FOOD AND DRUG
ADMINISTRATION
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CENTER FOR BIOLOGICS EVALUATION
AND RESEARCH
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VACCINES AND RELATED
BIOLOGICAL PRODUCTS
ADVISORY COMMITTEE
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MEETING BY
TELECONFERENCE
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OPEN SESSION
This
transcript has not been edited or corrected, but appears as received from the
commercial transcribing service.
Accordingly the Food and Drug Administration makes no representation as
to its accuracy.
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THURSDAY
SEPTEMBER 22, 2005
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COMMITTEE MEMBERS PRESENT:
GARY
D. OVERTURF, M.D. Chair
MONICA
M. FARLEY, M.D.
Member
RUTH
A. KARRON, M.D. Member
PHILIP
S. LaRUSSA, M.D. Member
DAVID
MARKOVITZ, M.D. Member
CINDY
LYN PROVINCE, R.N.,M.S.N.,M.A. Member
STEVEN
SELF, Ph.D. Member
WALTER
ROYAL III, M.D. Member
FDA STAFF PRESENT:
CHRISTINE WALSH, R.N. Executive Secretary
NORMAN BAYLOR, Ph.D. Director, Office of
Vaccines Research and
Review
IRA BERKOWER,M.D., Ph.D. Laboratory of
Immunoregulation,
Division of Viral
Products
MICHAEL BRENNAN, Ph.D. Assoc. Director of
Research, Office of
Vaccines Research
and Review
DRUSILLA L. BURNS, Ph.D. Laboratory of Respiratory
and Special
Pathogens,
Division of Bacterial
Parasitic & Allergenic
Products
KATHRYN CARBONE, M.D. Associate Director for
Research, CBER
WILLIAM FREAS, Ph.D.
HANA GOLDING, Ph.D. Laboratory of Retrovirus
Research, Division of
Viral Products
PHILIP KRAUSE, M.D.
BRUCE D. MEADE, Ph.D. Laboratory of
Methods
Development & Quality
Control, Division of
Bacterial Parasitic &
Allergenic Products
DENISE ROYSTER Committee Management
Specialist
RICHARD WALKER, Ph.D. Director, Division of
Bacterial Parasitic &
Allergenic Products
JERRY WEIR, Ph.D. Director, Division of
Viral Products
I
N D E X
AGENDA ITEM PAGE
Call to Order and Opening Remarks 4
Announcements/Administrative Matters 4
(Christine Walsh)
Laboratory of Retroviruses, Division of Viral 10
Products, Overview of Laboratory (Dr. Golding)
Laboratory of Immunoregulation, Division of 21
Viral Products, Overview (Dr. Berkower)
Laboratory of Respiratory & Special Pathogens, 32
Division of Bacterial Parasitic & Allergenic
Products, Overview (Dr. Burns)
Laboratory of Methods Development & Quality 44
Control, Division of Bacterial Parasitic &
Allergenic Products, Overview (Dr. Meade)
Open Public Hearing 57
P
R O C E E D I N G S
1:35
p.m.
MS.
WALSH: I'll start off the meeting. Good afternoon. I am Christine Walsh, the Executive Secretary for today's meeting
of the Vaccines and Related Biological Products Advisory Committee
meeting. I would like to welcome all of
you to this meeting of the Advisory Committee.
There
is a speakerphone for public participation located here in Conference Room C of
Building 29-B on the NIH campus.
This
afternoon's teleconference meeting will consist of sessions dealing with
presentations and committee discussions that are both open and closed to the
public, as described in the Federal
Register notice of August 30, 2005.
At
this time I would like to introduce the Committee members and ask that they
acknowledge by saying "Present" if they can hear me:
The
Committee Chair, Dr. Gary D. Overturf, Professor of Pediatrics and Pathology,
University of New Mexico Medical Center.
CHAIRMAN
OVERTURF: Present.
MS.
WALSH: Dr. Monica M. Farley, Profess of
Medicine, Emory University School of Medicine.
DR.
FARLEY: Present.
MS.
WALSH: Dr. Ruth A. Karron, Professor,
Johns Hopkins School of Hygiene and Public Health.
DR.
KARRON: Present.
MS.
WALSH: Dr. Philip S. LaRussa, Professor
of Clinical Pediatrics, Columbia University.
DR.
LaRUSSA: Present.
MS.
WALSH: Dr. David Markovitz, Professor,
University of Michigan Medical Center.
DR.
MARKOVITZ: Present.
MS.
WALSH: Ms. Cindy Lyn Province,
Associate Director, Bioethics Center of St. Louis.
MS.
PROVINCE: Present.
MS.
WALSH: Dr. Steven Self, Professor,
Department of Biostatistics, University of Washington.
DR.
SELF: Present.
MS.
WALSH: Dr. Walter Royal III, Associate
Professor, Department of Neurology, University of Maryland School of Medicine.
DR.
ROYAL: Present.
MS.
WALSH: Absent today is Dr. Bonnie M.
Word, Assistant Professor of Pediatrics, Baylor College of Medicine. Dr. Word is in a Hurricane Rita evacuation
area south of Houston. Our thoughts are
with her, for her family and her family's safety and wellness.
I
would like to thank all Committee members for taking the time to join us
today. Now I would like to introduce
come CBER staff members that will be participating in today's meeting and are
currently seated in the room:
Dr.
Michael Brennan, Associate Director of Research, Office of Vaccines Research
and Review;
Dr.
Kathryn Carbone, Associate Director for Research, CBER;
Dr.
Norman Baylor, Director, Office of Vaccines Research and Review;
Dr.
Jerry Weir, Director, Division of Viral Products;
Dr.
Richard Walker, Director, Division of Bacterial Parasitic and Allergenic
Products; and
Denise
Royster, Committee Management Specialist VRPAC Advisory Committee.
I
ask that all our Committee members identify themselves each time they
speak. We do have a transcriber present
who will need your assistance in order to accurately transcribe all comments to
the appropriate Committee member.
