever--I'm just trying to put a concrete example to the discussion--then I could say I don't need long-term follow-up because there's no cancer risk.  I don't think that there's any model design that would satisfy that, and that's why I don't think that in developing these sort of principles that the--for long-term follow-up I'm talking about now, not for efficacy.
	DR. SAUSVILLE:  Right.  It wouldn't--
	CHAIRMAN SALOMON:  If this is reasonable.
	DR. SAUSVILLE:  It wouldn't satisfy it, but, again, applying the principle of what proportion, again, it can certainly give some pretty good hints, right?  I mean--
	CHAIRMAN SALOMON:  I guess that's what I was getting at, that at a certain point here, if we can argue that it's getting gray enough, like plasmid, then maybe it's reasonable to go and argue--for example, if you're going to do a cell transplant, modification with plasmid, if I take a percentage of the cells that I was going to transplant and demonstrated that there was no integration at the time, you know, would that be useful?
	DR. SAUSVILLE:  To pursue the point, if we took a cystic fibrosis-related plasmid vector that gets inhaled into a bronchial tree, and then you follow the animals along and you show that within a certain finite period of time you can detect the DNA in some sort, but they never pass into the genome, they never develop any tumors within the lifetime that you would project the animal, I would feel pretty comfortable with having a relatively low threshold for mandating an onerous follow-up procedure to follow up all of those possibilities with that.
	Now, that's very different than the retrovirus situation where, you know, 1012 events and to something that's pumped back into the bone marrow and you get lymphoma later or leukemia, that to me is a far more, shall we say, pressing potential risk.
	DR. CHAMPLIN:  The sample size considerations here come into play.  You're talking about, you know, an unacceptable cancer risk, say, of 5 percent, you know, you need a huge n to be able to detect--
	DR. SAUSVILLE:  But as Carole pointed out, I mean, this gets into what you're trying to fix, and I think that, you know, given the magnitude of a disease that is frequently treated that patients can be given some sort of boundary conditions, and then they can make their choice.
	DR. CHAMPLIN:  But to even know if cystic fibrosis treatment is going to cause cancer in X percent of people, you need to study it.  And, you know, it's important information to have, either positive or negative.
	DR. SAUSVILLE:  Again, to make the distinction between--yes, I take the point.  But a person who--or a patient who receives a gene therapy within the lifetime of the model does not seem to indicate that you'd need to follow for neoplasms.  If 25 years from now they then all come down with this, I mean, that would form a very epidemiologically distinctive cohort that you could just say that wasn't well predicted by the model.  But you still would have been able to make that inference.  The issue is between 0 years--0 and 25, are you going to tell the originating company or sponsor or academic investigator, they're going to have to have in place a plan to collect samples for all that period of time?
	DR. CHAMPLIN:  I don't think you need samples, but I think you need a postcard:  How are you doing?  Do you have lung cancer?
	CHAIRMAN SALOMON:  That's a pleasant conversation with the government.  So, I mean, I want everyone to go on, but so one principle I see sort of being articulated here, which I think is very interesting and appropriate to add, is that in a situation in which you have, let's say, a retroviral vector or a latent viral vector, it's really clear that right now that you're going to either get integration or have a latent virus, et cetera, at least within the bounds of the science right now.  Then you've triggered by the principle that you'd have some form of long-term follow-up.
	When it gets grayer, like a plasmid, let's say, then it's reasonable to bring in a number of modifying factors into the decision, which we've heard could be excellent animal data, albeit issues that Dr. Champlin raises, that one would have to demonstrate what you'd expect in that population and what you'd predict and whether your animal model modeled that properly, like a 1 percent--0.1 percent or 5 percent; also would be the different patient populations, right?  Obviously a dying cancer patient, you know, in extremis might have a different risk profile than a young patient with a genetic defect that you were trying to ameliorate.
	DR. ANDERSON:  It's the second time that a number got tossed out that's an incorrect number, and I just want to correct it for the record.  Twice now a statement has been made about 1012 hits in blood from retrovirus.  That doesn't happen.  Adenovirus certainly you get 1012 hits because you can get a titer that's up high and there's--it's highly efficient.  Retrovirus, if you have a titer of 108, that's really good and you had to play a lot of games, and if you do 100 mils that's really extraordinary, which would be 1010, and that's 100 percent efficiency.  You don't get 100 percent efficiency.  So you're probably three orders of magnitude less than 1012.  The 1012 number I think came from, in those monkeys that had lymphoma and the report that I wrote, and I went back two lab notebooks--I mean, there was a lot of lab notebooks, so it was easy to get to them--lab notebooks, and there's a lot of information that report that it's not in any other published paper.  I calculated the total hits that it took in those animals, with 100 days, 120 days of retroviremia, and the total hits in the animal was in the 1012 range.  But that took months of chronic retroviremia.
	CHAIRMAN SALOMON:  Well, I think one of the things, though, that we--that I've learned as a transplanter over the last 20 years is 100 days may seem a long time to a fellow in the lab anxious to get his next paper out, but it's really meaningless, because I blink my eyes and it's, oh, my patient's back for their six-month visit.  So I think that, you know, one-year, two-year, five-year follow-ups is--you know, if there's really a risk, it's...Phil?
	DR. NOGUCHI:  I'd like a little bit of discussion on the question of animal models because, actually, earlier it was suggested that if you could demonstrate, let's say, in an animal--in a reasonable animal model that an irradiated cell that's transduced disappears after a certain amount of time, that that would--that we could potentially exempt that from long-term follow-up.  That seems to be something that could be reasonably done in an animal and would reasonably give you data.
	I think the question is really open about inputting something into an animal and really expecting that you're going to get a tumor at all.  I've spent many years with tumor models, and unless you put in a tumor cell, it's really hard to do the opposite with, say, DNA or chemicals or anything like that.  So we have two things with animal models.  One is where you can reasonably be sure it will give you data to make a decision, and the other could be just simply a stochastic determination that, well, at least we didn't see a tumor.  And is that sufficient?
	CHAIRMAN SALOMON:  I think that--Ed, you should comment, too, but I think that none of us are suggesting that there's any good animal model, because I think Ed and I sort of had that to and fro when he made--I mean, I don't think Ed's suggesting and I'm not suggesting that there's any animal model that's going to predict tumorigenesis very well.  I mean, if it does immediately and positively, no one's going to argue about it.  But I'm saying, you know, these sort of low risks, how many hits and how many animals, et cetera, I don't think anyone's suggesting that.
	I think where an animal model could be relevant is if I was a sponsor and I wanted to do a trial with plasmid, and you said, well, does it integrate, I think what Ed was saying is that you could potentially design an animal model that would allow us to sufficiently argue with you that it was gray enough that I would be asking for exemption from long-term follow-up based on that.
	DR. SAUSVILLE:  I would comment simply that, you know, the nice thing about DNA is you can follow the vector.  I mean, you can put boundary limits around what you would consider likely and unlikely events.  And with the issue of tumorigenesis, I certainly agree with you that if tumors are your endpoint, you're going to get a real spectrum because depending on the strain and the background and what you're inciting stimulus is, you can have 100 percent tumors or you can have 0.1 percent tumors as your readout.
	But I do think, though, that if you closely model the intended use that this would allow more or less certainty as to what expected behaviors might be.  And the "might be" is there whether you're dealing with genes or drugs or any of these substances.  The animal models only go so far.  But I do think that instead of just making blanket statements that if you're DNA, you've got to do X, Y, Z, A, B, C, that's where I think there could be a lot of useful input.
	DR. MILLER:  A point about exemption, and I guess that we could--you could do standards that say that these are the routine follow-ups that need to be done, but you can have sort of a proviso in there that if adequate studies are done and if the company wants to, instead of--or the sponsor instead wants to make a system for long-term follow-up, wants to spend enough money to develop reasonable model systems or collect the data that will be able to present it, and the FDA with their prerogative, similar to the secretary of state in Florida's prerogative to grant exemptions, would be able to say, you know, yes, this is--this we'll exempt.  But I think you should--if you set a minimum and then make it the burden to say why you don't need to meet those minimum, clearly if they got, you know, the case where the normal volunteers are getting sort of a--something that's not expected to have any integration attempt, and, you know, you just say that--you know, say that, but just, like, leave some latitude and there may be a very reasonable way of doing it, but set a minimum.
	DR. SIEGEL:  I guess what I'm envisioning, based on integrating this discussion, which has really, I think, touched well, if not yet completely, on all three of our questions, would be moving from a system which I would oversimplify by characterizing as saying we're requiring rather intensive annual in-person follow-up on all patients who receive retroviral vectors and we're treating other gene therapy pretty much as any other therapy that might have some long-acting effects, you know, and which you do your year or two study and wrap it up, to a system where we employ a much broader range of tools over a much--phased in based on the risk factors discussed, there might be a lot--a much broader range of therapies than just retrovirus where we should be collecting information long term, but at one end of the spectrum where the information is--where the risks are low, theoretical, but not negligible, that might be limited to just ability to track the patients so that somebody can come back and do an epidemiological study.  As the risks get higher, it might be intensive two- or five- or whatever-year follow-up as appropriate, followed by postcards that not only--and phone calls that not only support tracking but may ask the three or four critical questions about the complications of concern and potentially graduate from that in some particularly high-risk protocols to a more intensive follow-up requirement.
	That seems to be at least what I'm envisioning coming from this.  My guess is that--and I don't mean to wrap up this discussion because I'd like to hear more discussion--
	CHAIRMAN SALOMON:  But what you're doing now is exactly where I was going to go next, and that is, let's talk--we've sort of articulated principles that have stood the test of at least today's discussion, and, you know, they've given you--we've taken you all the way to the gray area and then added, you know, that whereby--we've given you, told you where animal models and other kind of studies could then be used by sponsors and investigators to argue one way or the other, and we've given you principles in which if you get integration, if you get survival of the cells, if you have replication-competent or latent virus, you have--you now fulfill the long-term follow-up, right?  I mean, so--and it's not just retroviral vectors, which I think is probably the most--one of the key things you should be hearing this morning.
	Then the next step would be what is long-term follow-up.  Right?  I mean, I think that's where we need to go next.
	So with that in mind, what--I mean, what kind of thinking do you have on this?  I mean, I think that it's really clear from the discussions that preceded all this that if we now get off on this indulgent, you know, sort of self-righteous thing of long-term follow-up means daily blood tests and, you know, archiving the right arm every week, you know, then I don't think that's going to work.  So, I mean, let's--what is long-term follow-up?
	DR. SAUSVILLE:  I like postcards.  Okay?  I mean, I think that is, shall we say, the most minimal position for everybody.  I'm open to the idea that for particular indications--and, again, this would be where the animal models and the nature of the therapy would be informative--it might be prudent to consider more invasive or more sample-driven things.  But to me, I think as long as you're able to construct a numerator and a denominator of who gets a problem and who has a basis for getting a problem, that's going to be setting the stage to be doing future science, should the need arise in a way that's going to cost fairly little.  And I would even go so far as to say, given the policy and confidentiality and proprietary natures of things, maybe even something that could be requested by the FDA as their special response to this concern and could be something that could be a right of the FDA, or--I mean, I just put that on the table.
	CHAIRMAN SALOMON:  I think that's important.  I mean, let's make sure that we all agree that what we're talking about right now isn't the first year.  Can we all agree that we're not discussing the first year?  We're going--we're not going to touch that area, right?  You're going to archive.  You're going to do the biopsies.  You know, if it's lung, you're going to get lung.  If it's blood, it's going to--okay?  So we're only talking about what goes on after the first year, not that those aren't important issues, but we're not--we're taking them off the table.  Okay.
	So getting back to this idea of is it postcards, I actually would go another step further, and I would think that what you need is a database like UNOS that's publicly supported.  And it's--but, remember, UNOS interactions are basically a postcard kind of interaction, so I'm not talking about any more intensive interaction with the patients, but I am talking about a little more organized than asking the sponsors to send postcards.  I don't buy that.
	DR. SAUSVILLE:  I mean, I agree.  I certainly think publicly supported--the issue of whether publicly available and such is clearly another separate issue.
	CHAIRMAN SALOMON:  I wasn't talking about publicly--I'm talking about publicly supported.  I think there's no way out of it that the recommendation--now, this is for discussion, but my position is there's no way out of the fact that someone's going to have to put a dollar down.  I'm not saying it's the FDA, but someone's going to have to support it, and then you have a competition, and like we do for the UNOS and for these other databases.  And whoever wins the competition, you know, basically gets the contract the next five years.
	DR. NOGUCHI:  Just remember, though, the UNOS public portion of the contract is relatively small.  Most of it is now done through user fees by UNOS.  So I would not want to imply that this is easily supported by simple public funding through grant mechanisms.
