Mereo BioPharma Group plc disclosed that its two Phase 3 studies—ORBIT and COSMIC—failed to meet the primary endpoints of reducing annualized clinical fracture rates in patients with osteogenesis imperfecta. The ORBIT study enrolled 159 children and adolescents aged 5‑25, while the COSMIC study enrolled 69 younger patients aged 2‑<7. Both trials did, however, achieve statistically significant improvements in bone mineral density, the secondary endpoint, and reported no new safety signals.
The shortfall in the primary endpoint is attributed to a lower than expected fracture rate in the placebo arm of the ORBIT study, which limited the ability to demonstrate a statistically significant difference. In the COSMIC study, the reduction in fracture rate did not reach statistical significance, reflecting the challenges of measuring clinical benefit in a rare pediatric population with a low baseline fracture frequency.
The results have immediate implications for Mereo’s pipeline strategy. The company will conduct additional analyses to determine the best path forward for setrusumab, while simultaneously tightening cash burn by cutting pre‑commercial and manufacturing activities. With a cash balance of $48.7 million at the end of Q3 2025, the company expects the runway to extend into 2027, but the setback may accelerate the need for new partnerships or alternative revenue streams. Mereo is also pursuing partnering discussions for its alvelestat program, which has orphan designation for alpha‑1 antitrypsin deficiency‑associated lung disease.
Dr. Denise Scots‑Knight, Mereo’s CEO, said, “Whilst we are disappointed by these results, we will be conducting additional analyses on the data, to assess next steps and the best path forward for the program, especially in pediatrics given the totality of the data and lack of other treatment options for individuals with OI.” She added that the company is “carefully managing our cash resources with immediate reductions in our pre‑commercial and manufacturing activities, and we are continuing to advance partnering discussions for alvelestat.”
Investors have reacted with heightened scrutiny of the setrusumab program, raising concerns about the viability of the company’s flagship therapy and the broader impact on its valuation. The failure to meet the primary endpoint—fracture reduction—has been identified as the key driver of this reaction, as fracture prevention is the clinically meaningful outcome that investors and patients prioritize.
Mereo’s Q3 2025 earnings report, released on November 10, 2025, showed an EPS of –$0.01 versus a consensus estimate of $0.00, and a cash balance of $48.7 million. The company’s financial position underscores the importance of the setrusumab results for its future growth prospects and the urgency of securing additional funding or partnerships to sustain its development pipeline.
The content on BeyondSPX is for informational purposes only and should not be construed as financial or investment advice. We are not financial advisors. Consult with a qualified professional before making any investment decisions. Any actions you take based on information from this site are solely at your own risk.