I
also ask our Committee members not to use cellular phones, since they may add
unnecessary background noise to the line.
Should during the teleconference a source of noise occur in your office,
we would appreciate it if you would use the mute button on your phone, if you
have that option. We ask that you do
not place us on hold, since many clinical centers have background music that
can be distracting to those remaining on the teleconference line.
I
would now like to read into public record the conflict of interest statement
for this meeting.
The
Food and Drug Administration, FDA, is convening today's meeting of the Vaccines
and Related Biological Products Advisory Committee under the authority of the
Federal Advisory Committee Act, FACA, of 1972.
All members of the Committee are Special Government Employees, SGEs, or
regular Federal employees from other agencies, and are subject to the Federal
conflict of interest laws and regulations.
The
following information on the status of this Advisory Committee's compliance
with Federal conflict of interest laws, including but not limited to 18 USC
20(a) and 21 USC 355(n)(4) is being provided to participants in today's meeting
and to the public.
FDA
has determined that members of this Advisory Committee are in compliance with
Federal ethics and conflict of interest laws, including but not limited to 18
USC Section 20(a) and 21 USC Section 355(n)(4).
Under
18 USC 20(a), applicable to all government agencies, and 21 (SC 355(n)(4),
applicable to certain FDA committees, Congress had authorized FDA to grant
waivers to Special Government Employees who have had financial conflicts when
it is determined that the agency's need for particular individuals' services
outweigh his or her potential financial conflict of interest (Section 20(a) and
where participation is necessary to afford essential expertise (Section 355).
Today's
agenda includes a review and discussion of the intramural research programs of
the Division of Viral Products and the Division of Bacterial Parasitic &
Allergenic Products. Based on the
agenda, it has been determined that the Committee discussion presents no actual
or appearance of a conflict of interest for today's meeting.
This
conflict of interest statement will be available for review at the registration
table. We would like to remind members
that, if the discussions involve any other products or firms not already on the
agenda for which an FDA participant has a personal or imputed financial
interest, the participants need to exclude themselves from such involvement,
and their exclusion will be noted for the record.
FDA
encourages all participants to advise the Committee of any financial
relationships that you may have with firms that could be affected by the
Committee discussions.
That
ends the reading of the conflict of interest statement. Can everyone hear me okay? Okay.
Dr.
Overturf, I turn the meeting over to you.
CHAIRMAN
OVERTURF: Thank you, Christine. I
want to welcome all the members to this meeting which, as Christine Walsh just
pointed out, will be to review four laboratories in the FDA CBER program. So we will go ahead and start through the
first speaker, which will be Dr. Hana Golding from the Laboratory of
Retroviruses.
DR.
GOLDING: Can everybody hear me? Okay.
So
I am the Chief of the Laboratory of Retrovirus Research in the Division of
Viral Products, and the lab is divided into three sections: Section on Retrovirus Pathogenesis, Section
of Retroviral Immunology, and Section of Molecular Retrovirology.
Those
sections have been actually formed sort of historically back in 1993, and as
you will see, some of the activities in the sections sort of crossed paths, and
there was a lot of interactions going on between members of the various
sections.
In
the Section of Retroviral Pathogenesis, include myself as well as Keith Peden
and Marina Zaitseva, who is a Senior Staff Fellow who worked with me for the
past 12 years, and Dennis Klinman in the Section of Retroviral Immunology, and
Arifa Khan is a PI in Molecular Retrovirology.
I
would actually start by describing the diversity of the regulatory work that is
covered by our laboratory. Since we are
responsible for providing all the CMC consultation regarding HIV vaccines, this
is the lion's share of the regulatory work in our group; and just to take a
tally, since the last site visit our group reviewed more than 50 pre-INDs, 70
original IND submissions, and close to 850 IND amendments.
In addition, members of the group have
been providing review regarding BLA and pre-BLA and BLA, usually in support of
other laboratories.
So
in addition to the immediate responsibilities, we provide expert opinion to
other CBER laboratories and divisions on issues related to novel cell
substrate, adventitious agent detection, retrovirus contamination, Lentivirus
based vectors, plasmid DNA vaccines, and CpG oligonucleotides and other
adjuvants.
In
addition to the review of the different applications, members of the lab have
been involved in multiple presentations to CBER Advisory Committees, and also
have been representing CBER and the FDA at the World Health Organization and
several other international regulatory authority meetings.
We
commonly participate in interagency working groups and have been involved in
organization or participation in special workshops on HIV vaccines, plasmid DNA
vaccines, and novel cell substrates.
Importantly,
during the past four years, several guidance documents have been worked upon by
members of our laboratory. All of them
have either been finalized or in last stages of finalization. Those included consideration for plasmid DNA
vaccines for infectious disease indications that was headed by Dr. Dennis
Klinman; characterization and qualification of cell substrates and other
biological starting materials for the production of viral vaccines, which was a
very important contribution by Dr. Keith Peden and Dr. Khan; and preclinical
toxicity assessments of preventive vaccines to support Phase 1 clinical
trials. I was involved in the
preparation of this guidance.
I
would like now to describe very briefly the main research activities in the
individual PI's laboratories in support of our regulatory mission. I want just to say in the start that, in
addition to the work related directly to the list of regulatory activities,
several of us have been paying, or devoting a significant amount of our
research toward agents of potential bioterrorism, and that will become evident
in the presentation.
So
Dr. Dennis Klinman's laboratory was mainly involved in monitoring the safety
and regulatory activity of DNA based products.
There are many such products that are regulated by CBER. DNA based products include DNA vaccines,
synthetic oligonucleotides or ODN; for therapy, immune modulation and
adjuvants.
In
addition, another aspect of DNA or cellular DNA -- It is existent as a
contaminant, unwanted contaminant in a variety of vaccines, as well as other
biological products.
So
the main achievements -- I think you have the packages. So you can get the details of the research
work done, but the main achievements or
accomplishments of Dr. Klinman's work is: He discovered and patented a new class of stimulatory CpG ODN
that have been under development as vaccine adjuvants, immunoprotective agents
and anti-allergens.
