Human Embryonic Stem Cells: Considerations for Therapeutic Development

1. 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

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

3. 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

4. Spinal Cord Injury: GRNOPC1 Transplantation

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

6. GRNOPC1 Contains Oligodendroglial Progenitors Phenotype Testing of Over 75 Lots Identity Purity Strength Potency Challenges • Multiple Markers Required • Lineage Specific Markers • Specific Antibodies • Detection and Quantitation Limits of Assays • Potency Assays

7. 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?

8. Pharmacology Studies 9 mos GRNOPC1 What Is the Activity of the Cells? hNuc EC • 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 1mm 100 mm 9 mos vehicle hNuc EC 1mm 100 mm

9. 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

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

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

12. Tumorigenicity Studies: Lessons Learned GRNOPC1 Deliberately Spiked with hESCs Important Factors In Teratoma Formation • hESCs Cell Number • Site of Implantation • Cell Aggregation State 2 x 106 Cells Intraspinal Cord Injection Assessment 12 mos.

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

14. 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

15. Design of Clinical TrialsKey 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 Interactions with: • Steering Committee • DMC • Outcomes Committee • Neurosurgeons • Radiologists • Investigators • ESCRO Committee

16. 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

17. 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