Positive Follow-Up Results in Patients With Hemophilia B Given Gene Therapy (Hemgenix)

Steven Pipe, MD, Professor of Pediatrics and Pathology at the University of Michigan, discusses positive follow-up results in patients with hemophilia B treated with Hemgenix (etranacogene dezaparvovec-drlb).

Hemophilia B is a rare bleeding disorder that slows the blood clotting process. People with this disorder experience prolonged bleeding or oozing following an injury or surgery. In severe cases of hemophilia, heavy bleeding occurs after minor injury or even in the absence of injury. Serious complications can result from bleeding into the joints, muscles, brain, or other internal organs. Hemophilia B is caused by genetic changes in the F9 gene.

Etranacogene dezaparvovec-drlb is a AAV5 vector gene therapy that reduces the rate of abnormal bleeding in patients with hemophilia B by enabling the production of factor IX. It was approved by the U.S. Food and Drug Administration (FDA) as the first gene therapy for treatment of hemophilia B.

The HOPE-B clinical trial is an ongoing, phase 3, multinational, open label, single-dose, single-arm study evaluating the safety and efficacy of etranacogene dezaparvovec-drlb in adult patients with hemophilia B. The study enrolled 54 patients, 51 of which completed four years of follow-up.

The primary endpoint was annualized bleeding rate (ABR) 52 weeks following achievement of stable factor IX expression compared with the six-month lead-in period. The mean adjusted ABR for all bleeds was reduced by about 90% from lead-in compared to year four. Additionally, joint bleeds were reduced from a mean ABR of 2.34 at lead-in to 0.09 at year four.

Secondary endpoints included assessment of factor IX activity. Mean factor IX levels were 41.5 IU/dL at year one, 36.7 IU/dL at year two, 38.6 IU/dL at year three and 37.4 IU/dL at year four post-infusion. In year four, 94% of patients were able to remain free of continuous prophylaxis treatment.

No serious treatment-related adverse events were observed. The most common adverse event was increase in alanine transaminase.

Chapters:
Introduction 00:00
HOPE-B Clinical Trial Results 00:41
Next Steps 15:58