FDA asks for more data on BioMarin gene therapy

Feb. 21, 2022

The FDA is asking BioMarin Pharmaceutical to run additional preclinical studies to better evaluate the cancer risk of their rare disease gene therapy. The information will help resolve a clinical hold the agency placed on the drug last year.

The gene therapy — called BMN 307 — is meant to treat adults with phenylketonuria (PKU), a genetic, metabolic disorder that causes an amino acid called phenylalanine to build up in the body.

While the theoretical oncogenic risk of gene therapies has been suspected, no definitive link has been made. However, last fall, FDA agents suspended testing for BMN 307 therapy due to safety concerns after data showed that the corrected gene delivered had fused itself into the genomes of six mice that went on to develop liver cancer.

Preclinical tests gathered in the last two decades have shown the use of adeno-associated viruses, or AAVs, to deliver gene therapies is largely safe. At the same time, the recent boom in gene therapy research has led to an unprecedented use of this technology.

"As leaders in the development of gene therapies, a novel treatment modality, it is our responsibility to answer new questions that arise for the benefit of patients, physicians, regulatory bodies, and for the field in general.  Patient safety is our utmost priority,” said Hank Fuchs, the president of Worldwide Research and Development at BioMarin. 

The company also said that complying with the agency’s data requests is expected to take several quarters and that they will communicate the next steps for the program when available.