Ultragenyx's Angelman gene therapy fails Phase 3, company to cut expenses

Ultragenyx reported that its late‑stage Aspire trial of apazunersen in Angelman syndrome did not meet its primary or secondary endpoints. The primary goal of improving the Bayley‑4 cognitive raw score was missed, and the drug also fell short on the Multidomain Responder Index measure of clinical function.

Company chief executive Emil Kakkis said the results were disappointing for both the team and the global patient community that has invested in early‑stage research. He noted that the Phase 1/2 program and long‑term extension study had been robust, but the Phase 3 outcome was a setback.

In response, Ultragenyx said it will implement significant expense reductions as it reassesses its pipeline and financial strategy. The company had recently celebrated FDA approval for Genglycos, but the Angelman trial failure has shifted its near‑term focus toward cost control and portfolio realignment.