Sangamo and Pfizer Announce Phase 1/2 Interim Data for Investigational Hemophilia A Gene Therapy

The following is an excerpt from a press release from Sangamo Therapeutics. Read the press release in its entirety here.

Sangamo Therapeutics Inc., a genomic medicine company, and Pfizer Inc. announced interim data from the Phase 1/2 Alta study evaluating investigational SB-525 gene therapy for severe hemophilia A. Data indicate that SB-525 was generally well-tolerated and demonstrated a dose-dependent increase in Factor VIII (FVIII) levels across the four dosage cohorts. Eight patients total were dosed. Based on these results, the Safety Monitoring Committee (SMC) recommended cohort expansion at the 3e13 vg/kg dose.
“The interim data from the first eight patients with hemophilia A treated with SB-525 gene therapy in the Alta study are encouraging and demonstrate a dose-dependent relationship, evidence of sustained factor levels, and low variability, both within each patient and within each cohort,” said Edward Conner, MD, Chief Medical Officer of Sangamo. “These interim results suggest that SB-525 may be well-tolerated and may prove to have the predictability and sustained treatment effect that can bring clinical benefit in patients with hemophilia A. We need to continue observing how the data mature and how additional patients in the expansion cohort respond to SB-525. We look forward to working with Pfizer to potentially advance SB-525 into a registrational study.”
The Phase 1/2 interim data include eight patients treated across four ascending dosage cohorts (9e11 vg/kg, 2e12 vg/kg, 1e13 vg/kg and 3e13 vg/kg, with two patients per cohort). Patients demonstrated a dose-dependent increase in FVIII levels, achieving clinically relevant increases in FVIII activity in the higher dosage cohorts and normal FVIII levels in the 3e13 vg/kg dose cohort (normal range: 50-150%). At week 6 post infusion, the two fourth dose cohort patients reached 140% and 94% of normal (as measured by one-stage clotting assay) and 93% and 65% (as measured by chromogenic assay). A dose-dependent reduction in the use of Factor VIII replacement therapy was also observed, with patients in the highest dose cohort not requiring factor replacement therapy after initial use of prophylactic factor and experiencing no bleeding events to date. SB-525 was generally well-tolerated, with one patient (treated with the 3e13 vg/kg dose) reporting a treatment-related serious adverse event of hypotension and fever, which occurred following vector infusion and resolved with treatment within 24 hours of completion of vector infusion.
“The interim results with SB-525 gene therapy for patients with severe hemophilia A are early but very promising,” said Barbara Konkle, MD, Bloodworks Northwest and Professor of Medicine at University of Washington and investigator of the Alta study. “It will be important to observe additional patients and for a longer follow-up duration to determine whether these positive interim findings are recapitulated and sustained.”
Read the press release in its entirety here.