SB-525, A NOVEL GENE THERAPY FOR TREATMENT OF HEMOPHILIA A Kathleen - PowerPoint PPT Presentation

SB-525, A NOVEL GENE THERAPY FOR TREATMENT OF HEMOPHILIA A Kathleen Meyer MPH, PhD, DABT Sangamo Therapeutics NorCal SOT Meeting October 24, 2019

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We are committed to translating ground-breaking science into genomic medicines that transform patients’ lives 3

Our capabilities allow us to design therapeutic approaches targeting the underlying genetic causes of disease Gene Therapy Gene therapy provides tractable, valuable near-term opportunities 4

Our capabilities allow us to design therapeutic approaches targeting the underlying genetic causes of disease Ex Vivo Gene Therapy Gene-Edited Cell Therapy Gene therapy provides Continue to advance tractable, valuable near-term ex vivo editing to opportunities create cell therapies 5

Our capabilities allow us to design therapeutic approaches targeting the underlying genetic causes of disease Ex Vivo In Vivo Gene Therapy Gene Regulation Genome Editing Gene-Edited Cell Therapy Gene therapy provides Continue to advance Sustain momentum toward the long-term goal with tractable, valuable near-term ex vivo editing to in vivo gene editing and gene regulation opportunities create cell therapies 6

Sangamo’s genomic medicines encompass a breadth of technical approaches and diverse pipeline assets Ex Vivo In Vivo Gene Therapy Gene Regulation Genome Editing Gene-Edited Cell Therapy SB-525: Hemophilia A ST-400: Beta thalassemia SB-913: MPS II Tauopathies ST-920: Fabry disease BIVV003: Sickle cell disease SB-318: MPS I C9ORF72-linked ALS/FTLD Undisclosed targets TX200: Solid organ transplant Huntington’s disease SB-FIX: Hemophilia B Undisclosed targets KITE-037: Allo-CD19 CAR-T Undisclosed targets Undisclosed targets 7

Robust pipeline of genomic medicines in clinical and preclinical stages of development Therapeutic Area Research Preclinical Phase I/II Phase III Collaborator Gene Therapy Hemophilia A (SB-525) Fabry disease (ST-920) Ex Vivo Gene-Edited Cell Therapy Hemoglobinopathies (ST-400, BIVV003) Solid organ transplant CAR-Treg (TX200) Allogeneic anti-CD19 CAR-T (KITE-037) In Vivo Genome Editing MPS II (SB-913) MPS I (SB-318) Hemophilia B (SB-FIX) In Vivo Gene Regulation Tauopathies ALS/FTLD - C9ORF72 Huntington’s Disease 8

Hemophilia A: chronic, disabling, painful and destructive disease • Deficiency in FVIII clotting factor • Bleeding disorder occurring most often inside joints and muscles • 70% of patients inherit Hemophilia A and 30% develop spontaneous genetic mutation • Approximate incidence (CDC) 1 in 5,000 male births • 16,000 patients in US • 108,000 patients identified globally (WFH) • Average annual Hemophilia A treatment cost in developed work $150 – 300K 9

FVIII and the coagulation cascade .

Evolution of hemophilia treatment Investigational therapies ► Gene therapy (2015 – ) ► Novel agents ► Biosimilars EHL clotting factors ► Humanized (2014 - ) Therapeutic Value ► Prolonged half-life (FVIII/FIX) Improved Safety Recombinant Clotting Factors FVIII, FIX, FVIIa (1990s) ► Eliminated potential for Recombinant Era transmission of blood borne pathogens Plasma-Derived Clotting ► Widespread viral Factors contamination (1969) Evolution of Products

Why gene therapy for hemophilia? • Single gene disorder – Clear cause and effect relationship • Replacement administration is demanding – Must be given 3x weekly iv • Wide therapeutic window – Low levels will improve outcome SB-525 – High levels welcome (up to a point) • Efficacy easy to assess – Clinical – Laboratory

SB-525 for the treatment of adults with hemophilia A • Recombinant adeno-associated virus (AAV) has been used extensively for nearly 20 years as a gene therapy vector in preclinical and clinical studies • Efficient transduction and long term, stable transgene expression in non-dividing cells such as liver, neurons and muscle • Non-pathogenic, replication-deficient • High degree of stability which allows for rigorous methods of vector purification • AAV vectors carrying capacity is small (~4.7 kb of DNA) • Composed of inverted terminal repeats (ITRs) flanking transgene AAV2/6 construct • SB-525 utilizes AAV2 ITRs and AAV6 capsid proteins 13

