Ultragenyx said its antisense oligonucleotide therapy GTX-102 for Angelman syndrome failed to show benefit in a Phase 3 trial, dealing a major blow to the company’s late-stage pipeline. The results follow earlier hopes after positive performance in earlier studies, and they remove a key profitability path for a biotech that has largely relied on ultra-rare disease revenue. As reported by STAT+, the Phase 3 program compared GTX-102 against a sham treatment and found no evidence of improvement on trial endpoints. The setback also highlights the difficulty of translating early signals in severe neurodevelopmental disorders into confirmatory data for regulatory approval. For Ultragenyx, the immediate impact is strategic and financial: investors had leaned on Angelman to drive future growth, while the company’s approved portfolio is concentrated in very rare indications. The company will need to reassess development plans for GTX-102 and how to redeploy resources across remaining assets.