Ultragenyx RARE Shares Plummet 45% on Apazunersen Clinical Trial Failure

Shares of Ultragenyx Pharmaceutical (RARE) plummeted 45% during extended trading after its experimental therapy apazunersen failed to demonstrate efficacy in a Phase 3 clinical study for Angelman syndrome.

The Aspire trial evaluated apazunersen's ability to enhance cognitive function and developmental progress in pediatric patients with the rare genetic disorder. Unfortunately, it did not achieve its primary goal of improving Bayley-4 cognitive raw scores or meet the critical secondary measure of net response using the Multidomain Responder Index (MDRI).

No statistically significant improvements were found between participants receiving apazunersen and those in the placebo arm. Despite this, the drug's safety profile was consistent with previous studies.

CEO Emil Kakkis expressed disappointment with the findings, acknowledging the impact on patients and their families who had invested hope in early-stage research.