FDA approves Hemgenix as first gene therapy for treatment of hemophilia B

November 22, 2022

2 min read


Ragni reports consultant/advisory board roles with or research funding/honoraria from Alnylam, Baxter Bioscience, Bayer, Biogen Idec, BioMarin, Bioverativ/Sanofi, Bristol Myers Squibb, CSL Behring, Spark Therapeutics, Tacere Benitec, Takeda Pharmaceuticals and Vega Therapeutics.

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The FDA approved etranacogene dezaparvovec-drlb, a single-dose gene therapy for treatment of adults with hemophilia B.

The indication applies to individuals who use factor IX prophylaxis therapy, have current or historical life-threatening hemorrhage, or have repeated, serious spontaneous bleeding episodes.

FDA HQ in Washington

“Gene therapy for hemophilia has been on the horizon for more than 2 decades,” Peter Marks, MD, PhD, director of FDA’s Center for Biologics Evaluation and Research, said in a press release. “Today’s approval provides a new treatment option for patients with hemophilia B and represents important progress in the development of innovative therapies for those experiencing a high burden of disease associated with this form of hemophilia.”

Etranacogene dezaparvovec (Hemgenix, CSL Behring) is an adeno-associated virus vector-based gene therapy that carries a gene for clotting factor IX and is given as a one-time IV infusion. The therapy causes the patient’s liver to produce factor IX protein, thereby increasing levels of factor IX in the blood and limiting bleeding episodes.

The agent previously received FDA priority review, orphan drug and breakthrough therapy designations.

Individuals who have deficient levels of factor IX experience spontaneous bleeds and often live in fear of engaging in activities that could lead to bleeding events, according to Margaret V. Ragni, MD, MPH, professor of medicine and clinical translational science at University of Pittsburgh School of Medicine, medical director at Hemophilia Center of Western Pennsylvania and expert with ASH.

The first FDA approval of a gene therapy for hemophilia B is a “real game changer,” she told Healio.

“Gene therapy provides patients not just freedom from bleeds and weekly infusions, but also freedom from fear,” Ragni said. “It allows them the ability to engage in a wider range of activities and improve quality of life.”

The therapy also has the potential to prevent further damage to joints, which could enable these patients to avert joint disease later in life, Ragni added.

“I’ve had several patients with hemophilia B who have undergone gene therapy, and it has dramatically changed their lives for the better,” she said.

Despite the potential benefits, Ragni said physicians who treat patients with etranacogene dezaparvovec should expect careful short- and long-term follow-up monitoring will be required.

“Clinicians will need to consider the use of steroids at the earliest sign of liver test elevations,” she told Healio.

Indeed, the prescribing information published by the manufacturer provides several warnings about potential liver toxicity and the procedure clinicians should follow.

The FDA based approval of etranacogene dezaparvovec on results of the ongoing phase 3 HOPE-B trial. Results of the study showed 94% of patients who received a single dose of the gene therapy were able to discontinue use of factor IX prophylaxis, according to a press release from the manufacturer.

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Margaret V. Ragni, MD, MPH, can be reached at [email protected]


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