Pfizer Inc. (NYSE:PFE) and Sangamo Therapeutics Inc. (NASDAQ:SGMO) have announced updated follow-up data from their Phase 1/2 giroctocogene fitelparvovec (PF-07055480 or SB-525) Alta study. Giroctocogene fitelparvovec is an experimental gene therapy for the treatment of severe hemophilia patients.
Pfizer and Sangamo reported Alta study data
The companies presented the data at the virtual 62nd American Society for Hematology Annual meeting that took place from December 5th to 8th 2020. Most importantly, the oral presentation slides included 85 weeks of follow-up data for the longest treated patient and they are available on the Sangamo website.
Interestingly, they have followed all the five high dose 3×1013 vg/kg cohort patients for at least one year. They demonstrated sustained factor VIII activity levels with group geometric FVIII activity of 70.4% and group median FVIII activity of 56.9% against chromogenic assay between weeks 9 and 52. Equally, all patients on the high dose cohort achieved steady-state FVIII after 9 weeks of giroctocogene fitelparvovec treatment without FVIII bleeding events and FVIII infusions within the first year. However, as of the August 31, 2020 cutoff date, one patient has a target joint bleed that required FVIII therapy, which occurred after 52 weeks.
Study to confirm findings in Phase 3
Andrew Leavitt, Alta, and AFFINE studies investigator said that it’s encouraging to seek how fast all the five patients in the high dose cohort attained steady-state FVIII activity levels without bleeding. He also said they were impressed that no patient required factor usage with the first 52 weeks with only one target joint bleed reported after a year. Leavitt added that their focus now is confirming the results in the phase 3 study, and collect follow-up data of the patients and others in the third phase study for extended periods.
There was generally well tolerability of giroctocogene fitelparvovec. However, as previously indicated one patient in the high dose cohort experienced treatment-related hypotension and fever with tachycardia and hypotension symptoms. These occurred six hours after giroctocogene fitelparvovec infusion and gully resolved after 24 hours. so far, no other treatment-related adverse event has been reported.