Confirmation Number:334284
Event Started: 3/15/2005
To extend a welcome to all of you, our guest speakers, RAC members and the public participants to be -- the safety symposium sponsored by the NIH RAC. I wanted to start the meeting off, not only with the welcome to you but to give you a thumbnail sketch of today's agenda and what we hope to accomplish during the wrap-up session and provide you with a little bit of context. The goal for today's meeting arely to promote not only scientific understanding but public awareness of the latest research findings regarding treatments for the combined immunodeficiency disorders and findings of genesis and its potential ideology. When you look at the agenda, the meeting is divided into three sessions. The first is aimed at providing a comprehensive overview of current U.S. and international trials. Looking at Gene transfer size a possible treatment for SCID. The second is focusing and drilling down on the latest research into retrovirus integration and mechanisms of insertional mutogenesis and the third and very important session explores the use of bone marrow and some cell transplantation as an alternative treatment for SCID. Each of these you will find in your packets a set of handouts. They're on lavendar-colored, purple-colored paper. There are a list of questions that the Ajjs -- agency and consultation with the moderators for today's meet having put together. Not only to facilitate the progress of today's discussion, but also to lead us to the wrap-up session where we'll be revisiting the recommendations that the committee made in February of 2003 on this very same topic. Certainly today's meeting is intended for a form of public discussions of more recent findings regarding the emergence of the case of the T-cell pro-liferation in the French X-SCID trial and I wanted as a backdrop for today's discussions to provide you with an overview of the recommending as, the findings and recommendations the RAC reached in 2003, and I think our keynote speaker will talk in some are specifics on this. The RAC reyou're -- reviewed the clinical and molecular data were at the time were two series of adverse events of studies conducted in France on SCID. We met in December of 2002 and February of 2003, and the February 2003 meeting was done in conjunction with the FDA biologic advisory committee. Several members of that committee, and the group conducted an analysis of the then-available data from the French studies, as well as all the other Gene transfer studies for the combined immunodid fishiencey disorders, and the RAC recommended on the basis of this analysis that pending further data or extent -- ex10iating data, studies should be reviewed on a case-by-case basis and that SCID should be limited to patients who have failed, identical or halfway identical cell transplant identification or for whom no suitable transplant -- stem cell donor can be identified. This case-by-case review would include an analysis, accompanied by implementation of appropriate informed consent and monitoring plaps. They also concluded that at the time there were not sufficient data or reports of adverse events directly attributable to the use of retroviral victors to warrant su -- other retroviral human jeep transfer studies, including studies for non-X-link sced. Such studies might be justified coptimplent upon the analysis of implementation of appropriate conformd -- informed concept and monitoring plans. So this is a backdrop of today's discussion. At the end of it, we'll have a wrap-up discussion, which is not only a summation of today's findings, but a very concrete revisiting of the 2003 recommendations. They need to be treated, to dothey need to be revamped or totally redone. So that's the specific task of before on the meeting participants today. I also wanted to take this opportunity because today's discussion is very imageatic of long-standing tradition of the committee to bring forward new scientific findings that fixes the problems for very open scientific deliberation and public discussion. I'm very happy to report and Dr. ZOHONI will come toward to -- tomorrow to present the Award on. March 10th, the NIH RAC was Awarded the scientific freedom and responsibility Award from the American Association for the Advancement of Science. We're thrilled the committee has been recognize inside this way. It was Awarded to the NIH RAC and here I'll read the citation. In recognition of the principles of transparency, public and ethical discourse that underpend the activities of this committee for the last 30 years and for its role in the advancement of specific understanding and progress. And the NIH firmly believes that this type of activity is exactly what scientific progress and public trust are predicated upon, and today's meeting is very exemplary of this Ideal open public process. With, that I will end and turn the proceedings over to the RAC chair, Diane Wara .
thank you, Dr. Patterson. Good morning, everybody. On behalf of the RAC membership, I want to welcome everyone who has come today to participate in and to listen to the planned symposium on Gene therapy in X-link combined immuned deficiency. A Pecal thank you to those of White House have -- a special thank you to those of White House agreed to come and speak today. It always takes time to prepare a thoughtful presentation, and because we're looking forward to hearing the scientific backdrop, the background for the field of jeep transfer in X-SCID. It's only in the context of that background that we as a group, meaning those of us who participate in Gene transfer and in the care of children with X-link severe combined immuned deficiency can make thought plans and proposals in terms of how we should move forward. A special thank you to those of White House have agreed to come to speak to us today. Our goal is, as Dr. Patterson mentioned is at the end of the day to revisit, carefully revisit, the statement that was put forward by the RAC in February 2003 on our perspective of how to proceed with Gene transfer in X-SCID. It's possible that that proposal will need no revision whatsoever after careful thought. It's a contained proposal and it may need no revision. On the other hand, it may and it's our job today, especially the members of the RAC, to make that decision and to another endorse or revise our statement. So that's our job and I am looking forward to the day in a great way. I should say on a very personal note, that I'm a pediatric immuneologist. I have spent the last 35 years as many others in this rule -- room have as Ltaking care of children, and which were not only with this inheritable nun -- immunodefish ynsy but others. It's a complicated issue that presents itself to me as a care provider and the issue in a straight-forward way is, these are children, babies with X-SCID who will die if they don't receive receive some form of immune reconstitution. And the end point in this disease is death, and it's death very early in life. Traditionally, we have used as those experts in the audience will tell us, we have used forms of bone marrow transplant and more recently stem cell transplant in efforts to reconstitute these babies. When the first experience was reported out of France of immuned reconstitution with jeep transfer, we were all thrilld -- Gene transfer, were all thrilled. We will learn all about today, the early message was it was a home run. And as we waited and watched, the news that Dr. Patterson has summarized for us a moment ago came forth and then the issue was what should we do now. Should we proceed with Gene transfer sending our patients to sites where Gene transfer occurred or should we retreat a bit and continue with our standard of care, which was and remains bone marrow transplant and/or stem cell transplant of various types what, we will hear about this morning. We still don't know the answer, and that's the delamy we're faced today. We're face -- dilemma we're face ised with today. We're faced with it as a community but as care providers with these children with a devastating and fatal disease W.that introduction, I'm going to turn things over to Dr. Ted Friedmann from the university of California, San Diego, a colleague of all of ours and a crept past chair of the RAC. Dr. Freedman. -- Dr. Friedmann .
Well, first of all, let me thank Dr. Patterson and Dr. Wara for having me back and I guess we're going to continue to do this until I get it right. So nice to be back. Thank you. So this symposium, safety symposium is really designed to, for members of the RAC to examine the issues surrounding the problems in the French X-SCID study and to help the RAC arrive at recommendations for investigators in the field and for the general public and for the other interested parties. I think Amy patterson has already told you of the presentation by the triple AS by the freedom and scientific freedom and responsibility Award, and I think that that indicates the 30-year history of the RAC in providing this kind of expert and much-needed advice to the scientific community in terms of, in the areas of recombinant DNA, work, and certainly over the last decade or two in gene therapy, and the RAC always seems to have the opportunity to rise in its responsibility to get over some of these problems that Arise inevitably in new and difficult science. So the development of the problems in the French X-SCID study is obviously a very challenging and very difficult period in the development of this field and it's the responsibility and the opportunity now of RAC to help sort out the difficulties. It's a critical time for the field because it comes, I think, at a time when we've had our first, or the field has had its first really robust clinical therapeutic effect and at the same time, it's most impressive and treatment-related difficulties and seems to me now this is very critical, pivotal time for the field and for the RAC now to give its best advice to investigators on how to proceed with this problem Okay. Okay. Well, I would like to spend these few minutes giving you sort of a personal view of the issue at hand and I am going to try to aim at some conclusions. I'm certainly going to run out of time, so I'll give you my conclusions at the beginning and the conclusions are these, and probably others. The emphasis on the first, that is gene therapy research is experimental and still is, and will be for some time and the technology is at a very immature and early stage. The technology is at a very nrption ACENT period of its development and the -- NACENT period of its development and the techniques are still refined and we can agree on all those points. On the other hand, we have to agree, I think, that the X-SCID Gene transfer study has really provided the first strong proof of principle for the therapeutic efficacy of Gene transferring and to some of us, at least, the phrase that we emphasize over and over again that what we're concerned with is Gene transfer research, rather than Gene therapy research. That's, that phrase and that waffling is a little bit harder to defend now, and really, it's clear that these children consider have had a treatment offered to them. They've been treated and they certainly have had a very powerful clinical response. It's certainly no question that the criteria of work in this area should, in fact, be related, should be examined with the same risk benefit analysis as other experimental procedures. Certainly no less and the same calcueulous of the risk to benefit ratio should be applied. Now, the point is, however, that with this study, I think the field has had the opportunity and the luxury, finally, to have a risk-benefit ratio calculable. There is a robust and effective therapy and benefit. For the first time, I think we have aical cowable risk benefit Asia -- calculable risk benefit ratio that is available for this field. The conclusion from that is that the field needs not less emphasis on problem-solving but more. More research and more applied research to overcome the scientific and medical obstacles. Obviously, a great emphasis on the development of solutions to these difficulties and rather than, rather than acquiesce in a way to what is very often kind of a strong negative response to many of these reversals in the field and setbacks, I think it's very clear that there has been a tendency to not minimize the problems, but to certainly emphasize the trees rather than the forrest to see the dif cu89 -- forest to see the difficulties and at the same time, not see what has happened in the field. That there is a forest here and that that forest is, I think, for the first time, a robust, therapeutic effect in the gene transfer experiment. So, we're here because of this study. And the whole discussion revolves, really, around the events related to this work by the French group Fisher and his colleagues and with similar work being carried out by Adrian Issue thatter and his group in -- Adrian Thrasher and his group in London and this was 2002 that Fisher reported a sustained correction of an X-link scud with Gene transfer approach -- SCID with Gene transfer approach . That result came as a wonderful blessing and a surprise to the field. Finally, we had something to grasp on to, and was consistent with the biacies that, and knowledge that existed in the field related to retroviral Gene transfer. As stated by really one of the fathers, maybe the original father of retroviral victorology, howard -- vectorology, the late howard TendOM, that stated this. Can you read it as well as I do, that retroviruses have an enormously valuable place of the development of Gene transfer studies and with the assumption that once the safety issues and thentgration issues were solved retroviruses would play a role in these kinds of studies. Nope understood integration at the time as well as howard 10 a.m., so this was a powerful impetus to those interested in retroviruses. The ORA, in fact, was the retroviruses have problems that relate to an integration, but those problems were sol uble. This is from something that I followed up with and, in '89. Again, reiterates the recognition that the retroviruses have baggage. That there are going to be problems related to integration. Again, concluded on an optimistic note that these are solble problems and -- soluble problems and retroviruses continue to be one of the major candidates for clinical application. Well, then, of course, came the, vents in 2002 with the two treatment-related leukemias and the knowledge that the integration events were probably responsible for the disease. Possibly because of the presence of the viral enhancer in the provirus, and potentially some have begun to see change itself in the development of the leukemia that was not known, still isn't very clear, but with the, also the knowledge that these two children responded well to the cancer chemotherapy and went into, rapidly went into clinical remission. And Dr. Patterson described to you to the NIH recommendation in February 2003. I won't reiterate those, but just to highlight the recommendations that the X-link SCID be a clinical targ carget -- target be for the retrovirus media Gene transfer, for those patients who failed or have failed identical stem cell transplantation or for whom no suitable donor is available, and with the caveat, too, that the date available for other retroviral models, including non-X-link SCID did not justify a restriction on those studies. And that's the, those are the criteria that one worked under until this winter, until three months ago when one child of the two original with leukemia died. A second is in remission and the third case of leukemia rose with somewhat different molecular characteristics. We'll learn more about these issues later on in the morning, but with a leukemia cell that has three integration sites in it. None apparently in Alamo II, and with no overexpression of Alamo II as far as one knows in the third case. Again with the complete and rapid