Pfizer and Sangamo have announced updated data from the phase 1/2 Alta study of giroctocogene fitelparvovec, an investigational gene therapy for patients with severe hemophilia A. The data was presented at the 62nd Annual American Society of Hematology meeting, held virtually December 5-8, 2020.
All five patients who were administered the high dose of giroctocogene fitelparvovec have been observed for at least one year and have showed sustained factor VIII (FVIII) activity levels, with a group median FVIII activity of 56.9% and a group mean FVIII activity of 70.4% measured from week 9 to 52. Further, steady-state FVIII activity was achieved for all patients in large dose group within 9 weeks of treatment with giroctocogene fitelparvovec, with no bleeding events and no FVIII infusions (beyond 3 weeks post-infusion) within the first year. As of the August 31st cutoff date, one patient had a single target joint bleed requiring FVIII therapy, which occurred after week 52.
According to a new press release, giroctocogene fitelparvovec was generally well tolerated. Among the five patients in the large dose group, four received oral corticosteroids for elevated liver enzymes known as alanine aminotransferase (ALT). All episodes of ALT elevations fully resolved with the steroid treatment, and as of the cutoff date no participants were on corticosteroids and no corticosteroid use has been initiated after week 52.
In addition, the phase 3 AFFINE study is evaluating the efficacy and safety of a single infusion of giroctocogene fitelparvovec in more than 60 adult (ages 18-64 years) participants with moderately severe to severe hemophilia A.
“We continue to be encouraged by the findings from this Phase 1/2 study, which now include durable factor VIII expression through one year of follow-up, and we look forward to continuing to follow these patients,” said Seng Cheng, Senior Vice President and Chief Scientific Officer of Pfizer’s Rare Disease Research Unit. “With the first patient dosed in the Phase 3 AFFINE study in October 2020, we are on track for a readout from this pivotal Phase 3 trial in 2022, which will allow us to better assess the potential of our gene therapy across a larger sample size.”
Source: Pfizer press release dated December 7, 2020