Shareholders Urged to Contact Wolf Haldenstein After Mereo BioPharma Losses

Law firm announces class action lawsuit over failed Phase 3 trials for Osteogenesis Imperfecta treatment

Published on Feb. 14, 2026

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Wolf Haldenstein Adler Freeman & Herz LLP has filed a class action lawsuit against Mereo BioPharma Group PLC (NASDAQ: MREO) on behalf of shareholders who purchased the company's American Depositary Shares (ADSs) between June 5, 2023 and December 26, 2025. The lawsuit alleges that Mereo and its executives made materially false and misleading statements about the likelihood of success for its Phase 3 clinical trials of setrusumab, a treatment for Osteogenesis Imperfecta (OI).

Why it matters

Investors lost over 87% of their shareholder value after Mereo disclosed in December 2025 that neither of its Phase 3 trials for setrusumab had achieved statistical significance or met their primary endpoint of reducing annualized fracture rates. This case highlights the risks investors face when companies provide overly optimistic projections about the success of their drug candidates.

The details

The lawsuit claims that Mereo repeatedly expressed confidence that its ORBIT and COSMIC Phase 3 trials would achieve statistical significance in reducing annualized fracture rates and position setrusumab for regulatory success. However, the complaint alleges the company concealed the fact that neither study was on track to meet its primary endpoint, and the trials ultimately failed to demonstrate a reduction in fracture rates versus control groups.

  • The class period spans from June 5, 2023 to December 26, 2025.
  • On December 29, 2025, Mereo issued a press release revealing that neither the ORBIT nor COSMIC trials had achieved statistical significance and the primary endpoint was not met.

The players

Mereo BioPharma Group PLC

A biopharmaceutical company focused on developing and commercializing innovative therapeutics.

Wolf Haldenstein Adler Freeman & Herz LLP

A law firm founded in 1888 that specializes in securities litigation and has a proven track record of protecting the rights of investors.

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What’s next

Investors seeking appointment as Lead Plaintiff may file a motion with the court no later than April 6, 2026.

The takeaway

This case highlights the importance of transparency and accurate disclosures from pharmaceutical companies, as investors rely on this information to make informed decisions. The significant loss in shareholder value underscores the need for rigorous oversight and accountability in the industry.