Sangamo/Pfizer's Giroctocogene Fitelparvovec Gene Therapy for Hemophilia- Clinical Update

Introduction of Giroctocogene Fitelparvovec Gene Therapy for Hemophilia A

Giroctocogene Fitelparvovec is an investigational gene therapy product for the treatment of Hemophilia A co-developed by Sangamo/Pfizer. Giroctocogene fitelparvovec (SB-525) is a liver-tropic recombinant adeno-associated virus (rAAV6) vector carrying a B-domain–deleted F8 gene that is delivered through a single IV infusion.

Sponsor: Sangamo Therapeutics/ Pfizer

Stage-  Phase 3

Phase 2 - NCT03061201

Phase 3 - NCT04370054 (First Patient Dose) 

Clinical Outcome 

Efficacy: Efficacy was observed with significant reduction of annualized bleeding rate and usage of factor VIII infusion in phase 2 at the vector dose 3e13 vg/kg (viral genome/kg) upto 36 weeks after treatment.

Safety: In phase 2 clinical studies, 4/5 subject at a vector dose of 3e13 vg/kg showed transient elevation of transaminases and required corticosteroid therapy. One treatment related SAE was observed. 

Durability: The gradual decline of the factor VIII activity after peaking at 23-26 weeks was observed in four year follow up of AAV5-FVIII hemophilia treatment developed by Biomarin.  In this phase 2 clinical study, factor VIII peaked at week 9 and the stable expression was observed up to 36 weeks follow up. Longer term study will should provide more information on the durability of the expression. 

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Sangamo Phase 3 Study (AFFINE) Update

AFFINE is a global Phase 3, open-label, multicenter, single arm study that will evaluate the efficacy and safety of giroctocogene fitelparvovec in patients with moderately severe to severe hemophilia A. 

The primary endpoint is impact on annual bleed rate (ABR) through 12 months following treatment with giroctocogene fitelparvovec, compared to ABR on Factor VIII (FVIII) replacement therapy collected in the Phase 3 lead-in study period. 

Participants will be analyzed throughout the 5-year study period following the single infusion to further assess the durability and efficacy.

On October 7, 2020; the first participant were dosed in the Phase 3 AFFINE study of giroctocogene fitelparvovec (SB-525), an investigational gene therapy for hemophilia A patients.

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 Key Finding From Phase 2 (Alta) Study Updated on June 18, 2020

Efficacy from Cohort 4 (3x1013 vg/kg)

• Steady-state FVIII activity achieved by week 9 post infusion
• FVIII activity values available up to week 30 and up to week 61
• Median steady-state (of geometric means since week 9) FVIII activity level 64.2% via central laboratory chromogenic assay
• No bleeding events 
• No FVIII infusions beyond initial use of prophylactic factor

Summary of Results from Phase 2 Clinical Study (WHF2020)

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Reference

Sangamo Therapeutics

Pfizer

ClinicalTrail.gov