Ultragenyx Hit With Securities Class Action Over Setrusumab Orbit Trial Disclosures

Ultragenyx faces class action over setrusumab trial disclosures

Allegations focus on Phase III Orbit trial statements

A securities fraud class action is underway against Ultragenyx Pharmaceutical, with plaintiffs alleging the company and certain executives misled investors about its experimental osteoporosis drug setrusumab and the design of the Phase III Orbit study. The complaint in Bailey v. Ultragenyx Pharmaceutical Inc., filed in the U.S. District Court for the Northern District of California, is brought on behalf of purchasers of Ultragenyx shares between August 3, 2023 and December 26, 2025. Law firms Kessler Topaz Meltzer & Check and Robbins Geller Rudman & Dowd notify potential class members of an April 6, 2026 deadline to seek appointment as lead plaintiff.

The complaint contends Ultragenyx presented an unjustified level of confidence in setrusumab’s performance across variable forms of osteogenesis imperfecta (OI) and downplayed the risk that the Orbit trial would fail to meet a second interim analysis benchmark for reduction in annualized fracture rate (AFR). Central to the allegations is the company’s reliance on Phase II results that lack a placebo control, which plaintiffs say could mean reported AFR reductions stem from improved standard of care or placebo effects rather than true drug efficacy. The suit argues those representations rendered public statements about the company’s business and prospects misleading or lacking a reasonable basis.

The filings point to company disclosures that the second interim analysis did not attain statistical significance and that both the Orbit and Cosmic Phase III studies later fail to meet their primary endpoints for reduction in clinical fracture rate versus placebo. Plaintiffs assert these outcomes underscore the alleged mischaracterization of trial evidence and benchmarks. The court docket reflects the complaint but does not include a corporate response; the law firms involved are soliciting eligible investors to preserve their rights.

Procedural notices and options for shareholders

Notifying investors via PR outlets and firm websites, Kessler Topaz and Robbins Geller offer free case evaluations and advise eligible shareholders they may retain counsel of choice or take no action, while emphasizing the April 6, 2026 lead plaintiff filing deadline.

Clinical and industry implications

The dispute highlights broader industry scrutiny of relying on uncontrolled early‑phase data to set Phase III expectations, particularly for rare-disease programs like OI, and may prompt renewed attention to trial design and benchmark communication practices among biopharma companies.