What is optimal for rAAV human F8 cDNA? • hF8 is not an ideal gene for AAV – Constrained by hF8 gene size o Optimal AAV transgene size is ~4.7 kg; full length hF8 is ~7kb • AAV dose required to achieve therapeutic hFVIII levels • Shorter coding sequence for hF8 • Optimized B-domain deleted sequence (BDD) • Optimized liver-specific promoter modules to drive hF8 expression • Improved virus yields 14

Optimization of AAV hF8 cDNA required multi-factorial modifications hF8 B-domain deleted (BDD) PolyA ITR ITR Liver-specific promoter Promoter module modifications Transgene modifications Other modifications • • • Optimized the F8 cassette Identified minimal synthetic polyA Assembled different permutations of liver- specific promoter elements • Removed unnecessary nucleic acids to • A systematic mutational design approach reduce size was used to improve regions of the promoter • Optimized sequences outside transgene module hFVIII protein has the same amino acid sequence as biologics currently in clinic 15

SB-525 liver directed AAV6 hF8 cDNA gene therapy for hemophilia A Transgene packaged into Transgene packaged into Therapeutic delivered by a AAV is delivered by a AAV traffics to liver to deliver AAV vectors single infusion AAV vectors single infusion transgene into nucleus of liver cells AAV vectors P TG transgene Liver Cell DNA Promoter P  liver- specific promoter TG therapeutic gene (F8)  Therapeutic Gene (hF8) Nucleus Liver Cell Transgene is expressed from the liver, Liver produces and secretes but remains separate from the cell’s DNA therapeutic hFVIII protein 16

Objective of the nonclinical program • Establishment of biological plausibility • Identification of biologically active dose levels • Selection of potential starting dose level, dose-escalation schedule and dosing regimen for clinical studies • Establishment of feasibility and reasonable safety of product’s proposed clinical route of administration • Support of patient eligibility criteria • Identification of physiological parameters that can guide clinical monitoring • Identification of potential public health risks 17

Nonclinical studies supporting First-in-Human study • In vitro studies in primary human hepatocytes showing hFVIII production • 3-month pharmacology study in hemophilia A mice • 2-month pharmacology and toxicity study with highly related variant of SB-525 • 3-month GLP pharmacology, biodistribution and toxicity study in mice • 2-month pharmacology, biodistribution and toxicity study in cynomolgus monkeys 18

Gene therapy FDA and EMA guidance documents 19

SB-525 pharmacodynamic activity in hemophilia A mice • Hemophilia A mouse model to demonstrate SB-525 Test article injection pharmacodynamic activity • SB-525 IV dose of 7.2E+12 vg/kg 0 7 14 21 28 days 3 months • Hemophilia A R593C mice are tolerized to hFVIII as they contain a hF8-R593C transgene under control of a mouse albumin promoter Plasma collection schedule • Human FVIII-R593C mutation is frequently found in Hemophilia A patients; in mice produces no detectable hFVIII protein Endpoint • Thought to be rapidly degraded in mice, with peptide fragments • Chromogenic assay for presented to the immune system hFVIII activity • Mice also contain a knockout of the mouse F8 gene and are • Tail vein transection deficient for endogenous mouse FVIII protein (TVT) for hemostasis 20

Hemophilia A mouse model shows SB-525 functional impact Bleed Time hFVIII Activity Tail Vein Transection (TVT) 458.1 T o ta l B le e d in g T im e (m in ) 6 0 0 h F V III (P e rc e n t N o rm a l) 5 0 p < 0 .0 0 0 1 4 0 4 0 0 3 0 2 0 2 0 0 1 0 n o r m a l b le e d in g tim e 0 0 F o rm u la tio n S B -5 2 5 F o rm u la tio n S B -5 2 5 Activity determined by TVT method based on Chromogenic Activity Assay Johansen et al., Haemophilia, 1-7, 2016 21

SB-525 pharmacology and toxicology NHP study design • 2-month study in cynomolgus monkeys Test article injection • SB-525 IV doses 2E+11 vg/kg to 6E+12 56 days 0 7 14 21 28 days vg/kg • Pharmacodynamic endpoints • Biodistribution endpoints Plasma collection schedule • Safety endpoints Immunosuppression (IS) regiment of rituximab and steroids; early and late IS regiment Endpoints • ELISA for hFVIII levels • qRT-PCR for hF8 mRNA • Biodistribution • Safety assessment 22