	CHAIRMAN SALOMON:  I guess I'm not talking about easy.  I'm just saying if you want a database, somebody's got to have to put a buck out.  But I think the committee has the right to disagree with what I'm saying, and they should now if they do.  But the question is where is going--where's the onus for this kind of follow-up?  And what I think is very important is that the onus shouldn't be on individual sponsors, because then what you have to do is you have to supervise 150 different sponsors who are in and out of academic positions and companies closing, et cetera.
	If you have a central group that says if a patient is--gets gene therapy just like a patient got a kidney transplant or a patient got a heart transplant, then you follow from a single spot.  Then you just have to follow the patients.
	DR. SIEGEL:  Let me follow up on this idea, because I'm not sure where it's going.  The group you propose--I mean, this is an interesting--an important policy proposal and one that needs discussion and consideration.  It has received a great deal of discussion and consideration, and input is appreciated.  There is no group sending out that postcard.  You're saying it shouldn't be the sponsor.  So if I get a protocol tomorrow, I shouldn't require that the sponsor follow up the patient because that's an unfair onus and I should just wait until some public group comes up with the money to do that?  Is that, in fact, what you're suggesting?  Okay.
	CHAIRMAN SALOMON:  You got me there.
	I think until--I think we're looking at--we're talking about what is long-term follow-up, right?  And I'm saying that the principle that I think the committee is agreeing is that long-term follow-up is really just knowing whether the patient's healthy, whether they've had--you know, the key issues of pregnancy, malignancy, autoimmune disease, neurologic disorder, and any other unexpected diseases.  You need follow-up on those patients long term.
	DR. MILLER:  I mean, the sponsor's required--I mean, I think it's clear that the sponsor, whoever is doing the therapy, is required to follow up the patient.  I disagree that it's in the public requirement to get the scientists together to figure out how to use that data.  You know, as an academic community, generally the people who are going to be doing these gene therapies, I think that it's through the grant mechanism and the volunteer--you know, it should be something like the IBMTR.  The reason UNOS can be some--a registry of scientific or a group of people who are doing gene therapy, get together and say we're going to pool our data, because I don't think that that--I don't think that there's a mechanism as well to really do that.
	Now, the reason UNOS works so well is because they can monitor the number of kidneys and transferring back and forth, and, you know, it's been legislated because there's a product that goes back and--I mean, in some way there's, you know, interstate and--isn't that what brought it up because there's interstate and a sharing of organs that can be--are a resource that has limits, where compared to this, where anybody can--who has a product can--can expand to fulfill the--to fulfill the need.  So I think it's very, very different.  I think it's up to the scientists to figure out how to use the data, but it's required in each individual to follow their patients because that's good clinical practice.
	CHAIRMAN SALOMON:  So there's two kinds of databases.  I just want to clarify one thing.  There are databases that have come up where groups of scientists have got together because they're interested in an area like the International Bone Marrow Transplant Registry, I think is a database like that, or the North American Pediatric Transplant Registry.  I'm not referring to that.
	In UNOS, actually the driving thing has been Medicare reimbursement for organ transplants, not interstate commerce, necessarily.
	DR. SAUSVILLE:  So, I mean, one point of difference that might exist, again, is--I mean, this field is so new and lots of things are going--lots of people are doing lots of different things, and I'm--I would be concerned that the survival of the relevant population may outlast the survival of the companies and academic affiliations of the investigators doing these things.  So, to me, that's one reason or could be construed as one reason as why--and, again, I look to our colleagues at FDA or my colleague at NIH and say everyone said there's a desirability to create some type of database.  We agree that it, you know, might not be public in the sense of a publicly grazeable database as a first cut.  I think whether it's funded as a line item from NIH or FDA as part of their appropriation or through a tax, ultimately, of currently acting companies to have ultimately a user's fee, someone's going to have to pay for this.  And I don't think it's going to productively arise from expecting voluntary sorts of--people who write grants for these things.
	DR. GORDON:  I think one way to tie in these sort of parallel issues of a database and what sort of follow-up should be needed is--but I always thought of the database being envisioned for gene therapy as an adverse events database in many respects, not the only thing but certainly one of the most important things.
	I think one thing I would glean from this discussion is that long-term follow-up is more likely to be recommended to be observational in nature than interventional in nature, and that there is already an onus on sponsors to report adverse events.  Long-term follow-up could be tailored to indicate that anything adverse that occurs to the patient down the road would be an observational process that would be then a reportable event to the database.  The only disadvantage of that is if the patient is cured, that wouldn't be an adverse event.  And, therefore, I'm not sure how to gather that information.
	Personally, I think if we get into this discussion of how to pay for this, we're going to get absolutely nowhere, because I'm sure that we're not going to figure it out, who's going to pay for it.
	CHAIRMAN SALOMON:  I think the--that's fair, and I think that's what I was resisting earlier in the day.  I don't want to get into who's going to pay for it.  But what I was putting on the table for discussion--and we are discussing it--is what this long-term follow-up will constitute.  Is this going to be something that each individual protocol will devolve back to the sponsors?  And I think we've heard multiple lines of reasoning why that's not a good long-term strategy.  And, therefore, I think what we need to consider if we're advising the NIH and the FDA on what long-term follow-up should be, I guess my point then, looking for feedback, is that we need to change the paradigm.  It needs to move from sponsor/investigator-oriented long-term follow-up to more of a follow-up such as--again, I exemplify by UNOS as a long-term follow-up of anyone who gets a bone--gets gene therapy trial.  And that follow-up is the responsibility of some government or a group of governmental agencies.
	DR. SIEGEL:  Of course, these are very different situations here.  We're talking about products under commercial development.  In UNOS we're not.  UNOS has certain enforcement--not enforcement powers, but obviously there's strong incentives to be a player with UNOS.
	But, you know, I would like to terminate this discussion, not because I don't think it's important but because I firmly believe that there's a fundamental presumption in current policy that if a sponsor sponsors and proposes a clinical trial, that they are responsible for collecting the safety data.  We can discuss the merits and the efficiencies of having a government essentially subsidize that and do that other ways, and, in fact, there's a lot of reasons why that's a good idea.  And I think there's a lot of discussion as to how best to do that.
	But I think that what we have to--we have to address now what information to collect, how to collect it, under the assumption that until something else exists, it's going to be collected by the sponsor.  And while further discussions need to be--need to occur about what else should exist, I think that in the interest of time and the issues we need to face immediately, I'd like to focus more on where we're going at the present time.
	CHAIRMAN SALOMON:  I guess my response--yeah, my response, Jay, is fine, but you guys started this off with a litany of reasons why sponsors are having trouble complying, investigators moving, companies going out of business, cost of a database, grants that only last five years; and yet when we tell you that, yes, maybe the response to what you introduced as the issues was to change the paradigm, your response is, well, that's not what we're here to talk about.  So I'm just putting it in context.
	Dr. Anderson--
	DR. SIEGEL:  That's right and that's fair, although I would note that those issues are on the table for any of a number of reasons.  It's important for the--if you look at the last part of Question 3, the issue is, okay, given all of those factors, given the fact that we know that even under the best paradigm we're not going to collect this information, should we just--is it unsafe to continue the research?  Because one can assume that if you can't collect on 100 percent of patients, you shouldn't do the research, or maybe the goal is to collect as much as possible and get a database, and maybe if you get 50 percent or 70 percent, it's every bit as good a database as 100 percent, in which case--and maybe you can improve that with techniques such as postcards, in which case, you know, it isn't--or it isn't so critical an issue or maybe the risks are smaller.
	So there are many issues on the table, but--and that's one--the one you keep coming back to is one of them, but it's just not one we're going to solve today, so I'd rather focus on those that we are going to try to solve, although I don't think--having said that, I should qualify that and say I'm not suspecting that we're going to solve this issue today.  What I see as a way we're probably going to move forward is integrating your advice to try to develop a somewhat more specific current approach and return perhaps to the RAC or to this committee, either way, supplemented with others, for further discussion and further input on that, and evolve as we move along.
	CHAIRMAN SALOMON:  Okay.  So let's accept that, you know, guidance from--
	DR. CHAMPLIN:  I have one quick comment.  There are sort of two levels of questions.  There's one product-related.  Is the individual product safe or unsafe?  And then there's the generic.  Is gene therapy safe or unsafe?  And a much broader scale where it's not one company's responsibility but more of a societal or professional responsibility of the field.
	And so a sort of tandem approach of the company having intense follow-up for maybe some period of time like five years, and then some registry function that would look at long-term generic risks, maybe picking up after five years of follow-up for individual patients.
	DR. SAUSVILLE:  Yeah, I would echo that, because even with the way the reporting requirements are constructed for drugs, I mean, you report adverse events that are expected at one level or another, or unexpected.  You sort of divide the world into that.  Long term is sort of beyond unexpected.  You're by definition sort of collecting things in an observational sort of way that are unexpected to the second power, but, nonetheless, by the nature of this therapy is called for, I think, at some level.  And that's the--that's what I'm seeing as a tension between what is reasonably expected of a sponsor and might then might devolve to somebody else.
	CHAIRMAN SALOMON:  French and then Amy.
	DR. ANDERSON:  I wanted to add one other thing on the record.  Several times you folks have talked about the scientists in the field, investigators in the field.  Well, what about the scientists and investigators in gene therapy?  And that is the American Society for Gene Therapy.
	Since I'm Chairman of the Government Affairs Committee and this is a government affair, I suppose I can speak for the society, and Xandra is also here and there are other people here.
	We have discussed at the board of directors for the society this very issue a number of times, and the American Society for Gene Therapy is absolutely in favor of long-term follow-up.  It's absolutely in favor of a database.  It will cooperate in every way possible.  But we have no way to do it ourselves.
	And so I just wanted to put on the record that the society of investigators in this field is very supportive and will cooperate in every way possible, but we can't do it.
	DR. PATTERSON:  I was wondering if it might be helpful to FDA if the discussion focused a bit on distinguishing between active surveillance and passive surveillance, and began to break out, for instance, for integrating or replication-competent vector systems what type of active surveillance would be appropriate during the first five years, and then to what extent and how would the passive surveillance in the subsequent 20 years be done, what types of questions.
	CHAIRMAN SALOMON:  So, I mean, let's take that.  So we all agree that there's a very active surveillance for the first year that we're not going to get into.  So let's talk about what we think is the level of surveillance for a vector that--for a gene therapy trial that fulfills the principles we articulated in the first part of the discussion, from year one to year five.  What should be the responsibility of the sponsors, Jay, during that four-year period?
	DR. NOGUCHI:  With respect, I'm not sure that that discussion is necessarily the focus here.  We do have on the record for retroviruses what we expect.  It's active for the first year and yearly thereafter.  It could be up to five years.  I'm concerned that without a lot of preparatory work, I wouldn't want to raise the bar higher without a lot of discussion and more surveillance of what would be the scientific issues.  In some of these areas we simply don't know.  Herpes, we only have two protocols ongoing.
	So I would just say while I appreciate Amy's concern there, I think that the level of the active surveillance is not something we--I don't think we want to really go there here.  We are concerned about the more general long-term follow-up.
	CHAIRMAN SALOMON:  Okay.  So help me here.  Now I'm a little off.  What is it--I mean, one thing I'm thinking of is that we basically are done.  We've answered your questions.  I think that there is very little sympathy from the committee for anything more than after the first year, I think, than passive follow-up.  Passive, maybe that's not the right word, actually.  I don't like that word.  Follow-up that would require, you know, sort of a series of epidemiological questions being answered and recorded in a database.  That's what I think everybody's been very clear about today.
	DR. SIEGEL:  Actually, I heard some committee members suggest a more active follow-up, and I thought you were going there, through up to five years may be appropriate, depending on the protocol, in terms of--
	CHAIRMAN SALOMON:  Well, I was going there.
	DR. BREAKEFIELD:  That's kind of the consensus I got, that maybe for five years of active follow-up and then have some kind of more passive follow-up after that.  I would say--I'm not sure--and I think the FDA has really dealt with sort of integrating vector in the context of retrovirus vectors, but I'm not sure we've really dealt with replication-competent vectors and whether we're really even now monitoring shedding well enough over that--potential shedding over that period, because you can't in an animal model, given the tropisms of these viruses, ever know in an animal model what that virus is going to do in the human body.  You have to accumulate that data.  I mean, hopefully it will be negative, but there's no other way to get the data.
	DR. SIEGEL:  Shedding of which virus?  I missed that.
	DR. BREAKEFIELD:  For instance, if you take a replication-competent virus like an adenovirus that now has an altered surface marker that potentially will change its tropism or has now one of its essential genes under a promoter that's for a particular, you know, human tissue, you just don't know what it's going to do.  You don't know whether it's going to replicate.  You don't know whether, you know, it's going to find a little niche where it's a little bit immune isolated and now it can replicate and be passed.  So I think we need to find that out.
	DR. SIEGEL:  Is there a specific concern, though, if such a virus were not replicating or not being shed at six months, a year, two years, that it might be at five years other than for, say, a herpesvirus?
