BioMarin's hemophilia A gene therapy further delayed amid new FDA questions

BioMarin’s commercial aspirations for its hemophilia gene therapy remain on ice after the FDA lobbed additional questions for the company to address, pushing back an expected approval submission to September.

BioMarin was vague on what the FDA is asking for, only specifying that the agency had requested additional details and analyses rather than more studies. The company also pointed out that updated three-year safety data of its phase 3 GENEr8-1 study will become available during the likely review period, although it was unclear whether the FDA would be requesting this. 

The Tuesday update was tucked into the release of additional data of a phase 1/2 trial, which noted a 95% reduction in the average annualized bleed rate over six years for patients with hemophilia A who took the drug. The FDA's request pushes back the likely regulatory submission to some point "by the end of September," according to BioMarin.

The regulatory update comes just over a month after the company reported that it was preparing to submit the approval filing of the med, valoctocogene roxaparvovec (ValRox), in June. With an expected six-month review procedure, the latest delay pushes back the prospect of any commercial launch until at least the first quarter of 2023.

The delayed filing extends what’s been a strung-out regulatory process for ValRox after it was initially rejected in August 2020 over durability concerns. At the time, the agency recommended that BioMarin compile two years of safety and efficacy data from the phase 3 trial, data that became available in November 2021. In January 2022, BioMarin reported that bleeding events remained rare two years post-treatment among trial participants, teeing up a second go at approval. 

If there’s any consolation for BioMarin, it’s that fellow competitors in the field have also faced regulatory holdups. Pfizer and its partner Sangamo Therapeutics had an FDA hold slapped on their hemophilia A gene therapy for four months before it was lifted, although the company says a voluntary pause remains. CSL Behring’s hemophilia B gene therapy similarly faced a hold and subsequent lift—with the med since securing an FDA priority review. 

As for ValRox’s overseas appeal, BioMarin noted that an opinion is expected by the European Medicine Agency’s Committee for Medicinal Products for Human Use by midyear 2022. The company has provided the two-year follow-up data to that body as well.