Cell, Tissue, and Gene Therapies

1. Cell, Tissue, and Gene Therapies Elizabeth Read, MD Adjunct Professor, Lab Medicine, UCSF May 13, 2010

2. My background • MD, Internal Medicine with Hematology/Oncology subspecialties • Immediately after fellowship, worked at NCI managing extramural cancer cooperative group clinical trials • Fellowship in Blood Banking/Immunohematology • On staff at NIH Clinical Center for 15 yrs – clinical lab support and product development/GMP manufacturing for hematopoietic transplantation, cellular gene therapies, immunotherapies, islet transplantation • 3 years ago, came to BSRI/UCSF to work with investigators on CIRM and NIH supported stem cell therapy development projects

3. CBER regulates • Blood, blood products, and plasma derivatives • Human cells, tissues, and cellular and tissue-based products (HCT/Ps) • Other biological products • Allergenics, vaccines • Antitoxins/antivenins/venoms • Gene therapy products • Xenotransplantation products • Devices related to licensed blood & cellular products • for processing & administration • In vitro diagnostic kits for testing • Some combination products

4. These products have the same general development/regulatory framework as drugs & other biologics…. Preclinical, CMC Clinical Studies BLA IND

5. But there are differences • History • Regulatory • CMC – product development & characterization • Preclinical studies • Clinical trials & safety issues

6. Cell & Tissue Therapies

7. Cell-based therapies originated with hematopoietic transplantation in 1970s • Bone marrow harvested, filtered, and transferred to blood bags in operating room • BM product carried directly to patient unit for infusion • Minimal donor & product testing, graft manipulation, quality systems • FDA still considers conventional autologous and allogeneic related BMT as “Practice of Medicine”

8. 1980s – 2000s • Advances in science & technology spurred novel approaches for development of cell-based therapies • Hematopoietic transplants with “engineered” grafts • Immunotherapies • T cells & subpopulations • Dendritic cell tumor vaccines • NK cells • Cellular gene therapies • Cells isolated from organs & tissues (e.g. pancreatic islets)

9. Advances were facilitated by development of large scale cell collection, separation & isolation technologies

10. … and use of closed systems (often with single-use disposables) for collecting & handling cells

11. 2000s – Stem Cells & Regenerative Medicine • Explosion in stem cell science has led to interest in use of stem cells for therapy of many diseases and conditions, from life-threatening to cosmetic • Multipotent • Adult stem cells from bone marrow, fat & other tissues • Fetal stem cells & placental stem cells are usually considered “adult” • Pluripotent • Embryonic stem (ES) cells • Induced pluripotent stem (iPS) cells

12. Published by the Repair Stem Cell Institute (RSCI) -- a Dallas- and Bangkok-based public affairs company that provides interested patients with contact information for stem cell treatment centers around the world.

13. Expert Commentary on “Super Stemmys” • " [The book]… was completely focused on bone marrow [stem cells] -- a very small subset of the whole stem cell field. Indeed, there is no mention of induced pluripotent stem cells or embryonic stem cells… All stem cells are not the same." • "It's just not a complete story. [The book] is also a bit unclear with regard to the science behind Doris's mission. It was very nebulous about how that cell would fix the heart...”

14. FDA definitionHuman cells, tissues, and cellular and tissue-based products • HCT/Ps are “articles containing human cells or tissues that are intended for implantation, transplantation, infusion, or transfer into a human recipient”

15. HCT/Ps include • Musculoskeletal tissue and skin • Ocular tissue • Cellular therapies • Hematopoietic stem/progenitor cells • Therapeutic cells (DLI) • Somatic cells (regardless of source) • Reproductive tissue • Combination tissue/device, tissue/drug • Human heart valve allografts • Human dura mater

16. HCT/Ps do not include

17. FDA’s Risk-Based Approach forHCT/Ps • Lower risk “361” • Autologous or family related donors and minimally manipulated and homologous use • Regulated under section 361 of Public Health Service Act • Higher risk “351” • Allogeneic unrelated donors and/or more than minimally manipulated and/or non-homologous use • Regulated under section 351 of Public Health Service Act, and subject to same rules as drugs & other biologics for IND and premarket approval

18. FDA framework for HCT/Ps

19. Tissue Rules • Apply to ALL cell and tissue-based products (but for 351 products can be superseded by more stringent CGMP regulations) • Focus is on preventing communicable disease transmission, and ensuring 2-way tracking/traceability between donor & recipient