	DR. BREAKEFIELD:  Well, I think that--I mean, basically you would decrease the frequency of monitoring, but there is the chance of kind of like a smoldering infection that it might at some point--because as the virus keeps replicating, it keeps accumulating mutations and it changes its properties, so there's a chance that you would have a very low level and then suddenly, boom, something new would pop out from that reservoir of actively replicating virus in a different tissue.
	DR. GORDON:  Yeah, I'd highlight the word observational more than passive, if you're looking for a word.  But, again, one has to look at the practicality of follow-up after a year and the active sort of follow-up.  That is, are we going to draw fluids from the person?  Are we going to biopsy the person or even bring them in for a physical exam?  And I appreciate what Xandra is saying, but I think one of the messages I take from that is that we really don't know what to expect.  It's very difficult from my point of view for us to devise a monitoring protocol that will cover us for everything that we don't expect.  I mean, we have to--
	CHAIRMAN SALOMON:  If you take that, then I think one of the things that I'm trying to anticipate where Phil wanted us to go is over the next--from year one to year five, if we don't know the answer to your question, then maybe one of the things we ought to expect is a yearly physical and archiving of blood and/or appropriate tissues, depending on the type of protocol.
	DR. GORDON:  Right.  I'm just saying that I feel a little bit--while I'd like to see that happen, I feel a little bit less zealous about it than perhaps you do.
	DR. BREAKEFIELD:  Well, there are certain standards for monitoring viral shedding.  You know, I wouldn't say we have to invent anything.  We just go to standard, you know, monitors of viral shedding, which can occur in different body fluids, which aren't that difficult to obtain, even.
	CHAIRMAN SALOMON:  I think that the issue here for me is that I think what we need to advise the FDA on in terms of the committee's opinion is how--you know, during this period of time, from year one to year five, how much should be demanded of the sponsor within reason.  And those are--this part of the discussion avoids a lot of the issues, you know, of what happens at seven and ten years when grants run out, et cetera, et cetera.
	So within five years, I would put on the table that it's very appropriate given that this is brand-new therapy, that there are many things that we don't know.  You pointed out viral shedding.  We've pointed out the possibility of integration events, reactivation of viruses that might be latent, unusual clinical events, antibodies that might develop, so-called inhibitors, et cetera, all of these things.
	I can't imagine any reasonable gene therapy protocol that isn't going to accept the onus of at least yearly contact with the patient via the PI or one of his or her designees.  And at that point, you know--so that I think is--that's what I'm putting on the table that we should expect of any sponsor, in that five years, at least yearly interaction with the patient and archiving of appropriate tissues, and that would be appropriate to the vector.  I mean, if there's an issue of shedding, then you do saliva or vaginal secretions or whatever is appropriate.
	So I'm putting that on the table for--
	DR. GORDON:  What I'm trying to say is that this all sounds fine to me, but to me, five years is an arbitrary amount of time.  I mean, we don't know that after five years we don't need to worry about it, and I don't think we should here be suggesting that we stop at five years because grants typically run five years.  I mean, this is a medical/biological question.  It's not an administrative question.
	CHAIRMAN SALOMON:  We accepted the onus early on of being practical, so I don't buy that that we can't put a five-year thing on it.  Secondly, you got to have some time frame.  The public doesn't want to hear that we discussed it and we said, well, just sort of we'd follow them but we're not really sure how long.  I mean, you've got to say something, and it will all be arbitrary, we agree, right?  But--
	DR. SAUSVILLE:  And, clearly, if new data emerges in the five years to sort of influence your thinking, you might extend it.  I mean, you know--but, clearly if we don't see anything at the end of five years, it's hard to make the case that you should build a superstructure or require sponsors to look beyond that, I think.
	DR. GORDON:  Well, I guess what I'm trying to say is that I could make an argument for a year in the sense that if something occurred in the patient that could be defined as an adverse event, it would immediately be very thoroughly characterized, and that would be a more sensitive way of finding them than looking at random, searching the innocent to find the guilty, as it were.  But, I mean, it's obviously, as you say, arbitrary.  I mean, I have no logical reason for objecting to five years.
	CHAIRMAN SALOMON:  Make it three years.  I mean, you know...
	DR. MILLER:  Well, then in your protocol you justify why it's not, and if the protocol then goes through--I mean, you--I mean, this should be the standard for which it's a reasonable assumption, but that if you want to diverge from that assumption, you just have to justify why your protocol doesn't require that, and if you provide enough information that the FDA will say yes, you can go ahead and push that protocol through, your IND is accepted, then you follow--as long as you follow what's written in your protocol, or at least attempt to--I mean, one of the things about this is that if then you can--sponsors can go back and put in their patients' consent forms.  The expectation is that you're supposed to be followed for five years.  The patients are told up front.
	Now, they can, just like with anything else, decide two years down the road that they hate Baltimore and never want to come back and see us again.  But everybody who comes to transplant is told up front, at least in our center, that the expectation included in our consent form that they're followed up for five years, but, you know--and I think that's something that we--that should be strived for, and there's some guidance from that standpoint.  But the patient can always refuse, but, you know, at least you're striving for that.
	CHAIRMAN SALOMON:  We also have plenty of examples where we follow patients that have left our transplant program, and you call the nephrologist up and, you know,   (?)  , and you tell him, you know, this is what I want to know, what's the renal function, you know, how are they doing, do they have a bunch of skin cancers.  So even then I think if the responsibility is in a finite period of time, a five-year period, and that's demanded of the investigator, I think that those are things that could be reasonably and practically dealt with.
	Now, that doesn't deal with the fact that two years after the protocol's over the PI leaves, but, I mean, I can't solve everything.
	DR. SIEGEL:  Are you suggesting for this sort of approach for five years of clinical follow-up for all gene therapy protocols or based on some of the factors that was discussed before?
	CHAIRMAN SALOMON:  I was just putting something on the table so it could be commented on, but I guess what I'm saying is, yes, and then as--I think taking Carole's point of view, that if a specific investigator has an argument that's compelling to the FDA's review group, that they only need a year follow-up or three years follow-up, then you should have the latitude to do that for a given study, but at least it gives you some sort of general guideline.
	French?
	DR. ANDERSON:  This is one of the few things I disagree with.  In principle, Carole, of course, the investigator can argue only to go three years, but the reality, that's not going to happen.  IRBs are not going to look kindly if the FDA and everybody else expect it to go five years, and you say, "Well, I only want to go three years."  The lawyers and the institution are not going to let you do it.  I mean, you're going to have to do it.
	So our job is to struggle exactly like we're doing and to say one year, absolutely, no question; five years, after five years, I think it's pretty clear now, postcards.
	Now, what is the category between one and five years?  It requires more intense.  And we were starting to get at that, replicating, integrating and so on, and I think we've got to come out--you know, we've got to bite the bullet and do it and provide it, so that when, say, if you're talking about a plasmid, you don't have to have as intense from the one to five years.
	CHAIRMAN SALOMON:  As I was arguing then, we use the principles we articulated earlier.  If you fulfill those principles, you got five years of follow-up.  If you don't and it's gray, you know, then you make your argument for how long the follow-up is.
	DR. ANDERSON:  But I think the issue is from the one to five years, maybe for something which, you know, an irradiated dendritic cell, which has a plasmid in it--I mean, ex vivo--that instead of a intense for five years, that could be an intense for three years.  But if there's some way we can give the FDA advice on that.
	DR. SAUSVILLE: That gets back to tailoring it to the expected biology of the issue, and that's something that really is going to have to be judged on a case-by-case basis, but I think the general principles that we've articulated, I mean, as you say, would pass the test being applied to most things that you could conceive of. 
	DR. SIEGEL:  I think that this has been an extremely useful discussion, notwithstanding some people's feeling, perhaps, that we haven't gotten anywhere.  I think we have a--there's a general sense that, I think this is an important notion, the notion of dividing long-term follow-up into that which needs to be accomplished with direct patient contact and that which can be accomplished through less direct--through postcards and phone calls, and that hopefully--and that latter can in fact--can and should be focused not on anything that might happen to the patient, so that everyone who gets a heart attack when they turn 65 is going to be in the database, but should focus on those issues that are of scientific concern, as I've said many--heard many say.
	And that both the intense personal--direct contact, as well as the follow-up, be triggered by scientific issues, and I think we can work with that to devise a scheme, which as I said, that we will undoubtedly want to--won't be able to devise a highly specific scheme, because, you know, there's new vectors and new issues arising all the time, and I think it would be inappropriate to try to apply rules to fluid concepts, but propose some general approaches that we can then come back, as I said, here, and/or RAC for further discussion, make sure we're in the right direction.
	CHAIRMAN SALOMON:  I think as a general principle from what, at least trying to summarize what the Committee's told you this morning, is that we've tried to be as pragmatic as possible, yet everyone around the table still sees a number of practical issues that have not been solved here yet, right?  And I don't think we need to go back over those again, and that's, of course, the problem that we can't solve this morning.
	There is an issue of monies, but at the moment, if you at least can define things as reasonably as we have, then you could potentially incorporate those sort of costs into NIH grant funding, and certainly the sponsors can deal with that.  I think when you start talking about these numbers that got thrown around this morning, where it's $500,000 a year to do the database follow-up, that makes me want to get out of my research job and take a database job.
	[Laughter.]
	CHAIRMAN SALOMON:  I don't know how many--I can't get my head around why it would cost that much.  And I think we have to just be--I think that maybe part of the issues that the FDA has to deal with--and I don't think that's for the Committee--but I think that one of the sense of the community is that if you make the reporting so onerous that it costs $500,000 a year to do follow-up, then really, you've not been responsible to the field either, and I think that's something you want to make sure that you're being as practical as we're trying to be.
	Lastly, I think it's really clear that the Committee is assuming that after five years, that there will be some form of long-term follow-up, and as I now would personally go back to making sure it remains on the record, that I think that long-term follow-up from five years on is societal and not as much any longer the sponsor's responsibility.  And I say that because I don't think it's that practical after five years.  But you made your point, that also conflicts with a basic principle of the FDA's, holding the sponsors responsible.
	DR. SIEGEL:  I think I agree with what you said.  I would add, so there's no confusion, as you and others have used the word "pragmatism" here, that it shouldn't be fully misconstrued.  It means two things.  There's the issue that French raised, that at some point you get--you have to draw a line somewhere on the curve, and there is some information--there's always some information which you could get for additional expenditure which is of some value, but of so little value that it's just not the right place to put your resources.  And that's a point well taken, and it's true.
	But I do want to highlight, before we leave this, as we talk about pragmatism in this context, there's another issue which I raised which Dr. O'Fallon mentioned, which is that, you know, if you go for--well, what our experience has showed us and what we know, and what epidemiologists know is that if you go for everything you want, you can wind up with nothing.  You wind up--you know, every time somebody gets a cold, you get so much into a database at such a low reliability level, that you just can't tell anything useful.  Whereas if you target what you want in a reasonable way of where you think the most likely information is and a reasonable way of getting it, then you stand a much better chance of getting the type of information that you need.
	CHAIRMAN SALOMON:  And my point is exactly, and that's why I was saying that the FDA then has to deal with the fact that its reporting requirements are not so onerous that it costs a half a million dollars a year to follow ten patients--100 patients.  Still, I'll still take that job.
	[Laughter.]
	DR. GORDON:  I wanted to make one additional, small seconding of Dr. Miller's comments in the context of pragmatism.  And I think one of the things we want to do in follow-up is, of course, forestall adverse events and protect people, as well as the general public, and of course, that's what we want to do.  It's not possible to completely cover every base there.  I would disagree that we cannot survive another death in gene therapy.  I would say that we not only can, but we will survive another death in gene therapy if there is one, because of the imperative of the therapy.  We're dealing with people who have nowhere else to turn, and we're dealing with potentially tremendously powerful technology for even better treatments of diseases for which there already is an approach of one sort or another.
	Therefore, I think worked into this notion of pragmatism in follow-up, must be the notion that we understand that we can't get every piece of information that in retrospect we feel that we should have had, that there's going to be--the system isn't going to be perfect, but that there is a great imperative for proceeding.
	DR. SIEGEL:  I'm assuming that that answers our final question for this session, the concerns regarding long-term safety of integrating vectors sufficient to warrant stopping such research until these issues can be better addressed.  But there's not a sentiment here that until we have a better mechanism implemented or whatever, that we stop this research.
	CHAIRMAN SALOMON:  I think it's disappointing that we don't have a--I think that, speaking for myself, I think it's disappointing that we don't have a better mechanism in place after over ten years of this, but I don't think that's an issue in terms of going forward.  I think the imperative I agree with is to go forward.
