ISEMBYLD (apitegromab-mstn) approved as the first muscle-targeted treatment for spinal muscular atrophy, for adults and children 2 years and older already receiving an SMN2-targeted therapy (Sep 11 2026).
Run-up into the decision (T-120 → T+5)
Daily close, T-120 (3/20/26) through T+1. Run-up high $60.04 on 8/26/26, low $42.3 on 3/24/26 (T-120 to T-1). FDA decision 9/11/26. Historical price action, not a forecast.
Key facts
FDA decision date2026-09-11
OutcomeApproved
Drug / candidateISEMBYLD (apitegromab-mstn)
IndicationSpinal muscular atrophy (SMA)
CompanyScholar Rock Holding Corporation
Market-cap tierMid
120-day run-up (T-120→T-1)+24.7%
Cohort decision-day move (history)2.2% median (n=233)
The PDUFA goal date was September 30, 2026 and the FDA approved on September 11, 19 days early. That goal date came from Scholar Rock's own 8-K of May 7, 2026, which is why the gap is quoted here as a measurement rather than an impression. The BLA was a resubmission: the FDA issued a Complete Response Letter on September 22, 2025 over observations at a third-party fill-finish facility, not over apitegromab's efficacy or safety, and Scholar Rock resubmitted on March 31, 2026 with two fill-finish facilities included.
Run-up figures are the stock's own daily closing path over the 120 trading days before the decision, from our price history. Cohort move is the historical median absolute decision-day move for this market-cap tier. History, not a prediction.
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