On January 12, 2026 Mereo BioPharma Group plc (NASDAQ: MREO) ("Mereo" or the "Company"), a clinical-stage biopharmaceutical company focused on rare diseases, reported an update on its programs, setrusumab for the treatment of osteogenesis imperfecta (OI) and alvelestat, which is being studied for the treatment of alpha-1 antitrypsin deficiency-associated lung disease (AATD-LD), and revised its cash runway guidance.
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Data from the Phase 3 Orbit and Cosmic studies of setrusumab in osteogenesis imperfecta, including data on bone mineral density, vertebral fractures, and patient reported outcomes on pain and physical function, will be presented at the J.P. Morgan Healthcare Conference.
The Company is also updating its previous cash runway guidance. As of December 31, 2025, cash and cash equivalents were approximately $41 million, which are expected to fund operations to mid-2027.
"The reductions and delays in pre-commercial and manufacturing activities related to setrusumab that we implemented following the recent top-line data from the Phase 3 Orbit and Cosmic studies have extended our cash runway to mid-2027 and we will continue to tightly manage our resources as we assess potential next steps for the program, alongside our partner, Ultragenyx," said Dr. Denise Scots-Knight, Chief Executive Officer of Mereo. "There are no FDA or EMA approved treatments for people living with OI. Although bisphosphonates are used to improve bone mineral density, OI remains a high unmet need. We will continue to assess the totality of the Phase 3 trial data to determine next steps, including potential interactions with the regulators. In parallel, we are advancing partnering discussions for our Phase 3 ready program, alvelestat in AATD-LD."
Dr. Scots-Knight is scheduled to present at the 44th Annual J.P. Morgan Healthcare Conference on Wednesday, January 14, 2026 at 1:30pm PT (9:30pm GMT). A live audio webcast of the presentation can be accessed through the news and events section of the Company’s website at www.mereobiopharma.com/news. Following the conclusion of the live event, an archived replay will be available on the Company’s website.
Setrusumab (UX143)
As announced on December 29, 2025, the Phase 3 Orbit and Cosmic studies of setrusumab in OI did not achieve statistical significance against the primary endpoints of reduction in annualized clinical fracture rate compared to placebo or bisphosphonates, respectively. Both studies achieved strong statistical significance against the key secondary endpoint of improvement in bone mineral density versus comparator. The improvement in bone mineral density in the Cosmic study was associated with a decreased rate of fracture in this younger more highly fracturing patient population, although this was not statistically significant. The safety profile of setrusumab was consistent with that observed in prior studies.
Further analyses of the data from both studies are ongoing to determine the path forward, including potential regulatory interactions.
There is a high unmet medical need in OI, which is associated with a substantial clinical, humanistic and economic burden of illness due to the complexity of the condition and necessary medical care and support. As well as fractures, people living with OI present with a broad spectrum of skeletal features including bone deformity, scoliosis and growth impairment. Pain is the most common and impactful sign, symptom or clinical event reported in children and adolescents.
There are no EMA or FDA approved treatments for OI (except for neridronate, which is approved nationally in Italy). Bisphosphonates are used off-label in children in Europe and the U.S., despite the lack of clinical evidence to support their effectiveness in reducing fractures.
Alvelestat (MPH-966)
The Company is continuing to advance key activities to support the planned initiation of the global Phase 3 pivotal study. Based on previous discussions with the FDA and EMA, Mereo anticipates a single Phase 3 trial enrolling approximately 220 early- and late-stage AATD-LD patients evaluating alvelestat over an 18-month treatment period will support regulatory submissions in both the U.S. and Europe. The primary efficacy endpoint for U.S. approval will be the St. George’s Respiratory Questionnaire (SGRQ) Total Score, with lung density measured by CT scan serving as the primary endpoint for potential European regulatory approval.
Mereo continues to be in active discussions with potential partners for the Phase 3 development and commercialization of alvelestat.
Vantictumab (OMP18R5)
The Company out-licensed vantictumab for autosomal dominant osteopetrosis Type 2 (ADO2) to āshibio, Inc. whilst retaining European rights. āshibio, Inc. is responsible for funding the global program and following regulatory discussions, plans to initiate a Phase 2 study in 2H 2026. Vantictumab was previously investigated in Phase 1a/b oncology trials in around 100 patients with biomarker evidence of potential impact on osteoclast function and high bone turnover which led to fragility fractures in some patients. āshibio, Inc. reported promising pre-clinical data at ASBMR 2025 in ADO2 mouse model. Vantictumab significantly decreased areal bone mineral density and rescued the bone phenotype in the ADO2 mouse model.
(Press release, Mereo BioPharma, JAN 12, 2026, View Source [SID1234661958])