The FDA issued a complete response letter to Scholar Rock’s selective anti-latent myostatin antibody apitegromab for spinal muscular atrophy, citing ongoing manufacturing quality concerns at Novo Nordisk’s contract facility. Scholar Rock plans to address the contamination and resubmit, but no clear timeline has been provided. The rejection delays the potential approval of the first skeletal muscle-enhancing therapy in SMA, a condition where treatment advances remain critical.