	DR. SIEGEL:  I would just like to comment on that though, that I think--I think it was Dr. Champlin made a very important remark, which is there are the risks of a specific therapy and the risks of a class of therapy.  And databases are most useful for risks of a class of therapy, because the IND process is well designed for the risk of an individual therapy, and I think--I would say, first of all, if you look at the experience of the last ten years, there's barely emerging a class of therapies, in that there just haven't been more than a handful of trials with anything that could be classed together as a class of therapies, and I believe that--and I firmly believe that our systems in the FDA of having reviewers who are working with related therapies discuss things and share ideas and share information, given the size of what we've seen and the number of protocols in any one type of vector or one type of class of therapy, have been reasonably functional to accomplish that, although one might hope and project that growth in this field would be such that that may change.
	CHAIRMAN SALOMON:  I'd like to bring the morning session to a close.  I think all of this served well to summarize things, but before we absolutely close, I want to ask is there anyone else on the Committee or at the table who would feel that we haven't adequately summarized it or they have an additional comment?  I think these are very important issues, and I think we got consensus on a number of them, but I think there's still some issues out there.  So any other comments?  I don't see anyone jumping.  Amy, specifically?  Phil, did you get what you wanted out of that?  Carole?  Okay.
	It's almost 11:25.  Can we take a 15-minute break, and then we'll be back and start the second session.  Thank you.
	[Recess.]
	CHAIRMAN SALOMON:  I apologize for being a little bit later.  I got to talking to Dr. Siegel and Noguchi about some of the controversial issues and didn't check out, so I apologize to everybody.
	So this is the last session, Session IV of the meeting.  And these now carry over into one aspect of long-term follow-up, and that's the issue of germline transmission.  So just in the interest of time, I'd like to get right on with it.  So what I'm going to try and do is finish at 1:30, which is an hour and a half from now.  So if we can maybe make the presentations quick and to the point, and then we'll get into the discussion, and that way everybody gets what they want.
	So, Mercedes Serabian is going to give the FDA introduction.
	MS. SERABIAN:  My talk is kind of a lead-in, if you will, to the next talk after mine, which is specifically regarding germline transmission of a product that Chiron has.
	What I want to do is present a brief overview of basically at this point CBER's recommendations for current performance of preclinical biodistribution studies.
	Okay.  Basically, first, what is a biodistribution study?  They're preclinical animal studies that are designed to determine the distribution of vector to sites others than the intended therapeutic site.
	So, obviously, then you want to know what are the goals of the study?  What are you trying to look for?  What are you trying to achieve?  Well, first of all, there's mainly two issues.  First there's evaluation of the potential dissemination of a vector to the germline, and that's obviously the assay of gonadal tissue.  Second is the evaluation of potential distribution of the vector to non-target tissues, and this can be gained from information such as potential target organs for toxicity studies.  And it's important to try to determine the kinetics of the vector transduction and persistence in these studies.
	Okay.  Now, one way to address these goals is obviously by assaying the PCR--excuse me--DNA-PCR.  And both issues can be addressed in the same preclinical study as we discussed yesterday, either using normal intact animals or even possibly the use of animal models of disease.  And that's an important point I think. 
	The March 12, 1999 RAC meeting centered--one of the discussion points centered around the issue of gonadal distribution.  Basically one of the conclusions they came to at that meeting was that the risk of foreign gene transfer to germ cells on future progeny was perceived to be low, and this was the acceptance by those present in context of somatic cell gene therapies.
	And again, some of the results from this meeting is that evaluation of biodistribution to the gonads--and this is important--may not be needed prior to all Phase I clinical trials.  The consent form in this case then should address the issue whether there's a lack of data in that you have not done preclinical studies yet, or the unknown risk, which is always the case, I think.
	What I did--and I divided this into two slides, because it was a bit on one--but this is a sample informed consent form.  And again, I stress the word "sample", just as an idea as to what would go into an informed consent form.
	"Risks associated with treatment in this study could cause permanent genetic changes in some of your sperm (men) or eggs (women).  These changes could be neutral or may eventually cause abnormalities.  Some of these changes could lead to miscarriage or abnormalities in your future children.  Other changes may have no apparent effects but could still be passed on to future generations."
	And to continue with that, "The likelihood of such outcomes is currently unknown."  And there are certain scenarios you could put in there, such as:  "Studies to estimate the likelihood of such effects have not been done in animals or humans."
	"Some studies (animals/humans) have been performed, but the information available does not allow estimation of the likelihood of such effects."
	Or "Conclusive data regarding these potential effects in animals and humans are not yet available."
	So, obviously, then one question that comes up is when can you postpone performing these biodistribution studies?  Several scenarios that one could think of would be, first of all, if you have a previously defined vector, which would be previous experience with a similar vector, similar route of administration, formulation and schedule.  One example give here--and there's many others--is adeno type 5 vectors.
	Another thing would be if a transgene product is innocuous if expressed ectopically, or if the size of the vector is not excessively different.
	And when in some cases do you need to perform biodistribution studies prior to Phase I trials?  New class of vector, a vector that we've had little or no experience with--and again, these are just some examples, and this will change, obviously, as time goes on:  AAV, lentivirus and other vectors; there's a change in the formulation such as the lipid carrier; if there's a change to intentional systemic route of administration with an established vector, or a change in the route of administration; if the transgene has the potential to induce toxicity if it's aberrantly expressed in non-target organs.
	And this is, again, I stress the word, sample.  A regulatory letter that maybe would go out for studies that have not performed biodistribution in animals at this point would say something like:  "The present submission does not contain data that demonstrate the extent to which this vector is able to disseminate out of the injection site and distribute to gonadal tissues.  These data are necessary to determine the risk of inadvertent gene transfer to the germ cells, which may result in genetic changes in subsequent progeny."
	I apologize for the small print, but I was just trying to get it on a slide.
	"In the course of development of your product, you will be required to obtain these data and provide them to the Agency for review and comment.  Data may be obtained either from biodistribution studies in animals, analysis of clinical samples, or from a combination of preclinical and clinical sample analyses.  Clinical data should be derived from peripheral blood cells and semen samples during the treatment and follow-up periods for the clinical trial, and from gonadal tissues (primarily ova) obtained at autopsy from consenting patients.  We will require that these data be provided in a timely fashion so that the results may be used to guide further development and optimization of your product as a therapeutic agent."
	Last but not least, "Please update the Agency on the status of these studies at the time of each annual report."
	Well, so now the next question is, okay, we're talking about biodistribution studies.  Well, how do you design a study, what do you do?  What needs to be entailed in the study?
	Well, first of all--and we heard discussion yesterday--species selection is important, and notice I stress here that non-human primates is not always needed.  The next thing, animal gender.  Could be male and/or female, and this would reflect a patient population, such as hemophilia, for example.  Animal numbers are a crucial point, and I state here 3 to 5 per sex per group minimum, definitely minimum.  Use of smaller animals such as rodents, obviously, allows for inclusion of larger numbers.
	Dose selection, important issue.  You're going to include the appropriate controls.  You're going to include a maximally feasible and clinically relevant dose level.  You want to be able to establish, to maximize exposure, and then you're going to do a lower dose to establish a no-effect level, no observable adverse effect level, which we went over yesterday what that meant.  I'm not going to get into that.  For vector presence in the target tissue, so you want to see a dose response basically.
	And then ROA or route of administration for short.  And, obviously, this should mimic the intended clinical route of administration to the greatest extent possible.  And it's important to note that worse-case scenario may not adequately represent the risk.  It's your intended clinical route which is of primary importance.
	When do you kill these animals?  When do you sacrifice them?  When do you sample tissues?  Well, there's certain time points that we suggest in order to appropriately evaluate the kinetics of the vector persistence, as well as the transduction peak.  Early, at the time of peak vector transduction or expression, and again, it depends on your particular vector.  Later, to be determined by intended clinical route, and even later still, in order to determine the clearance of signal from the gonads and the non-target organs.
	So you kill these animals.  Well, you need to sample them.  What tissues do you take?  Well, this is a recommended list.  It's by no means all-inclusive.  It's just strictly a minimal recommended list.  Initially, peripheral blood, gonads, injection site, at a minimum need to be obtained.  Highly-perfused organs for determination of toxicity.  Some of them I've listed here: brain, liver, lung, kidneys, heart, spleen, et cetera, okay, major organs.
	Then there's other tissues, and that's based on the toxicology or pathology of your transgene.  For example, interferon, bone marrow.  You know, you need to know your product.  And it could be based on the route of administration.  If you're giving sub-cu or IM, you could be taking additional tissues, so it's important.
	Okay.  I'm not going into specifics on the detection assay, other than just to say that the methodology should detect a sequence of vector that's unique to that product, and that the methodology should be appropriate to adequately detect vector sequence.
	And what's important is that tissue samples from preclinical animal studies--you should also have, obviously, a methodology that works for clinical samples during--that you obtain during the clinical trial.
	And on the NIH website, at the RAC discussion on March 12, 1999, Dr. Steve Bauer, who spoke yesterday, went through a bit of detail as to recommended methodology for PCR assays, such as sensitivity, spiking, et cetera.  So I'm not going to go into detail on that, because it's out there, and you can also--he nicely volunteered that he is physically here, so if you've got specific questions, you can ask him.
	Okay.  So briefly then, in summary, biodistribution studies are designed to evaluate vector dissemination out of the injected site in both gonadal and other non-target tissues.  The current method right now is DNA-PCR analysis.  And these studies are not always required prior to initiation of Phase I trials.  It depends on previously defined vectors, the clinical context, and obviously, you know, your data will be required during the course of product development.
	And last but not least, I found this slide, and I thought it was appropriate for the lead-in for the next study.  It says, "Hey, was I supposed to wear a tie?"  So you always have that one that you're worried about.
	[Laughter.]
	MS. SERABIAN:  So I guess we just continue on then with the next presentation to keep moving, Debbie.  Okay.
	CHAIRMAN SALOMON:  The next speaker is Dr. Deborah Hurst from Chiron.  She's going to talk about the use of germline transduction after direct injection of retroviral vectors. And again, as yesterday, we--I know I speak for the FDA in appreciating that willingness of sponsors to step forward with real data, because it's very important, and to share it with us.
	And I also point out that I will follow the same guidelines as yesterday, that once the discussion gets started, your specific protocol is not, you know, going to necessarily be on target.
	DR. HURST:  Okay.  I'm grateful to hear that.
	You've already introduced me.  I'm Deborah Hurst.  I'm director of clinical development at Chiron, Corporation.  I'm in charge of the Phase I retroviral vector trial in hemophilia.  I'd like to thank the FDA for inviting us to present our data on yet another difficult issue facing this Committee.
	I'm going to first very briefly review Chiron's history of retroviral vectors in the clinic and the rationale for the current use of retroviral vector for the hemophilia indication, then review our preclinical data on germline transduction that was used to support the progression to the Phase I study in the clinic, then present data from the clinical trial, which is ongoing, and finally, a proposal for follow-up based on our protocol.
	Chiron began using retroviral vectors in the clinic in 1993, first by ex vivo transduction techniques for cancer, and then in 1994, moving to direct tissue injection, intratumor or IM injections for cancer and immunotherapy for HIV.  A total of 250 subjects received this direct injection of vector, and this formed basically the safety basis for proceeding to an intravenous vector for the current hemophilia study.
	Now, patients who received repeated IM injections over a period of up to 18 months, also had semen testing on a previous protocol.  104 subjects actually were tested by a PCR assay with single-copy sensitivity, and all samples were negative in this past study.
	Moving now to hemophilia, the choice of the retroviral vector was based on the well-known property of stable integration with a potential for long-term expression of the expressed protein, and in addition, retroviral vector's excellent safety record in the clinic since 1990 in over 1,000 patients.  In addition, transduction with the Chiron retroviral vector for Factor VIII resulted in therapeutic Factor VIII levels measured in preclinical models.  So even though transduction rates can be low with retroviral vector, in hemophilia, of course, even a 2 to 5 percent increase in protein expression can make a tremendous difference in a clinical course, and so this vector was successful in the preclinical models in showing efficacy.
	Finally, the decision to go with intravenous delivery was based, of course, on the fact that this was non-invasive.  Basically, it's administered through a 25-gauge needle in a hand vein, so it's no more invasive than a patient's regular Factor VIII concentrate infusions, and this avoids the increased risk and cost of surgical procedures in this patient population, as well as avoids possible risk related to delivering high concentrations of vector particles directly to the liver in a population that has underlying liver dysfunction.
	Finally, Factor VIII can be expressed in multiple tissues, so delivery via a peripheral IV injection, which of course may go anywhere in the body, may be appropriate for Factor VIII.  We know that because this is a secreted protein, which is unstable unless it binds to von Willebrand's factor in the blood, that any cell expressing Factor VIII needs to have direct access to the bloodstream.
