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

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

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

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

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

Cell & Tissue Therapies

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”

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)

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

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

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

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.

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...”

FDA definition Human 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”

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

HCT/Ps do not include Vascularized whole organs HRSA regulates Bone marrow, minimally manipulated, homologous use - AUTO or FAMILY DONOR Practice of medicine (not regulated by FDA) Bone marrow, minimally manipulated, homologous use – UNRELATED DONOR HRSA regulates Xenografts FDA separate regs Blood & blood products FDA separate regs Secreted or extracted products (e.g., human milk, collagen, cell factors) FDA separate regs In vitro diagnostic products FDA separate regs

FDA’s Risk-Based Approach for HCT/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

FDA framework for HCT/Ps 361 HCT/Ps 351 HCT/Ps (Tissue) Establishment registration√√ (Tissue) Donor eligibility√√ (Tissue) CGTP manufacturing√√ CGMP regulations√ IND / IDE regulations√ Premarket approval (BLA)√

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

HCT/P Development Issues

CMC Interesting 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

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

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?

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

Preclinical animal study Safety 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

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)

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

Gene Therapies

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

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

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

Gene therapy: history : 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

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

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

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

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

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

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)

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)

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

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

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

But there’s a lot in the pipeline

CIRM Grant Funding by Disease Categories as of Dec 2009