Muscle‑saving drug combo trial
A Phase 2 study has combined bimagrumab—a drug designed to preserve or increase muscle—with semaglutide to treat obesity, testing whether muscle can be spared while maximizing fat loss X post. The approach targets a common clinical worry: large drug‑induced weight loss can reduce lean mass, so pairing an anabolic agent could improve function and metabolic outcomes X post.
The BELIEVE randomized Phase 2b trial enrolled 507 adults with BMI ≥30 kg/m² (or ≥27 kg/m² plus an obesity‑related complication) and ran a 48‑week double‑blind treatment period. (nature.com) Participants were assigned across nine arms to receive intravenous bimagrumab (10 or 30 mg/kg every 12 weeks) and/or subcutaneous semaglutide (1.0 mg or 2.4 mg once weekly) for the primary 48‑week analysis. (nature.com) Least‑squares mean weight changes at week 48 were −9.3 kg for bimagrumab 30 mg/kg, −14.2 kg for semaglutide 2.4 mg, −17.8 kg for the high‑dose combination and −3.3 kg for placebo. (nature.com) The high‑dose combination produced a mean 22.1% weight reduction with 92.8% of that loss attributable to fat mass, versus a 15.7% mean weight loss with semaglutide alone of which 71.8% was fat. (pbrc.edu) Bimagrumab monotherapy yielded a 10.8% mean weight loss with all loss from fat and a reported 2.5% increase in total lean mass, while combination treatment largely preserved lean tissue. (pbrc.edu) Common adverse events differed by drug: bimagrumab was associated with muscle spasms, diarrhea and acne, whereas semaglutide most often caused nausea, diarrhea, constipation and fatigue; the trial also included an open‑label extension to week 72. (nature.com) The study is recorded as ClinicalTrials.gov identifier NCT05616013 and was run after bimagrumab’s developer program was folded into Eli Lilly following Lilly’s announced acquisition of Versanis for up to $1.925 billion in July 2023. (clinicaltrials.gov) The randomized results were reported in a manuscript submitted to Nature Medicine (accepted 5 January 2026) and presented previously at major conferences during 2025. (nature.com)