response to chemotherapy and with the report that the remaining children in the study, in the French studdet and study remain well. Immunologically reconstituted and some going into their sixth year post-treatment, and so the summary, overall summary is that there is something like 18, the number's a little bit difficult for me to pin down, but something like 18 patients altogether and with one original non-response, 17 immune reconstitutions, three life-threatening SAEs and one debt. The regulatory response to the third leukemia by the French is a clinical hold at the request of Dr. Fisher and his colleagues with the intention of developing safer vectors to reduce this integration of the insertional mutogenesis effect and better time to understand the vectorology at the U.S. FDA as you all know, several weeks ago put a clinical hold on X-SCID application protocol, but also recommended that ADA SCID and other retrovirus space protocols perceived under the conditions that they had been evaluated until now. I -- I don't know, perhaps someone here knows better than I, what the events have been in the Italian and Japanese studies. Both countries have studies both with ADA SCID and with X-SCID, I think. That we would like to know about. Their regulatory response and in England, the English regulatory agency has responded as it did originally with the first two leukemias, that is to say that in their experience and in their view, there is far more robust clinical benefits than there is risks in this study, and so they're proceeding to Wtheir study into accruing new patients into their X-study, X-SCID study . So here's the dilemma in front of the RAC and in front of us all. Obviously, there is very severe risks in the contexts, now different from other gene transfer and gene therapy protocols and that these risks have Arise -- Arisen in the context of a robust clinical success. At least a robust clinical phenomenon of therapeutic effect. -- affect. There is little doubt that there has been a treatment for these which were, the treatment, they're living normalized lives, not normal but normalized lives with the possibility even in some patients of what might be called, eventually a cure of this disorder by this procedure and some of this makes it a different kind of phenomenon from other SAE's and other Gene transfer protocol. Gee recognize there is a high risk of SAE, leukemia but the current technology through the mechanism of insertional mutogenesis probably, but this risk is inherent in the biology of the vector system chosen. That is that the integration of cells is responsible for the event and then until the integration mechanisms are maniplable, that's unlikely to change drastically. We'll hear later from Rick Bushman that there is evidence, at least some ideas of how to do that, but we're certainly not there yet. And so that raises the question, of course, of the, the generic question of what is the study? Is it, in fact, a study in human experimentation, is it a human experimentation issue or is it therapy, and when one looks at the alternatives much this protocol, when does this high-risk experimentation become justifiable therapy? I think that will be an issue that the RAC should, should consider in this deliberations today and then make recommending as for the future. While, of course, acknowledging that it's important to develop now and better technology, the question, the dilemma, really, for the clinical application is what one does between now and then what. Does one do until this now technology appears what. Does one do with patients who are rearing treatment? Well, so that's all the obvious issues that you all see as well as I do. I wanted to put all of this discussion in the context of some history and remind us that this is not a new issue. This dilemma is not new in clinical medicine and that there are a number of examples of, in history of the development of new and very difficult treatments which have re, which have gone through this thing, or something like this thinking process, and it's something to remember what we might gleam what we can from the development of these treatments and there are a number of examples that are particularly telling, the treatments of childhood lymphocytic leukemia, Hodgkin's disease, transplantation and endocroneal antibody development. The development of chemotherapy for childhood leukemia in some people's eyes had -- with this work by Sidney Fasher and his colleagues in 1948. The development of chemical methods for manipulating the growth of cells in T-cell leukemia, development of EMINOPTRIN as an antagnist for this disorder and in 1948, between 1948 and 1962 to '66, treatment of which were with lymphocytic leukemia took on this sort of development. There was a very, very poor long-term survival. A very high level of remission, but not very much in the way of long-term survival. And then came the development of chemotherapeutic agents, PNS agents and can you see between 84, between 62 and 66 with the development of CNS to radiation and new drugs, the survival rate increased from minimal amounts to very high levels. 40 to 60% to the point today, I think, that we'll hear better from Dr. Buckly, but certainly expectation of cure, long-term survival and cures up into the 80, 90% range and then some possibly. So let's, let's try to imagine what the discussion might have looked like in no one 62. While we're going through this kind of, this kind of analysis with respect to childhood limbfocytic leukemia. If we imagine the field was here at that time, that expectation, that kind of improvement over the next couple of decades. One imagines the -- might be an equivalent point of this, we might look forward to the history of increasing technology and efficacy if we're look -- if we're lucky. Similarly about with Hodgkin's disease, this is the treatment of Hodgkin's disease, what it looked like in the early days before 1963 or around 1963 with the development of the first ALCOLLATING agents with some improvement in initial with a clinical response, but not until the development by DEVITTA and his colleagues here at the NIH -- with the clinical efficacy increased to this sort of level resulted in something like 60, 70% or better, long-term survival. That survival came, that clinical efficacy came at a cost in that cost, the treatment-related leukemia in many patients and many patients meaning something like this incidents up to 5% or more depending on, on the efficacy of the therapy and, in fact, this is an interesting point here that might be relevant to the discussion of X-SCID and that's the more effective the therapy became in this disorder, the more common was the long-term SEQUELIE of the treatment, the secondary-treatment -- secondary treatment-related leukemias. Similarly for tissue transplantation, for liver transplantation, this is from an article from Tom StarZell. In 1963, the treatment of liver transplantation looks something like this with the early supression provided by spreadno zone and AZIOPIRAZENE, patient survival and graph survival. With the implementation of CYCLOSPORIN in 1980, the survival of graph&and patient survival improved up to 60%. In the decade, the experience of the immunosupression approaches became far grader and drugs, of course, improved. Technology in this case improved to the point where liver transplantation was successful and provided long-term surviveal to many, many patients who otherwise would have died. And, again, that improvement in therapy came at a cost and that cost remains with the field as far as I know until today, and that is certain incidents of renal failure, secondary malignancies in renal transplantation, in liver transplantation . So, what I don't want to imply or state is that Gene therapy field is the same, that there are certainly unique problems in Gene transfer technology, but we might, in fact, learn something from the history of these other treatments, these other developments of the therapies, but the research in human gene transfer and human Gene transfer experimentation has, to some extent, been different from these other therapis. Gene therapy has Arisen, of course, in an Era of far greater visibility and overall, and oversight and scrutiny than these other areas of therapy had, even at its most NACENT stage. The field was born under the microscope and remains under the microscope far more than other areas of research. Other areas of clinical research. Secondly, the field has been burdened, I think, remains burdened a little bit by some of its history, by the history of some exaggeration and hype that we went through in the early '90s. Expectation, elevated expectation of quick clinical delivery and efficacy and, really, undeliverable promises of efficacy. There's been an additional burden provided by the very -- and additional help, of course, provided by the powerful influence of the commercial interest in the field of Gene transfer, gene therapy research to deliver the technology sooner rather than later to clinical, to critical clinical issues, and that really didn't complicate the life of these other therapies nearly as much as it does for Gene therapy . So the issues, I think, facing the RAC and the discussion today, overall general issues are something like this: First and foremost, of course Swhat to do now with the X-SCID study, how to provide -- proceed with current studies and current technology. What to recommend in terms of vector modification, specifically with respect to the insertion inclusion of elements that provide insulator effect, suicide functions and ablation elements to the vector and to the transgene. The question of expectation of additional possibility of additional adverse, vents in this initial X-SCID study raises the issue, the potential for pro -- proof Lakic chemotherapy in some of the which were and at what point they should be treated in the course of the development, the early stages of the clinical leukemia. The question of what are the goals of the clinical hold until when, what is the end-point of the clinical hold and what, in fact, does one do in the meanwhile to the question of accrual and the treatment of existing patients. Admitting that the treatment is difficult and has -- hazardous. Clearly one has to define long-term research goals what, it is about vector designs that needs to be incorporated into future studies, the choice of target cells, the effects of integration sites need to be understood better. The potential role in this study, of, again, the C-chain itself of potential oncology talking with other, other cellular functions, other cellular oncogenes. The potential for targeting the integration event to a safe site or to toan inocular site. We know it's one of the holy grails of the field but is unlikely to be with us for some time. Again, we'll hear from Dr. Bushman about some of that. The general generic question of how one handles a therapeutic approach, therapeutic technique that borders, that sits somewhere between experiment ail -- experimentation and therapy, how one identifies that transition point and how one finally says on which side of the line one is sitting, when does human experimentation become a therapy, and specifically then how the RAC feels about revisiting the pend exam and looking at additional questions to be proposed to investigators. Those are the genEric issues, but I think the specific end points of today's, today's discussion, I suggest might be the following: The most parent is -- important is, of course, to look at and re-examine the February 2003 RAC position. Either affirm it or modify it, but take a strong position on that statement. And, in fact, to determine whether, whether any of the thinking of that statement ought to be extended to other stable transducing systems at the systems such as herpes and adenovirus. I think that in the discussion today when -- one has to anticipate there might be additional SAE's in the X-SCID study and how the discussion today will be shaped by the emergence of those additional SAE's, ought to be included in the considerations for today. Very specifically with respect to the pend exam and we'll see this also in other discussions dug the next couple of days. The question of whether appendix in its current form raises sufficient questions to the investigators with respect to the following issues: One, the minimizeation of the transdug -- transducing, the transduction event. The minimization of the number of integration sites, the minimization of the number of grafts itselfs -- grafted cells with the system of therapeutic effect, but using one as little as one needs to achieve the therapeutic elect -- efect. That's based on the assumption that the fewer integrations one has, the less likely it will be to induce a cellular oncojeep. With respect, also, to the inclusion in opco gene. With respect to the jeep transferring procedures to regulate gene expression, are there methods available to turn the gene up and down, on and off as need be. Other mechanisms included in the study to ablate the phenomenon. To remove the cells, to kill them or to reverse their effect if they go Awry. And also to ask investigators what their thoughts are about archiving and testing cells, either prospectively or post-grafting to ensure that any cells going Awry will be detected quickly and there is a plan in place to deal with that affect. The issues are not all technical for the RAC and RAC has an educated, very important educational role, and I think that also ought to be part of the thinking today that there is a need to discuss in public again in its educational role the question of, and the ethical and policy questions of human experimentation as they relate to this study. When does a high-risk human experimentation procedure become therapy? I think the X-SCID model provides a very good starting point for that discussion, because it's clearly been therapeutic, it's clearly experimental and when do we, when do we accept the experimental, when do we accept the therapeutic aspect of the study as being compelling? And that can be done in the context of the policy conditions, or policy conferences that the RAC might insty gate. Well, I think -- might instigate. LI think that's all I wanted to say as a historical introduction to the discussion there. Is a feeling, I certainly have a feeling that there's very good news in the field in all of this that there is a forest that we have to be able to discern why we're paying, obviously, very close attention to the trees. The trees in this case being very sec little children and, I think, we all -- sick little children and I think we all agree that we extend our best sympathyes and our best wishes to these children. The RAC's responsibility is, of course, to, as it's proven over the past 30 years by the AAAS Award to foster the field and to help investigators swim through these difficult issues to enhance the field, and I think the RAC now has an opportunity today in this discussion to do that, and I wish us all well. Thanks very much. [ Applause ]
Dr. Fried mann. I can't thank you very much -- Dr. Friedmann. Thank you very much. We're going to defer questions until the wrap-up period. I want to refer everyone to the pink packet on the left of your folder. It's called discussion questions for X-SCID. And the questions that we put together for each of the overall sessions are summarized here. I'm not going to review them with you. I would like you to review them by yourself, and then at the end of the day, in fact, the end of each session, we will come back and have a period for questions and answers. And, Ted, I want to thank you very much for putting the dilemma of the X-SCID gene transfer experience in context for those of us who are members of the RAC. Putting it in context for us in terms of our specific scientific and public responsibilities. I'm going ask Dr. Patterson next to read us our conflict of interest guidance and then we'll move forward. Dr. Patterson.
