Regenxbio said the FDA will reconsider its Hunter syndrome gene therapy after the agency reversed course following rejection. The company plans to resubmit its application for RGX-121, with resubmission timing expected in the third quarter. Regenxbio reported the FDA acknowledged its existing clinical data are sufficient for an accelerated approval pathway and no longer requires additional enrollment or a new untreated control arm. The company previously faced an FDA stance that uncertainties around eligibility criteria and external controls warranted more stringent comparator designs. The update follows a broader pattern of rare-disease regulatory reversals after leadership departures within the FDA’s biologics oversight teams. If the FDA accepts a resubmission, it could re-open a previously stalled program for a condition with limited options and intensify scrutiny on how external controls and endpoint justification are evaluated across gene therapy submissions.