BioMarin Must Collect More Data to Resolve PKU Gene Therapy Hold

The FDA has asked BioMarin Pharmaceutical to conduct more preclinical studies to resolve a phase 1/2 clinical hold of its gene therapy for phenylketonuria (PKU) — a rare inherited disorder that causes excess buildup of an amino acid called phenylalanine.

BioMarin said that gathering the additional data is likely to take “several quarters.” The FDA hold on the gene therapy, AAV5-human phenylalanine hydroxylase, has been in place since September 2021, after liver tumors were discovered in animals given the drug.

Separately, BioMarin completed enrollment for a phase 3 study evaluating a different AAV5 gene therapy, valoctocogene roxaparvovec plus corticosteroids, in people with severe hemophilia A. The company said results from that study should be available during the first half of 2023.