Follow-up data from the phase 1/2 Alta study of giroctocogene fitelparvovec gene therapy continues to show positive results for patients with moderately severe to severe hemophilia A, as announced by Pfizer and Sangamo Therapeutics in a press release.

“These latest results further suggest the potential of this investigational therapy to bring transformational benefit to eligible patients living with severe hemophilia A, if confirmed in ongoing clinical trials,” Seng H. Cheng, senior vice president, and chief scientific officer of Pfizer Rare Disease said.

Five patients taking the highest dose of 3e13 vg/kg presented with a mean factor VIII (FVIII) activity of 25.4% at week 104. They had mean annualized bleeding rates of 0.0 in the first year after infusion, which increased to 1.4 throughout the total duration of follow-up.

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These bleeding events occurred after week 69 of infusion. In 2 patients, the management of the bleeding events required treatment with exogenous FVIII. None of the patients have resumed prophylaxis.

Treatment with giroctocogene fitelparvovec was generally well-tolerated. From the 5 patients analyzed, 4 experienced elevations in liver enzymes alanine aminotransferase and aspartate transaminase, which were fully resolved with oral corticosteroids.

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One patient had a grade 3 serious adverse event of hypotension and grade 2 fever, accompanied by symptoms of headache and tachycardia. The episode occurred 6 hours after infusion and was resolved in approximately 12 hours.

At the cutoff date of October 1, 2021, a total of 26 treatment-related adverse events were reported in 6 patients across all 4 study cohorts. Neither confirmed FVIII inhibitor development nor thrombotic events were reported.

“We believe these two-year results demonstrate the potential of this gene therapy candidate to minimize significant symptoms associated with hemophilia A and become an alternative to the current burden of disease management,” Rob Schott, MD, MPH, FACC, head of development at Sangamo said.

The Alta study findings in patients with severe hemophilia A were presented on December 12, 2021, at the 63rd American Society for Hematology Annual Meeting and Exposition, being held virtually and in Atlanta, Georgia from December 11-14.


Pfizer and Sangamo announce updated phase 1/2 results showing sustained bleeding control in highest dose cohort through two years following hemophilia A gene therapy. News release. Pfizer; December 12, 2021.