Sangamo and Pfizer recently announced updated results from a phase 1/2 study of their hemophilia gene therapy candidate SB-525. Known as Alta, the dose ranging clinical study is designed to assess both the safety and tolerability of SB-525 in patients with severe hemophilia A. The new data was presented on December 7, 2019 during the 61st American Society of Hematology (ASH) Annual Meeting in Orlando, Florida.
SB-525 is developed using recombinant adeno-associated viruses (AAVs) as vectors to deliver the genetic codes that illicit factor VIII (FVIII) production in hemophilia A patients. These AAVs deliver the modified genetic material into an individual’s liver cells without causing disease or triggering significant immune responses.
According to a Pfizer press release, the Alta data presented at ASH included 11 patients treated across four varied dose groups. The data showed that SB-525 was generally well tolerated and demonstrated sustained increased FVIII levels following treatment with SB-525 through to 44 weeks, which is the extent of follow-up for the longest treated patient in the high dose group. The high dose group patients achieved normal range FVIII activity within 5-7 weeks of treatment with SB-525. It was also reported that the therapy was “generally well tolerated” across all dose groups.
“I am pleased that all five patients in the high dose (3e13 vg/kg) cohort rapidly achieved normal levels of factor VIII, and that factor VIII levels have been stable and durable in the normal range for the first two patients up to 44 and 37 weeks following treatment respectively, with no bleeding events or factor usage up to a follow up of 44 weeks in the longest treated patient,” said Barbara Konkle, MD, Bloodworks Northwest, Professor of Medicine at University of Washington and a Principal Investigator of the Alta study. “It is important to continue to follow these patients to determine whether these results are sustained in the longer term as the combination of a favorable safety profile coupled with sustained expression at a level that prevents bleeding and allows normal activity will be the hallmark of a successful gene therapy for hemophilia A.”
Source: Pfizer press release dated December 7, 2019
