Clinical/Endpoint CRL, RGX-121 (MPS II): FDA cited uncertainty on study eligibility criteria, natural-history external-control comparability, and the surrogate endpoint (CSF HS D2S6).
Price into the decision (T-120)
Daily close, T-120 (8/22/25) through T+5. Run-up high $15.98 on 1/22/26, low $8.03 on 8/26/25 (T-120 to T-1). FDA decision 2/8/26. Historical price action, not a forecast.
CRL reasonClinical/Endpoint, RGX-121 (MPS II): FDA cited uncertainty on study eligibility criteria, natural-history external-control comparability, and the surrogate endpoint (CSF HS D2S6).
ValidationOutcome consistent with price; primary-source verification in progress.
Market-cap tierSmall
Cohort decision-day move (history)3.6% median (n=280)
Cohort move is the historical median absolute decision-day move for this market-cap tier across our run-up study. History, not a prediction.
Not in this review cycle. On February 8, 2026 the FDA issued a Complete Response Letter, declining to approve the application for RGX in its current form. A CRL is not final; the primary source is linked on this page.
How did RGNX stock react to the FDA decision?
On the decision day RGNX moved -0.2%. That is the recorded reaction to this specific event -- historical measurement, not a prediction, and not investment advice.