Health Canada approves Hemgenix gene therapy for hemophilia B

OK makes it first gene therapy for patients who rely on routine prophylaxis

Lindsey Shapiro, PhD avatar

by Lindsey Shapiro, PhD |

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Health Canada has approved the gene therapy Hemgenix (etranacogene dezaparvovec) for treating adults with hemophilia B who rely on routine prophylactic therapies to prevent or reduce bleeding episodes.

Hemgenix is now the first and only gene therapy available to this patient group.

“The approval of Hemgenix in Canada marks an important milestone and we look forward to collaborating with the hemophilia B community to provide access to this innovative treatment option,” Philippe Hebert, Canada’s general manager at CSL Behring, Hemgenix’s developer, said in a company press release. “We are proud to add this treatment to our portfolio of coagulation [blood clotting] therapies and look forward to patients benefiting from this therapy.”

Hemgenix is approved in the U.S. for adults on prophylaxis, have had life-threatening bleeds, or have repeated and serious spontaneous bleeds. It’s conditionally approved in the U.K. and European Union for adults with moderate to severe hemophilia B who don’t have a history of neutralizing antibodies against factor IX (FIX). FIX is the blood clotting protein that’s missing in hemophilia B due to mutations in the F9 gene that encodes its production. This makes patients susceptible to prolonged or spontaneous bleeding.

Patients typically rely on routine infusions of FIX replacement therapies to temporarily provide the missing clotting factor and prevent or reduce bleeds.

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What is Hemgenix and how does it work?

Originally developed by uniQure and acquired by CSL, Hemgenix is a onetime gene therapy that provides patients with a highly functional version of the F9 gene, enabling the body to continuously produce its own FIX.

It’s packaged into a viral carrier called adeno-associated virus 5 (AAV5) that helps deliver it to liver cells, where clotting factors are mainly produced, when infused into the bloodstream.

“We believe Hemgenix has the potential to change the treatment paradigm for people living with hemophilia B and the healthcare professionals who treat them, as it addresses the cause of the condition — faulty factor IX gene expression [activity],” said Bill Mezzanotte, MD, head of research and development at CSL.

Hemgenix’s approvals are based on results from the ongoing Phase 3 HOPE-B trial (NCT03569891), the largest gene therapy clinical trial in hemophilia B to date. The study enrolled 54 men with moderate to severe hemophilia B who didn’t have FIX inhibitors and were on preventive therapy.

Top-line trial data showed annualized bleeding rates seven to 18 months after the infusion dropped by more than 50% compared to a six-month run-in period preceding Hemgenix’s administration. The gene therapy also led to stable and sustained FIX levels, which reached about 37% of normal after 1.5 years.

These findings were sustained up to two years, at which point nearly all patients (94%) were able to stop using routine replacement therapies altogether, and FIX usage fell by 96%.

No serious treatment-related side effects were reported. The most commonly reported side effects associated with Hemgenix include liver enzyme elevations, headache, and flu-like illness.

The participants are still being monitored. HOPE-B is expected to finish in March 2025.

As in other areas where Hemgenix is approved, Canadian patients must be screened for FIX inhibitors and AAV5 antibodies, as these can reduce the therapy’s effectiveness. Patients’ liver health must also be evaluated before dosing.

“This approval continues to demonstrate CSL’s promise to pursue, develop, and deliver new innovative treatment options that meet the needs of the rare disease community,” Mezzanotte said.