	The retroviral vector Chiron developed was derived from a Moloney Murine leukemia virus that was amphotropic and replication deficient, and carries the gene for a B-domain deleted form of Human Factor VIII.  There were two novel features of this vector.  It was produced in a human cell line to render it human complement-resistant, and prolong the half life in circulation.  And also, it was manufactured at a high titer, 108 to 109 transduction units per ml, so that a large number of particles could be delivered in a relatively small volume of IV infusion.  In fact, the volumes have ranged from 23 mils to 40 mils in the doses given to date in the clinic.
	Now, any systemic administration of retroviral vector, of course, raises the question of--and the concern about biolocalization, so extensive preclinical studies were carried out in 122 rabbits and 4 hemophilic dogs that had received intravenous vector.  Tissue samples were obtained at various time points after infusion, early time points to get--at peak transduction and later time points for steady state.  And a PCR assay was used, which was validated for single-copy sensitivity.  Multiple replicates were tested, 1 microgram per DNA per replicate, the equivalent of 150,000 diploid genome equivalents per replicate.  So the sensitivity was basically the detection of 1 cell out of 150,000.
	And for frequency analysis of PCR signals standards, statistical assumptions were made, that the reactions were independent of each other, and that sampling was representative of the vector distribution in the specimen.
	Results of this study are summarized here.  Basically, the highest signal was seen consistently in liver and spleen, and this was seen in 4 out of 4 replicates in PCR studies, and this persisted as long as the animals were followed or out as long as two years.
	There was also high signal initially in bone marrow and peripheral blood mononuclear cells.  However, this signal declined and was essentially gone after 70 days in rabbits.
	The brain showed no PCR signals, and other tissue showed intermittent, threshold low-level signals.  These tissues included lung, thymus, kidney, lymph node and testes.
	Now, of course, actually seeing even a very low-frequency signal in gonadal tissue raised a red flag, and resulted in additional studies.  These were done in a collection from semen samples.  We tested 2 available hemophilic dogs at 6 months and 2 years, and semen samples were negative in these animals.  In addition, an extensive rabbit semen analysis study was done, which I'm going to describe in a minute.
	But first I want to review a little bit more about the testicular localization data, because actually this is the data that allowed us to go forward into the Phase I study in fertile individuals.  And these data were presented at the March '99 RAC meeting.
	Basically, this figure shows the probability of a transduced cell in rabbit testes over a period of time.  There are four time points tested: 4 days, 15 days, 90 days, which would be following a cycle of spermatogenesis in rabbits, and then 2 years to represent long-term steady state.  And notice the signal was higher at first and then declined very quickly to practically undetectable levels over time.  And probably the most important thing to point out is that even initially, the highest point was still a probability of only 0.00005 or 10-5 of finding one cell in the testes that was transduced with vector genome.
	The semen analysis study was designed together with the FDA to look at the tissue that was of course our direct concern, sperm cells, and this was carried out in adult male rabbits who were treated with intravenous Factor VIII at clinically relevant doses that showed therapeutic Human Factor VIII levels in the blood, and also gave a positive PCR signal in the testes.
	The semen samples were collected weekly for PCR testing, and the duration of the study was 21 weeks in order to span multiple cycles of spermatogenesis.
	For each sample 20 replicates were tested, 10 replicates at each of 2 primer sets, and no positive semen samples were confirmed in this study.  There was a low incidence of sporadic unconfirmed signals that was actually higher in the control animals, 1 in 800, compared to the treated animals, 3 in over 4,000 replicates tested.  So the false positive PCR rate for this assay was about 0.08 percent, which was certainly considered acceptable, and in fact, lower than published rates from other labs.
	The PCR results then, in rabbit testes and semen, confirmed that the risk of any germline transmission event was extremely low, and testes, after one cycle spermatogenesis or 90 days, the risk of any single rabbit testes cell containing the vector genome with 99 percent confidence, was 1 in 709,000 cells.  And in semen, all samples were negative throughout weekly testing over multiple cycles of spermatogenesis.
	So our conclusion from the preclinical work was that a positive PCR signal for vector genome in the gonadal tissue was not associated with transduced sperm cells in the semen.
	Moving then to the Phase I study.  Again, this study actually started on the basis of the frequency of signal found in testicular tissue and the rabbit semen study concluded, as the patients were dosed with a lower dose from the study.  It was a single-treatment study design dose escalation with end points of safety and circulating Factor VIII levels.  Subjects were adult men with severe Hemophilia A.  Informed consent required barrier contraception for the study period, and an indefinite period thereafter if semen samples were positive, and extensive information regarding the possible risk of inadvertent germline transmission and the implications thereof.
	Now, semen test points include a baseline, and then weeks 2, 6, 9, 11, 17, 29 and 53, plus additional samples would be obtained in case of any positive result, and the study's duration was one year.
	Currently 12 subjects have been on study for at least 3 months, and 4 dose levels have been administered, with 3 subjects receiving each dose level.  Infusions have been well tolerated, and all subjects are alive in their usual states of health.
	Semen PCR results are available from 11 subjects through week 17, 8 subjects through week 29, and 3 subjects through week 53 at the end of study.
	The clinical PCR assay consists of testing of 10 one-microgram DNA replicates per sample, again, with a validated single-copy sensitivity, for a detection rate of 1 in 300,000 haploid cells, 1 in 300,000 sperm cells.
	The assay procedures were designed, again, in consultation with the FDA to minimize common sources of contamination leading the false positives.
	And collections were scheduled to maximize the chance of detecting transduced sperm.  The schedule was based on our model spermatogenesis.  First we assumed that germ cells that were accessible to blood-borne retroviral vector must be both dividing, and also on the blood side of the Sertoli-cell barrier, otherwise known as, quote, "blood testes barrier."  And this would be then proliferating differentiating spermatogonia of which there would be many rapidly dividing cells, and then some smaller number of dividing stem cells.  This would mean that spermatocytes, spermatids and spermatozoa were not accessible to transduction, these later-stage germ cells.
	The timing of the transduced sperm in semen was predictable, timing of appearance, based on the time required for maturation from transduced precursor cells, and this can be calculated out to be a period between 49 to 92 days after vector infusion, but equivalent of out study weeks 8 to 14.
	This is a timeline just showing the semen sample time points on a timeline, which also shows the first possible appearance of semen in semen of transduced sperm, and the last expected sperm in semen from the first cycle of spermatogenesis.  And the darker bar indicates the time of expected peak appearance of a transduced sperm.
	Sample collection points were planned so that two samples would be collected during this peak period.  In addition, in case our model assumptions were perhaps not right, and also to collect additional information, we have two samples before this period, a sample after what would be the expected washout period, and additional samples, which aren't shown on this slide, at week 29 and 53.  And, of course, per protocol, additional samples are obtained following any positive test result until three consecutive samples test negative.
	Results to date have been obtained on 63 semen samples tested from 11 subjects.  61 have been negative.  We've had 1 positive in 1 out of 10 replicates tested, and 1 indeterminate with contamination suspected.
	Our positive sample occurred in a subject who was treated at a dose 4, which is the highest dose that's been completed to date.  It occurred after two previous subjects had received the same dose and had had negative samples through this period, the first 18 weeks.  At week--the positive sample occurred at week 9, which, as you can see, would be early in the time of highest risk of transduced sperm possibly appearing in semen.  Following this, two samples were obtained also in the risk period, and these were both negative, and two additional samples since the period have also been obtained in addition, and these were negative as well.  And the samples prior to the risk period were negative.  So the patient has had only the single sample with the 1 out of 10 replicates positive, and all the rest have been negative.
	So, what's the interpretation of this result?  Well, there are several possible interpretations.  First, it's possible that the signal is coming from a non-sperm cell, some somatic cell.  The semen contains granulocytes, macrophages, lymphocytes, epithelial cells, in addition to sperm.  And we know that the subject's peripheral blood mononuclear cells are PCR-positive for vector in 4 out of 4 replicates throughout this period.
	Also, despite efforts to reduce the chance of test contamination, in any very sensitive PCR assay test, contamination can't be ruled out.
	And, finally, of course, the signal could be coming from a sperm that was produced from a transduced differentiating spermatogonia.  The signal's low frequency, detected during the first cycle of spermatogenesis, and repeat samples were negative. So again, this all supports an interpretation that probably this was a late-stage differentiating spermatogonia that was transduced, which was on a one-way path to developing into sperm and would not be a source of continuing bursts of sperm production.
	We went on to perform a frequency analysis to better define the risk of possible germline transmission, assuming that the signal was in sperm cells, looking at the three subjects who had received dose level 4.
	First we looked at pool data from all time points measured, and see an instance of 1 positive out of 109 replicates, for a probability of any 1 sperm cell being transduced of 1 in 57 million, or 99 percent confidence bound probability of 1 in 8.6 million.
	We then looked only at the data from the high-risk period, in other words, the study weeks 9 and 11 samples.  And this would give an incidence of 1 out of 70 positive replicates for a probability of a sperm cell being transduced of 1 in 21 million, or a 99 percent confidence bound probability of 1 in 3.1 million.
	In summary then, with 99 percent confidence, the worse-case frequency of a transduced sperm in our study data so far to date is 1 in 3 to 9 million cells, or a probability of 0.0000003, which is 10-7.  No positive samples have been detected after the first cycle of spermatogenesis, again, providing no evidence of a sperm cell transduction or a continuing event, continuing release of transduced sperm.
	Our conclusions then are that current human data in semen is consistent with preclinical data, supporting the fact that the probability of the germline cell being transduced is very low, and the probability of inadvertent germline transmission with this retroviral genome at the current dose is remote.
	Now, FDA's current policy is to place a clinical trial on hold if there's any positive PCR signal, regardless of its intensity.  However, with risk levels as low as were presented here, we think that the approach is unwarranted, and that in such cases the trial should be allowed to continue while further investigation is conducted.
	Features are built into the trial which are sufficient to prevent safety issues.  For instance, all subjects are required to use barrier contraception, and all are advised in the informed consent about possible risks and implication of germ cell transduction events.
	On the other hand, a clinical hold would be appropriate if the subject's PCR signal were stronger, if multiple patients showed positive signals, or if timing of a signal suggested a continuing event based on the biology of spermatogenesis.
	For follow-up of individuals with positive testing, our recommendations would follow the current protocol.  Repeat tests should be obtained as soon as possible, and if three tests were negative over a period of 3 months, which would represent another cycle of spermatogenesis, and negative following the routine testing schedule to the study end at one year, then no additional extra semen collection would be required.
	If repeat tests are positive or sporadically positive after the first three months and to study end, a situation which we haven't encountered yet, then, of course, one would ideally like to perform a cell fractionation procedure in order to test sperm and other cells in the semen, and determine once and for all whether sperm cells are in fact the source of the signal.
	However, there are technical difficulties in performing a fractionation which would be pure enough to be accurate and provide a reliable conclusion because of the sensitivity of the PCR assay.  In our research, we basically couldn't find that there was a technique that was workable on frozen semen samples.  One would need to use fresh semen and use probably a dual technique of sperm swim-up technique, centrifugation, coupled with a discontinuous percol [ph] gradient, and in that way, get a close to pure sperm separation.
	But because, as I said, we had one single sample of a very low-frequency in a frozen sample, and so we were unable to perform, even attempt to perform any study such as this. But in a person who had repeated positivity, you would certainly want to do the best you could and see if you could accomplish this.
	Following this, however, if it was possible not to completely rule out the possibility of a sperm being transduced, one would estimate the risk of germline transmission based on signal frequency, and then provide genetic counseling to the individual regarding possible outcomes of conception and reproductive alternatives.  If the conclusion of the risk calculation was similar to the risk that was identified in our study to date, in other words, very low, then it's highly unlikely that there would be any effect on reproductive decision making based on these data.
	Okay.  I'd like to thank you, and be glad to try to answer any questions.
	[Applause.]
	CHAIRMAN SALOMON:  Thank you very much.  So we have one hour to go into this.  Are there any questions specifically to Dr. Hurst to clarify anything she's presented, or should we go on to--
	DR. BREAKEFIELD:  I just have one question.  When the FDA does put it on hold, what do you do in the interim?  Do you do--
	DR. HURST:  Well, getting additional semen samples on the patients.
	CHAIRMAN SALOMON:  Okay.  I think it's probably good that we don't have a whole lot of questions, because again, we didn't want to put your particular protocol under examination.  I don't think that's the intention here.  Thank you.
	Okay.  This one is--this is easy, right?  No, just kidding.  So the questions to the Committee are two, and I have, unfortunately, about six or seven different issues though that I've put down in my own notes.  So, we'll see where this goes.
	So the first question is: if semen positivity is identified in patients in a clinical trial, our current approach is to place a clinical hold on the study until it is determined that semen positivity is transient, at which time the trial may be resumed.  Please discuss whether this approach is appropriate.
	In cases where a positive PCR signal is observed in patient semen samples, discuss methods to determine the cell source for the positive signal, in situ hybridization, fractionation of the sperm, et cetera.