In
addition, he discovered and patented a new class of suppressive ODN that may be
used for prevention or treatment of autoimmune and inflammatory diseases, and
he is actively involved in trying to understand the mechanism of action of
these ODN.
In
my laboratory there are actually three main areas of research that took place
in the past four or five years. We
continued in our duties on HIV cell entry with emphasis on HIV co-receptor
expression and function in primary human cells, which are targets for HIV
infection, and also involved in new entry inhibitors targeting the HIV
co-receptors or CCR5.
In
addition, significant efforts have been conducted in the area of HIV vaccine
trials. Specifically, a new HIV EIA
was developed for differential diagnosis of HIV infections in the presence of
vaccine generated antibodies, and in the counter-terrorism preparedness we were
involved in developing new in vitro
assays and animal models for evaluation of smallpox vaccines potency and
safety.
Back
to the HIV EIA, we termed it HIV-SELECTEST, because it is important to emphasis
its cell activity. So all uninfected
vaccine trial participants score negative in our assay, while all HIV
infections are diagnosed early after infection.
This
is a very simple and economical test.
It can be implemented in sites of future HIV vaccine trials and in blood
collection centers around the globe.
In
the area of smallpox vaccine evaluation, we developed a reporter gene based
vaccinia neutralization assay. Again,
it is a high throughput assay that was adopted by an HHS working group to be
used in current clinical trials of new smallpox vaccines.
Using
this in vitro assay, we continue in
multiple collaborative work, among others on the monkeypox primate challenge
that will eventually be validated for the "2-animal rule" for
licensure of future smallpox vaccines.
We
also are working on the development of mouse models for tracking vaccinia
dissemination in order to evaluate vaccine safety and post-exposure
prophylaxis.
Marina
Zaitseva has developed an independent program regarding cellular genes involved
in thymic reconstitution and immune modulation. She developed murine models of transient thymic atrophy that
included low dose irradiation of single injection with dexamethasone or
estrogen, and then used this model to identify salvage mechanisms which are
important for thymic regeneration.
Currently,
she is extending these studies in irradiated mice to follow reconstitution of T
cells in the Gut-associated lymphoid tissues.
I
am now moving to the work conducted in the laboratory of Dr. Keith Peden in the
Section of Retroviral Pathogenesis. In
that lab, there are three major directions.
One is safety of tumorigenic cell substrates for vaccine manufacture,
SV40 contamination in human vaccines, and HIV co-receptor evolution and
pathogenesis.
With
regard to the tumorigenic -- to the use of tumorigenic cell substrates, it was
important to develop animal models to assess the oncogenic activity of cellular
DNA. In order to do that, Dr. Peden, in
collaboration with Dr. Andrew Lewis, developed animal model in which a
combination of oncogene-expressing plasmids induced tumors primarily in newborn
mice.
This
animal model is now ready, all the positive controls are in place, and are
ready to test molecular DNA from new cell substrates, including tumorigenic
cells.
In
parallel, efforts are done to actually provide quantitative means to evaluate the
risk associated with residual DNA in vaccines produced in mammalian cells. So Dr. Peden has been putting some effort
into developing quantitative assays to measure the infectivity of integrated
retroviral DNA. This is just as a model
system.
That
allows him to come up with estimates for safe levels of residual cell substrate
DNA in viral vaccines, and we now have the tools to evaluate the removal of
cellular DNA. We hope that this kind of
studies will be the basis for future FDA recommendations on the safe amount of
residual DNA in viral vaccines.
In
a separate area, Dr. Keith Peden's lab developed quantitative assays to detect
the presence of primate polyomavirus DNA in biological specimens, as well as a
single-cycle, reporter-gene based neutralization assay for BKV, JCV and
SV40. This will be particularly
important in lieu of the recent reports in the past several years that some
tumors contain SV40 sequences, and there was the possibility that it was somehow
associated with the contaminated polio vaccines of the early Sixties and
Fifties.
I
would like to then move to Dr. Arifa Khan in the Section of Molecular
Retrovirology. Dr. Khan has been
focused on several areas: First, Simian
Foamy virus transmission studies in order to assess the risk of human infection
by SFV-infected blood donors, as well as studies of Simian Foamy Virus
replication in order to estimate the potential risk of SFV propagation in
simian and human cells used for vaccine manufacturing.
In
a separate project, Dr. Khan's laboratory is developing strategies for
detection if infectious agents in vaccine cell substrates. That involves quantitative assays for
detection of retroviruses, especially QPCR type assays, induction of endogenous
retroviruses in cells from different animal species, and the induction of HHV-8
as a model of latent DNA virus.
That
is the end of my presentation.
CHAIRMAN
OVERTURF: We have a few minutes. This is Dr. Overturf. We have a few more minutes for questions. I would like to ask one question of Dr.
Golding.
It
seems to me that there are other laboratories that I recall that we have had
presented to us that are also looking at adventitious agents in vaccine and
vaccine products. You didn't mention in
your presentation whether Dr. Peden is collaborating with any of those other
laboratories in that effort, or are they working completely independently?
DR.
GOLDING: That is a very good
question. Actually, there is very
extensive interaction which we think is really the strength of our adventitious
agent program. There was a very close
interaction between Dr. Phil Krause, Keith Peden, Andrew Lewis, who really
complement each other in many of the adventitious agents that they are looking
at, as well as the assays development, and actually as a team they were able to
obtain several important external funding to support this effort.
I
think it is really the -- The strength of the program is they are complementary
in the interaction between these investigators.
CHAIRMAN
OVERTURF: This is Gary Overturf. Are there any other questions from Committee
members for Dr. Golding? Okay, hearing
no further questions, I think we can proceed to the next presentation, which is
on the Laboratory of Immunoregulation, Division of Viral Products, and the
overview of the laboratory is going to be presented by Dr. Ira Berkower.
DR.
BERKOWER: Yes. Hi.
I hope you can all hear me. I
appreciate this opportunity this afternoon to describe the research program of
the Laboratory of Immunoregulation. The
first slide on the handout shows the organization of the laboratory.