Thank you. For the record and also just as a refresher to the committee members because, again, at the closure of today we'll not only discuss the findings but we'll actually hopefully craft a recommendation and refresh a recommendation on the basis of the new data that is available and because of that, it's important for to you keep in mind whether you have any potential conflicts of interest that need to be taken into account as we come up with the new recommendations. So, for the record, and for to you keep in mind as the day moves forward, I would like to read to you the rules of conduct and conflict of interest. Being a member of the committee makes you a special government employee, and thereby, subject to the rules of conduct that apply to government's employees. The rules and regulations are explained in the report that I know you have all studied. The standards of ethical conduct for employees of the executive branch and you each received a copy of the document when you were appointed to the committee. At every meeting, in addition to reminding you of the importance of following the ethics rules, we always like to review the steps that we take and that we ask to you take to ensure that any conflicts of interest are addressed. As you know before every meeting, you provide us with information about your personal, your professional and your financial interests. We then use that information as a basis for assessing whether you have any real potential or parent conflicts of interest that could compromise your ability to be objective and getting advice during committee meetings. Now, while we wave conflicts of interest for general matters because we believe that your ability to be objective will not be affected by your interested in such which were matters, we rely to a great deal on your judgement to be attentive during the meeting to the possibility that an issue meet come up that could affect or at least appear to affect your interest in a specific way. And if this happens, we ask to you recluse -- recuse yourself from the discussion and to leave the room. As always, if any of you have any questions about the rules of conduct or conflict of interest, our committee management officers will be happy to address them and can you also speak to me during the meeting or during the break. Thank you.
Thank you. Thank you, Dr. Patterson. Our first speaker in session I, which is current SCID gene transfer experience is Dr. Jennifer Puck from the National Human Genome Research Institute at NIH, and Dr. Puck will discuss approaches to the patient with X-link SCID who has failed standard bone marrow treatment. Dr. Puck .
I'd like to thank the members of the committee and the members of the public who have come today and what I would like first to do is give a brief introduction to the disease that we're talking about. Severe combined immunodeficiency includes a spectrum of genetic disorders and the X-linked form is one of these. We don't actually know -- thank you -- the exact incidence because these conditions are rare and it's estimated to be one in 50 to one in 100,000 births. The definition of this syndrome is that patients have a very profound lack of both their T cell and B cell immunity leading them to suffer excessive recurrent and opportunistic infections very early in life when their maternal antibodies wane. They then develop failure to thrive and this condition is fatal in infancy unless an immune system can be provided for the infants . As an estimate of how common this disorder is, I can give you my personal lab's experience because I run a molecular diagnostic mutation detection lab for anyone who wants to enroll and sudden samples and, of course, this is your tax dollars at work, so we don't charge for the testing, but I'm sure I don't have every sample from every SCID patient sent to me. This is a typical year in which I received 34 samples and 19 had genetic defects in the X-linked gene. Which is about half or about what one would expect from published studies. If you look at the incidents just comparing this number to the number of beferghts in the U.S. which, is four million, then you would say that I diagnosed X-link SCID in one and 210,000 infants. If you accept that X-link SCID is half of all SCIDs, that means the incidents would be 1 in 100,000 if I were support all the X-SCIDs in the whole country, so I'm sure this is an underestimate. Certainly we also know SCID is diagnosed at autopsy and some infants who died of infections before the disease was considered and in 1997, NIH held a conference for SCID families in which they were brought to the NIH without having to pay and even so, it was noted that of the participants whose babies had been diagnosed with SCID, their median income was nearly twice the national average. This suggests to me that SCID is diagnosed much more readily in families with resources and, perhaps, missed in families without resources. As we talk about this disease X-linked SCID, should bear in mind the genetics illustrated in 24 Pedigree. Only males are affected with this condition because they have one X chromosome, and females who might be carriers are themselves unaffected. On the other hand, this is actually the most common presentation of SCID. These days, our family sizes are small in the U.S., and also, X-linked conditions have a high, spontaneous new mutation rate. This is a patient with SCID showing oral CANDIODISIS. One of the early signs but not a specific sign so the condition might be missed, and this pie diagram shows some of the genes we'll hear about ADA deficiency shortly, but this is the X-linked form of SCID caution certainly more cases than any other form. Because of the rapid advances in the field, we can diagnose molecular cause of SCID in the great majority of patients today. This was not the case a decade ago, and research has been rapid in this area. Certainly knowing the molecular diagnosis not only enables us to do carrier and prenatal diagnosis in families who have been identified. It may help us predict responses and tailor the standard bone marrow transplant treatment and it certainly is a prerequisite for gene therapy. The gene we're talking about includes this protein shown in yellow in this slide, which is the commongamma chain because it's common to -- common gamma chain because it's common to many different CYTOKYNEs. They signal cells to undergo activate -- activation. And the jeep is encoded in a -- the gene contains eight X-ONS and they span the entire range of the gene but there is little clinical diversity, most of the pacifics are very severely affected. The great majority. SCID is treatable by bone marrow transplant and the best results are obtained as will hear this afternoon, if the transplant is done early in life before serious infections set in. By far, the best results are obtained if a patient has an HLA-matched sibling to be the donor. Even without a matched sibling, some patients might be completely or substantially cured by bone marrow transplant. However, many patients require long-term Emoono glob ulip replacement after a transplant, and some are only -- imuno globulin and some are partially reconstituted and a few left. Gene therapy has been thought of as a good alternative for SCID because transplant patient is not perfect and the method is to take hemapoetic Tim cells out of the patient to transduce them with the retrovirus and reinfuse them and the reasons why we think that this particular gene is an excellent pilot for gene therapy is, first of all, the gene product is expressed in all blood lineages and it itself is not teetly regulated whereas the partner chains in the receptors that it's matched up with do have much more exquisite regulation. The immunes elimination of corrected cells is the BANE of many gene therapy approaches. But, of course, in this disease where the immune system is lacking, that's not a problem and very importantly, there is an in vivo selected advantage for cells expressing the common gamma chain so that they can expand. The NIH X-SCID gene therapy trial which, you will hear a little bit more about from Dr. MALECH in a minute is a salvage treatment protocol. Our idea from the start is that a risky new therapy should be considered first for patients who don't have other options so we have decided to focus on children who, despite in many cases repeated bone marrow transplant attempts, have unsatisfactory immune immune reconstitution. This is a summary of some of our patients who have been considered at the NIH in this regard and you can see that their ages are from 6 to 19 at the time they were evaluated. They have had from one to four bone marrow transplant taes.. Everyone over age six -- attempts. Everyone over age 6 has had growth failure with very low height and weight. They have many chronic conditions including skin infections, respiratory infections and asthma. And chronic gastrointestinal disease. And I would just point out that some of the patients are on I have a nutrition because they don't -- on IVY nutrition because they gopt eat properly. Some get GASTROSTITY feedings and many get chronic conditions, sianosis and fibrosis of the lungs are seen with increasing frequency as the age of the patients increases and the oldest of the patients is a victim of cancer. He has a hepatocell color -- hepatocellular carcinoma, possibly related to a virus but one we have probably not been able to identify. So in the patient 245s we have studied, we have looked for evidence of -- we have studied, we have looked for evidence in grafted cells. This is an artificial mixture mixing maternal cells into a patient's cells to show by PCR how we detect a maternal contribution so can you see that down to 0.1%, we can see some sign of these cells and if we look at the different separated lineages from a SCID patient in this case, the patient has engrafted T cells but not at all B cells, myelloid cells, the CB 34 stem cell enriched population. Those are all hosts derived completely compared to the T cells and some of our patients have minimal or no maternal T cells. The T cells they have are not, in many cases, doing the proper job. Here is a T cell inflammatory response in the dud on numb of the patient, which is -- DUDONEUM of the patient which is causing the intestinal disease there. Is -- the limbfo cites that they do have, and when we -- lymphocytes that we did have. When we look for new production of cells, this is an analysis of T cell receptor excision circles or treks compared to adult controls and those are CD-8 and CD-4. Cytotoxic and helper phenotype cells being produced in the THYMUS. The levels in our patients are extremely low to even undetectable. This is an indication that whatever transplant they might have had has run out of steam and no new production of T cells or very low production of T cells is taking place. Nonetheless, our patients have beenably to respond to GCSF treatment to mobilize their CD-34 cells, whichy that do in a way that is compparable to healthy adults. So, our trial has beenably to use mobilization and poriferal Harvest of still cremes to -- of stem cells to treat with the gene therapy agent. Okay and I think I will stop there and turn yet over to Harry maherb to tell but the -- Harry MALECH to tell you about the actual trial. [ Applause ]
Thank you very much, Dr. Puck. Dr. MALECH, also from NIAID is going to talk with us about preliminary results of an NEH trial of retroviral receptor gene transfer treatment for older SCID patients. Thank you, Dr. MALECH .
Dr. War ADr. Patterson, members of the RAC and guests, thank you for inviting us to speak today and I am the second half of the of a tag team here. Dr. Puck and I have, together as co-investigators began a protocol at NIH which you see the title there. The protocol number is there also. Doctor Puck has provided introduction to you which provides the justification for the study. Some of the things I say will repeat a little bit of what Dr. Puck has said, but then -- Dr. Puck has said but then we'll go forward from there. Just to remind you, the patient characteristics of our trial at the NEH is that this is a protocol that is designed to be salvage therapy for patients without an HLA match sibling who continue to have:ically significant impairment of immune function despite previous treatment or treatments with a identical donor. With that, we mean a pear antiwill -- parental lymphocyte depletd -- depleted bone marrow graft. The patient characteristics as Dr. Puck alluded to is the trial was designed to treat up to six patients with X-asked. They all had to have a previous history of Hepplo identical bone marrow transplant and hey had to be two to 22 years of ageing. Hey had to have lower limb 230 -- lemfo sight and T epgrafts. They had to about IVIG depend and have evidence of recurrent bacterial and viral infections and in addition they had to have some clinical evidence of severe chronic disease and in the case of the two patients I'm going to describe today, they both had growth failure, chronic diarrhea and malabsorption, progressive lung disease, eczema and hair loss and a variety of other problems. Two patients have been enrolled in our clinical trial and their clinical status before gene therapy is noted below. As I indicated, they have growth failure of less than 3% of heightened weight, diarrhea and so forth. They have had frequent scoog absences. In fact, patient number two has been mostly home schooled and not very well at that because of his chronic condition. Patient number one is 12 years of age, patient two is two years of age. Patient one, I think is important at this juncture to say something very specific about patient one and patient two with respect to their sort of genetic background. Patient one is what I would term kind of a variant SCID that. Is to say Dr. Puck has shown this patient has a defect in the poll-8 tail region such as the RNA is not, is not processed properly and so that patient makes a very tiny amount of actual normal common gamma chain, and so that patient is well enough to have rejected every attempt at transplant. So this patient has no donor cells at all whereas patient two is what I would call a more conventional X-SCID part who has a trunkation near the the termination of the protein leading to the protein actually being present on the cell but having a trunchtated tail so there is no signaling. It's a functionalist protein but antigen positive. This patient has had two at the same times at bone marrow transplant and as I'll show further on, actually has a, a partial T cell graft from the mother but with very low numbers of total T cells and no evidence of engasting -- epgrafting either in CD-34 cells or any other of the patient's lineages. This patient has no NK cells. This patient at times is a tiny number of NK cells, patient one as expected, B cell numbers are normal but the B cells are functional of thes in that no immunoglobulin is made and the IVA entravineousglobulin depend. This patient, despite having some of his own T cells has very poor MITOGEN or antigen proliferation as does this in despite the modest graft from the mother. So I think one of the things that I actually want to, I would like to go back to this again and make one statement relating to say slide I probably should have put in and probably didn't put in. Many of you probably know that both in the study in the united kingdom and in France, there were some -- in each case, an older patient was treated and 92 that situation, the gene therapy sort of failed and they published a paper recently in the Lancet and so you meet come Away with the idea that the, that treating older patients is a waste of time. I would like to, I would like to at least throw out a possible hepossibility sis and I would like you to keep it in mind whole you see the outcome in those two patients. I believe that in general older patients probably are enriched in those who are variants. That