UniQure said the U.S. Food and Drug Administration signaled that data from its phase I/II AMT‑130 program compared with an external control group may not be adequate to support a biologics license application. The company said the agency’s reversal is “a key shift from prior communications” and that the timing of any BLA submission is now unclear. AMT‑130 is an experimental in‑brain gene therapy for Huntington’s disease; uniQure’s stock plunged on the news as investors reassessed the regulatory pathway. External‑control designs use historical or untreated patient data in lieu of a randomized placebo arm; the FDA’s change raises questions about when single‑arm or small cohort gene‑therapy data will suffice for approval. UniQure said it will urgently engage the agency to seek a path forward but warned that its planned submission timeline is uncertain.