We
have two principal investigators, Dr. Carol Weiss and myself. Each laboratory has a rather senior
microbiologist, technician type, two post-doctoral fellows, and a pre-doctoral
student or post-baccalaureate students who have worked on these projects. On this slide I have also included some of
our principal collaborators at the NIH and at the Vaccine Research Center of
the NIH.
ON
my next slide, I show that the Laboratory of Immunoregulation is active in
several regulatory areas. These include
licensed vaccines. We approved the
Hepatitis A/Hepatitis B combined vaccine which has been used subsequently in
millions of people around the world.
We
participate in clinical trials of new vaccines, and during the period under
review we have reviewed over 250 IND documents, many of which were focused on a
specialty that we have somehow evolved, which is therapeutic vaccines for HIV
infection. Among these, we completed
the review of the first large Phase 3 clinical trial of a therapeutic vaccine
which involved over 3,000 subjects.
We
are also active in the formulation of vaccine policy at the Office level and at
the Center level I am the co-chairman of the guidance document for
peptides. We worked on an important
issue that was presented to your Committee in the past, which was eliminating
the risk of BSE somehow creeping into the vaccines that are given to all the
children; and I also served, along with Drusilla Burns here, as CBER's
representative to the Interagency Committee on Select Agents of Bioterrorism,
which helped the CDC implement the new laws on bioterrorism.
For
the rest of this, I would just like to focus on our research program. Our research focus is on the factors that
affect vaccine potency and efficacy, including the biology of the virus and the
immune response of the host.
Our
goals in this work are to advance the science of AIDS vaccines, and to improve
our expertise so we can add value at each step of the regulatory process.
Now
I have divided up the rest of this talk into discussing the work of the Weiss
lab and then my own lab. The Weiss lab
is focused in HIV vaccines and on smallpox vaccines.
Their
HIV work has defined conserved neutralizing determinants in the Envelope gp41
protein that enabled the virus to enter the cell, and they have characterized
these envelope structures as immunogens for eliciting broadly neutralizing
antibodies.
This
is possible, because these conserved structures are shared among many different
virus isolates. So antibodies that
neutralize one would probably neutralize all, and there are examples of this in
the literature. They have elucidated
the mechanism of antibody neutralization by targeting these sites, as measured
in a variety of neutralization assays.
With
regard to smallpox vaccines, they have analyzed the neutralizing antibodies
that are elicited by the current vaccine, Dryvax, and they have evaluated the
role of these antibodies in a protection assay.
For
HIV: For an envelope virus like HIV to
enter a cell, it must fuse its lipid envelope with the lipid vi-layer of the
cell membrane. This process is a highly
evolved function of the virus that proceeds via a fusion intermediate, and it is
this fusion intermediate that is the target of a great deal of interest in the
field.
It
is well known, for example, that peptides corresponding to the fusion proteins
can get in there and interfere with the fusion process. But in addition to that, Dr. Weiss showed
that two highly conserved sites on the envelope fusion intermediate can be
targeted for inhibition.
She
has designed a structure-based strategy for raising antibodies to these
conserved sites, and evaluated the antibodies for the ability to neutralize the
virus, and studied the potential barriers to antibody access -- for example,
the transient nature of the fusion intermediate.
In
addition, she has subjected the virus to selective pressure and identified
envelope mutations and potential resistance mechanisms by which the virus can
escape inhibition at these sites.
This
work is highly relevant to vaccines. As
I mentioned above, by targeting conserved sites on gp41, this work leads to new
strategies for developing vaccines that can induce broadly neutralizing
antibodies, which are the goal of much current AIDS vaccine research.
They
provide new methods for characterizing envelope immunogens, and they explain
the mechanism of envelope escape from inhibitors such as enpuvaritype which
have been observed in the clinic. This
work also increases our expertise on neutralizing assays and on evaluating
potential quality of protection.
In
the smallpox area, Dr. Weiss demonstrated that a recombinant vaccinial protein
called A27 can elicit potent neutralizing and protective antibodies that are
measured in a passive protection assay in immunocompromised animals and show
protective value by themselves and also, in combination, can augment the
protection afforded by vaccinia-immune globulin.
Interestingly,
she found that antibodies to this protein are only a minor component of the
antibodies that are induced by the current vaccine, suggesting that additional
specificities may be available if A27 can be made more immunogenic. By understanding the protective response to
Dryvax, we can aid in the development of new vaccines by identifying viral
antigens that induce protective antibodies.
The immune response can be optimized in these new vaccines and, finally,
identifying new targets for antibodies, it can lead to improved therapeutic
immunoglobulins, perhaps by augmenting and adding new specificities to VIG,
vaccinia immunoglobulin, as we currently have.
Now
with regard to my own lab, we have focused on two projects, two areas. One is creating virus-like particles that
are rich in gp120, and the second one is exposing conserved sites on gp120 for
the induction of neutralizing antibodies.
With
regard to the first point, we note that many successful vaccines are virus-like
particles. IPV for polio and HBsAg for
hepatitis B are two examples where the formation of particles is critical for
vaccine potency and efficacy.
We
have found that we can enhance HIV vaccine potency by incorporating gp120 or
gp41 into virus-like particles. In
addition, the HIV envelope has conserved and valuable antigenic
determinants. It is well known that the
variability of the virus is a huge problem for vaccines.
In
addition, it is now known that the envelope protein can migrate between two
structural confirmations, which I would describe as the open form and the
closed form. In the absence of a figure
of this, I would just like to use the analogy of my hand. The palm of my hand is the open form, and
the fist is the closed form.
What
we have found is ways to modify the envelope to keep it in the open form. This would expose the conserved sites in my
palm and favor the induction of cross-reactive neutralizing antibodies. I would like to illustrate these two points
in the coming slides.
