Class action alleges Ultragenyx misled investors about setrusumab Phase 3 trial outcomes

Legal Challenge Alleges Misleading Clinical Communications at Ultragenyx

Berger Montague files a securities class action against Ultragenyx Pharmaceutical, asserting the company made overly positive public statements about two Phase 3 trials of setrusumab for osteogenesis imperfecta (OI). The complaint centers on the ORBIT and COSMIC programs and contends that Ultragenyx’s characterizations of the studies’ prospects and interim data misrepresent the trials’ likelihood of success. The plaintiff firm frames those statements as material to investors who relied on the company’s public narrative about clinical progress.

The suit further alleges that Ultragenyx fails to adequately disclose risks around trial design, endpoints and expected outcomes for setrusumab, a monoclonal antibody intended to reduce fracture rates in OI patients. Plaintiffs say the company’s communications create an inflated view of the drug’s potential by stressing positive aspects while downplaying the possibility that the studies might not meet their primary endpoint. The action highlights tensions in rare-disease drug development between managing investor and stakeholder expectations and conveying the uncertainties inherent in late-stage clinical testing.

The complaint follows Ultragenyx’s December 29, 2025 disclosure that neither ORBIT nor COSMIC meets its primary endpoint of reducing the annualized clinical fracture rate. Berger Montague frames that disclosure as the moment when the contention that prior statements were misleading crystallizes, and it seeks class-wide remedies under federal securities laws. The case underscores how trial outcomes and sponsor communications increasingly become focal points for litigation in the biopharma sector, particularly where high unmet need and small patient populations heighten attention on clinical signals.

Plaintiff firm invites affected investors to seek lead-plaintiff status by April 6, 2026. Berger Montague provides contacts for potential class members — Andrew Abramowitz at (215) 875-3015 or [email protected], and Caitlin Adorni at (267) 764-4865 or [email protected] — and encourages prompt action to preserve rights under the complaint, which covers purchases of Ultragenyx common stock between August 3, 2023 and December 26, 2025.

Ultragenyx, headquartered in Novato, California, is a biopharmaceutical company focused on novel therapies for rare genetic diseases. The company’s setrusumab program addresses a significant unmet need in OI; the ORBIT and COSMIC Phase 3 trials represent the most advanced clinical tests of the candidate, and the litigation draws attention to how late-stage failures can reverberate across company communications, regulatory strategy and investor relations in the rare-disease drug development field.