Ultragenyx’s Angelman therapy fails Phase 3, stock drops over 43% and company announces strategic review

Ultragenyx reported that its investigational Angelman syndrome drug apazunersen did not meet the primary cognitive endpoints in a Phase 3 trial. The lack of efficacy means the therapy will not provide the near-term milestone investors had hoped for.

Following the announcement, the company's shares fell more than 43% in after-hours trading, reflecting the market's disappointment in the high-risk bet.

In response, Ultragenyx said it will assess its planned operations and shift focus to its growing commercial business. The firm also indicated it will implement significant expense reductions, though details on potential layoffs were not provided.

The biotech still markets several approved products, including the recently cleared gene therapy Genglycos for glycogen storage disease type Ia, and it continues to await a decision on its UX111 gene therapy for Sanfilippo syndrome.