PTC hits Huntington biomarker, but approval path still uncertain

Despite meeting the primary endpoint, new Phase II data from PTC failed to clarify the path to accelerated approval of PTC518 to treat Huntington disease, sending the company’s shares down 19% Monday.

FDA had previously said it was open to basing an accelerated approval on a reduction of HTT — the gene that’s mutated in the disease and the drug’s target — if PTC Therapeutics Inc. (NASDAQ:PTCT) could show “associations” between HTT reduction and clinical outcomes. The latest data cut offered a mixed picture of outcomes...