is patients who survived anyway despite the fact that they get very poor engraftment. And then there are others who just plain have very poor epgraftment, have classic disease and get sicker and sicker and probably don't make it very old. And I would also postulate that possibly the outcome of gene therapy in those two types of patients mean wife rent -- different, and I'm anticipating the results of my, of our study. So just to move on to the protocol characterestics of our NIH trial, the X-ZEBO transduced trial was the stem progenitor cells obtained by GCF immune -- mobilization and enig matic B purification. The vector we used is the MFGS which, is derived from the malining marion leukemia virus and is very similar, perhaps, three or four base pair of changes relative to the MFG vector that was used in the study in France. It contains the interliken II receptorgam gam Aopen reading -- receptor gam Athe pseudoframe and the leukemia envelope. Culture conditions for our gene therapy were [ Indiscernible ] With stem cell factor from -- flit through LYGAN at 50 millimeters, interliken 6 at 25 per millilighter and a low dose of interlucken 3 of 10 per milliliter in the RETRINEKIN -- [ Indiscernible ] Gas peermiable plastic bags. Our transduction conditions are actually not so different from that used both in the study in France and in the united Kingdom that we had an 18-hour prestomach lesion followed by seven our transductions each day for four days and an MOI in the rainfall of probably two or three. Just -- range of probably two or three. Just to remind you, we use GSF mobilization we collected by Afore easis and for both of these patients, we did not a singleby several collections of CD-34 cells done at sevon done at several months to at one case more than a year Apart. And the cells were collected by Aforeeasis, -- APHORESIS, frozen and thawed on the day of use. We had about 500 million CD-34 cells from each of the patients paying for the X-ZEBO transduction from both part one and two. To remind you, 100% of the CD-34 cell when is done in our laboratory, when tested in our laboratory using the PCR-based assays for cimerism, we're at host origin. There were no donor CD-34 cells in there. This gives you an idea for those of White House may not be familiar with the technique, and this is a, the transduction is done in the flexible plastic bags. Which simplifies handling, allows handling of a lot of cells and increases the surface area in which the cells and the virus can enter face with the fiberNECTIN. In the case of patient one, wereably to use slow cytoRemtri on the product to demonstrate the product was 40% expressing gamma chain and PCR analysis showed that that also correlated. We also knew the average copy number of what went into the part was a little more than one, about 1.4 or '5. That is of the 40% that were transduced. This is an example what have the cells looked like after they have been grown in culture for four days. There is about a 3.5fold proliferation and if you remember in the French study, there was quite a bit of variation among the patient and in the case of the two young of the patients, there was speculation that because proliferation was almost 6fold in those patients -- sixfold in thathose patients, that should had some role to play. With the third patient and the amount of proliferation, it was sort of average to the group and in this range, that probably is not, or may not be a critical cash -- critical issue. 80% of the controls were still CD-34 positive at the end of culture, at, as I mentioned, 40% transduction efficiency and coincidentally, it was 40% for both patients in what went in to the patient so when you add all that up, each patient got in the rage of 30 to 32 million cells transducing the CD-34 cells per coolo gram body weight. A fairly robust number of cells. So this is the, this is the bottom line and in this table, we're, we're -- the vector copies and blood cell lip yams are expressed as a percentage relative to single copy control, equaling a hundred percent. When you look at the numbers, for example, down here, 137% really means a copy, more conventionally, a copy number of 1.37. Just an tooryent you. Type iss it gets confusing, whether you're talking about percentages or copy numbers. Part one at six months had, if one assumes about one copy per transduced cells B4.3% of his -- about 4.3% of his CD-3 cells were positive for vector, at 12 months it still remains at 2.6% even though this is a relatively low number, it does demonstrate a level of selective advantage because these cells here are very low and CD-15 meaning the myelloid lineages are also very low. In the case of patient two, cho is -- who isol at six months, we had a -- is only at six months, we had a copy number of 1.37 which suggests that most of his circulating T cells probably now have a, a vector insert. Interestingly, even his B cells showed a lot of marking consider whereas his CD-15 granuular sites, meaning myo -- mieloid lineage, there is detectable marking which is low showing a similar advantage, similar to what was seen in the French and in the studies in France and the united kingdom. So right Away, you can see this quite a dramatic difference between the outcome in the two patients and I need to remind you of the sort of genetic difference between the two patients. So one of the other things -- so in patient one who had a, an abnormally-low, but significant number of CD-4 cells, those cells initially rose and then sort of modestly stayed where they are and we're sort of -- it's interesting but we remain disappointed that there was not any sort of robust increase in CD 4 kills. CD-4, CD-45 RA, meaning the new cells processed by whatever sign is left, is still almost undetectable in patient one. Patient two, however, has now added six months and has been at six months a, sort of a robust increase in the number of CD-4 cells, almost a tripling. Still a very low number, abnormally low, but a significant increase. What is most important is that we have gone from no detectable CD-4, CD-45 RA cells to actual detectable, slow but detectable numbers of nowly processed cells. What is also interesting in patient two, if you remember, patient one has no donor cells at all. That patient's working on its own cells. Patient two started out with a relatively poor graft, meaning low numbers of cells but, but, but we're about 50%. We're maternal, which is this bend corresponds to the, this is shared, this one is -- donor is host-specific. This is donor-specific. So this is the important one we're looking at here, and this donor-specific band, PCR band, has gone down at six months so that 86% of recipient cells are now 86% of the CD-3 cells are recipient cells what. Is happening is that as these numbers are going up, the patient's new cells are replacing the donor's cells what. Is important, and I think it's important to emphasize, it's not a sudden disappearance as the patient's donor's cells. The patient isn't suddenly having a cell come in and they're reacting to or killing the donor cells. They're just sort of outgrowing and replacing. I think that's important when thinking about whether such patience might be appropriate for performing gene therapy and you might be worried well, if they're sort of living on their maternal or paternal HEPALO paternal limbfo cites, could you risk a situation where some cells came in, killed all the donor cells but you didn't do anything much for the patient. Admittedly, we're talking about the end of one. I think it's an important end of one. So what happened clinically? -- interestingly, part one during the first six months of gene therapy had a number of Curious clinical changes. This patient suffered from lifelong alopecia and that sort of normalized out. Remember what we believe is happening here is the patient from biopsies as Dr. Puck had shown and, remember, it's not graft versus host disease, the patients have no donor cells. Like many patients with immuned deficiencies, it's important to think of one as an immuned disregulation than a deficiency. This patient had a lot of the autoimmune-type phenomena. This is improving disboot the fact that we didn't see any robest increase in Legg Masonfo seats. Perhaps we're seeing mild correction of regulation before we see any sort of robust overall correction. Just to summarize. Patient one had improved well-bing, improved school days. This can be a placebo affect. Resolution of abdominal -- abdominal pain. One can't Dean the fact that this patient had a sudden growth and after a growth and two centimeters in six months, there was some new cervical lymph nodes and topsiles that appeared, reduced abdominal distinction and improvement in the patient's ecswrema. Part two suffered from a lot of headaches, which is, this again, plasheeb -- placebo or something real, hard to say, but had future makes and reduced frequency of his daily dearrhea. Had a significant growth in height suddenly and in weight and those -- in those six months. All right, I won't dwell on. This I want to move long, but we have know about -- have been as required by regulation, we have been doing this land PCR and we find that in both patients, the marking is definitely polycleanal in fact richly polycleanal in both of the patients with no evidence of any prominent band. Sometimes when people present the slides they forget to note and I will note it here so when others of you look at slides like this, you remember the technique is amplifying an internal fragment inside the vector. Unless you do something to make that go Away, all of these gels will result in a prominent, what we sometimes call control band, but it's an internal fragment of this method. So this is not a, not an abnormal abnormal prominent clone band. All I can say is there is nothing particularly interesting about that relative to what others have already talked about, presented or published. So we conclude there were no adverse affects to date and to preadolescents with X-SCID who received gene therapy, post infusion peripheral blood shows polycloneal etof the reduced cells and testing in the products and patient cells. In terms of efficacy, there is multilineage marketing of blood cells with evidence of selective marking of T cells, Mod nest patient one. Quite robust in patient two. There is -- modest in patient two. There is provirus marking as I indicated and in part two at six months, we observed an increase in CD-4 T cells, an increase in naive T cells and new substantial proliferation response, particularly to Canada which was absent and now is quite robust. I will acknowledge the fact that this is a collaboration between Dr. Puck's lab and my lab, and I particularly want to note -- [ Indiscernible ] Who not only provided most of the day-to-day care for the patients but prepared a lot of the slides you saw. So, thank you very much . [ Applause ]
Thank you very much, Dr. MALECH. Are there questions from the audience or members of the RAC or any clarifications that you would like to have made? From either Dr. Puck or Dr. MALECH. We'll have another opportunity when we finish this session. All right, let's move on then to Dr. Candotti, also from NIH, who will discuss retroverag -- retroviral gene transfer for treatment of X-SCID and ADA-SCID. Dr. Candotti .
good morning and thank you for inviting me here this morning. I also need to thank Dr. Thrasher, Ian Thrasher from London who agreed share his data with the committee and asked May to present them to you this morning. I will start with this data that regards to X-ling for combined immunodefish ynsy but the collaborators believed that patients who have no match sibling donor or R-related sibling donors should be eligible for treatment of the trial after their diagnose sis confirmed molecularly 1c3, this trial is similar to the French trial you that will hear about later -- used in Paris, mean a little different in the side but that should be not very relevant. One different is that this vector is packaged in the -- [ Indiscernible ] Leukemia virus envelope. Other differences in terms of protocol are the fact that the pressure protocol called -- called for -- [ Indiscernible ] Culture conditions and uses as a lower level of therapy compared to the French trial, but the rest of the procedure -- [ Indiscernible ] There is a pre-activation for almost two days and then a transduction that goes on for three consecutive days and the cells after safety that is our injected and the patient will follow . This is a -- [ Indiscernible ] Of the details of the first severed classical SCID patients. In this trial, I also treated a 20-year-old patient who faild -- [ Indiscernible ] Reported in the blood paper by the French and the investigators. As can you see the first seven patients are with different age but most are at a young age of four months up to three years of age. There are differences in terms of perhapses or absence of the engraft -- engraphment. The changes of the gamma chain and those were compatible more or less with residual expression of the gamma chain. Using the number of the infused C-34 cells, the total number. I don't have the data for that tells me what a percentage of T cells where transduced and expressive gamma in the -- [ Indiscernible ] That was presented and published by the group. There is a, between 78 and 200 million cells per kilo were injected here. And this is the reconstitution in the first six patients, seven patients and on the next slide as can you see, after gene therapy, 20 to 40 weeks after gene therapy, there is a robust increase of C-3 numbers, the solid black line and that is composed by increase of both C-4 and CD-ity republican republican -- CD-8 numbers so the dash line is CD-8. The dash line is CD-4. For the first six parts that have a degree of follow-up and this was patient number seven recently treated also. Shows a similar part from early increased of the cell numbers. And this is the followup summary slide. Can you see there are at least three patients that are above the 30-month threshhold that seem to trouble zone period in the French trial, there are three patients below the threshhole, they're all Alive and well, and four of the seven are off chemoprophylaxisics and AG prophylaxisis. Later -- [ Indiscernible ] Discuss the integration cites in these patients, so I will skip this slowed but physically, there is the conclusion that there is a difference in the terms of the decrease of the cites compared to the French trial and any other information available for integration compared to the treatment -- [ Indiscernible ] And genomic sequence for each of the genes. I will -- a compatibility problem here. They're talking about ADA efficiency and I will start by saying that this is a forest, another form of immunocombined de -- efinish yepsy combined between 15 and 20%, according to published supports. It affects both males and femaless. What this slide show tells -- tells you is that this is a metabolic disease of old cells and the lack, the immunodeficiency are suffering from the lack of the enswrom and the patients also have the effects of -- [ Indiscernible ] Skeletal system, so it's a global disease that can present as a severe form with a classical presentation of combine -- combined immunodeficiencies with a setback of infection or a more delayed and milder form of combined deficiency and patients are later on diagnosed in life. The conventional treatment for the -- [ Indiscernible ] Deficiency, based on the -- [ Indiscernible ] Cell transplantation and the results from a European sorry have a, recent European survey, indicates if they have an identical sibling donor, that part is very successful in survival of the patient. The results of parental transplantation are much less sattis factory and actually is -- sattis factory and should also look at this survival rate. We'll hear more about transplantation for ADA deficiency, I believe, in the afternoon for