Mereo BioPharma Group Faces Class Action

A class action lawsuit has been filed against Mereo BioPharma Group by Wolf Haldenstein Adler Freeman & Herz LLP on behalf of investors who purchased Mereo American Depositary Shares between June 5, 2023, and December 26, 2025. The lawsuit alleges that Mereo BioPharma Group and its executives made false and misleading statements about the likelihood of success of its Phase 3 clinical trials for setrusumab, a treatment for Osteogenesis Imperfecta. The company had repeatedly expressed confidence that the ORBIT and COSMIC Phase 3 trials would achieve statistical significance in reducing annualized fracture rates and position setrusumab for regulatory success. However, the complaint claims the company concealed adverse facts indicating that neither study was on track to meet its primary endpoint. On December 29, 2025, Mereo BioPharma Group disclosed that neither trial achieved statistical significance, and the primary endpoint was not met. Following this disclosure, Mereo BioPharma Group's share price fell from $2.31 to $0.29 in one trading session, representing a loss of over 87% of shareholder value.