	French?
	DR. ANDERSON:  Well, the issue of inadvertent germline transfer has been, of course, with gene therapy from the very beginning.  It is an issue that I particularly have to deal with because we are developing protocols for in utero gene transfer, where germline is at even greater issue, and therefore, we've had to deal with these issues in some detail.
	I'm pretty certain, in fact, I'm pretty positive, that we are the only program that has actually obtained an animal--in this case, sheep--this is with Ishna [ph], then Johnny--where the semen was positive, and we were able to fractionate and show that it's not in the sperm, it's in the semen itself, the non-sperm portion.  And all of that has been published and was at the RAC's in utero gene therapy policy conference and so on.
	This study that was done by Chiron--it's a beautiful study--there have been a number of other studies.  In addition, we have the description of Hank [ph] Kazazian at the March '99--Hank, by the way, is right upstairs at an HLVI meeting right now.  And so I wonder if--I have to say one other thing in preface.  I'm very much aware of the political issues, the social pressures that are on all of us because of the issue of germline, and this has prevented, at least at the RAC--how can I put it appropriately without upsetting our RAC members here--a really rational discussion of the issues.
	And I'm very much aware of the issues.  When our in utero came out, I had lots of hate mail, death threats and so on, because of it would appear that we were going to do intentional germline gene transfer, so I'm aware of the political issues.
	But I really wonder if with all the data that is now available, if we aren't getting pretty high up on this patient safety versus cost, and we're starting to put so much money into studies that hone down, it's not really 3,100,000 sperm, it's actually 2,845,000 sperm?  I mean, every piece of data says, "This is really, really rare."
	I've talked with two pathologists in two different institutions at two different times, who tried to specialize in pathology of the reproductive system, and their feeling was based on the presence of--and so on, and specifically retroviral vectors, that the chances of a retroviral vector actually getting into the sperm is extremely rare.  That's what all the data says.
	So I just put out on the table--I'm aware that politically we have to keep doing this, and we'll keep doing our studies, but I really think we're way up on that curve and we're doing an awful lot of posturing about an issue that is really pretty minor.
	CHAIRMAN SALOMON:  Okay.  Well, I think, number one, we'll take on French's challenge that we have a rational discussion here, as opposed to other groups.
	[Laughter.]
	CHAIRMAN SALOMON:  But you guys can hold me to that one later.  I'm already in trouble.  I know that.
	Anyway, so I think that there--I think, French, you've done a good job of sort of setting the stage here.  The question that's on the table though, you did confuse it a little bit, in that one question, which we should talk about, is how much we should demand as proof that we're not getting transmission to the germline, but that's not what the first question was.
	The first question was: if we could demonstrate that sperm were indeed positive, regardless of all the semen--no, no, no, no--I know--but I'm saying that if semen positivity is identified in a clinical trial, they put it on hold.  And the FDA wants us, I think, to go either tell them, "Yes, that's great; any time semen's positive, put it on hold."  Or whether we should break it down and say, "If semen is positive, you don't put it on hold unless you can demonstrate that the sperm is positive."  So that's kind of the way I see the first question.  So I'd like to make sure that we focus on that, and not all these more complicated things that French put on the table about, you know, if it was positive, but it was only in 1 in 8 million sperm, what the impact of that would be.  I don't mind getting to that later, but that's not what I want to discuss first.
	So, Dr. Gordon, and then Xandra.
	DR. GORDON:  I think I was probably invited to this meeting because of my background in this field.
	I think what we have to consider here is--you can call it political if you want to--but the fact is that the insertion of new genetic elements into the germline has with it special characteristics, which I think makes it incumbent upon anybody regulating to do their utmost to make sure it doesn't happen.  I think it is intuitively improbable, but I also think that a 1 in 1,000 event will certainly occur if you do the procedure 1,000 times.  There's also the problem of vector proliferation and diversification.  And so, while we may think this or that with retrovirus vectors that we use today, we don't really know what we're in for down the road as vectors diversify.
	So I would say that it is reasonable to put a study on clinical hold if semen is positive, pending a more close examination of exactly what cells have it, and sperm fractionation, while it was sort of thought of as maybe imperfect in the previous discussion, really is pretty good.  It is true you run the risk that it will also be positive because of an occasional white cell in there after discontinuous percol gradients, but reality is that it's a reasonable thing to go forward to do while a study is on hold.  It's not that difficult to hold a study for a period of time.
	CHAIRMAN SALOMON:  Okay.  That's very clear.  Xandra?
	DR. BREAKEFIELD:  Yeah, I just wanted to add also, that I think there is a lot of data, and maybe at certain doses and certain routes, maybe it shouldn't be required, but I think in this example of this type of case, where you're going suddenly intravenous, which hasn't been done before, and you're starting to escalate, and then you're looking at a situation where you say--well, I forgot exactly--we're on the highest dose, but let's say 1 out of 3 people on the highest dose had it, I think you do need to pause and consider, because you're in a different--it's not the database you have.  You're escalating dose, you're changing route, and you have a small number of people within that category that you're evaluating.
	CHAIRMAN SALOMON:  So, I don't want to put words in your mouth, but you also are supporting the idea that if in the conduct of a trial, the semen is positive, then you hold the trial until they investigate what's positive in the semen?
	DR. BREAKEFIELD:  I would say certainly in a trial like this where there's a novel route and a dose escalation.  On the other hand, if it's a route that's been done extensively and there's a lot of semen data already available and they've been negative, I'm not sure that I would--and there was one positive, I think I'd be more--I don't know what it means to put on hold to a company, but I'd be more inclined to think it's maybe an--if there's a lot of data out there, and depending how serious it is, when you say you put it on hold, it sounds like oh my gosh, you know--
	CHAIRMAN SALOMON:  Well, Xandra--
	DR. BREAKEFIELD:  That's what I ask, what happens when you put it on hold?  Is it like put in limbo for a year, or can they do something to get out of hold?
	DR. WEISS:  Sure.  It's not necessarily a permanent hold.  It depends on what the issues are, and we usually outline what it would take to get off hold, and that just depends on how long those additional data take to come to the FDA.
	CHAIRMAN SALOMON:  So I think, Xandra, one of the things you said was, if you are monitoring semen samples and it's positive, what to do?  And then you sort of began to segue into another question, would be, when do you demand in a protocol that you monitor semen samples?  Which I don't think is irrelevant, but I think there's two things there.
	So we're still basically--I still want to just come to at least one clear piece on this first question, because I think this is a big issue for the FDA, and I want to be responsive.  So do we so far agree that if you're monitoring semen samples--we're not talking yet about which situations you should monitor--but if you are monitoring it and one is positive, should put it on hold?
	DR. TORBETT:  If it's an ex vivo kind of therapy, for example, T-cell therapy, put the cells in, there is a risk of getting T-cells in the semen.  And under that criteria, without paying attention to say categories, then that would be considered on hold.
	CHAIRMAN SALOMON:  Okay.  Well, I mean, I guess that's a point of saying if you were doing--I guess there we're kind of getting into what kind of a trial needs to have semen samples monitored.
	DR. TORBETT:  I guess so.  Yeah, exactly.  you have to look at the biology of the system and also what kind of trials are being done.  It doesn't make sense to me if it's a T-cell therapy trial, for example, independent of RCR, that if you see positive cells in the semen, you would say, "Gee, perhaps we should put this trial on hold." And I would submit that perhaps this isn't--you know, this would be considered different than injecting it IV or in the brain or wherever.
	CHAIRMAN SALOMON:  Point made.  It's a good point.  But I think that again the point here is, if the FDA agreed to be monitoring the semen samples, you know you could argue that now as being a study that didn't need semen samples monitored, and we could talk about that in a second, but still, if semen samples are being monitored, and one's positive, then the trial goes on hold.  Is that--I mean, again, is there a consensus on that?
	DR. NOGUCHI:  Well, a couple of clarifications.  We do not require semen analysis for ex vivo transduced cells, one.  And the second is the question is just slightly different, because it describes a situation where there's a positive sample, and on the next sampling or somewhere down the line on sampling, the sample no longer is positive.  So that's all we're asking.  Is it appropriate to call a halt, look for further samples, and then take them off hold if it becomes negative?
	The second question is really trying to focus on what are the current methodologies for us to go further and distinguish between transduction of cells and just carrier vector.
	CHAIRMAN SALOMON:  Well, let me follow up on that then.  So if we would agree that if in the course of a study, a semen sample is positive, I won't know what the sample is going to be a week from now, so you're going to put the trial on hold, unless someone on the Committee wants to argue that that's not appropriate.
	Then we can talk about whether--you know, how many negative samples after that you should have before you take the trial off hold, right?
	DR. ANDERSON:  Having said my piece, but if nobody is going to respond to that, then I feel compelled to respond.
	I can understand that the FDA still wants to be in that position and the Committee still wants to be in a position to say if there's a positive semen sample, put it on hold.  But that's a whole different category of clinical hold than everything else you do.  You put on clinical hold when there is a real problem.  And having what all the data says will turn out to be a minor incident, and even if 1 in 100 sperm samples is a positive, one can then go on protection so that one doesn't go on and have a pregnancy and so on.  But I'll simply raise this so it's on the record.  I know if we'd vote for it, I'd vote to say go on, put it on hold and so on, because politically you sort of have to do that.  But it really doesn't make sense.  There isn't any danger for the patient.  There isn't any danger anywhere around.  It isn't a patient safety issue.  It is simply that it is--until we get more information, it's nicer to do.
	DR. SIEGEL:  Just as a clarification on the first part, our reasons for hold--one of our reasons for hold is significant and unreasonable risk, but another reason for hold is insufficient information to assess risk.  So one could make a reasonable determination that if you had a positive semen, and you yet had follow-ups or fractionation, you don't know if you do have something that's in the sperm cell, you don't know if you have something that's going to persist for years or just be transient for days or weeks, that that in a sense raises you to an--
	And one other point about this that probably ought to be considered in the mix, is if you don't stop a trial at this point, you are in a somewhat awkward position regarding consent of new patients that you enroll.  As good clinical practices creates an obligation to inform patients of any information that might influence their willingness to be in a trial.  So now you're in the awkward situation of saying, "Well, somebody's had this in their sperm, but it may well be artifact, false positive"--I mean, in their semen--"it may not be in the sperm at all, and it may be something that lasts a week, but we don't know yet."  So it's something to think about as the option if you still continue enrolling in a setting that you have to figure out what to tell the next patient that comes into the study.
	CHAIRMAN SALOMON:  Good point.  Dick?
	DR. CHAMPLIN:  I'm just wondering if this is an overreaction.  I mean, what's the worse-case scenario if you put--a normal Factor VIII somehow got into a sperm?  I mean, it's a situation where even if that was passed on, would not produce disease.  So it strikes me as a sort of paranoid, worse-view situation of a non-event.  And clearly, any patient going on a study like this should not be having children in the middle of the study.  We use a lot of drugs routinely that we know is teratogenic, and we get consent of patients not to have children while they're receiving thalidomide, for example, as a therapy for a variety of immunologic conditions.  So, that should be part of the consent process.
	And the tradeoff, I would think, curing hemophilia, would certainly be a major positive in terms of a benefit, and we're talking about a theoretical risk that could be minimized by an agreement not to have children in the course of the trial.
	DR. NOGUCHI:  Of course, that assumes that the hemophilia gene is properly expressed when integrated and so forth.  So I think that the question of potentially curing your offspring is highly speculative at this time, and you could get exactly the opposite--
	DR. CHAMPLIN:  I wasn't saying it was a way to cure your offspring, but I would say the likelihood of even if it was somehow passed on, it would not produce a disease.  You know, you could envision there would be genes that would be dangerous.  I mean, you put an oncogene in--
	DR. SIEGEL:  I mean, I don't--I concur in general that we're talking about extremely low-level theoretical risks, but it's non-zero.  Even a normal gene can insert in an area under abnormal regulation, so that it's expression is pathogenic, or certainly can insert in an area where it's mutagenic, and even if it's not disease forming, it raises other issues that need some consideration.  So I think we can agree we're talking very small risks, but not--
	DR. ANDERSON:  You want to bring up Hank Kazazian with him, or I will--
	DR. GORDON:  I don't think we should go on the record as saying anything relating to if the gene goes through, it will probably be okay anyway, because I don't think the public is very likely to accept that probably true statement.
	But I just want to give you an example of how--first of all, my intuition runs the same as those who have talked.  But let me just say that if you have a CMV P-53 gene that you're putting into somebody for a reason, let's say they have a liver malignancy, you may do a wonderful job of helping that malignancy in the liver.  If that is transmitted to the germline and P-53 is expressed ubiquitously throughout a developing embryo, I think it could be highly teratogenic, and could be a pregnancy disaster.  Furthermore, we all know that the people who say they're not going to conceive for an assumed period of time, do, and it's a matter of the profile of this type of anomaly that we're dealing with.