what concerns American experience, but based on those results, many patients are treated with a second therfy -- therapy for -- [ Indiscernible ] Replacement therapy providing ADA -- [ Indiscernible ] Increasing the stability and using the gen -- JENOCITY. [ Indiscernible ] Presented in the meeting in 2002 showed that there were more than 100 patients treated with this therapy, which can provid protective immunet of normal in four out of five patients. However, these patients have really a correctional -- [ Indiscernible ] That all development antibody and gapes. As soon as their immune system improves and in 10% of the cases, the antibodies become utilizing, complicating things. And overall in the patients that respond, there is a mortality of 25% soreo. So, because of the imperfect results, of course, there has been a lot of work in the developing of the therapy of the disease, and this is around all the trials that have been performed over the years, and I will go through those briefly . Start be -- starting with approaches in the early '80s and '90s, targeting T cells as an easier approaching in those days, it was a technical challenge. I will go through is this quickly to tell you that two patients were treated at NIH in '90 and '91 with a result of treatment that targeted T cells. They were obtaining the EX VEVO from patients on the treatment, expanded transduce with a retroviral vector and infused back into the parts. This is patient number one that -- [ Indiscernible ] After the last treatment still carries around 20% of marked cells and that is simply a data that needs to be considered for the safety of this procedure. So this, this persistencey is -- [ Indiscernible ] And the cells still produce ADA activity, which is around 16 units, which is between 1/5 and 1/6 of what a normal PBMC will produce. This was a T cell gene therapy. The second trial, comes in chronological order, was started -- started intally, where you would take eight hours from the young and combine the T cell and the -- [ Indiscernible ] Stem cell target approach and they had three patients. Two patients with this strategy of being published, I believe, after five more patients telling you of the T cells that data is not published yet. The results of this trial has shown that there was a marking of between five and 18% in the crenical sites and -- clinical cites and looking at conforming units as high as 8% of progenitors by this approach. The next trial is, of course, the newborn trial where Dr. Con and collaborators in collaboration with NIH have treated three newborns that we were diagnosing with ADA deficiency, targeting C-34 positive cells obtained from the core blood of the patients at birth . This is one of the long-term studies,or survey of marking in the cells of their patient number one, the patient that has the highest marking as can you see these are the T cells where in the 10% marketing and myelloid cells with the AXE wherearound in the highest level at 1% at 54 months after birth what. Is more significant is the perhaps now at 12 years after treatment of still a 3% marking in PBMC's and a detectable marking of granulocytes and this is data that they shared at the FDA advisory meeting a couple of weeks ago. So this Wthis approach with the technique that the technology was available now more than 10 years ago, this patient still carries long-term marking. Now in the same time, a collaborative effort teen Dr. Fisher, Dr. LEWINSKI and Dr. Capped lairia targ -- [ Indiscernible ] Format cells from ADA patients to girls from UK and one patient from France to do with this approach, which I was not successful. There was a very short mashing in all. Three patients and based on the -- short marking in all. [ Indiscernible ] The very good result the Dutch group observed in the system after myeloablation, however, this was, the orders of this experiment first indicated that maybe success of gene therapy for ADA-SCID would need some kind of myeloablation. And then in 1995, our colleagues in Japan and Dr. YAKIMA and his partner ran a trial that was a copy of the NIH T cell trials in one part. And I will just say that bite end of the trial, the overall impression of the overall conclusions were that gene therapy for ADA efficiency had not been very successful for the results of -- [ Indiscernible ] The improvement were not clear and none of these patient his been corrected enough to be able to suspend ADA treatment. It was a very important background information, but there was no clinical benefit that one could really point to. And thises started to change after -- [ Indiscernible ] And his group probably subscribing to the theory generated by the Dutch colleagues decide to introduce a significant steps of non-myelograding of gene therapy in patients. These have been the results of -- [ Indiscernible ] Being published early in 202 N.science, where they depleted -- [ Indiscernible ] In the absence of concomminant treatment with ADA buzz the -- because the patients had no access to the treatment. They had shown very, very important results. Can you see he had for patient number one as soon as 120 days after gene therapy, this patient had a normal number of T cells, B cells and next&K cells. Other investigational -- investigation of the group showing anything they could measure became normal in this patient and based on these results they went on and so far they have treated six patients and this is based on personal communications by Dr. ONCAROLA and Dr. BIONIONE and he'll see summary slides of these six six patients at different age and therapy and they're followed for a different amount of time and, again here, the three patients at 30 month thrrbhold. that we always hear about. The first five patients were followed long enough for the investigators to say that the immunodoppler -- constitution had occurred for all patients except patient number two, that was an older patient receiving less cells per kilo. All patients at home and well without need of it. There is a result definitely, a clinical result that can be measured in these patients and that is difent from -- different from what we have seen in our trial, and when we study a trial and, one, we don't describe to the theory of chemotherapy, we caught that improving expression by the use of vectors was the way to go and so we tried it on vectors that were expressing -- expressing continue to 15 times higher ADA activity compared to the vectors used in the the early clinical trials. This is just a presentation of, or a summary of what our patients look like. This is a 5-year-old female that received more than 10 million, 74 cells per kilo, roughly half of them were used looking at the presence of ADA by takeman or colony BCR and there was a software in transfused that was a ADA activity that was similar to normal or both normal in normalcy, the four cells we expect to have on the hundred unit of-from-ADA. So what we saw in these parts was an initial increase in cells and lymphocytes. However, did not reach the low-range of normal and I will just take a minute to say that these values are very low and those are the values that you see in a patient on the treatment. Just to say that the ADA, although it keeps the patients off the risk of the infections, clearly doesn't give you a normal number of lymphocytes. And over time, however, the cell number to turn to biasline and held with the eye of hope can you see a trend here. But, obviously, the other numbers are very low and goes, reflects the numbers, low numbers, reflect the low, the percentage of markings that.
seen in this place next all of our patients of what we have seen N.this trial, I failed to mention we use two VECS because we have selected over the years two very good vectors. We didn't know which was better. We didn't know how to decide which one was better. We decide to test them in enreef iso, one against the other -- test them in vivo one against the other. Each part would receive both vectors and we would be able to detect each by a specific PCR and this is a vector that uses the M&D, -- [ Indiscernible ] Mosted to resist the inactivation in ES and -- [ Indiscernible ] As can you see from the square sim bowl -- symbols indicate cells or unseparated -- [ Indiscernible ] Earlier in the trial, we had three to five percent markings in the cells but that marking went, obviously, down, and now at 30 months after yet, we have a two in 10,000 cells marked for lymphocytes and no marking for myelloid cells. In this vehicleor, this carries the unmodified myelo -- [ Indiscernible ] And the marking as you see is a log lower throughout. We have marking in the, a little more the one cells per 10,000 cell in unseparated granulocytes at 30 months in this patient. But the summary of our four patients with this approach show that we had low level of Len yaj marking that was long-lasting for more than one year and two patients and should last in the other two patients. We treated two patients that were one, five years of age, and two others were 15 and 20 years of age, and we definitely saw a higher marks in a yonger part, which is similar to the experience in the X-SCID trial, if you compare the chafckal X-SCID patients with the adult parts described in the blood pavement as was referring to before. There was high markings compared to the myelloid cells and that is expected since we know that ADA positive, ADA expressing have a select advantage and we didn't see one in the three-year followup. But obviously we have not penetrated. We can really spook up. Our colleagues in Japan visit have taken the next logical step. Our conclusion from our trial is that in the presence of peg ADA and without myoAblag, the strategy, the jeep transfer -- [ Indiscernible ] Leads to a low marking and no benefit. Again, our colleagues in Japan were not totally in using myeloAblag. They decided to take one step and remove the ADA from the equation and stop the ADA before gene transfer but did not yield chemotherapy, and there have to be two patients so far and they used our vector whole our vectors did so and desire. The data from that trial is the 4-year-old and the 12-year-old that enrolled and one million cells per kilo and roughly half transdoused and very good activity in the south of the world. Unfortunately as you see, the number of lymphocytes remained below the low rainfall of normal, again, you know, if you're an optimist me, can you see a trend in it, but obviously there is nothing that is similar to the Italian style where the normallization of a T cell, the lymphocyte number occurs bee 120 days and here we are out one year for both parts. There is marking in these patients, this is patient number one and you can see there is marking in PBMC's and in the granulocites. It seems to increase over time. Patient number one and in patient number two. Again, this is any quantative PCR there. Is no tap month -- [ Indiscernible ] No realtime. Quant Tative PCR a date available for this trial. But in a 10 months after treatment, there is clear presence of the hygiene, the transfer vector. That brings us to the last trial of the series and that was started by Dr. Thrasher again and collaborators in London. They, they believedma thamyeloablation is to be used and used a full dose -- [ Indiscernible ] Instead of a low dose. There is no data published from this trial. Patients were teg triggered in November 2003. But it's been used from the local newspapers that indicates that this one patient is doing very well and is being called as a revolution -- [ Indiscernible ] Before the disease as well follows. Following the success on the same group for the X-SCID troll. -- trial. So if you follow the progression of the results of this therapy, I think it's interesting that now we have a almost full array of approaches from our trial where we started from the safest of the position, or where we didn't do anything to the current group of patients. We're adding gene therapy to patients on the ADA. The marking that is the results there were poor and then there is an intermediate position where the ADA was moved but no chemotherapy was given and in those two patients where there was that approach, the results are potentially promising but obviously not as exciting as the results that come from two trials where myeloablation was used and ADA was stopped in this case and not available from the start in the Italian case. So we have, you know, at wide spectrum, almost all responsible variation, and I think this is the case for gene therapy to work for ADA deficiency, we'll have to most likely go through some meelo ablation before the -- myeloablation. In summary, we have for gene transfer into stem cells, the most relevant issue for this meeting today, there have been 22 patients treated, 19 were infants of children, two and one adult. Eight patients are Alive and in the absence of adverseIVANT with gene marking, very viable gene marking from our parts, that are one in 10,000 cells to 100% of cells in the Italian trial.
gene marking for more than 21, eight patients. Overall, 7 error error parts -- 7 patients though these markings by this approach there. Is no complication by any of these patients and the available data on the -- [ Indiscernible ] Does now show a difference between the pattern of ADA vector integrations compared to the extra trials. That seems to be a different I would like to offer this is a safety for this disease as it might be indicating ADsa, a different disease and potentially the risks involved with jeep therapy in that disease are from the ones that gra are obvious for X-SCID. And I will stop there. I will thank Dr. Thrasher again for sharing his results and my collaborators at the NIH, Dr. -- [ Indiscernible ] And the infection of -- [ Indiscernible ] Helping with the trial and the collaborators in Los Angeles and east France. Thank you. [ Applause ]
Dr. Candotti, thank you very much for walking us through the jeep transfer experience and ADA definishience -- deficient SCIDs. It spans a long period of time, it's complicated and for me, at least, it was presented in a very coherent manner for us. So, thank you. We're going to move on to Dr. Friedmann again from uC San Diego, who will give us a summary of the recent safety data emerging from the French X-SCID trial. Dr. Friedmann . [ No Audio ] -- including elevated levels of the expression. The -- the child had a complicate family history with the existence of some family history of cancer ands child responded well to bone marrow, to chemotherapy and eventually to bone marrow transplantation. Eventually relapse and that was the child that died in October last year, five years after the treatment. Patient number five was treated at three months of age to help clinical leukemia more or less at the same time, the same kinetics as the first child 34 months after the treatment had three leukemic T cell clones with the same single integration site upstream from, not in, but upstream from Alamo II. That child did not have a family history of leukemia, but did show chromosomeal aberrations in the Lou cim -- leukemic cells. Again, responded well to chemotherapy and is under arrest Kently Alive and well -- and is currently Alive and well. After the two cases, the criteria for inclusion in the study were modified to some extent and included age greater than six months because of the leukemias and the two younger children who were much young her they were treated. The inclusion criteria was elevated to include children on the over-six months of age and with a history of at least one serious past infectious episode and the absence of family history of cancer, and no sign of genetic abnormality in the cells and with the reduction in the number of transduced cells to less than 10 times 10 to the six per kilo to be infused. The third leukemia developed in the child who was the patient, was in good health until November of last year. In January of this year, developed a round of larn.
