Ultragenyx’s Phase 3 program for Angelman syndrome delivered an outcome investors had been waiting for—and it wasn’t the one the company needed. The biotech said its antisense oligonucleotide GTX-102 showed no benefit versus sham treatment in a large late-stage trial. The failure is a major setback for a program that had produced encouraging early results and positioned Angelman as a potential path to profitability. The company’s investor narrative had leaned heavily on its ability to translate early signals into clinical benefit. With GTX-102 now stalled after Phase 3, Ultragenyx will likely refocus capital allocation across its remaining ultra-rare pipeline—while families and clinicians await alternatives for severe neurodevelopmental outcomes.