Scholar Rock is a clinical-stage biopharmaceutical company focused on rare neuromuscular diseases. Its lead program, apitegromab, is an IV-administered monoclonal antibody that inhibits myostatin activation in skeletal muscle. Myostatin suppresses muscle growth, so blocking it promotes muscle mass and strength. Apitegromab is being developed primarily for spinal muscular atrophy (SMA), a rare genetic disease causing progressive muscle weakness. Three approved therapies address SMA at the neurological level by targeting SMN protein deficiency, but none address muscle wasting directly — apitegromab is positioned as the first muscle-targeted add-on therapy to be used alongside these existing SMN-directed treatments. The addressable population is roughly 35,000 SMA patients globally who have already received an SMN-targeted therapy but continue to experience functional decline. Scholar Rock submitted a BLA to the FDA in January 2025, but received a Complete Response Letter in September 2025 due solely to manufacturing compliance issues at a third-party fill-finish facility — not safety or efficacy concerns. EMA review is ongoing with a decision expected around mid-2026. Beyond SMA, Scholar Rock is developing apitegromab for facioscapulohumeral muscular dystrophy (FSHD), a rare progressive muscle disease affecting roughly 30,000 patients in the U.S. and Europe with no approved treatments. The company also has a next-generation subcutaneous anti-myostatin antibody, SRK-439, in Phase 1. Scholar Rock is pre-revenue, outsources all manufacturing to third-party CDMOs, and plans to sell directly through a lean U.S. commercial field team targeting SMA treatment centers and prescribing physicians.