The
next slide shows our strategy for particle formation. We have expressed gp120 in tandem with a carrier protein,
HBsAg. As shown in the lower left,
HBsAg is an integral membrane protein that incorporates itself into the lipid
bi-layer, and in doing so it anchors gp120 to the surface of a lipid; and when
enough of these get together, they butt off to form particles and incorporate
gp120 into the particles.
The
interesting thing about the particles is gp120 is now expressed in its natural
milieu at a lipid-water interface. The
results that we have obtained with these particles are described on the next
slide.
Hybrid
proteins assemble efficiently into 20-30 nanometer size particles rich in
gp120. The efficiency is greater than
90 percent.
gp120
is in the native conformation, and it changes conformation in response to CD4
binding from the closed form to the open form.
I doing so, gp120 on the particles functions just like gp120 on the
virus.
With
regard to immunogenicity, the particles elicit neutralizing antibodies earlier
than native gp120 alone, and the neutralization is more efficient relative the
ELISA titers. However, the antibodies
are still limited to neutralizing the immunizing strains.
Now
since the time of the site visit, we have made a lot of progress on the second
part of this. We know that gp120 exists
in two conformations, based on X-ray crystallography, for example, and on
monoclonal antibody binding. The closed
form is found on the virus. The open
form occurs after the virus binds CD4 receptor on cells. All gp120 vaccines tested so far have been
in the closed form.
What
we have done is we have identified five structural sites on the gp120 that
changed position as gp120 migrates to the open form, and we have found that
removing one of the loops favors the open form and exposes the CD4 binding site
for antibody binding.
We
have measured increased binding by two different monoclonal antibodies to the
CD4 binding site that are favored by this loop deletion. This mutant will allow us, for the first
time, to immunize with the open form in order to elicit antibodies to conserve
neutralizing sites that are normally hidden.
This
antibody research is quite relevant for HIV vaccines. We know that HIV-infected patients make broadly cross-reactive
neutralizing antibodies in response to their infection. Monoclonal antibodies, human monoclonal
antibodies, derived from these patients target a shared neutralizing
determinant on gp120 or on gp41, and they neutralize broadly, despite the
variability of the virus.
We
also know that a cocktail of these monoclonals gave potent protection in a
macaque challenge model, with sterilizing immunity in most cases. And so a vaccine that exposes the functional
sites targeted by these antibodies would have the best chance of inducing
protective immunity.
A
successful AIDS vaccine most likely will elicit both neutralizing antibodies
and effector T cells. Antibodies that
target essential viral functions, as I have shown here, functions such as
receptor binding or membrane fusion, as I described in the first parts, will
cross-react broadly among different viruses, because they all have to do this
same function. So they all share
conserved sequences to perform this function.
Successfully
modified forms of gp120, which expose neutralizing determinants, can lead us
toward immunogens with enhanced vaccine potencies, and the ability to
neutralize broadly.
Studies
of viral neutralization will help us, in addition -- neutralization and
protection will help us to evaluate new vaccine candidates as they come along
and, hopefully, to define the correlates of immunity.
Any
questions?
CHAIRMAN
OVERTURF: This is Gary Overturf. Are there questions for Dr. Berkower by the
Committee members? A fascinating
discussion. This is again Dr.
Overturf. A fascinating discussion, and
I think highly relevant to AIDS vaccine research, Dr. Berkower. I appreciate that very much.
DR.
BERKOWER: Thank you very much.
CHAIRMAN
OVERTURF: We are getting ourselves a
little ahead of time, but feel free to ask questions as we go along. So I will try to ask after each
presentation.
The
next presentation is by Dr. Drusilla Burns of the Laboratory of Respiratory
& Special Pathogens, Division of Bacterial Parasitic & Allergenic
Products. Dr. Burns.
DR.
BURNS: Yes. Good afternoon. I am the
Chief of the Laboratory of Respiratory & Special Pathogens, and I am going
to tell you a little bit about that lab today, both our regulatory
responsibilities and our research responsibilities.
Before
I do, I wanted to give you a little history of this lab as well as Bruce
Meade's lab, the Laboratory of Methods Development and Quality Control, that
you will hear about next, since we both evolved from the same laboratory, and I
think understanding the history will help you better understand the two labs.
As
I said, we both -- Both the labs evolved from the Laboratory of Pertussis,
which is a laboratory that has been in -- was in existence at this institution
since the 1960s. The Laboratory of
Pertussis was responsible for regulation of pertussis vaccines, and during the
1980s and most of the 1990s played a very big role in the development,
evaluation and licensure of the new acellular pertussis vaccines, and there was
quite a bit of activity in that area for that period of time.
In
1996 the first acellular pertussis vaccine was licensed for infants, and by
1998 most, but not all, of the acellular pertussis vaccines have been licensed.
So
in 1998 the regulatory activity in this area began to subside somewhat, and we
took a close look at the lab and said, well, you know, is there something that
we could do that would help the Division and CBER in a better way than just
sticking with pertussis vaccines.
There
was one obvious area that needed some coverage, and that was looking at the
vaccines that involve bioterror agents.
In 1998 the anthrax vaccine was -- The military decided to give the
anthrax vaccine to every member of the military.
So
while the anthrax vaccine hadn't been used much before that, all of a sudden
there was a tremendous amount of activity in that area. Of course, as we now know, in 2001 there
were the anthrax letters which also put a lot of attention on both anthrax
vaccines as well as other vaccines for bioterror agents.
So
we felt that it would be best to expand the laboratory to include these
vaccines, not only anthrax vaccines but some other vaccines for bioterror
agents. So the name of the laboratory
was changed in late 1999 to the Laboratory of Respiratory and Special Pathogens.
At
that time, we then looked at the people -- the personnel in the lab, and we
decided that perhaps we should split the lab into two laboratories, one that
would contain the product area specialists or would look at the manufacturing
issues and the evaluation of the vaccines, and the other laboratory which would
specialize in test development. That
laboratory is the laboratory that Bruce is going to tell you about in just a
few minutes, and that is the Laboratory of Methods Development and Quality
Control.
So
now let me focus on the Laboratory of Respiratory and Special Pathogens. It has three principal investigators, each
with our own independent research program, myself, Tod Merkel and Karen
Meysick.
