The FDA cleared Scholar Rock’s myostatin inhibitor apitegromab (branded Isembyld) for spinal muscular atrophy, including adults and children at least 2 years old who are receiving an SMN-targeted therapy. The approval followed manufacturing-related holds and a prior complete response delay, and it changes the SMA treatment mix by adding a muscle-targeted mechanism. Scholar Rock said the clearance comes alongside existing targeted SMA therapies, positioning Isembyld to improve motor outcomes by blocking myostatin’s inhibition of muscle growth. For SMA developers and payers, the decision clarifies label scope for add-on use and further intensifies competitive dynamics around combination regimens.