Astellas said it will pause development of AT132 (resamirigene bilparvovec), a gene therapy for X-linked myotubular myopathy after prior safety concerns including four deaths tied to liver failure and an FDA hold. The company will shift resources to ASP2957, a new muscle-targeted AAV candidate now in Phase 1/2 enrollment. Astellas stated ASP2957 is designed to increase muscle specificity and reduce liver targeting, enabling clinical study initiation at about 100-fold lower dose levels compared with AT132, based on preclinical findings. Astellas also said it dropped two Phase 1 candidates and fully ended development of additional assets reported in its 2025 financial results. The move highlights how gene therapy programs are being re-engineered and reprioritized after safety events, with dosing strategy and vector targeting becoming central to next-step clinical plans.