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

Pfizer on Wednesday said its experimental gene therapy for a rare genetic blood-clotting disorder succeeded in a large late-stage trial, paving the way for a potential approval.

The treatment for hemophilia A could become the company’s second gene therapy to enter the U.S. market after Beqvez, which was cleared in April for a less common type of the bleeding disorder called hemophilia B. 

Pfizer is co-developing the therapy with Sangamo Therapeutics, whose shares rose more than 60% on Wednesday following the data release before paring some of those gains. Pfizer’s stock was essentially flat on Wednesday.

Pfizer is among several drugmakers to invest in the rapidly growing field of gene and cell therapies — one-time, costly treatments that target a patient’s genetic source or cell to cure or significantly alter the course of a disease. Some industry health experts anticipate those therapies to replace traditional lifelong treatments that patients take to manage chronic conditions.

Hemophilia A is a lifelong disease caused by a lack of blood-clotting protein called factor VIII. Without enough of that protein, the blood cannot clot properly, increasing the risk of spontaneous bleeding and severe bleeding after surgery. The condition occurs in roughly 25 in every 100,000 male births worldwide, Pfizer said in a release, citing data. 

Pfizer said its one-time treatment significantly cut the number of annual bleeding episodes in patients with moderately severe to severe hemophilia A after 15 months. The company said the drug also performed better than the current standard treatment for the disease, which is routine infusions that replace the Factor VIII protein.

“For people living with hemophilia A, the physical and emotional impact of needing to prevent and treat bleeding episodes through frequent IV infusions or injections cannot be underestimated,” said Dr. Andrew Leavitt, the lead investigator of the trial, in a statement. 

Pfizer said the study is ongoing and it will present additional data at upcoming medical meetings.

If approved, Pfizer’s therapy will compete with BioMarin Pharmaceutical‘s one-time treatment Roctavian. BioMarin’s therapy has had a slow rollout since it won approval in the U.S. last year, raising questions about how many patients would take Pfizer’s drug if it enters the market.

BioMarin is reportedly considering whether to divest its hemophilia A therapy, which costs $2.9 million.