Ultragenyx's Angelman Syndrome Drug Fails Late-Stage Trial

Ultragenyx said Wednesday that its experimental therapy for Angelman syndrome, a rare genetic disease that causes severe intellectual disability and developmental delays, showed no benefit over a sham treatment in a large late-stage clinical trial.

The drug, called GTX-102, had shown strong results in earlier, smaller trials, raising hopes among families affected by the condition. Advocates for patients with other neurological and intellectual disability conditions had also hoped it could become the first of a new generation of medicines to improve cognition and communication for such patients.

The failed trial is also a setback for Ultragenyx's business. The company already sells several approved medicines, but these treat mostly ultra-rare diseases, and investors had been counting on the Angelman drug to be its path to profitability.