Ultragenyx Pharmaceutical Faces Class Action

The class action lawsuit centers on the experimental drug setrusumab, which was being tested as a treatment for osteogenesis imperfecta, a genetic disorder characterized by brittle bones. The suit alleges that Ultragenyx made overly positive and misleading statements about the drug's potential, based on a Phase 2 study that lacked a placebo control group for comparison. Investor confidence was high leading up to the release of Phase 3 trial data. However, on July 9, 2025, the company announced that the first of its two large-scale studies, the Orbit study, failed to show a statistically significant reduction in fracture rates during an interim analysis. This news sent the company's stock price tumbling by more than 25%. The final blow came on December 29, 2025, when Ultragenyx revealed that neither the Orbit study nor the second Phase 3 trial, known as the Cosmic study, had met their primary goals of reducing annualized fracture rates. Following this announcement, the company's stock plummeted over 42% in a single day, falling from $34.19 to $19.72 per share. In response to the trial results, Ultragenyx CEO Emil D. Kakkis expressed surprise and disappointment. The company has since announced a strategic restructuring plan that includes a 10% workforce reduction, impacting approximately 130 employees, as it aims to reduce expenses and focus on other pipeline candidates.