Sangamo and Pfizer Announce Updated Phase 1/2 Results for SB-525 Investigational Hemophilia A Gene Therapy Showing Sustained Increased Factor VIII Levels
Sangamo Therapeutics, Inc. (NASDAQ: SGMO), a genomic medicine company, and Pfizer, Inc. (NYSE: PFE) today announced updated results from the Phase 1/2 Alta study evaluating investigational SB-525 gene therapy for severe hemophilia A. The data showed that SB-525 was generally well-tolerated and demonstrated a dose-dependent increase in Factor VIII (FVIII) activity levels. The first two patients treated at the 3e13 vg/kg dose rapidly achieved normal levels of FVIII activity as measured using a chromogenic assay, with no reported bleeding events, and the response continues to be durable for as long as 24 weeks, the extent of follow-up. The two patients more recently treated at the 3e13 vg/kg dose level are demonstrating FVIII activity kinetics that appear consistent with the first two patients treated in this dose cohort at similar early time points. Data from 10 patients treated with SB-525 were presented during an oral presentation on July 6 at the XXVII Congress of the International Society on Thrombosis and Haemostasis (ISTH), in Melbourne, Australia. The SB-525 ISTH presentation slides, which include the full data set, are available on Sangamo’s website in the Investors and Media section under Events and Presentations.
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“The initial results with SB-525 gene therapy for patients with severe hemophilia A continue to look very promising,” said Barbara Konkle, M.D., Bloodworks Northwest, Professor of Medicine at University of Washington and a Principal Investigator of the Alta study. “It is encouraging that patients in the 3e13 vg/kg cohort have attained normal Factor VIII levels within 5-7 weeks of treatment with SB-525 gene therapy and have sustained Factor VIII activity with no bleeding episodes. It will be important to continue to follow these patients to understand the potential long-term durability of this gene therapy.”
Alta study data presented at ISTH included 10 patients treated across four ascending dose cohorts: 9e11 vg/kg (2 patients), 2e12 vg/kg (2 patients), 1e13 vg/kg (2 patients) and 3e13 vg/kg (4 patients). Factor VIII activity data presented at ISTH included results through June 18, 2019. All other data presented at ISTH were as of May 30, 2019.
Across the dose cohorts, patients demonstrated a dose-dependent increase in FVIII levels and a dose-dependent reduction in the use of FVIII replacement therapy. In the two patients treated with the 1e13 vg/kg dose, FVIII activity levels have been durable through weeks 52 and 32. For the four patients in the 3e13 vg/kg cohort, FVIII activity data were available through 24, 19, 6, and 4 weeks of follow-up, respectively. The first two patients treated in the 3e13 vg/kg cohort (Patients 7 and 8) remained in the normal range, as measured using a chromogenic assay, through 24 and 19 weeks of follow-up, respectively. The next two patients in the 3e13 vg/kg cohort (Patients 9 and 10), with 6 and 4 weeks of follow-up, respectively, demonstrated rapid FVIII activity kinetics that appear consistent with Patients 7 and 8 at similar early time points. Also noted in the presentation at ISTH, Patient 9 attained normal FVIII activity levels at week 7, subsequent to the data transfer for the conference. No patient in the 3e13 vg/kg dose cohort has experienced bleeding events as of the data cut-off date, nor have patients in this dose cohort required factor replacement following initial use of prophylactic factor.