FAYUVI (rebisufligene etisparvovec-hopf, UX111) approved as the first treatment for pediatric patients with Sanfilippo syndrome type A, a standard full approval with a Priority Review Voucher (Sep 17 2026).
Run-up into the decision (T-120 → T+5)
Daily close, T-120 (3/26/26) through T+1. Run-up high $35.87 on 7/7/26, low $12.88 on 9/16/26 (T-120 to T-1). FDA decision 9/17/26. Historical price action, not a forecast.
Key facts
FDA decision date2026-09-17
OutcomeApproved
Drug / candidateFAYUVI (rebisufligene etisparvovec-hopf; UX111)
IndicationMucopolysaccharidosis type IIIA (Sanfilippo syndrome type A), pediatric patients
CompanyUltragenyx Pharmaceutical Inc.
Market-cap tierMid
120-day run-up (T-120→T-1)-35.6%
Cohort decision-day move (history)2.2% median (n=233)
The PDUFA action date was September 19, 2026 and the FDA approved on September 17, two days early. That goal date came from Ultragenyx's own 8-K of April 2, 2026 ("The FDA set a Prescription Drug User Fee Act (PDUFA) action date of September 19, 2026"), which is why the margin is quoted as a measurement. The BLA was a resubmission after an earlier Complete Response Letter; UX111 was licensed from Abeona Therapeutics.
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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