This and wheezing with progressive cervical adenopathy with respiratory distress from enlarged mediaSTYNUM. That child was found to have single proliferated cortical clone. Some blood cells in the blood and in the marrow and NODES. The leukemic cell in that child contained three integrated proviruses. The integration cites as of last week when I heard from Dr. Fisher, those cites are unidentified but they're not -- cytes, they're not Alamo 2 II. This is not anentgration into or near Alamo II and there is no increased expression of Alamo EI there. Is obviously something different -- Alamo II, so there is something different from this event and the first two events. The kinnets of the development of clinical disease, similar to 30 to 34 months after treatment is when the clinical disease became manifest. This child shows no cyteogenetic abnormality in the proliferating cells and responded accurately and well to corticosteroid treatment and is currently in complete remission. I heard from Dr. Fisher several days ago who was very kindly letting us know what his thinking is in this study. And in form he feels that the study for now remains on clinical hold. He has the feeling that one of the major Avenues they're going to pursue in the near future is the development of the virus vector system, -- [ Indiscernible ] Self--inactivated vector. We'll hear about about that later in the day, and we'll hear some of the details of how the antivirus system integration mechanism is different from the, from the current leukemia-based retroviral integration events. In any event, this is the last I heard to professor Fisher, allen Fisher's current views about the gene transfer methodology, a shift to the virus system, rather than the leukemia-based vectors and I think that's all that I have in terms of report of the thinking and the progress and the French study, and I think we will hear more about that from later speakers, from Dr. MANKALA and Dr. Bushman. [ Applause ]
Thank you very much. We're going conclude the first session. I've lost it. But presentation with Dr. Carolyn Wilson from the food and drug administration and she will talk with us about the U.S. FDA perspective. Dr. Wilson .
Thank you. Okay. And I wanted to thank the committee for an opportunity for the FDA to present an update on what we've been doing from a regulatory perspective. I wanted to start by giving an overview of what I am presenting to you today. I apologize. I'm just getting over a cold. I hope can you hear me all right and hopefully my voice will last. Anyway, I want to start, actually, two years ago as you know, as you already heard, when these events first began. The actions we took in response to the first two children that developed leukemia in the French clinical trial and also bring you up to date in terms of how IMD's placed on hold at that time have responded. Then I will come to the present time and discuss what actions we took in January of this year in response to this notification from the French of the third child and then I will finish with a discussion of our advisory committee that we copveeped on March 4th -- convened on March 4th and reviewed for you what was discussed, what questions we asked the committee and what their recommendations were. So, going back to January of 2003, we support -- actually three different flavors of a letter to sponsors of retrovectors IND. Okay. So the first cat gorry is shown here. This was sent to sponsors that had active IND's that used ex vivo transduction wit rethvo -- retroviral vectors with hamatopoetic stem cells and INDs and any other that uses this. They received a letter placing them on hold until that were able to revise their concept reform documents as well as methods to monitor the clinical et -- [ Indiscernible ] As you heard from Dr. MALECH. The second category went to sponsors who had IND's who were at that time inactive but were taking the same approach in terms of ex vivo transduction and they were basically notified if they were turnover reseem a clinical trial under that IND, they needed to satisfy the same requirements and then all other clinical trials using target kills other than hamatopoetic stem cells, receive a -- received a letter informing them and suggesting that could revise the informed consent documents and methods to the cloneal et. These were recommendations. They were not in the form of a clinical hold. In addition, all sponsors were asked to provide a risk benefit analysis and SEBER has evaluated each response as it's come in. So to give you a snapshot in February of this year of where we were with administrative and IND status of the 28 IND's placed on hold on January of '03, we can see then in response to that letter four and subsequently withdrawn, an additional four responded to the hold letter and became in affect but then subsequently inactivated another IND holder just went ahead and inactivated at that time. Nine IND holders have responded adequately to the letter and are currently in affect and then 10 are on clinical hold. I wanted to break that down for you. Of these 10, three are actually in the SCID clinical indication, and I won't go into the details in today's talk, but those IND's actually had responded to the hold issue in January of '03 and between those, in their two-year increment had come off the hold and replaced back on hold in January of '03. They're capturing here the February timepoint. Six of these IND's never responded to the January letter. Those are mostly older IMD's and are probably no longer accruing patients, and one responded to the letter but was insufficient in his continued on hold. Just to let you know since January of 2003, we have also received an additional 15 new submissions using retroviral vectors in the breakdown of the target cells as shown here. So, now to come forward two years to the present, in response to the recent developments that we just heard about from Dr. Fried onmann, in January of 2005, the -- of Dr. FriedMann, the FDA put two on clinical hold, two for X-SCID, one for ADA-SCID. The letter sent to the sponsors was to request they revise the innocent documents and notify their IRB's, and also to let them know that we were having an advisory committee to discuss these events. We also support a letter to all sponsors of retroviral victors -- vectors to inform them of the new, vents, as well as notifying IRB's that regulate the clinical trials again to just make sure they were aware of the new events. As I mentioned previously, we convened a meeting of our advisory committee and mentioned the new names for those not familiar. It's got the catchy title. Cellular tissues and gene therapy's advisory committee, CTGGAC. This is formally the BURMACK committee, you might be familiar with. Now, I want to go through the information that was presented at that advisory committee meeting. I want to also mention that at this time, the transcripts are not available but at some point in the future, I think by the end of March, all the transcripts and 42 slide presentations will be ac -- and some slide presentations will be accessible to the public on the website as indicated. The meeting began by a presentation by the FDA where we reviewed the mechanism of rethvo ryeral immunogenesis, we updated the committee on the SCID trial in France and the regulatory actions taken. And we also reviewed what had happened when they -- at the advisory committee in February 2003, what their recommending as were and what subsequent actions were taken in response to the recommending as and finally, we, like Dr. FriedMann, were fortunate and having cooperation from professor TREVAN in collaboration with Dr. s Fisher and KELVO -- [ Indiscernible ] From the hospital to be able to provide a more detailed update on the events in France. So, in addition to that presentation, we had three speakers to provide updates from animal models that we thought spoke to the issues of insertional mutogenesis. Dr. Cindy Dunbar presented information from a non-human primate study using ex-reef iso transduction of hemapo at the time -- hemapoetic stem cells where six years later, one primate developed a myelloidsaur coma positive for vector cells and the exact link ang -- linkage of that event with that victor is still under investigation. But we thought that was important Dade -- data to make the committee aware of. Dr. BALDAVE spoke to his data from a mouse model using wild-type rethvo retro viruses. You will be hearing today from Keepland similar information and Dr. BANAN using ex vivo transduction with hemapoetic stem cells with the retroviral vector where he reported observation of leukemias where these animals, when they were performed at high dose of vector. And then finally, we also heard an update from the Dr. Donaldcon on the human experience with ADA-SCID. I wanted to finish by going through the questions we asked our committee and what their recommending as were and I also wanted to give the caveat that our interpretation of the recommendations found on these slides are based on rather cumulative comparison of individuals notes within the FDA, but the Trents have not been made available, so hopefully these are fairly accurate capture of what was said. So, I know this is a long question and I apologize, but I'm going just read it to just make it sleer. The code of federal regulations part 312.42 defines the base ease for FDA to place the study on clinical hold. Subpart B-4, also known as insufficient information was seated previously as a base for replacing IND's on clinical hold in response to the development of leukemia and subjects in X-SCID clinical trials. However, we note CFR 312 part D-1 that states FDA may place a study on hold if it finds a human subjects are or would be exposed to an unreasonable and significant risk of illness or injury. We asked the committee with this requirement in mind to discuss the current incidents of leukemia in depth of one subject from leukemia reporting the clinical trial in France relative to the potential benefit of retroviral victor -- vector media gene transfer X-SCID. We asked them to consider risk benefit of gene therapy versus bone marrow transplantation. We asked them to also consider how they would view these risk benefit issues should another leukemia develop in this trial or in trial. Their recommendation was to say that -- to change the risk benefit in a more favorable manner. Rethvo -- retro viral should be used under the following divisions. Bone marrow transplant or those that have no reasonable alternative therapies. For example, patients precluded from transplantation because of an acceptibly high risk of previous infects. Question two, we asked them to comment on what changes, if any, would reduce the risks to subjects in clinical trials using retroviral immune O' -- Imeanogene transfer in SCID, asking them to reduce the number of transduced cells, the total number of transduced cells going back to basics and altering the retroviral design. We should not consider the number or ways to address the risk in gene therapy for X-SCID but strongly encourage investigating alternative approaches including new retroviral vector products to lessen risk, suicide vector systems were mentioned as one where they considered feasible and in all cases, they asked that adequate testing in the model should be performed in order to validate any novel approach. And the third question: Please discuss the impact if any of the severe adverse event X-SCID combined with the development of myelloid sarcoma in the single monkey administered hemapoetic stem cells on the vector of the use of retroviral vectors on the clinical -- we asked them to discuss the risk issues in ADASCID as well as X-SCID in other clinical -- [ Indiscernible ] The committee recommended these trials should be allowed to proceed. They wanted to make clear the risks are still present and investigators and patients should be informed of strong and clear communication of these risks. They also noted if a retroviral were to be administered in the future, that the FDA be advised to -- [ Indiscernible ] Likewise, in other non-SCID, they allow cripical trials to proceed but, again, acknowledging the risks are present. Then finally, question 4 which was something more forward-thinking because of the potential use of retroviral vectors to transduce a much higher efficiency than the traditional gamma retroviral vectors, we asked given the transduced cells reducing in copies per cell, up to 10 have been reported, please discuss other restrictions on vector copy number per cell warranted for the vectors and ex vivoduction clinical protocols and if so, what limit would you advice. The committee didn't recommend a specific number, but acknowledged that it is an important issue. They suggested that we assess each IND based on available data and animal models should be used by investigators to assess the relative risk of leukemia induction with increased copy number. So, with that, I just want to finish that from the FDA's perspective, I think we're really at a crossroads in terms of trying to find just the right balance as really it's been mentioned by multiple speakers this morning between what we now see as an actual benefit in the treatment of X-SCID at the very minimum versus these actual risks from the treatment as well. So with that, I thank you for your attention. [ Applause ]
Dr. Wilson, thank you very much. I would like to take just a minute before we go into the general discussion. Are there questions either from members of the RAC and those at the table or from those who are in the audience for either Dr. Friedmann or Dr. Wilson, regarding the third child with leukemia in the French study or regarding Dr. Wilson's summary of the recent FDA stance. Dr. DOLUCA.
Dr. Friedmann, I don't know if you mentioned what was the ageing of the third patient in the X ? Nine months?
Trying to find yet on my slide. I'm told it was nine months of age of treatment.
That was the 35 months ago. So he's --
Two years.
Is he the third youngest in the group?
Pardon?
Is he the third youngest in the group of 12?
I don't know that. I will get that information for you.
Could you tell me if the Cynthia Dunbar result with the one monkey, how many other monkeys were there in that study?
So what she's doing is collecting, if you will, non-human primates that have been involved in various retroviral vector transduction protocols and trying to get them transferred to do long-term surveys for just these types of events and if I recall the numbers correctly, I think she has a total of 78 and the median times of follow-up will be four years, so this was one of the longer ones and I forget the longest time point, but it's not like it's a coherent single study of sort of an aggregation of all the serious monkeys used in a variety of different trials by investigators throughout the country even.
So they represent a lot of different retrovirus vectors, a lot of different doses itself?
Dr. lo.
I have a question for Dr. Wilson, please, a clarification of the recommendations on question number one. I won't try, for the March 2005 meeting, I won't try to pronounce the new acronym. With, this was this a narrowing of the indications for X-SCID trials from the January 2003 and could you explain exactly what --
Yes, actually committee hadn't taken astringent a stance on the use of gene therapy for X-SCID at that time as the RAC did .
Yes. Dr. Friedmann. Or is it Dr. Rosenberg -- it's Dr. Friedmann.
I just wanted to mention that there are these three other patients, maybe four, but certainly three others in the French fighting -- [ Indiscernible ] Younger treatment so well. Six months, seven months and eight months.
Dr. Friedmann, could you clarify weather those three younger patients have whether those three younger patients have reached a three-year time post-gene transfer .
Yes. One is 3.1 years. One is -- another is 3.1 years and the third one is 5.8 years.
Those are still --
Thank you, doctor Patterson.