20. HCT/P Development Issues

21. CMCInteresting but erroneous statements I’ve heard • CMC is good to go if I have described a small scale method • I’ll do all the development in my research lab • I’ve done most of the real work-- product development should take only month or two • My research reagents are the only ones that will work • We won’t worry about the product until we finish the preclinical animal studies

23. CMC development for all HCT/Ps • Donor qualification • Protocol/product-specific donor requirements (biologic variability) • Donor eligibility (DE) rule – effective May 2005 • Manufacturing methods • Cell source qualification – bioburden issues • Closed systems and/or aseptic methods in classified environment (terminal sterilization is not possible) • Scale up for cell collection, culture, selection, harvest • Containers – interaction with cells • Ancillary reagents (availability & qualification) • Product stability in relationship to timing of administration is especially critical, because most HCT/Ps consist of live cells • Delivery methods/devices/structural components result in combination product issues • Product assays (in-process and final release) must be appropriately developed and validated

24. CMC concerns for HCT/Ps derived from pluripotent and fetal stem cells • Donor source • Documentation of donor consent? • Donor eligibility – prospective, full screening and testing usually not done for ES and fetal cells • Product consistency (requires assays) • Source variability • Consistency through differentiation process • Product stability (requires assays) • What are most appropriate assays for master cell bank, working cell bank, and final product? • Phenotype of desired & other cell populations • Detection of residual pluripotent cells • Karyotype, genetic and epigenetic profiles • Potency assays?

25. Preclinical animal studies for HCT/Ps • CBER’s Office of Cellular, Tissue, and Gene Therapies (OCTGT) has a Pharm/Tox group that • Encourages informal pre-pre-IND meetings for planning and review of preclinical studies • Uses a case-by-case approach • Often recommends “hybrid” efficacy/safety studies using animal model of human disease, with concurrent evaluation of both efficacy and safety endpoints • Is always concerned with • comparability of products used for POC studies, pivotal safety studies, and clinical trial • appropriate modeling of product delivery

26. Preclinical animal studySafety endpoints – stem cell therapies • Implant site reaction • Inflammatory response in target & non-target tissue • Host immune response • Morphologic alterations in target & non-target tissues • Cell survival post transplantation • Cell migration/homing • Cellular fate-plasticity: differentiation, transdifferentiation, fusion • Integration into host tissue • Tumorigenicity

27. Clinical Protocol:CDER & CBER Guidance • CDER has numerous disease-specific and other clinical trial guidances focused on study design, patient population, endpoints • CBER product/disease-specific guidances for cellular therapies • Therapeutic Cancer Vaccines (2009 – draft) • Pancreatic Islet Cell Products (2009) • Somatic Cell Therapy for Cardiac Disease (2009 – draft) • Products to Repair or Replace Knee Cartilage (2007)

28. Clinical Protocol: How are stem cell trials different? • For novel stem cell products, risk : benefit assessment is difficult • Rationale for clinical trial must be justified by especially strong proof of concept • Greater emphasis placed on product characterization and preclinical testing

29. Gene Therapies

30. Gene therapy: history • 1974: NIH established Recombinant DNA Advisory Committee (RAC) • NIH Guidelines on recombinant DNA research • 1980s: New subcommittee of RAC to oversee clinical gene therapy • Appendix M to NIH Guidelines – covered design of preclinical & clinical research, consent issues, AE reporting • PUBLIC review of gene transfer protocols • 1989: First clinical gene transfer study (gene marking) using retroviral vector • 1990: First clinical gene transfer study (therapeutic intent) using retroviral vector

31. Gene therapy: history • 1995: No real clinical efficacy demonstrated, and NIH report concluded that enthusiasm had outstripped knowledge • Back to the bench for research on improved gene delivery methods (e.g., higher titer vectors, use of stromal feeder layer or fibronectin for HSC transductions) • By 1995, NIH RAC • Had approved 149 GT clinical protocols • No dire consequences • Policy change: public review & approval only for GT protocols that presented novel or unresolved issues • 1997: Role of NIH RAC modified – still required public review, but not “approval” of novel GT protocols

