Beqvez (fidanacogene elaparvovec)

A one-time gene therapy for hemophilia B that the FDA approved in April 2024 for adults with moderate to severe disease. In February 2025 Pfizer said it was ending development and sales worldwide, citing limited interest from patients and doctors in hemophilia gene therapy. It is no longer available. It delivered a high-activity form of the factor IX gene to the liver so the body could make its own clotting factor.

Beqvez uses a harmless virus shell called AAVRh74var to carry a factor IX gene to liver cells. The gene makes a high-activity form of factor IX called FIX-R338L, or FIX-Padua, so a modest amount of the protein can still help blood clot. People who already had antibodies to the AAVRh74var shell could not receive it. In the Phase 3 trial, 188 of 316 men screened (59.5%) were ruled out for this reason.

The label has no boxed warning. The most common side effect in studies was a rise in liver enzymes (transaminases). Warnings cover liver injury, infusion reactions including serious allergic reactions, a theoretical risk of liver cancer if the vector's DNA joins the body's own DNA, and the need to check factor IX levels and factor IX inhibitors. Liver enzyme and factor IX blood tests are needed once or twice a week for the first 16 weeks, then less often, down to once a year after year 6. Doctors may give a course of corticosteroids if liver enzymes rise or factor IX falls. In the Phase 3 trial, 28 of 45 men (62%) received steroids for these reasons.

Single one-time intravenous infusion. Requires pre-treatment screening and extended post-treatment liver monitoring. Administered at specialized hemophilia treatment centers.

The FDA approved Fidanacogene elaparvovec (Beqvez) in 2024 for Hemophilia B, but Pfizer has since stopped selling it, so it is no longer available.

Pfizer said in February 2025 that it was ending development and sales of Beqvez worldwide because of the limited interest patients and their doctors had shown in hemophilia gene therapies. BioPharma Dive and Fierce Pharma reported the decision at the time.

The label calls for liver and factor IX blood tests for years after the infusion, so anyone treated should stay in touch with their hemophilia treatment center. In the Phase 3 trial, 6 of 45 men went back to regular factor IX prophylaxis.

The Padua variant is a single change in the factor IX gene, called R338L, that makes the factor IX protein more active than usual. The label calls it a high specific activity variant, so a modest amount of protein can still support clotting.

They were never compared in a head-to-head trial. Both deliver a high-activity Padua form of factor IX to the liver, but Beqvez uses an AAVRh74var shell and Hemgenix uses an AAV5 shell. In Beqvez's Phase 3 BENEGENE-2 trial, 60% of men had no bleeds after treatment, compared with 29% during the lead-in on factor IX prophylaxis. Hemgenix is still available.

No study has tested Hemgenix in people who already received Beqvez. After any AAV gene therapy the body makes antibodies against the virus shell, which may block a second AAV treatment. A hemophilia treatment center can advise on options, including non-factor treatments such as Alhemo, Hympavzi and Qfitlia.

Fidanacogene elaparvovec was developed under the codes PF-07055480 (Pfizer designation) and SPK-9001 (original Spark Therapeutics designation, before Pfizer acquired the program).