- By late November, the Food and Drug Administration will decide whether to OK an experimental gene therapy for hemophilia, granting priority review to a treatment from CSL Behring and partner UniQure.
- The companies announced on Tuesday that the regulator had accepted their application for approval of etranacogene dezaparvovec, which treats the less common "B" form of the inherited bleeding condition.
- Clinical testing conducted by UniQure showed treatment could boost levels of a blood-clotting protein that's scarce or absent in people with severe hemophilia B to near the normal range, helping curb the bleeding episodes that are typical of the disease. UniQure sold rights to the treatment to CSL in 2020 for $450 million.
The FDA has approved two gene therapies for inherited diseases: the blindness treatment Luxturna in 2017 and the neuromuscular disease therapy Zolgensma in 2019.
Since then, despite a boom in gene therapy research among biotech and pharma companies, safety hurdles in clinical trials and a seeming shift in the FDA's thinking have slowed development somewhat. In 2020, for instance, the FDA rejected another hemophilia gene therapy from BioMarin Pharmaceutical, requesting additional data the drugmaker claimed wasn't originally required.
Yet, over the coming months and year, the FDA could clear several more gene therapies. The agency is nearing a decision on two from Bluebird bio, with an important advisory committee meeting scheduled for early June. The acceptance of CSL and UniQure's application sets up another approval decision toward the end of the year, while BioMarin plans to resubmit its treatment, which is for hemophilia A, by June. PTC Therapeutics, Krystal Biotech and Rocket Pharmaceuticals are also planning FDA submissions over the next year for the rare disease therapies they're developing.
An approval of CSL and UniQure's therapy, should it be granted by the FDA, would bring a powerful new option to patients with severe hemophilia B, who typically control their disease through regular infusions of the clotting protein, or "factor," that they lack. But the treatment is also likely to be costly, potentially renewing debates around treatment value and patient access.
Under its deal with UniQure, CSL holds responsibility for all regulatory interactions and would commercialize the therapy if approved.
Etranacogene dezaparvovec, or etranadez for short, uses a type of non-infectious virus to deliver into cells a functional copy of the gene that encodes for the clotting protein Factor IX. Once delivered, the replacement gene allows the cells to produce Factor IX on their own, helping control bleeding.