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Updated follow-up data through one year from the Phase 1/2 Alta study of giroctocogene fitelparvovec gene therapy were presented in December

In December, Pfizer and partner Sangamo Therapeutics, Inc., announced updated one-year follow-up data from the Phase 1/2 Alta study evaluating giroctocogene fitelparvovec (formerly SB-525) gene therapy for patients with severe hemophilia A. The data were presented at the American Society for Hematology annual meeting and showed that all five patients in the high-dose cohort (3e13vg/kg) had sustained factor VIII (FVIII) activity levels, with steady-state FVIII activity achieved within nine weeks of treatment with giroctocogene fitelparvovec, no bleeding events and no FVIII infusions (beyond three weeks post-infusion) within the first year. As of the cutoff date of August 31, only one patient had a bleed requiring FVIII therapy, occurring in a target joint, after week 52. Overall, giroctocogene fitelparvovec was generally well tolerated.

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. We look forward to continuing to follow these patients.”​​​​​​​

Seng Cheng

Chief Scientific Officer, Rare Disease Research Unit

These latest results are promising. They demonstrate that giroctocogene fitelparvovec may bring clinical benefit to patients and have the potential to serve as a compelling alternative to repeated administrations of FVIII or non-factor replacement therapies, which are the current standard-of-care for hemophilia A. Pfizer and Sangamo plan to present additional follow-up data from the Alta study when all five patients in the high-dose cohort have been followed for at least two years. The first patient in the pivotal Phase 3 AFFINE study for giroctocogene fitelparvovec, has been dosed to better assess the gene therapy's potential across a larger sample size.

“The initiation of the pivotal Phase 3 dosing study of giroctocogene fitelparvovec is a significant achievement for Pfizer as we continue our longstanding commitment to improving care for the hemophilia community,” said Brenda Cooperstone, Chief Development Officer, Rare Disease, Pfizer Global Product Development. “Given the Phase 1/2 study findings to date, we believe that giroctocogene fitelparvovec has the potential to sustain factor levels and reduce annual bleed rates, suggesting this one-time gene therapy could potentially transform the standard of care for eligible patients worldwide.”

Gene therapy is a new generation of medicine where a functioning gene is delivered to a targeted tissue in the body to produce a missing or nonfunctioning protein. By using genes as medicine, the underlying cause of a disease can be targeted at the cellular level, potentially with just one treatment.

Hemophilia is a genetic hematological rare disease that results in a deficiency of a protein that is required for normal blood clotting – clotting factor VIII in hemophilia A.1 The severity of hemophilia that a person has is determined by the amount of factor in the blood. The lower the amount of the factor, the more likely it is that bleeding will occur which can lead to serious health problems.1,2

1 in every

Hemophilia A occurs in approximately one in every 5,000-10,000 male births worldwide.3 

For people who live with hemophilia A, there is an increased risk of spontaneous bleeding as well as bleeding following injuries or surgery.1 It is a lifelong disease that requires constant monitoring and therapy.4


1Sharma A et al. Gene therapy for haemophilia. Cochrane Database Syst. Rev. 2016;2016(12):CD010822.

2Salen P, Babiker HM. Hemophilia A. StatPearls [Internet] 2020;  https://www.statpearls.com/articlelibrary/viewarticle/22743/

3P. H. Bolton-Maggs PH, Pasi KJ. Haemophilias A and B. Lancet, 2003; 361(9371):1801–1809.

​​​​​​​4Tiede A. Half-life extended factor VIII for the treatment of hemophilia A. J. Thromb Haemost. 2015;13(suppl 1):S176-179.


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