UniQure’s Huntington’s disease gene therapy AMT-130 continued to slow progression after four years, but the company disclosed that the magnitude of benefit has waned compared with prior analyses. In the update, a high dose slowed disease progression versus a matched external control group, though the difference was not statistically significant in the new analysis. The report describes a challenging setup for the FDA marketing review as the company works through durability and endpoint interpretation concerns. Investors reacted sharply to the weaker signal magnitude, reflecting heightened sensitivity to statistical confidence at longer follow-up windows. For biotech developers, the case illustrates how long-term durability evidence can become the central gating issue even when early efficacy remains evident in functional or exploratory endpoints.