	So my recommendation would be that if a positive semen sample is detected--and this takes into account not retroviruses with Factor VIII, but let's face it, we're looking at a huge variety of vectors and genes down the road--that you're put on hold for one cycle of spermatogenesis, pending repeat cycles, but that that hold could be removed if sperm fractionation in the interim determined that it was not in sperm.
	CHAIRMAN SALOMON:  French?
	DR. ANDERSON:  Jay, the FDA put on the RAC agenda, back in March '99, this issue, and you remember that Hank Kazazian was brought in--I might have the numbers a little bit off--but it was something like the number of active retrotransposons [ph] present in the germline tissue was such--if the numbers aren't exactly right, they're close--that a couple would need to have something like seven children in order to have a mutation caused by a retrotransposon, and they'd have to have something like 6 million children in order to have a mutation caused by a retrovirus.
	Now, so, your statement, although correct, is quantitative, orders of magnitude or from what happens naturally all the time.
	DR. SIEGEL:  No, I don't think so, because I said we were talking about very rare events.  I'm not sure how that could be orders of magnitude higher than anything.  It depends on what "rare" means.  But basically, I was simply trying to say what Dr. Gordon said much more eloquently than I did, simply that we can't call it zero.  But I concur that we're talking--
	DR. BREAKEFIELD:  Let me also add--just according with what Jon Gordon said--that it's one thing to do just random mutagenesis, and I think that's going on all the time.  It's another thing to take in a very strong promoter or some gene that can have biologic consequences and was expressed in the wrong tissue.
	CHAIRMAN SALOMON:  I think basically I think we can say as a consensus, that we agree that if a semen sample is positive--now, that's providing that a trial was designed with semen sampling as part of its demand--is positive, then it is appropriate to put things on hold until we do what we'll discuss next.  And that is, analyze what is positive.  And I think what I hear as an underlying principle to the whole thing is essentially a deal that is--to the public--that we will not use gene therapy at the moment now, at least within our ability, to inadvertently transfer anything into the germline, regardless of our decision process about how significant it is, how likely it is, that it seems to be sort of a deal we're making to go forward, that we're not going to do this at this point.
	I think, is everyone comfortable with that as sort of a consensus?
	DR. GORDON:  I just want to say one other thing as a way of arguing with Dr. Anderson there.  It's not that I disagree with a single fact he says, but I can just not view the scenario of a semen sample being positive, and then somebody saying, "Well, go ahead.  Go ahead and do what you want", and then have to face the consequences of that later, however remote those consequences might be.  I mean, it just wouldn't make any sense to the consumer advocate if that approach were taken.
	DR. ANDERSON:  I agree.  I agree, Jon.
	CHAIRMAN SALOMON:   I think that's fair.  And the other thing that I would say to French would be, in his experience with current retroviral vectors, we also can make these kind of calculations that you might need 6 million children.  I wasn't present for those kind of calculations, but that even exceeds the wildest dream of any group I know of for having children.
	But essentially, we also have admitted already, several times in the discussion, that we don't--that this is all such a changing target, that we're all working toward these hybrid vectors, et cetera.  So I think that if we're advising on general principles for FDA regulation, I think we should be very cautious, rather than say, "Well, you know, I know what it's like for retrovirus."
	Okay.  So then--
	DR. CHAMPLIN:  I wonder if the test should be different.  If semen is--if you're going to give systemic treatment, the semen is likely to be involved passively in that process, and some more direct sperm test should be selected.
	CHAIRMAN SALOMON:  Let's go there.  That's exactly where we should go now.  So what--do we agree that we should be monitoring semen?  And I'd like to point out that if we do, then one of the questions I want to ask everyone is: then, to me, if you want to be intellectually consistent, that means that none of these trials should be done in women.
	[Laughter.]
	DR. MILLER:  A surrogate marker.  I mean, it says surrogate marker.  I mean, you use what you can have.  I mean, I don't think you--
	CHAIRMAN SALOMON:  Well, wait a minute.  Now I'm having a problem, because, I mean--this is one of my notes here--but if you tell me that we have--we just went through this whole thing.  I don't want to repeat myself.  This principle is we're not going to, you know, as a deal with the public, allow inadvertent transmission to the germline, but you tell me--and we're going to monitor the males in the trial, but you can't monitor the females.  And so, why shouldn't we say that females then shouldn't be allowed into these kind of trials until a point at which you can confirm through enough data that it isn't being transmitted into the germline?  I mean, I'm just trying to be--
	DR. ANDERSON:  Okay.  There is a scientific answer to that, and that is, a number of mitotic events occurring in the female is so much less the number of mitotic events occurring in the male, that the risk factor is whatever it is, 7 orders of magnitude or 8 orders of magnitude or something.
	DR. GORDON:  I'd like to speak to the female a bit.  First of all, I was quite taken aback, and I must say, a little bit put off by the notion that women of reproductive age would be denied gene therapy because of--they have to wait till they were in menopause or something like that.  The ovary is quite a bit different than the testes.  The primordial oocyte in a primordial--the primary oocyte in the primordial follicle is the most accessible of all of those cells, but even that cell is very difficult to access.  It's surrounded totally by theca cells which are very tightly opposed.  The minute the oocyte starts to develop, the zona pellucida develops.  It's almost impossible to get compounds across the zona pellucida.  The egg does not divide.  One of them is ovulated every month, and that is out of 400,000 that sit in the ovary.
	Now, that doesn't mean that there's no risk, and I think that if the FDA told a woman to not conceive during the period of gene therapy, that might be a good idea, but I think if they told her to not conceive ever again in her life because a primordial oocyte, infected when she was 20, might be ovulated when she was 40, would be unfair to women.
	I do think though that in conjunction with this inability to be formal about the woman, as we can with the man, that we need provocative animal-testing systems for these vectors to know what their real potential is for getting them into the egg.
	And I'd like to take just one more minute to describe examples of that that we're doing in our lab.  For example, we have adenoviruses that express Lac-Z [ph].  Sometimes people have found animal ovaries to be positive during somatic gene therapy.  We have said to ourselves, "If that's a rare event that we could get it into an egg, let's make it less rare."  So we put 10 billion adenoviruses into a mouse ovary, injected it directly in, looked for Lac-Z. Couldn't even get the virus into the ovarian follicle.  The follicles are in fact surrounded by blue stain from Lac-Z.  You can actually see where the eggs are because they're not stained.  We then took 1,500 eggs out of mice, removed the zona, so in the rare circumstance of a naked egg, exposed them to 108 adenoviruses for an hour, fertilized them, saw no evidence of entry.
	Now, these are studies which are different from "Let's make a sheep, and then if it has a few lambs, check them."  Now, these are looking at a few cells out of hundreds of thousands, but if you are looking at the very same cells that are exposed to the vector to see whether or not they've taken it up, it's far more sensitive.  And I think one of the things we could recommend to the FDA is they look aggressively towards designing test paradigms for each new vector that comes along that will really look at this, but I know I'm opposed to barring women who are dreadfully ill from undergoing gene therapy or from conceiving for the rest of their lives because they underwent it.
	DR. MILLER:  Underscoring the need for long-term follow-up.
	CHAIRMAN SALOMON:  Okay.  Well, that was great.  I mean, that is a very good scientific answer to my query about whether it was intellectually consistent to a lot of the women in the trial, so the question--
	DR. SIEGEL:  Now the question should be whether we should allow men.
	[Laughter.]
	CHAIRMAN SALOMON:  So the recommendation here would be that in any trial, as it's moved forward with new vectors, new class of vectors, hybrid vectors, that there should be definitely some sort of germline transmission experimental work, and that should be part of the submission for the trial.  I think that's a very clear kind of recommendation.
	DR. GORDON:  Can I just add one other detail here, which hasn't made it to the RAC yet or to the FDA's--this venue yet.  And that is women who undergo assisted reproduction.  The number of women who undergo assisted reproduction, in vitro fertilization, is rising every year.  There were 40,000 cycles of IVF done in the US and Canada last year about.  An increasing number of these involved violating the integrity of the zona pellucida, which is a major barrier exogenous vector access.  Sperm injection now takes place in a very large percentage of women.  When embryos are biopsied for pre-implantation diagnosis, the zona is opened.  Women over the age of 38, every women over the age of 38 in my in vitro program, has the zona opened because it helps the embryo hatch to implant, and it gives a very slight percentage of increase of pregnancy rates.
	These women who undergo assisted reproduction are at exceptional risk for exogenous DNA integration; embryos are very permissive for being infected, they like to integrate things, as Rudy Inish [ph] will tell you about retroviruses, and I think that this is a category where I think the FDA should advise a sponsor to tell a women not to undertake assisted reproductive technologies during the time of gene therapy.  This risk would pass quickly, but it is a significant risk if it is undertaken during the time of gene therapy.
	CHAIRMAN SALOMON:  Would you think that then if the husband or the significant other, I should say, was a male--was the male, and was undergoing the gene therapy, that artificial insemination shouldn't be done during the period of gene therapy?
	DR. GORDON:  Well, not only artificial insemination, but now that we're thinking about this, if a man was contributing sperm to an assisted reproduction procedure, which artificial insemination would not qualify because the zona's intact there.  But suppose a man was giving his sperm for sperm injection or so-called ICZ [ph], what's already been demonstrated in mice, you have about a 30 percent gene transfer rate if you mix sperm heads with DNA and inject them.  And that's a very reliable investigator.  So, I think that men who would contribute to an assisted reproduction procedure should be advised not to do that during a time of gene therapy.
	CHAIRMAN SALOMON:  So the next question I have down as a note is, we need to talk about how you should tell--how you should separate--how you should analyze a positive semen sample now.
	But one question I wanted to ask sort of as lead-in to that, is if you have a replication competent virus in the semen, and even if it's not in the sperm, and you have sexual relations, does that mean that you can't transmit it in the uterus to the developing eggs?  In other words, is proving that it's not in the sperm, yet it is in the semen, an argument that, you know, you should not put the trial on hold and it should go on?
	DR. GORDON:  My answer to that would be it would be okay for the trial to go on, because there's no evidence that DNA-carrying or nucleic-containing agents in raw semen, can make their way into the oocyte during the process of normal fertilization and early development.  It's actually rather an interesting point because the embryo has to get out of the zona to implant, where you'd think it would be susceptible, but the fact is that vertical transmission in viremic people is not a documented phenomenon to my knowledge.
	CHAIRMAN SALOMON:  Okay.  So if we have a positive semen sample, I think the next issue--question two is: what should be done to analyze a positive semen sample?
	DR. GORDON:  Again, I would propose that the clinical study be put on hold for one cycle of spermatogenesis, which is several weeks time--I don't know the exact numbers of days in humans; I work more with mice--during which time fractionation could be done.  Discontinuous percol gradients are very good at enriching for pure sperm, and I think if a repeat study is done with a discontinuous percol gradient--don't forget, you can always get another sample the next day; depending on the age of the man, you might have to wait a few days.  I mean, I don't know, but whatever--
	[Laughter.]
	DR. GORDON:  You get another sample, and you know, you can PCR a fractionated sample in discontinuous percol gradients or swim-ups.  Both work well, though the discontinuous percol gradient works better.  It's not difficult to do, by the way.  And if that were negative, I would say take the study off hold and let them go forward.
	CHAIRMAN SALOMON:  So let's say you were--just to play--I think--let me stop here.  There's two ways we could go here.  We could spend a little more time talking about, you know, should you do in situ hybridization, should you do flow cytometry, should you do discontinuous percol gradient?  I'm not really certain that's very fruitful, but I don't mind going that direction.
	The other direction would be, you know, the way I would see another question here would be, if you were doing a trial, and you had one semen sample was positive, and then one sperm rotation later which--did you say it was 90 days was the period of time in the human, Dr. Hurst?
	DR. HURST:  Well, that will be completely through the washout period, yes.
	CHAIRMAN SALOMON:  Yes.  So, let's say in a 90-day period of time you would now be negative.  One question I would have is, how many times do you allow that to go through before you put the trial on hold for multiple--for a longer period of time?  So in other words, so you find out whether it's 1 patient in 10 or 5 patients in 10?
	DR. CHAMPLIN:  What if it's 1 patient in 100, and you have one positive; would you put the entire study on hold or just that one patient?
	CHAIRMAN SALOMON:  No, I guess I was just--no, I'm not trying to make it more complicated.  I'm actually trying to say that if--you know, one thing I have sympathy for is if a semen sample comes up positive, you put the trial on hold until it turns out to be negative.  That's okay, because if it never turns out to be negative, then we have to think about what we do next, right?  If it turns out to be negative, the only question I was now asking would be, okay, fine.  Obviously, we'd agree to allow the trial to go on, but how many times would that happen in a trial before you'd have to say the trial really needs to be reevaluated?  In other words, after ten patients came up positive and 90 days later were negative, does that mean the FDA should look at that again, or do you just repeat that for a hundred times, which of course, would drive the sponsor crazy and likely the FDA crazy.
