Mereo Biopharma Group Plc Class Action Lawsuit – MREO
Introduction to Mereo Biopharma Group Plc (MREO) Securities Class Action Lawsuit
A securities fraud class action has been filed against Mereo Biopharma Group Plc (NASDAQ: MREO) in the Southern District of New York, under federal securities laws. The case covers investors who bought Mereo American Depositary Shares ticker MREO on the NASDAQ between June 5, 2023 and December 26, 2025. Investors allege the company and its executives misled the market about expected results from the Phase 3 ORBIT and COSMIC studies of setrusumab for osteogenesis imperfecta, while concealing adverse facts and making material misrepresentations.
The complaint states that, contrary to those representations, the ORBIT study failed an interim statistical hurdle on July 9, 2025, and on December 29, 2025 the company announced that neither ORBIT nor COSMIC met their primary endpoints of reducing annualized clinical fracture rates (versus placebo in ORBIT and bisphosphonates in COSMIC). Shares fell sharply on both disclosures, including single-day drops of 42.52% and 87.7%.
“Most MREO shareholders never file or join the class action, which means they miss out on potential recovery funds,” said Attorney Joseph Levi.
Mereo Biopharma Group Plc (MREO) Securities Lawsuit Case Details
Case Name: Dodge v. Mereo Biopharma Group Plc et al.
Case No.: 1:26-cv-988
Jurisdiction: U.S. District Court, Southern District of New York
Filed on: February 4, 2026
Mereo Biopharma Group Plc (MREO) Company Profile
Mereo is a NASDAQ-listed biopharmaceutical company developing therapeutics for rare diseases (rare disease therapeutics), including setrusumab for osteogenesis imperfecta, evaluated in Phase 3 clinical trials ORBIT and COSMIC and alvelestat for Alpha-1 Antitrypsin Deficiency-associated lung disease. Its strategy is to acquire and develop clinical-stage programs with substantial prior data packages.
Mereo Biopharma Group Plc (MREO) Securities Lawsuit Class Period
June 5, 2023 –December 26, 2025, inclusive.
All investors who purchased or otherwise acquired Mereo ADS during this period, inclusive, are included in the proposed class, including purchases on the NASDAQ exchange, and may be eligible to join the Mereo Biopharma Group Plc (MREO) class action lawsuit.
Allegations in the Mereo Biopharma Group Plc (MREO) Securities Class Action Lawsuit
According to the complaint, the lawsuit targets Mereo Biopharma Group Plc, its co-founder and CEO Denise Scots-Knight, and its Chief Scientific Officer John A. Lewicki. During the class period, investors allege these defendants provided upbeat information about expected Phase 3 results for investigational setrusumab in the ORBIT and COSMIC studies while disseminating false and materially misleading statements and concealing adverse facts about the true state of those programs.
The narrative begins on June 5, 2023, when a company press release quoted Gary Gottesman, MD, describing "striking" increases in bone mineralization on DXA scans (bone mineral density) and the potential for denser, stronger bone. On July 6, 2023, Ultragenyx's Chief Medical Officer, Eric Crombez, said Phase 2 Orbit data showed increases in bone formation and bone mineral density and highlighted a comprehensive Phase 3 program designed to study clinical fracture risk reduction.
As the program advanced, the complaint alleges defendants continued to issue upbeat statements about setrusumab and its Phase 3 studies. On April 30, 2024, Crombez said interim Phase 2 Orbit results showed a rapid and clinically meaningful decrease in fractures (annualized fracture rate). At the JP Morgan Healthcare Conference on January 16, 2025, CEO Denise Scots-Knight told investors there was a "medium 67% reduction in annualized fracture rate," identifying that measure as the Phase 3 metric and primary endpoint for Orbit, while CSO John Lewicki said fractures became "very infrequent" on treatment and expressed confidence in the IA-2 analysis.
Meanwhile, the complaint alleges the ORBIT and COSMIC Phase 3 programs were not on track to reach statistical significance on their primary endpoint: reduction in annualized clinical fracture rate versus the placebo control group or a bisphosphonate comparator. Investors allege defendants concealed material adverse facts and misrepresented the viability of these trials and the underlying efficacy data.
The Truth Emerges
The first break in the story came on July 9, 2025, when Mereo issued a press release stating the Phase 3 ORBIT study failed to achieve statistical significance at the second interim analysis (IA-2) on the primary endpoint and would continue toward a final analysis. In the July 9, 2025 joint press release, Ultragenyx CEO Emil D. Kakkis stated that the companies had ‘hoped to be able to stop the study early’ before the full 24-month dataset became available.
The full picture arrived on December 29, 2025. In a press release, Mereo disclosed that neither ORBIT nor COSMIC achieved statistical significance and that neither met its primary endpoint of reducing annualized clinical fracture rates versus their control groups (placebo and bisphosphonates). CEO Denise Scots-Knight acknowledged disappointment and said the company would conduct additional analyses to assess next steps, contradicting prior confidence in setrusumab's ability to reduce clinical fractures.
