Human Embryonic Stem Cells: Considerations for Therapeutic Development Jane Lebkowski Ph.D. Geron Corporation Cell, Tissue and Gene Therapy Advisory Committee Meeting April 10, 2008

Human Embryonic Stem Cells Blastocyst Human Embryonic Stem Cells Neural Cells Spinal Cord Injury Parkinson’s Disease Cardiomyocytes Heart Failure Islets Diabetes Osteoblasts Osteoporosis And Bone Fractures Chondrocytes Arthritis Hepatocytes Drug Discovery Liver Failure Dendritic Cells Tolerance Induction Cancer Immunotherapy Large Characterized cGMP Banks Therapeutic Cells

hESCs: New Cell Type for Potential Broad Therapeutic Application  Simplify, Standardize, and Scale hESC Growth  Develop Reproducible Methods to Selectively Differentiate Cells  Develop Parameters to Characterize Differentiated Cell Populations  Define Efficacy, Potency, & Safety of Cell Populations  Develop Methods to Deliver Cells to Target Tissue  Define Need for Immunosuppression  Demonstrate Safety & Efficacy in Clinical Trials  Develop Scaled Low Cost Production Methods Necessary Technological Developments

Spinal Cord Injury: GRNOPC1 Transplantation

Differentiation Process Characterization of Materials Starting Material Adventitious Agents Characterization of Unit Operations Cell Density Culture Format Timing of Induction Storage Release Testing

GRNOPC1 Contains Oligodendroglial Progenitors LineageMarker Neural ProgenitorsNestin Oligodendroglial ProgenitorsOlig 1 Oligodendroglial ProgenitorsNG2 Oligodendroglial ProgenitorsPDGFRa Early EctodermPax 6 Early EctodermSox 10 Neurons  TubIII AstrocytesGFAP Early Endoderm HNF3  EndodermAFP Early MesodermGATA4 MesodermMSA Undifferentiated hESCsOCT4 Undifferentiated hESCsTra-1-60 Phenotype Testing of Over 75 Lots Multiple Markers Required Lineage Specific Markers Specific Antibodies Detection and Quantitation Limits of Assays Potency Assays Challenges Identity Purity Strength Potency

Considerations for Nonclinical Studies for hESC-Based Therapeutics Final Product: What is the Product Designed to Do? What is the Target Site for Activity? Final Product Production Scale: Does Scale Effect Composition? Formulation: Cryopreserved Format? Selective Cell Survival? Clinical Administration: Site of Administration? Effects on Performance and Potential Adverse Events? Need for Immunosuppression? Dose Required?

Pharmacology Studies 9 mos GRNOPC1 hNuc EC 1mm 100  m 9 mos vehicle hNuc EC 1mm 100  m In Vitro Activity Protein and Gene Expression Factor Production Structural/ Metabolic Activity In Vivo Survival Survive Delivery Immune Responses Phenotype In Vitro and In Vivo Maturation Over Time Proliferative Capacity Activity in Disease Models Clinical Efficacy Histological Efficacy Dose Human Equivalent Dose Delivery Site and Volume Timing of Treatment What Is the Activity of the Cells?

Where Do The Cells Go? Safety and Efficacy Implications Sensitivity of Assay Site for Intended Activity Sufficient Cells at Site Distribution Outside Target Site Migration at Local Site Over Extended Time

Toxicology Studies Toxicity of Delivery Doses of Product Tox Model Feasibility of Model Duration of Studies Duration of Human Cell Survival GRNOPC1 Toxicity of Delivery Animal Survival Clinical Observations Systemic Toxicity Hematological Coagulation Parameters Clinical Chemistries Macropathology Micropathology Allodynia Considerations

Tumorigenicity Studies Teratomas Ectopic Tissues Local Injection Site Distal Sites Challenges Human Dose Long-Term Cell Survival Large Numbers of Animals Mimic Human Setting Large Animals? Homologous ESC Systems?

GRNOPC1 Deliberately Spiked with hESCs Tumorigenicity Studies: Lessons Learned Important Factors In Teratoma Formation hESCs Cell Number Site of Implantation Cell Aggregation State 2 x 10 6 Cells Intraspinal Cord Injection Assessment 12 mos.

Allogenicity Studies Immunosuppression Required? Duration of Immunosuppression? Challenges hESC-Based Products are Xenografts in All Animal Models Allogenicity of Maturing Cells In Vivo Humanized Models Challenging In Vitro Analyses Allogenicity In Vitro Inflammatory Site Remove Immunosuppression? Monitor Engraftment? Monitor Rejection? Effects of Rejection Approaches

Cell Delivery in the Clinic Considerations Local Delivery Delivery Site Intraoperative Delivery Rate of Delivery Skill Set Required for Delivery Effect of Delivery Device on Cells Training

Design of Clinical Trials Key Consideration: Patient Safety Protocol Delivery Logistics of Trial Minimize Potential Risks Balance Risk with Potential Efficacy Define Adverse Events Monitor for Adverse Events Monitor Cell Survival Assess Outcome Measures Short and Long-Term Follow-up Steering Committee DMC Outcomes Committee Neurosurgeons Radiologists Investigators ESCRO Committee Interactions with:

Phase 1 Multi-Center Trial Open Label Trial Subacute, Functionally Complete T3-T12 Lesions Transplant 7-14 Days Post Injury Temporary Immunosuppression Primary Endpoints: Safety Assessments Secondary Endpoints: Multiple Outcome Measurements Frequent Short and Long-Term MRIs Immunological Monitoring

Conclusions Numerous Considerations in Developing Cell Therapies Some Questions Common To All Cell Therapies Some Questions More Specific to hESC-Based Therapies Specific Nonclinical Study Designs Based on Clinical Considerations Clinical Trial Designs Require Interdisciplinary Input Frequent Monitoring Required