The FDA approved Scholar Rock’s Isembyld (myostatin inhibitor, used with SMN2-targeted therapy) for spinal muscular atrophy muscle loss in adults and children aged 2 and older, based on late-stage data showing improved motor outcomes versus placebo. The decision marks the first FDA-cleared therapy aimed specifically at muscle loss in SMA, not SMN2 biology. In a separate regulatory item, the FDA issued a second complete response letter (CRL) to Seikagaku for its condoliase resubmitted BLA (SI-6603), citing unresolved deficiencies tied to drug substance manufacturing and new cGMP issues at a contract facility for drug product manufacturing. Together, the moves highlight how SMA-specific mechanism expansion is advancing while certain manufacturing-and-quality hurdles remain decisive for other neuromuscular and pain programs.