Ultragenyx's Angelman Syndrome Drug Fails Late-Stage Trial

The drug, apazunersen, was tested ‌as a ⁠treatment ⁠for Angelman syndrome, a condition that affects the nervous system and impairs typical brain development in childhood.

In the trial, the drug did not show meaningful ​improvement on a test of young children's cognitive and nonverbal reasoning abilities or on an overall measure of response across multiple developmental ​areas.

There were no differences between the treated ⁠and control groups ‌that could support efficacy, the company said, ​adding it will ​evaluate the apazunersen program in light of ⁠this outcome and make a decision on its disposition.

William ​Blair analyst Sami Corwin said the trial ​results has negative implications for the company's other study, Aurora, testing apazunersen in Angelman syndrome patients with other genotypes.

"We believe that even if the Aurora study meets its primary endpoint, commercialization will be challenging given the limited size of the addressable population" said ‌Corwin.

Angelman syndrome currently has no approved disease-modifying treatment. Care focuses on controlling seizures, improving sleep, supporting communication and development, ​and managing ​movement, feeding, and ⁠other medical complications.

The condition occurs in about 1 in 15,000 live births. It is usually caused by a loss of function in ​the UBE3A gene on the 15th chromosome, specifically the copy inherited from the mother.

Last month, the company's gene therapy, Genglycos, became the first to receive the U.S. Food and Drug Administration's approval to treat a rare metabolic disorder called Von Gierke disease.