32. Gene therapy: history • 1999: Jessie Gelsinger case – first human gene therapy death. All gene therapy trials placed on hold. • 18 year old with a clinically mild form of ornithine transcarbamylase deficiency volunteered for a clinical trial of gene therapy at the University of Pennsylvania • Adenoviral vector caused massive immune response, multi-organ failure, and death within 4 days • Ethical issues • Adverse events in primate studies • Adverse events in 2 previous human subjects • Informed consent • Principal investigator conflict of interest

33. Gene therapy: history • 2000-2007: X-linked SCID trials, using gamma retroviral vectors to deliver the corrective gene (IL2RG) to autologous hematopoietic progenitor cells • 5 of 20 pts developed T cell leukemia-like proliferative disorder, caused by INSERTIONAL ONCOGENESIS • Retroviral vector integrated adjacent to one or more cellular proto-oncogenes (LMO-2 in 4 of the cases), which increased their expression, leading to malignant transformation and outgrowth of clonal population of T cells

34. Gene therapy approaches • IN VIVO: Vector administered directly to patient, and transfers genetic information to patient cells in vivo • Intravenously administered vector delivers gene for factor IX to patient with hemophilia B • EX VIVO: Vector used to transfer genetic information to cells ex vivo, then cells are administered to patient • Vector that delivers gene for enzyme adenosine deaminase is incubated ex vivo with autologous lymphocytes of patient with ADA-deficient form of SCID (severe combined immunodeficiency), and genetically modified cells are infused to patient

35. Gene delivery methods • Vector = an agent used to introduce genetic material into cells • Vectors can be • Viral • Non-viral • Plasmid DNA • Liposomes or other agents that facilitate entry into cell

36. Viral vectors • Retrovirus and lentivirus (developed to overcome inability of retroviral vectors to infect non-dividing cells) • Adenovirus • Parvovirus (Adeno-associated virus or AAV) • Herpes simplex virus • Poxvirus • Togavirus

37. Vector selection depends on… • Disease state • Route of administration • Size of payload • genetic sequences, regulatory elements • Cell cycling • Lentivirus, adenovirus, AAV do not require cycling cells • Intended duration of expression • Retrovirus and lentivirus give stable integration • Plasmid used for transient expression • Target cells • Poor expression of adenoviral CAR receptor on hematopoietic cells

38. More advanced vector design features • Conditional replication-competence • Control of gene expression • Tissue-specific promoters • Drug-responsive promoters • Suicide genes • Ganciclovir administered to patient will kill cells with thymidine kinase gene

39. Safety issues • Observed to date • Insertional mutagenesis/oncogenesis • Immunogenicity • Vector • Transgene • FBS (bovine protein used to manufacture vector) • Potential • Inadvertent transmission & expression in non-target cells (including germline, transplacental)

40. FDA regulations & guidance for gene therapies • Overall similar to biotechnology products • ICH guidances • Gene therapy CMC guidance 2008 • Vector description, map, sequence analysis • Cell banks, viral banks, cell lines (packaging, producer, feeder) • Vector production/purification • Documentation of RAC review • For ex vivo gene therapy, cell requirements same as HCT/Ps (i.e. CMC guidance, tissue rules)

41. FDA guidance for gene therapy clinical trials • 2006 – Guidance on long-term follow up for delayed adverse events • Recommends preclinical study designs to assess clinical risk • Requires long term clinical follow up, based on preclinical studies, for • In vivo gene therapy with persistence of vector sequences, when sequences are integrated • Ex vivo gene therapy with sequences integrated, or not integrated but have potential for latency & reactivation • Specific follow up observations yearly for at least 10 years, and reporting to FDA • Informed consent for long term follow up, and for use of retroviral vectors

42. FDA guidance for gene therapy clinical trials • 2006 – Supplemental guidance on testing for replication-competent retrovirus (RCR) • Product testing • Master cell bank • Working cell bank • End of production cells • Vector-containing supernatant • Ex vivo transduced cells • Patient testing • Pre-treatment • 3 months, 6 months, 1 year, and yearly thereafter • If negative through 1 year, archive samples

43. How many cell, tissue, and gene therapy products have been approved by FDA? • Carticel (Genzyme) – autologous chondrocytes for knee repair • Provenge (Dendreon) – autologous tumor vaccine for prostate cancer • Skin replacement products for wounds or burns (regulated as devices) • Epicel • Dermagraft • Transcyte • Apligraf • Gene therapies – NONE approved yet

44. But there’s a lot in the pipeline

45. CIRMGrant Funding by Disease Categoriesas of Dec 2009