Pfizer’s Hemophilia A gene therapy succeeds in late-stage trial

USA – American pharmaceutical giant Pfizer has announced that its experimental gene therapy for a rare genetic blood-clotting disorder has succeeded in a large late-stage trial.

This development follows the positive results from the Phase 3 AFFINE study (NCT04370054), which evaluated giroctocogene fitelparvovec, an investigational gene therapy for treating adults with moderately severe to severe hemophilia A. These promising results pave the way for potential approval.

The AFFINE study achieved its primary objective, demonstrating non-inferiority and superiority of the total annualized bleeding rate (ABR) from Week 12 through at least 15 months of follow-up post-infusion compared with routine Factor VIII (FVIII) replacement prophylaxis treatment.

Pfizer reported that its one-time treatment significantly reduced the number of annual bleeding episodes in patients with moderately severe to severe hemophilia A from week 12 to at least 15 months.

Furthermore, Pfizer highlighted that the drug outperformed the current standard treatment for the disease, which involves routine infusions to replace the Factor VIII protein.

If approved, this treatment for hemophilia A could become the company’s second gene therapy to enter the U.S. market, following the approval of Beqvez in April for a less common type of bleeding disorder called hemophilia B.

Expressing his excitement about the results, Professor Andrew Leavitt, M.D., AFFINE lead investigator, noted that the strength of these positive outcomes from the AFFINE trial shows that this gene therapy candidate provides superior bleed protection compared with routine FVIII prophylaxis.

He emphasized that it also helps relieve the treatment burden for people living with hemophilia A.

Professor Leavitt further explained that this drug would significantly benefit individuals dealing with hemophilia A, highlighting the physical and emotional impact of needing to prevent and treat bleeding episodes through frequent IV infusions or injections.

James Rusnak, M.D., Ph.D., Senior Vice President, Chief Development Officer, Internal Medicine and Infectious Diseases, Research and Development at Pfizer, expressed his pleasure with these positive results from the Phase 3 AFFINE study.

He noted that the safety and efficacy of their one-time gene therapy candidate for people with hemophilia A are demonstrated through these findings.

Dr. Rusnak also mentioned his anticipation of advancing this latest innovation to help address the medical and treatment burden associated with frequent and time-consuming IV infusions or injections, building on Pfizer’s more than 40-year effort to advance hemophilia treatment.

In addition to Pfizer’s efforts, several other drugmakers have also invested in the rapidly growing field of gene and cell therapies.

These one-time, costly treatments target a patient’s genetic source or cells to cure or significantly alter the course of a disease. Hemophilia A is a lifelong condition caused by a lack of the blood-clotting protein called Factor VIII.

Without sufficient levels of this protein, blood cannot clot properly, increasing the risk of spontaneous bleeding and severe bleeding after surgery. This condition affects approximately 25 out of every 100,000 male births globally.

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