I have two questions for Dr. Wilson. First in the slide when you recap the administrative and IND status of the 28 IND's replaced on hold on January 2003, you noted that among the quote, unquote, active IND's that six had no response and my question is: Howe have you followed up with those sponsor -- have you followed up with those sponsors in their readdressing the potential risk and need for monitoring of those patients, nonetheless, and with regard to all of the IND's addressed with the sponsors, their plans for long-tomorrow monitoring and could you speak to that. And then my second question is: You have presented the answers to the questions as recommendations of the committee, but do they represent the views of your agency?
The first part of your question in January of '03, the letter that we sent to all, those sponsors that were on hold did tell them that they did well -- as you probably already know, actually from many, since early 1990s, we asked life-long surveys of subjects on clinical trials using retroviral vectors and the policy was still in place, so we also looked for that information through the sponsor's annual report. So, even if they're on hold, they still need to submit an annual report. We're still monitoring that information. And then secondly as far as following up, we feel that the information we sent in the January '03 letter actually lays out very clearly. I mean remembering the 10 in active status are still on clinical hold so they're no longer treating. They have been told very clearly they need to notify patients, the ERB's and so on. That was all in the -- IRB's and soa on. That was all in the January letter. The second question you had as far as the FDA stance is is that right now as you know, this is still very fresh. We haven't had a chance to review the transcripts in detail, so we're actually, at this point, waiting for the Trents of it, you know, so we can be -- the transcripts so that we're not misinterpreting what the committee members they Mai have said and probably toward the end of March, we will internally sit down and assess our own position. It's really too soon to comment.
I just wanted that destchingz made. Yeah.
Thank you for making that distinction .
[ Indiscernible ]
I thought that at one of the prior meetings there meet have been mention that even though there were two children that had gotten leukemia, there might have been a third where there was not clinical disease but there was some suspicion. Is that the same as the third child who now had --
I will answer that. I don't believe we have that information. Dr. Win -- Dr. Wilson.
I think we can dedeuce it's a different child. All previous time points on the child were different integrations and the child you're calling from the previous meeting had an element or two of integration . [pausing to switch captioners ] don't know.
Any questions from those of how are in the audience? Doctor?
Question for Dr. Friedmann or anyone. This first patient who died, sounds like he had acute graft versus host. As a terminal event, is it clear that his death was directly related to the leukemia or to the treatment or -- but in any case it sounds like his leukemia did not respond to the therapies.
Did you want to comment? [ Microphone, please ] .
My understanding it was it was not so much the transplant-related issues but that he basically had reflak try leukemia. .
He I hadn't either, Dr. O'Reilly that this was graft versus host.
No.
It was conveyed to me as a relapse, not graft versus host.
Since during the first session, the serious adverse event in the third patient was defined. I have a question which is I think a very obvious one but I don't have the answer. The third patient for me confuses the issue much more than clarifying it because everything about the third patient seems quite different from the first and second. Except the kinetics. The kinetics are within the three-year time point. But the third patient to my understanding has a proliferation of TCR V-beta five, it's a single clone, it is immtur cortical thymus-related. There is no increased expression of LMO2 which seems to be one of the driving forces for subjects one and two. And there was no cytogenetic abnormality so it confuses the issue for me of the relationship of the serious adverse events, that is, the development of leukemia in this particular patient group following gene transfer. And it makes it less clear that LMO2, not clear that LMO2 is not central and not clear that, uhm, the gamma chain transgene is central. I'm just -- if someone could clarify that for me, yes? .
I'm not sure I can completely clarify that. But I think some of the retrovirology experts that we have could certainly comment that based on studies of retroviral integration, there isn't a single pathway or single target gene that we can point to in some circumstances, you might say, there is a particular target gene that's frequently involved. But there are other examples and maybe Dr. Copeland, particularly, might want to comment further.
Maybe we should hold that question until after the retrovirus talks because I have some data that --
No, I'll hold it. The problem that I see is that moving into the discussion segment, which we'll do in one moment, for the first session, the specific relevance of subject 3 is the underpinnings for that discussion. And so I find it a bit complicated to complete the discussion without that. Can you give us some sense, Dr. Copeland?
Well, the -- I mean, naomi said I think right and that's that I mean, my take on it is that when you put IL2RG in a retrovirus that's an oncogenic event and when you give it to a patient that's one mutation. It integrates all over the genome and it can deregulate. LMO2 is one strong cooperating partner but there are probably lots of other cooperating partners so I would think that patient number 3 could have an integration in another Gene that could substitute for lmo2 or it could have another spontaneous mutation with another gene that could cooperate with IL2RG. Does that make sense?
Absolutely. But it broadens, let's see -- it broadens the significance of the leukemias observed in the first two subjects.
I guess I don't no what you mean by broadens the significance.
Hm [ Pause ] .
In my mind, the first two subjects although not identical, have very similar patterns. And so there was for me, at least, one could look at that as a fairly narrow series of events, specific -- I have to be careful about what I'm saying, but specific Orelively specific -- or relatively specific for this disease and this vector. Dr. Rosenberg?
I think -- and I think, uhm... Neale would -- Neal would probably agree with this, that long history of experience with the way these viruses Clint to tumor development in model systems, really predicts that we can't to a single event and to me, the importance, if you will, with respect to the issue you're addressing of the third patient is that that reinforces the fact that what we know for from these model systems -- what we know from these model systems is going to be of real consequence for individuals that participate in trials such as this. So I think it's really just showing us that we can't rely on looking for insertions near LMO2 as prognostic of what may --
I agree. If you base it on the model systems like in mice there are these preferred integration regions like LMO2 but you also hit other genes, too. It's more broad. And this is exactly what you would predict. You would certainly not predict all of the integrations are going to be in lmo2.
Right. Thank you. Other questions or comments before we move on? .
Dr. O'Reilly?
Yes. The critical variable here remains, though, that's these are tcll, and in this age group it's an unusual mode. The other issue that comes up is the unique biology of is he severed combined immuno-deficiency because these kids have a thymus that's fetal and nonlittle foid. So you basically the first population to reconstitute is going to be the T-cell population within that thymus and in fact even in the nonreduced pads for SCID that's where you see the selective growth so if you are going to talk about a really major growth emphasis, that's where it's going to be and the possibilities for altered recombinations would certainly be at the highest level. .
Dr. Friedmann?
Couple of questions that have occurred to me in discussions with some of the members of this panel and also Dr. Fisher and others. Two things that might be approached by some of the later speakers. One is whether this third case sounds fast it might be something different from the first two in terms of its clinical presentation. And I have heard this third case described more or less as lymphoma-like sort of rather than leukemia. Now, I don't know where the differences lie. But is there significance in that differentiation? And also, do the clinicians have any feelings about this kind of monotonous 34-month window between treatment and clinical disease? Does that suggest anything in terms of whether this is -- which hit this is in the pathogenesis of the disease? 33, 34 months for all three children, and does that suggest anything to you? It might be not the time to discuss it but bring it up later.
Dr. O'Reilly.
There have been several studies looking at thish eye of the pathogenesis in -- issue of pathogenesis in leukemia children particular from studies from the University of Vermont and you know, in terms of the issue of level of production and rearranged clones, this is a peak period at about three years to five years of age in normal kids. But it's usually what we're look caught in the context -- looking at in the con teiveghts rearrangements in the b cell. Now, that niche for most of these kids with SCID may be relatively filled. So it's both sides of these in terms of little foid development, that's a sort of peak time and it's been looked at and thought about as one of the reasons for the pathogenesis of leukemia in normal kids. .
We are going to take a 15-minute break and then we'll begin a more broader discussion of the first session. Thank you. [ Short break ] Please stand byfor realtime transcript. Stand by, please. [ Standing by ] Stand by, please. [ Standing by for audio connection ] Standing by for audio.
Thank you all. Dr. Bernard Lo and I will be chairing the discussion of the first section. We decided to divide it in two. The questions that we structured for this section are from the RAC, are primarily database questions. There are a second group of questions which were framed by the FDA during their discussion. And what Dr. Lo and I would like to do is to quickly and I mean quickly, uhm, go through the database questions, be certain that everyone agrees to a response which we do want to agree on. And then move to the FDA questions and answers and ask simply are we in green or is there something we would like to add or change? So how do we move forward with these? Do I go up there? I guess I do. .
I can do it for you.
Oh, good. So the first set of questions we were posing is, what data is available regarding the research participant who developed the third leukemia and it's divided into four sections, I think the answers to these sections are fairly clear. Is the third patient described at the February '03 RAC meeting, is this the same patient as having two integrations in the LMO2 gene and the answer is no. Second, has to do with clonal expansion and this all relates to again the third subject, the cell type, TCRV beta 5, the methods for early detection of clone at appear to be AAMPCR and tack man PCR. No question about that. Time course of expansion. Three years.
Dr. O'Reilly?
34 months. That's right. And time from vector administration to malignant transformation in comparison to the events in the two previous participants.
Sorry, claudio.
To qualify to the expansion, this patient was negative for oligo clo national in December and then came down with the onset of the leukemia in January. So it's not 34 months. It's 3 months. The time course of expansion I suspect should be three months and the next question which asks for the time from vector administration to malignant transformation is what should be 34 months. The next set of questions really don't have good answers because they involve vector integration. As I understand it, the site or sites of integration are unknown. The detected expression from cellular genes due to integration is an open question. Unknown. Function of the cellular genes EG okay he could gene again unknown. -- oncogene, again unknown. The nature of cellular gene activation, these all depend on definition of the integration sites and the biology that will ensue following that definition. Other incircumstances observed in the -- insertions observed in the participant cells prior to clonal expansion... don't believe we have information about that either. Dr. Von Kalle do you have information regarding the section on vector integration that you could share with us?
I think what I have I'll -- I will present if my talk.
All right. Then we will defer these, the vector dose, the number of transduesed cells administered, appear to be 11 times 10 to the 6th per kilogram. Relatively high but in the same range really as patients 1 and 2 with leukemias. How does -- question 2, so that the entire database for question one really is open to further definition but does expand beyond patients 1 and 2 where there appear to be a definite link with the LMO2 gene. Question 2. How does the data from the third participant compare to that from the two previous participants who developed leukemia? And what we can say is, that the data is different, the site of integration is unknown. The expanded clone cell type is TCRV beta 57. There is no increased expression of LMO2. The timing from receipt of the vector to the development of leukemia was 34 months right around three years. So that is relatively the same but the biological consequences that followed are significantly different. -- from patients one and 2, other than T-cell leukemia. I agree. And I think that's really important to emphasize and Dr. O'Reilly did during the earlier discussion period, that is T-cell leukemia is rare in young children. All three of the subjects in the French x SCIDs trial developed p cell leukemias not the more common d cell leukemia that we see in young children and then I'm going to skip to question 4 and go back to three as the final discussion point. Question 4, what data is available from the other clinical or preclinical studies regarding either maintenance of polyclone national or the range of integration sites. This a very broad question for which we really don't have a good answer. We are going to hear more about this later today. If we go back to question 3, this is where we should spend a few minutes from the lessons learned after the first two leukemia cases after the fren k skids trials it was apsyched that they could be minimized by limiting enrollment to research participants older than three months of age and lowering the number of transduced CD34 cells administered to participants to 3 million CD34 gamma c cells per kilogram of body weight. Dozen the development of a third case of leukemia call for change in these safety precautions? I'm interested to hear if there is anyone who feels -- I would POSIT that the correct answer is yes. It calls for change in the safety precautions. That safety precautions that are limited to age of the participant and dose of cells are likely not adequate to address the scope of this serious adverse event. Is there anyone who disagrees with that perspective? Okay. Dr. Puck.
I might just add that infants diagnosed with X-linked SCID who are within the first three months of life are unlikely to have had as serious infections and other adverse environmental insults that make them poor bone marrow transplant candidates, and so if you're looking at the risk benefit equation, I think you need to also consider that the standard transplant treatment for these patients might be more successful. There is published data from Dr. Buckley's group and others that underlined the relative Ben fifth early -- benefit of early bone marrow transplant. .
Dr. Somari and this Dr. O'Reilly.
This it says these were assumptions but they weren't explicitly stated in our recommendations from February 2003 nor do I see them in any of the FDA things.
Correct.
So where did the assumption come from and where was it explicitly stated?