Market Reaction
The market reacted in two sharp moves tied to these disclosures. After the July 9, 2025 interim failure update, Mereo's ADS (ticker MREO) fell on July 10, 2025 from a prior close of $2.94 to $1.69, a single-day stock price decline of $1.25 or 42.52%. When the company announced the complete Phase 3 failures on December 29, 2025, the stock fell from a December 26 close of $2.31 to $0.29, a decline of $2.02 or 87.7% in one day, reflecting substantial investor losses. These declines reflect investor reassessment once the alleged truth became clear.
Next Steps:
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The Court will issue its order for lead plaintiff and counsel in the weeks after submissions are due.
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The Court will then consider motion for class certification.
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The Court will later consider a motion to dismiss.
Disclaimer: This shareholder alert is for informational purposes only and does not constitute legal advice. Consult a qualified attorney for personalized guidance. No specific outcomes are guaranteed.
Frequently Asked Questions
What is the Mereo BioPharma securities class action lawsuit about?
The lawsuit alleges that Mereo BioPharma Group plc (NASDAQ: MREO) and certain executives violated federal securities laws by making materially false and misleading statements about the company's Phase 3 ORBIT and COSMIC clinical trials for setrusumab, a treatment for osteogenesis imperfecta (OI). According to the complaint, defendants overstated confidence in the drug's ability to reduce fracture rates while allegedly concealing material adverse information about the trials' likelihood of achieving their primary endpoints.
What is the class period for the Mereo BioPharma lawsuit?
The class period covers investors who purchased or acquired Mereo American Depositary Shares (ADS) between June 5, 2023, and December 26, 2025, inclusive. Investors who purchased MREO stock during this timeframe and suffered losses may be eligible to participate in the class action.
What were the key stock drops associated with this case?
The complaint identifies two significant stock declines:
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On July 10, 2025, Mereo's ADS fell approximately 42.52% (from $2.94 to $1.69) after the company announced the Phase 3 ORBIT study failed to achieve statistical significance at its second interim analysis
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On December 29, 2025, shares dropped more than 87.7% (from $2.31 to $0.29) when the company disclosed that neither the ORBIT nor COSMIC studies met their primary endpoints
What allegedly happened with the Phase 3 ORBIT and COSMIC trials?
According to the complaint, both Phase 3 studies failed to achieve statistical significance for their primary endpoints of reducing annualized clinical fracture rates compared to placebo (ORBIT) or bisphosphonates (COSMIC). The lawsuit alleges that while defendants repeatedly expressed confidence in setrusumab's efficacy based on earlier Phase 2 data showing improved bone mineral density, they knew or recklessly disregarded that this data lacked proper control group comparisons to support their claims.
Who are the defendants named in the Mereo lawsuit?
The complaint names Mereo BioPharma Group plc as a corporate defendant, along with two individual defendants: Denise Scots-Knight, the company's co-founder and Chief Executive Officer, and John A. Lewicki, the Chief Scientific Officer. The lawsuit alleges these executives had knowledge of material non-public information and controlled the company's public statements during the class period.
What legal claims are alleged against Mereo BioPharma?
The complaint asserts two counts under federal securities laws:
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Violations of Section 10(b) of the Securities Exchange Act and SEC Rule 10b-5 against all defendants for allegedly making materially false and misleading statements
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Violations of Section 20(a) of the Exchange Act against the individual defendants as alleged "controlling persons" of the company
Where was the Mereo securities lawsuit filed?
The class action complaint was filed on February 4, 2026, in the United States District Court for the Southern District of New York. The case is captioned Dodge v. Mereo BioPharma Group plc, et al., Case No. 1:26-cv-988.
What is the Mereo BioPharma class action about?
The lawsuit alleges Mereo (NASDAQ: MREO) and executives made false statements about Phase 3 clinical trials for setrusumab, a drug for osteogenesis imperfecta. The complaint claims defendants overstated confidence in the drug's efficacy while concealing material information about trial outcomes.
What is the class period for the MREO lawsuit?
The class period is June 5, 2023, through December 26, 2025. Investors who purchased Mereo ADS during this time and suffered losses may be eligible to participate in the securities class action.
How much did Mereo stock drop?
According to the complaint, MREO shares fell approximately 42.52% on July 10, 2025, after interim trial results were disclosed. Shares dropped over 87.7% on December 29, 2025, when both Phase 3 studies failed to meet primary endpoints.
What happened to the setrusumab clinical trials?
The complaint alleges both Phase 3 ORBIT and COSMIC studies failed to achieve statistical significance for reducing fracture rates compared to placebo or bisphosphonates, despite earlier positive Phase 2 data on bone mineral density improvements.
Who are the defendants in the Mereo lawsuit?
The defendants include Mereo BioPharma Group plc, CEO Denise Scots-Knight, and Chief Scientific Officer John A. Lewicki. The complaint alleges they controlled the company's misleading public statements during the class period.
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