Biomarin Reports Leukemia in Patient on Gene Therapy

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BioMarin Pharmaceutical says it reported an adverse event to FDA about a patient participating in the company’s hemophilia A Phase 3 gene therapy trial of valoctocogene roxaparvovec (BMN 270) being diagnosed with B-cell acute lymphoblastic leukemia. “Based on BioMarin’s assessment of the case to date, including initial genetic testing of the leukemic cells, BioMarin believes at this time that this cancer is unrelated to BMN 270,” the company says. “The overall rate of all cancers observed in all BMN 270 trial patients (two in approximately 400 patient years of observation) appears consistent with expected rates of cancer in persons with hemophilia.”

The company says it has not been issued any clinicals holds on any trial at this time. “Currently, all trials of BMN 270 are ongoing, including additional enrollments, with no modifications, and BioMarin does not expect to make any modifications in the future due to this event,” it says. “The company’s independent data safety monitoring board agreed that this case did not require any modification to BioMarin’s ongoing trials at this time.

In 8/2020, FDA issued a complete response letter on a BLA for the therapy that requested two years of data from the Phase 3 study to provide evidence of a durable effect using annualized bleeding rate as the primary endpoint. BioMarin says it will file a resubmission by the end of the month. Last month, the European Commission granted conditional marketing authorization for the treatment. “Typically, BLA resubmissions are followed by a six-month review procedure,” BioMarin says. “However, the company anticipates three additional months of review may be necessary based on the number of data read-outs that will emerge during the procedure.”

Additionally, the company said in May that based on “recent feedback received from the FDA related to BioMarin’s plans for the upcoming BLA, the agency has requested additional information and analyses of data to be included in the BLA prior to submission.” While the agency has not requested additional pre-clinical or clinical studies, according to the company, data on three years after dosing will become available during the expected BLA review.

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