Ultragenyx Pharmaceuticals disclosed that its Phase 3 Aspire trial of apazunersen (GTX-102) in Angelman syndrome failed to hit both primary and key secondary endpoints. The miss centered on change from baseline in the Bayley-4 Cognitive raw score, alongside failure to achieve net upside in the Multidomain Responder Index. The safety profile was consistent with earlier-phase findings as the company signals cost-reduction steps and evaluates next moves. The setback is likely to reshape expectations for Ultragenyx’s pipeline economics in a rare-disease space with limited approved options.