I don't think it's state police thely stated -- I don't think it's explicitly stated. It came out of a conference call from a number of us looking at the commonalities between subjects 1 and -- the first two subjects who developed T-cell leukemia. And these were commonalities. Dr. O'Reilly?
It came out of an article that -- it actually came out of an article that Fisher wrote suggesting that these were the way that they were going to go and this article was the most stringent one where they dropped it down to 3 million but I think the French FDA had actually recommended 10 million as being the dose.
Dr. O'Reilly.
I have to say that bz you know, the -- the scientific rationale for giving the limited dose to a degree escapes me. I understand that because you are going to quote, unquote give fewer pro general tores but in if you are going to drive a single cell to multiple replications, you give a limited dose of stem cells. You know, it would seem to me that actually if you gave a larger dose of stem cells the likelihood of having this kind of a transvehicle AT&T would be largely reduced this would go along with some of the studies in [ Indiscernible ] models where if you give limited dose stem cells you can have mice that are cruising along on one single stem cell or two single stem cells from the studies of lumishka for a period of years so my sense of it would be that you would rather give -- if you are going to do this, do it with a -- a large dose because you are like -- your like lie hood of developing -- your likelihood of developing a clonal population would be reduced. I don't know exactly what the -- the readout was or why should you give 3 million. Last time we did this was when we were doing, Diane can remember ago, you do matched transplants for severe combined immune deficiency and the whole idea was you give a small number that way you are going to get less problems and GVAs. The fact of the matter is when you gave the small number those are the only patients I know of with SCIDs who developed chronic GVH who got problems. .
Dr. Copeland.
Yes. I mean, I would think just the opposite actually. So if you believe what's going on is this virus is oncogenic and it's integrating all over the genome essentially at random and had some probability in a cell of integrating at LMO2, the more cells you have and the more integrations, the more cells that you transplant are going to have LMO2, which is a cooperating event with IL2RG. So if you transplant two cells, then the probability of having an interdiscrimination and a cooperating gene is essentially zero. And therefore, you would have -- you wouldn't have the cooperating event. So what I would argue is if you give them a large amount of infected cells, say 10 or 100 might have LMO2 integration, what's happening over that three-year period is the cell or cells that have the cooperating mutation are selected and they grow out over time and that that's what you see. So the -- I would -- I would argue that the more cells you transplant, the bigger the problem.
Now, I think if that's been the premise on which the cell number issue was based.
Right.
Who -- Dr. Malech.
Yes. I would actually like to try to mud dit water a little bit rather than cla -- muddy the water a little bit than clarify things. Number one, those of how attended the FDA committee meeting and heard Cindy Dunbar's presentation about her monkey, what was special about that animal actually was that it was extraordinarily Oligo clonal, maybe even monoclonal in its en graftment and it probably was that monoclone that eventually transformed. Bringing up the issue that when you -- that there is -- that there may well be a Lou keemgenic effect to running marrow cells through a narrow window in itself. Which is not to say that Dr. Copeland is incorrect. It almost certainly is correct that the more chances you give to hitting the wrong place, you probably have a problem, as well. And that's why I say I'm not clarifying but rather, muddying the water. And to muddy it further, there -- you know, I remember that one wit said the safest thing to gene therapy is not to give at that time all and, of course, you can work your way down to doses that are not therapeutic whatsoever. And there is a lot of evidence to suggest -- and I would draw your attention to some nice studies done by Peter fellsberg with his dog model of X-SCID in which he gave limiting doses of CD34 cells and found that there really was a threshold effect and that what you ended up with if you gave too few cells was -- was engraftment -- actually curiously a little bit like the Patient 1 that I presented this morning where you get evidence of selective engraftment but you don't get a take-off and it's a little like having a cell culture that's split too thin. There are probably auto crine factors and you have to reach the level and the problem is I don't think anybody has any idea what that is what the right number is and it may vary depending on how old the patient is, how the patient comes to the table, what's been done before. So therefore, you know, I think before you take a chance on regulating dose, you need more data on what is the sufficient dose in a specific situation, which is not to say it isn't a good idea. We just don't have the data.
I could make another comment? And address --
Yes, go ahead, Dr. Copeland.
So Cindy Dunbar and I just two hours ago gave the grand rands talk down at nci and she talked about this data. So basically the monkey that you're talking about that got leukemia and was kind of monoclonal early on, early on I don't know how many months that was because -- uhm, actually has two integrations and one of the integrations is in the BCL2-like gene. She can't prove that that is -- that that insertion is cooperating but it's very likely, it's a pro -- it's an anti-apoptotic gene. The idea is you are giving the monkeys a lot of stem cells and what was selected out early was a stem cell where the integration occurred into the BCL2 gene. That was selected but not enough to get leukemia and then over time, you acquired other presumably spontaneous events that cooped cooperated and then you got this massive expansion in the leukemia. I don't see how that really muddles the water. Maybe I'm miss understanding something.
Go ahead.
One more comment, Dr. O'Reilly.
I mean, I think the biologic evaluation of this, which is always the one that sort of gets me, is the experience in aplastic anemia where you are basically dealing with a limited pool of progenitor cells. We can drive those systems, in some instances, with cytocions or with ATG but the fact of the matter is you have a hematopoietic system that's under stress and the studies that have been done indicate again that it's relatively oglioclonal and about 30 percent of those individuals if followed over the course of around 15 years will then go into an overt mild displastic syndrome and AML. The only sensible mode of this has always been the idea that basically you have single clone under stress requiring multiple divisions, the chance with each division of having one of these events becomes stronger. That's basically one of the reasons why I get out of this. And the other reason why I'm at this also is because as I said before, these are all T-cell ALLs and the one thing that you do know is that in these kids with SCID, their thymus is fetal thymus about the size of the end of this pen. And that's it. And it is basically a lymphoid. It has no lymphoid cells whatsoever. Somewhere around 3 to 4 months after you give these grafts, that thymus fills in and you can literally watch it grow. And basically, the more pro general tore cells it would seem to me that you cede to the thymus, the more likely it would be that you are going to have sort of continuing normal growth of cells not in the con telephones integration. We don't have evidence that that integration caused leukemia. Rather what we have is a series of kids with intergrants where they have required second or at least demonstrate second or third hits that are involved. And those second or third hits are secondary events that are occurring in the context of division. So that's my really major concern about limiting dose. That if you do so, you put stem cells under stress because if you give three million of those cells, quote, unquote, that are transinvestigated, the actual population is likely to be a true stem cell is probably not much more than 1 and 10 to the third or fourth at max. .
Dr. Rosenberg?
I think for me there needs to be a middle ground in what Dr. O'Reilly is saying and what Dr. Copeland is saying but the problem that we face is that we don't know what the middle ground is. Certainly, there is I think compelling evidence that having one single stem cell clone contributing places incredible stress on that particular clone and that's not a good situation. However, I also agree with Dr. Copeland that if there are large numbers of cells, particularly with large numbers of integrations, I think that maybe a missing piece that is not emphasized in what we started here, multiple hits per cell, large numbers of cells, that that also greatly increases the risk that one of those or more than one of those integrations will be near a gene that either influences growth apoptosis, some other process, and really the problem that we're facing is that we don't know how to modulate those two things so we don't wind up with monoclonality of a normal cell that then accumulates events, nor do we wind up with outgrowth because there have been so many retroviral hits. And the chances of that is very high because the cell dose is huge.
Just one last comment. I grow with you completely and I think it really can be boiled down to the fact that you -- that you need efficacy and you need safety.
Right.
And the safety issue you don't want too many. And you don't want too few or the get monoclonal or oligoclonal factors that establish cancer itself which is well established as Dr. O'Reilly put and Dr. Copeland is right if you give enough cells you constantly increase your chance but if you have no efficacy you can take the whole thing and go home. And what we don't know is we don't know how much we need and what setting for efficacy. And that's why more work needs to be done.
I think we all agree that paradigm of merely limiting the number of cells giving given to the subject and limiting the age of the subject is not adequate to control for the risk and Dr. Malech from my per perspective you have targeted the issue. How much and what kind do we need for efficacy and how can we reduce the risk of that to make it acceptable? I want to leave this discussion by adding that I hope it strongly suggests to everyone that additional work needs to be done on the vector itself to improve the safety profile of the vector and we'll have some of that discussion this afternoon. Dr. Lo, you were going to take the discussion in a somewhat different direction for us. .
Right. I wanted to lay out some issues that have already been touched on by our -- this morning's speaker that I think will be important as we come to deliberations. Dr. freed -- it's a double comparison so that on the one hand we're weighing risks and benefits in that final slide that Dr. Wilson shows has the balance we are trying to reach in our minds but it's really a double comparison. You know, it's a comparison of the risks and benefits of Gene transfer versus the risk and benefits of the alternatives. I think that's where the next session comes in with the evidence with transplantation. But as a nonsort of pediatrician, I just want to make sure that we all are clear on sort of some of the more call tatety of aspects of risk and benefit. .
I As I understand it I want to raits issue of quality of life, those kids who get x link SCIDs and undergo a successful gene transfer intervention and have some immune system reconstitution I want to sort of make sure we automatic understand what that achievement means in terms of their daily lives. They are off Indiscernible ] these people in the not all but most 5 out of --
Most are off -- they are not taking prophylactic antibiotics, is that right? And they're back in regular school, playing, rolling around in the dirt and getting the scuffles on the playground all that stuff. So they are living fairly unrestricted lives without concerns about limitations on on activity or avoiding activities because there is concern. That's the goal. But I guess I'm trying to understand how successful is that goal achieved in these gene transfer protocols that seem to reconstitute immunologically. That's something I think we need to compare to the other alternatives we'll be hearing about in the next session.
So comments?
What I think of this issue, I go back to the table of all the patients in the yellow sheets here, uhm, and it's clear to me that out of the four -- out of the four patients who got over 10 to the 7 kilograms per cell, three of them, three out of of four of those have a high risk of getting cancer -- okay, I got cancer so under those conditions, the risk are very high. And, of course, the benefits nonexistent. However, if you go down to one times 10 to the 6th, then you are of course very safe but as you can see, one of the -- it didn't -- the -- one of the immune -- one of the -- didn't respond well so only one out of two of them benefitted. However, in between there, around three times 10 to the 6th to 35 to 7 times 10 to the 6th there are no adverse events and they are all reconstituted. I wanted to put that question in light of the previous discussion about the number of cells. It's true that of three out of the four that got over 10 to the 7th cells, three of them are the ones who got the little no proliferative disorder. The fourth that got the highest is at the 3-year limit right now. .
That's I meant about this likely being the basis for the comments about cell number that the French had put forth. It almost an unintended Phase I... Which I -- I think we should look at from that perspective. I also believe that that perspective is too simplistic to guide the overall work that needs to move forward.
I agree.
It is --
I agree but it's real data.
Yeah, it's obvious data. Doctor?
let me ask a question from somebody who knows cancer itology. Let's assume that we drop the number of retrovirus integrations so it's less than one so you don't have double hits on average. So you are not going to inactivate or activate two different cancer-causing genes. So that's not the issue. Now you have a -- an unlimited number of these cells and you are asking the question, if you go in with a large number, your chance is greater of getting cancer than a small number. So imagine you go in with a large number and you have polyclonality. If you get that second hit by natural spontaneous mutation, isn't that cell going to have a very high selective advantage? Does it really matter whether you are going in at high or low under those circumstances?
Dr. Copeland?
I guess it depends on what's the spontaneous frequency of cancer mutations versus retroviral insertional.
But that was what were you were assuming was happening, right?
Yes. I didn't understander point. You are going to give a cell less than one so you don't get a hit into a cooperating gene?
That's correct. We don't have double hits by the retrovirus --
I'm confused by what you mean by double hits.
No I understand. You are not hitting two different genes for -- that might cause cancer. You have a high probability --
So you only have let's say LMO2 and IL2RG.
You have less than one. Yes.
IL2RG in some cell integrated LMO2 you have two hits presumably that's not enough to cause the cancer so then you are saying the rest will be spontaneous, right, versus --
Well, in principle that must be what's happening, right? Under those circumstances does it really matter whether you are going with a high or low number of cells?
I think -- I don't know. That's a -- I think it's an impossible question right now in the current state-of-the-art of knowledge to, you know, knowledge to... To answer. But clearly the more cells you give