Single dose gene therapy is potentially life changing for adults with hemophilia B

Adults with hemophilia Bsaw their number of bleeding episodes drop by an average of 71% after a single infusion of gene therapy, according to an international Phase III clinical trial. The results are published in the New England Journal of Medicine by researchers from thePerelman School of Medicineand a multicenter group of investigators.

Hemophilia is a genetic disorder that limits the blood's ability to clot and affects around 30,000 people in the United States, mostly males. Left untreated, it can cause spontaneous bleeding, particularly internal bleeding into the joints, which, over time, can cause painful joint damage and mobility issues. Hemophilia B is caused by a lack of clotting factor IX. The gene therapy enables the liver to create factor IX, which allows the blood to clot and protects patients from frequent bleeds.

"What we saw from patients in this study was that within a few days of receiving the gene therapy infusion, it took root, and their bodies started making factor IX for the first time in their lives," says study investigator and lead author Adam Cuker, section chief for hematology, and clinical director of the Penn Blood Disorders Centerand the Penn Comprehensive Hemophilia Program. "We always want to be careful about using the word 'cure' especially until we have longer follow-up data, but for many of these patients, it's been life changing."

Based on the results of this study, the FDA approved the gene therapy (fidanacogene elaparvovec) in April 2024. Cuker was the site lead for the clinical trial at Penn Medicine, which was one of the top-enrolling sites for the study.

"We hear from people born with hemophilia that-even if their disease is well-managed-there's this burden that's always in the back of their mind. The frequent infusions, the cost of treatment, the need to plan for infusions when traveling, what happens if they do experience a bleed, and so on, is always there," Cuker says. "Now that we have patients who were treated on this study and are essentially cured of their hemophilia, they're telling us about realizing a new, 'hemophilia-free state of mind.' As a physician, it's amazing to see my patients so happy with their new reality."

Read more at Penn Medicine News.