I
will tell you a little bit about the research program in just a few minutes,
but first let me focus in on our regulatory activity. We have three areas that we look at primarily. We still look at pertussis vaccines. We also are responsible for anthrax vaccines
and the plague vaccines.
As
far as pertussis vaccines are concerned, while the activity in that area has
subsided since the late 1990s, there is still a considerable amount of
activity, and that is we have to monitor and evaluate changes in
formulation. This includes major
changes in formulation, such as the Tdap vaccines that your Committee heard
about in March and which were recently licensed, those vaccines for --
pertussis vaccines for adults and adolescents.
We
also look at a number of other combination vaccines that contain pertussis
components or major changes in manufacturing such as the removal of thimerosal
that occurred a few years ago. Any
change in the manufacturing process is reviewed by our laboratory, and we
monitor the vaccines on an ongoing basis.
As
far as anthrax vaccines are concerned, there is one licensed anthrax
vaccine. That is AVA, the vaccine that
was given to the military, and we monitor that vaccine and any change in
manufacturing of that vaccine we are responsible for evaluating.
In
addition, we are assessing the new generation anthrax vaccines that consist of
purified single component, the recombinant protective antigen; and importantly,
we have been instrumental or taken a lead role within the Center in using the
Animal Rule to demonstrate efficacy of these bioterror vaccines.
For
those of you who may not be familiar with the Animal Rule, this was instituted
a few years ago. There are certain
vaccines such as the anthrax vaccine which cannot be feasibly or ethically
tested for efficacy in humans. In order
to show efficacy of those vaccines, FDA promulgated a rule, a regulation, a few
years ago that allows for efficacy testing to be done in animals.
While
this sounds very simple, and it sounds like it could be a shortcut to
determining efficacy of vaccines, in reality it is quite complex to come up
with a really scientifically sound strategy for translating efficacy in animals
to humans. That has been a challenge
for us and something that we spent a considerable amount of time on.
As
far as plague vaccines are concerned, we are responsible for the new generation
of plague vaccines, and again the Animal Rule will have to be used to license
these vaccines, and we have been working to come up with a sound strategy as
far as plague vaccines are concerned.
The
division of regulatory work in our laboratory is shown on the next slide. I am responsible for both pertussis and
anthrax as well as Tod Merkel and his group.
This redundancy is actually done on purpose, because both of these areas
have a considerable amount of activity, and we need that sort of redundancy to
make sure we have adequate people available at all times to do the regulatory
work.
Karen
Meysick is responsible for the plague vaccines, and I serve as her back-up when
needed.
Our
regulatory workload is shown on the next slide. Since 2000, we have reviewed a number of INDs and amendments, as
well as BLAs and BLA supplements. Also,
as I indicated, we have taken a lead role within the Center on implementation
of the Animal Rule. We have held
several workshops on the subject. We
have given presentations at various places to get the word out, how we are --
our strategy for licensing these vaccines, and have worked closely with other
government agencies, especially NIH who is running the program to evaluate the
new anthrax and plague vaccines.
So
while I have given you some numbers of INDs and BLAs that we have reviewed, I
don't think that the numbers are that important, because sometimes you can
review something very quickly. Other
times, something takes a very, very -- a lot of work. Suffice it to say that each principal investigator in the
laboratory spends about one-third to one-half of their time on strictly the
regulatory aspects of our work.
Now
I would like to switch to the research program and briefly describe the
research of each of the individual principal investigators.
First,
I have a research program, a small program in both Bordetella pertussis and
Bacillus anthracis. While each program
is small, I think that it is important to have a program in each of these areas
to give the people who are doing the regulation hands-on expertise in those
areas, and it also gives us credibility in each of those individual fields.
My
program on Bordetella pertussis in both structure/function studies of pertussis
toxin and specifically, we focus lately on the studies on the mechanism of
action of secretion of pertussis toxin.
My program on Bacillus anthracis focuses on the role of surface proteins
in virulence.
Tod
Merkel's research: Again, he has two
areas of research, one on Bacillus anthracis, one on Bordetella pertussis,
because he and his group are responsible for both of those areas as far as
regulation is concerned.
He
has identified important virulence factors in Bacillus anthracis and done a
very nice job of developing a mouse aerosol challenge model for inhalation
anthrax that has really been an important resource both for our Center as well
as a number of members of the academic community. His work on Bordetella pertussis involves characterization of
critical virulence regulatory pathways.
Karen
Meysick's work is focused on Yersinia, and she is looking at -- She is
analyzing a novel type III secretion system of Yersinia, and characterizing the
phospholipases of Yersinia that are likely to play an important role in
virulence.
She
has just started a program on the development of biological assays to
demonstrate the correlates of protection for plague vaccines.
Now
in the next slide I have listed a couple of specific areas in which research
has helped our regulatory mission. It
has helped us design release tests for the DTaP vaccines. It helps manufacturers optimize production
of pertussis toxin.
The
work that Tod has done has provided proof of concept studies that will justify
further development of anthrax vaccines and therapeutics. Karen's work is likely to identify new
candidate vaccine antigens for plague vaccines, and development of functional
assays that can be used to define correlates of protection for plague vaccines.
I
think, just important as these more specific areas in which our research has
affected our regulatory mission, are sort of less concrete but very important
ways in which research helps us to regulation.
First
of all, it gives of state of the art knowledge of the areas that we regulate,
which are quite technical in nature, and it is really critical to have this
knowledge.
It
gives us the expertise to best evaluate tests to assess the safety, purity and
potency of vaccines. In our own
research, we are actually conducting these sorts of assays, and we can evaluate
which ones would be best to use to monitor the manufacturing of a vaccine.
As
I had indicated, it gives us the expertise to design and evaluate the efficacy
studies for vaccines licensed under the Animal Rule, and again we have really
played a lead role in setting the strategy for anthrax vaccines, along with
people in Bruce's lab, as you will hear about in a few minutes.
