The FDA has approved Scholar Rock’s Isembyld (myostatin inhibition) as the first therapy specifically targeting muscle loss in spinal muscular atrophy (SMA), covering adults and children 2 years and older who are already receiving SMN2-targeting treatments. In late-stage data highlighted in the FDA decision coverage, Isembyld used in combination with an SMN2-targeting drug improved motor outcomes at one year versus placebo, with young patients showing benefit while the placebo group declined. The approval adds a new mechanism layered on top of the SMN2 standard-of-care. For SMA developers and payers, the decision also reinforces a sequencing model—combining muscle-loss targeting with SMN-restoring strategies—potentially shaping future labeling, clinical trial designs, and combination adoption.