Core Insights - Mereo BioPharma announced that neither the Phase 3 ORBIT nor COSMIC studies for setrusumab (UX143) achieved their primary endpoint of reducing annualized clinical fracture rates compared to placebo or bisphosphonates, respectively. However, both studies successfully met their secondary endpoints, showing significant improvements in bone mineral density (BMD) [1][2][3]. Study Results - In the ORBIT study, participants showed statistically significant improvements in BMD compared to placebo, consistent with Phase 2 study results, but did not see a corresponding reduction in fracture rates [3]. - The pediatric COSMIC study revealed that patients had a higher baseline fracture rate compared to those in ORBIT. Although setrusumab-treated patients showed meaningful BMD improvements and a reduction in fracture rates compared to bisphosphonate-treated patients, this reduction did not reach statistical significance [4]. Financial and Strategic Considerations - Mereo's cash balance was reported at $48.7 million at the end of Q3 2025. The company plans to manage cash resources carefully, implementing immediate reductions in pre-commercial and manufacturing activities while continuing to analyze the setrusumab data for future steps [5]. - The company is also advancing discussions for partnerships related to alvelestat, another of its drug candidates [2][9]. Product Development Context - Setrusumab is being developed for pediatric and young adult patients with Osteogenesis Imperfecta (OI) across various sub-types, with the ORBIT and COSMIC studies being pivotal in this development [6][8]. - The ORBIT study involved 159 patients aged 5 to 25 years, while the COSMIC study enrolled 69 patients aged 2 to under 7 years, both randomized to receive either setrusumab or a comparator [7][8]. Company Overview - Mereo BioPharma focuses on developing innovative therapeutics for rare diseases, with setrusumab being one of its key candidates for OI. The company has retained commercial rights in the EU and UK and has partnered with Ultragenyx Pharmaceutical for the development of setrusumab [12].

Core Insights - Mereo BioPharma is approaching a significant transition with the Phase 3 Orbit and Cosmic studies of setrusumab for osteogenesis imperfecta (OI) expected to report results by the end of 2025 [2][3] - The company has $48.7 million in cash as of September 30, 2025, which is anticipated to support operations into 2027 [2][9] Company Developments - The Phase 3 studies for setrusumab are being conducted in partnership with Ultragenyx and are focused on pediatric and young adult patients [6][11] - Mereo is also advancing discussions for partnerships related to alvelestat and has retained European commercial rights for vantictumab, which is being developed for autosomal dominant osteopetrosis type 2 [2][4] Financial Performance - Research and development expenses increased by $1.1 million from $3.2 million in Q3 2024 to $4.3 million in Q3 2025, primarily due to costs associated with setrusumab and alvelestat [5][7] - General and administrative expenses decreased by $0.2 million from $6.2 million in Q3 2024 to $6.0 million in Q3 2025 [8] - The net loss for Q3 2025 was $7.0 million, a reduction from $15.0 million in Q3 2024, reflecting an operating loss of $10.0 million and a foreign currency transaction gain of $1.9 million [8][19] Cash Position and Guidance - As of September 30, 2025, Mereo's cash and cash equivalents were $48.7 million, down from $69.8 million at the end of 2024, but the company expects this to fund its clinical trials and operational needs through 2027 [9][16] - The company has not included potential partnership payments for alvelestat in its cash guidance [9]