It
gives us a credibility in the field that we wouldn't otherwise have. We ourselves are peer reviewed not only by
the site review, but every time we publish our manuscripts undergo peer
review. And most importantly, I think,
it gives us a whole different mentality on how to approach things in that we
have approached things with a problem solving approach instead of just a
problem identifying approach.
So
we work very, very closely with the manufacturers whenever a problem arises to
try and solve that problem as quickly as possible. Having been in this business for, I think, 20 years or so, I have
really seen it work, especially at going through the licensing of the pertussis
vaccines. I think having that sort of
problem solving approach really cut a significant amount of time off of the
licensure of the pertussis vaccines.
So
I think I will stop here and take any questions that you might have.
CHAIRMAN
OVERTURF: This is Gary Overturf
again. Are there questions for Dr.
Burns regarding the Laboratory of Respiratory and Special Pathogens? We are crystal clear, Dr. Burns.
DR.
BURNS: Okay.
CHAIRMAN
OVERTURF: So we are about 15 minutes
ahead of time. Is the next speaker
here? Dr. Meade?
DR.
MEADE: Yes, I am.
CHAIRMAN
OVERTURF: Okay. So he will
present the Laboratory of Methods Development & Quality Control,
Division of Bacterial Parasitic & Allergenic Products. Dr. Meade.
DR.
MEADE: Well, thanks. Given this is, I think, a very difficult
forum to go into much detail, what I have tried to do is put together a very
short talk, giving sort of an overview on both our research and regulatory
activities and generally the kinds of problems we approach and the strategies
we take for moving forward and taking on projects.
As
you will note, Drusilla Burns' lab and our lab -- and we have worked together a
lot many years; so you are going to see some parallelism in the way we've put
together the talks, but I also want to -- One of the goals is to illustrate, I
think, sort of the difference in the approach and how I think they are
complementary approaches.
So
again, the second slide really just
identifies the areas in which we have a role in both the research and
regulatory activities in our area. It
is really three areas. One is the
clinical immunoassay, and that is really what we consider the assays that are
used for clinical evaluation, and given that many of the new vaccines,
especially in bioterrorism, will be evaluated using animal efficacy models, we
include the clinical immunoassay to include those assays that will be used in
those relevant efficacy models with the Animal Rule.
We
are going to have a major program in product testing and quality control, and
another area that we have taken on again recently in the last few years is to
work within the Division and, in fact, within the Office of Vaccines on
implementation of laboratory quality system for those official testing
activities.
Again,
I just wanted to highlight that at least our goal of setting up the laboratory
is really to be testing specialists and not limit our activities to a given
product area, although in reality we haven't gotten very far from our roots due
to workload issues, but again I think we have -- I can highlight a little bit
where we have moved in some areas.
The
next slide just illustrates the current staff in our laboratory. There is five permanent staff, including one
other doctoral level investigator, Juan Arciniega, two post-docs who have been
with us for about a year and a half, and Sandra Menzies is a permanent member
of the lab, who has non-laboratory
responsibilities dealing with the quality control activities for the full
Division.
The
next slide talks briefly of the history, which again I think Drusilla mentioned
already. At our last site visit in
September '97 we were both -- both Drusilla's section and ours were members of
the Laboratory of Pertussis.
Drusilla
mentioned that in February '98 we assumed the responsibilities for anthrax
vaccines, which came just a couple of months after the Army decided to immunize
all the troops, even though there wasn't an adequate supply of vaccines. So it ended up being a major set of
activities for our lab for the next several years. Then in October '99 we split into the two labs, as you have
heard.
The
next slide tries to illustrate, I think, again what I perceive as the
difference in perspective and approach between the product area specialist
laboratory such as Dr. Burns' laboratory versus our laboratory as testing
specialists.
I
think that, really, when you think about tests, there's really two types of
questions. One is, is it the right
test, meaning is it a relevant test that is addressing appropriate
characteristics of the product or immune response.
Then
there is the other aspect of the test evaluation that deals with, well, is the
test right? Is it a reliable test? Is it appropriately controlled, designed,
and adequate for the intended purpose?
Again, I think, so our view is -- Our approach is to serve as testing
specialists and, as it evolves, to work with multiple labs and product
specialists within the Division as we evolve.
Again, I think they represent different approaches.
Again,
just to provide an overview of our activities, again in the regulatory area
I'll mention the regulatory review responsibilities, which I would define as
non-laboratory regulatory activities.
But in the regulatory forum, we also have laboratory activities related
to the quality control and product testing activities. The research program which was described --
which was covered under the review, deals with the other laboratory activities,
separate from the quality control.
Again,
our main projects are still pertussis and anthrax. Due to workload, we have begun to do some work in the laboratory
with diphtheria vaccines and review with others.
So
I'll do a couple of slides here which will give an overview of the regulatory
activities, again just to give an overview.
There's review activities related to the licensing which you have heard
before from the previous speakers, both at the investigation of new drug
applications and biologic license applications. There's post-approval review, which deal with supplements to the
license.
Again,
our areas primarily are tests assessing manufacturing that measure -- assess
manufacturing or clinical response.
Again, in review, our primary activities are pertussis and anthrax, but
we have also had a role with the other vaccines listed there, diphtheria,
cholera, Lyme, malaria and typhoid, again focusing on the testing issues.
Again,
with respect to the Animal Rule, we have been involved with that. Again, our expertise is in animal bioassay,
and at one level we think the animal efficacy models are just a very
sophisticated, well developed animal bioassay.
So our many years of experience between Dr. Arciniega and I and others
in the lab really has been applied to the standardization and development of
the models, again as a bioassay. Also,
we have looked at the assays that will be measuring the functioning responses
and how you can evaluate whether or not the response in humans is comparable to
that in the animals.
I'll
just mention some of the other areas of our regulatory activities: The establishment inspections. Again, we typically go out -- Each of us go
out once a year for an extended site visit at the establishments.
Again,
the other part that we have not mentioned is that we do the lot release for the
currently licensed pertussis and anthrax vaccines. Lot releases have not been mentioned.
