Ultragenyx Angelman syndrome drug fails Phase III test

USA-based rare disease specialist Ultragenyx Pharmaceutical (Nasdaq: RARE) has reported that apazunersen (GTX-102) failed to separate from control on either of the two main measures in the Phase III Aspire study in Angelman syndrome, ending the first late-stage test of an antisense drug in the genetic disorder.

The trial missed its primary endpoint, change from baseline in the Bayley-4 cognitive raw score, and also the key secondary endpoint of net response on the Multidomain Responder Index (MDRI). Ultragenyx said the randomized groups were comparable at the start and that neither the cognitive scores nor the MDRI showed anything to support a treatment effect. Safety matched Phase I/II.