Scholar Rock Pharmaceuticals reported that its investigational myostatin-blocking antibody, apitegromab, successfully preserved lean muscle mass in patients taking Eli Lilly's obesity drug Zepbound during a Phase 2 trial. Combination therapy over 24 weeks resulted in weight loss with a significantly higher proportion of fat mass loss versus placebo, which saw greater lean mass loss. The data supports anti-myostatin drugs as adjuncts to obesity treatments to counteract muscle wasting, a growing concern with potent weight loss agents. Scholar Rock plans to advance a next-generation compound, SRK-439, aiming for enhanced myostatin binding and clinical effect.