Every
lot of those vaccines that is submitted for commercial distribution has to be
released by us based on review of documentation on their manufacturing and
testing, which occurs on all lots. We
also have the option of testing of samples submitted by the manufacturer, again
which is done in our laboratory.
I
highlighted just two other aspects of the testing on this slide. One is the -- The other issue is that the
testing experience we gain has been very helpful with -- We have been able to
stay involved with the international community in harmonization and
standardization of product assays, and again we list official testing
activities. We have been very active in
the initiative to implement a quality system for those activities.
Now
let's go on briefly to give an overview of the research activities that were
presented at the site visit in more detail.
Again,
the two areas we discussed in some detail were -- One is the clinical
immunoassay, which I presented, and again I define that as assays used in the
clinical evaluation, both in clinical studies and again in animals from the
efficacy models for the Animal Rule.
Then Dr. Juan Arciniega discussed the activities related to product
testing and quality control of products.
Then
just to the next slide to give a quick overview on the clinical immunoassay
projects: In the area of pertussis
vaccine, this has really been a very long standing activity that has gone on
for over 15 years in the laboratory. As
a program most recently and where we presented at the site visit was the work
we have done recently on a serologic diagnosis of pertussis.
Pertussis,
as you all know, is a disease that is increasing both in adults, adolescents
and in the very young infants, and one of the major limitations is diagnostic
tools that can recognize -- help recognize the infection in adults and
adolescents.
So
we have been working with the CDC for several years now for developing an
assay, and in the last year and a half we have made very good progress in
developing a test, again done by a post-doc in our lab, Vijay Kadwad, who has
been here for about a year and a half, where he has developed a prototype kit
which we are ready for some interlaboratory validation studies, moving
eventually to clinical assessment.
Again,
we have also been involved for several years with statisticians, primarily with
the NIH or with CBER statisticians, on statistical ways of approaching
statistical evaluation of immunoassay data.
Again, the last bullet is safety and immunogenicity of DTaP. Again, this is an ongoing -- was an ongoing
long term project with NIH where we worked with them on the clinical assessment
of DTaP vaccines, which led again to the licensure and the increased use of the
acellular vaccines.
Anthrax
vaccines -- we have been, again, very involved with some of the clinical
immunoassay development evaluation.
Again,
the last summary of the product testing and quality control subjects presented
by Dr. Arciniega: In pertussis vaccine
-- again, that was very active several years ago where we worked on toxicity
and potency testing methods, and in the recent years the emphasis has been on
working with the international community at implementing these and
standardizing them and harmonizing at the international level.
For
the anthrax projects, which has been our more recent emphasis, Dr. Arciniega
talked in detail about the anthrax vaccine potency development, which again we
view as an essential step in the development of the new generation anthrax
vaccines, and we have been increasingly working with the companies and
potential companies on those models.
Again, we have been working on appropriate standards for those tests,
looking at formulation of the vaccine formulation issues, as well as looking at
new HPLC based methods for monitoring antigens in in-process product
control.
Then
we have been working, again, on some international collaborative studies with
the diphtheria vaccine.
So
I just want to close with the last two slides, again, which will look in some
respects very similar to the messages you have heard from the other talks, but
again I think this is sort of a summary of our approach.
Again,
in terms of the relevance of our research in regulation, again we think it has
been very important to have state of the art knowledge on the areas we
regulate. The laboratory activities
give us firsthand experience for designing and evaluating tests for both
product assessment and product quality.
Ongoing
efforts: We have been able to work with
companies, troubleshooting problems in testing. We have been very active in international harmonization activities
and, again as I mentioned earlier, we have used our bioassay experience related
to the Animal Rule. And again as
Drusilla mentioned, I think the lab activities has given us credibility, and
again we have been able to work with a problem solving approach.
So
I just wanted to close on the last slide with some very quick examples of what
I think has been the impact on the regulatory mission of some of the activities
looking over the longer view of the last 10-15 years.
For
acellular vaccines, the clinical immunoassay experience we had: We served as basically a
national/international reference laboratory where we distributed methods,
reagents, provided training as necessary, and actually participated as appropriate
with clinical studies.
The
potency tests, the mouse immunogenicity potency tests developed here have
really served as the basis of the potency test that is now described in WHO
guidelines and the monographs of the European Pharmacopoeia.
With
respect to the anthrax vaccines, which is more the ongoing, again as I have
mentioned, we have applied our bioassay experience to the animal efficacy
models. We are working on tests that
can used in assessment of potency, and been very active with NIH and others and
the companies at optimizing and standardizing assays for clinical and product
evaluation.
Again,
in the diphtheria vaccine there is a major initiative for developing
alternative animal models for assessment of vaccines. So we have been active in some of the international projects.
So
again, that is just to provide a couple of examples of some of the impact, we
think, of some of our activities, and I
will close with that, and certainly respond to any comments or questions.
CHAIRMAN
OVERTURF: Gary Overturf again, Chair of
the Committee. Are there questions for
Dr. Meade? Go ahead and speak up, and
please state your name before you ask a question.
Again,
there appears to be no questions, Dr. Meade.
So I will dismiss you.
It
now must be about 2:40 and change on Eastern Standard Time, and we were to
proceed to an Open Public Hearing. So I
will ask Christine Walsh whether we can proceed to that now or whether we will
have to wait until three o'clock.
MS.
WALSH: This is Christine. We can proceed.
CHAIRMAN
OVERTURF: Okay. Are there persons wishing to speak at the
Open Public Hearing? MS. WALSH: I see no response in the room, Dr. Overturf. I just have one comment. I have received one comment from a person
who was not able to attend the meeting.
The comments have been distributed to Committee members, are attached to
the public notebook, and are posted on the FDA website.
I
believe there is no one else in the room who would like to address the
Committee at this time. So I will turn
the meeting back over to you.
CHAIRMAN
OVERTURF: I think we can then proceed
to the Closed Session at this time.
(Whereupon,
the Open Session of the Committee was adjourned at 2:45 p.m.)
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