	DR. CHAMPLIN:  But if the definitive test is the sperm analysis, and you can do that the next day after your positive test, you should probably just go to that definitive test before doing anything.
	DR. SIEGEL:  I guess the question is--is the question you're asking, well, what if it's in the sperm but transient?  Does that mean you just should stop the research, or does that mean you just should make sure people are aware and take extra care?
	CHAIRMAN SALOMON:  Well, I was just--I mean, at some point it's easy to say if one's positive, you stop and you get it in 90 days.  I was suggesting that the next thing that could happen, it seems to me, is that if every other patient this was happening to, and then I was just saying do you want to--I mean, shouldn't we maybe then--
	DR. SIEGEL:  Right.  But Richard's pointing out that, I guess, that you could--it could be in the sperm, and I think in the paradigm you said that was suggested, we might then--the sponsor might then do discontinuous percol, and if they had another positive specimen and it was clear that all the positivity was not in the sperm, was in other cells in the semen, they might move ahead.  So in which case you don't have to wait 90 days.  You just know you've got something in the leukocytes.  But what if it--I was wondering if your question was, so what if they--if whether if they do that and it is in the sperm, is transient expression in the sperm acceptable?  Or are you simply saying, what if they can't find that out?
	CHAIRMAN SALOMON:  I guess I was just thinking of--here's a scenario.  These guys are doing this trial.  A patient comes along on Tuesday positive in the semen.  Put the trial on hold.  We already said we agreed with that.  And now the trial is on hold.  90 days go by or 30 days go by, and it's now demonstrated that the semen is negative, and further testing shows that the sperm were never positive.  It was a leukocyte in the semen.  Now it's Thursday. Another patient comes up semen positive.  I mean, how many times are you going to put the trial on hold until you finally say that, hey, we know what's happening here, so stop putting the trial on hold for a positive semen sample.
	DR. SAUSVILLE:  I mean, at one level--I mean, this is similar to the familiar grading sort of system for adverse events.  I mean, clearly, if you document with reliability that it's the white cells that are the problem, and we've agreed that it's--that's something we basically live with, I think probably stopping it a few times to establish that is reasonable, but once you've reached the ends that statisticians are familiar, telling us that that's what it is, I have no problem going forward.
	Now, on the other hand, if you do document  that it's actually in the sperm, okay, unexpectedly, I guess, then I mean, that's sort of the way we've defined the terms of this discussion.  That's sort of a like a grade 3 societal adverse event, and if you do it with any degree of frequency, that's--then the trial has failed, and that's a problem.
	CHAIRMAN SALOMON:  So let's take now two possibilities, just for point of discussion.  So the first possibility is that how many times can the semen be positive and we demonstrate that it's in the semen but not in the sperm, before we tell--before we relax and say it's not an issue that we have to worry about for the rest of the trial?
	And then the second issue is, how many times--if the sperm is positive, is that the end of the trial?
	DR. NOGUCHI:  Well, we need to add some practicality, reality in here.  The occurrence of this event is rare to the point that you may only have one semen sample, that the next time you sample the same patient it's negative, but you don't have enough to do any fractionation.  You only have enough to do a PCR reaction or maybe a repeat PCR reaction, because they're doing 10 to 20 samples at a time, replicates.
	So you may be in a situation where let's say out of a dozen people, three of them come down with one positive event at some point during the course.  You may never be able to answer the second question, that is, is it in the semen or the sperm?
	DR. GORDON:  I would propose that if a semen sample is positive, there's no number of times that would make me relax, but on the other--that should be taken in the context of what Phil said.  You're not going to--with the current generation of vectors and administration procedures, you're not going to come up with a very high number of positive people.  But let me also say, to get another sample and fractionate it, we're talking about 72 hours.  I mean, it's not difficult to do a procedure with fractionation.
	DR. NOGUCHI:  That's correct, but it may not have a positive signal.
	DR. GORDON:  I would say that if it didn't have a positive signal on repeat with fractionation, that you take the study off hold.
	CHAIRMAN SALOMON:  I guess what Phil's saying is, if I understand right, is that these are relatively low frequency events, and so that if you wanted to be--am I following you--so if you wanted to be really careful, to wait 72 hours or whatever, and get another semen sample and it's negative, isn't necessarily when you should take the sample on hold.  You maybe need multiple negatives before you could convince yourself that it would be negative.
	Then that's in addition to what I was saying, is how many patients can have semen samples that are positive before you relax?  And I guess then part of it is how many semen samples should be positive that you prove are not in sperm before you relax and say it will never be in sperm and stop putting the trial on hold.
	DR. SAUSVILLE:  But doesn't this equally address how confident you are that you're positive?  I mean, you know, we're giving lots of weight to one test that may be by PCR, and depending on who's doing the assay, and what travel to the lab, the--you know, this gets sort of very complicated from a statistical point of view, right?
	DR. NOGUCHI:  I was not trying to put words in anybody's mouth, but merely to point out it is a rare event.  The sample is limited.  We may not be able to, on any given sample, do both PCR and do any fractionation or in situ.  So part of the question is: when have we discharged to the best of our ability at the current level of technology, our best attempts at ascertaining what does this mean?
	DR. SIEGEL:  I guess there's--in response to your question, there's no number of events of it occurring where it's somewhere other than in the sperm that's going to tell you that, that there's no possibility that it's in the sperm.  But what might happen, I suppose, if you were to study a population where leukocytosis in the semen is high, perhaps because of the nature of the population or the disease, and with a vector where there's a high level of transduction of leukocytes, then you might have a trial where you're going to anticipate a more than rare event, and when you start seeing it, you might ask, is it pragmatic to put the trial on hold in an event that you expect to occur in half the patients and not to be a risk, but simply the transduced leukocytes occurring in the semen like as expected.  And I'm not sure we're facing that situation yet, is what Phil's saying, but we probably can use some common sense when we do.
	CHAIRMAN SALOMON:  I mean, another way to deal with it would be not to test semen, but rather to test sperm.  So, I mean would it be--does anyone want to comment on that?  I mean, if it's not that difficult to separate the sperm for these kinds of trials--I mean we're talking about 100 patients at a time--would it be reasonable then to separate the sperm, do the PCR on the sperm.  If the PCR in the sperm was positive, then you put the trial on hold and you investigate it further.  If you don't, then at least you stop putting the trial on hold every five minutes for negative sperm, positive semen samples.
	DR. GORDON:  My own view of that right now is that the frequency at which it's being discovered is low enough, so they're--probably looking at semen alone is more cost effective than going forward with fractionation.  And down the road, it may appear to be needed, that you need to do fractionation from the get-go.
	I do think one other idea should be introduced here though as proliferation of vectors, et cetera, goes on and different types of patients are treated, if you think the risk is much significantly higher, we can also tell men to freeze sperm before they undergo gene therapy.  This doesn't mean they won't have unscheduled sex with the sperm that are inside their bodies, but if they really want to conceive during the time of gene therapy safely, it's quite simple to freeze sperm and use them in artificial insemination.
	CHAIRMAN SALOMON:  Though of course if it--that's fine, right.  But I think then I would be--you could modify what I said just modestly, and then say that you start off a trial by screening semen.  When you get a positive semen sample, now you realize that you have an issue.  From there on, you just recommend to go to sperm separation, that would be fine.  And I'm trying to do that by way of helping the sponsors and the FDA, because I can just see them, you know, going back and forth every five minutes and some trial canceling their study, because I think there are a lot of leukocytes in semen.
	DR. CHAMPLIN:  What if you have a true positive?
	CHAIRMAN SALOMON:  A true positive sperm?
	DR. CHAMPLIN:  Yes.
	CHAIRMAN SALOMON:  Okay.  Well, that was the second thing we said we would talk about.
	DR. CHAMPLIN:  What's the frequency of that that would be tolerable?
	CHAIRMAN SALOMON:  That's a really good question as we sort of wrap up here.  So let's say now we've dealt with the negatives.  Though we realize that there's a gray here about how to do it, but I think the next question is, if you get a positive in the sperm in one patient in the trial--I mean, that's the start--what happens next?  I mean, what do you guys think?
	DR. SAUSVILLE:  Revise the informed consent and do another one. And then if you do two and you get it two times, then that's a problem.
	CHAIRMAN SALOMON:  I'm okay with that.
	DR. GORDON:  I think the other males who have received the vector just need to be advised a positive sample was found, and it's under further study, and I think sperm fractionation should then proceed in a held trial.
	CHAIRMAN SALOMON:  So there's nothing you can do about--
	DR. GORDON:  That's what I just said, yeah.
	CHAIRMAN SALOMON:  So the question would be modify the informed consent, and you go on with the trial.  So now after X number of samples are positive, what is it that we're finally saying here?  I mean, maybe we can't say.  Maybe we shouldn't be saying it.  And maybe if it turns out that a particular protocol was making sperm positive again and again, maybe that's not for this advisory committee to deal with.  That could be a societal or a philosophical issue, what you want to do next.
	DR. SAUSVILLE:  It's societal, and it would also have to be couched in what you're trying to fix of cure and how much it's working, et cetera, et cetera, et cetera.
	DR. CHAMPLIN:  Again, we deal with teratogenic drugs routinely all the time with the provision that you don't have children while you're taking thalidomide.
	DR. SAUSVILLE:  That's why for the oncologists in the crowd, this discussion is sort of interesting.
	DR. GORDON:  Well, I think a proper thing to advise the FDA in the area of what about the future, is again, that they need to look at preemptively provocative testing systems that will give them some idea what risks they're really facing.  We don't really have great animal test systems out there yet, and I think we should recommend to them that they try to develop them or RFAs try to develop them.
	CHAIRMAN SALOMON:  Well, I certainly think that, you know, I agree with what Ed and Dick just said.  It certainly was the direction I was thinking as well, and that is, if sperm continues to be positive, then it's simply a matter of deciding for the specific patient group what the relative risks versus the benefits of the gene therapy are at that point and making a decision intelligently on that basis.
	DR. WEISS:  Also, that if it's positive in a large number of patients, you'd still want to know the duration of positivity and how would that then--I mean, if it's only through one cycle of spermatogenesis, then it still might--that needs to be factored in, obviously, to anybody's decision.
	CHAIRMAN SALOMON:  Yes.  I think that that's a good point.  So if the situation was that on day minus 8 or day plus 8, you've got an infusion of a replication competent vector or something, and then there was a transient 90-day period where you might have positive sperm.  But after that, there was no further positive sperm and there was no further injection of the vector, one could relax and go forward with it, and the idea then would be the informed consent should be amended to say that, you know, during that whatever--you know, reasonable period of time, 180 days, around the time of the injection at day 8, that's when you don't have--we don't advise having unprotected sexual intercourse.  Is that reasonable?  I think that's--
	DR. SIEGEL:  I would just add to this discussion that, you know, in the hypothetical--one of the hypotheticals that was discussed--and I'm not sure how much discussion of various unlikely hypotheticals are necessary, but in the hypothetical that there was repeated positivity that was--could be localized to the sperm cell itself, I suspect that we would make a determination that that's something that merited public discussion, notwithstanding the issues that we know there are teratogenic mutations in sperm that occur all the time.  If a particular vector and approach were found to do that, I think that would be information we would want to have out in the public domain.  We'd probably analyze it and discuss it.  So I don't think we need to decide so much in advance what to do.  We'd probably be at the RAC or here or somewhere, saying, "Well, here are the data.  What should we do?"  Rather than the--
	CHAIRMAN SALOMON:  No, I agree.  And that's what I was saying, at a certain point here it's not really the purview or the point of this advisory committee that there--if there are societal issues, then those should be dealt with in whichever way that society feels comfortable working them out.
	Though it does get interesting.  It goes back to what French put on the table right at the beginning, and that is, even if you had a positivity of sperm, you know, he correctly pointed out that at least for the current generation of vectors that we have experience for, albeit we don't know what's going to change in the future, but for that current generation, we don't even know what the--you know, the risks may be much less than natural retroposition mutations are, and so that the significance of it is very clear.
	DR. SIEGEL:  Right.  No, and I wasn't suggesting that would be a cause for panic, just a suggestion that this is--the nature of this issue is such that we would want to make sure that there were public discussion of what's happening.
	CHAIRMAN SALOMON:  I think we've answered the questions.  So, 5 minutes early.  So anyway, I'd like to bring the session to a close.  And thank, first of all, all the FDA staff, particularly Gail Dapolito and Rosanna, and Bill Fries and the others.
	[Applause.]
	CHAIRMAN SALOMON:  And also all the speakers, and all the members of the committee and the audience.  Thank you very much.
	[Whereupon, at 1:25 p.m., the meeting was adjourned.]