Astellas Gene Therapies announced a partnership and exclusive license with Kate Therapeutics/Novartis assets to develop ASP2957 (MyoAAV3.8‑MHCK7‑hMTM1), a MyoAAV capsid‑based gene therapy for X‑linked myotubular myopathy (XLMTM). The program follows safety failures in prior AAV XLMTM trials; Astellas says the MyoAAV capsid improves muscle uptake and enables lower dosing, which it expects will reduce dose‑related toxicity risks. Astellas is recruiting for the Phase I/II VALOR trial (NCT07052929) to evaluate safety and initial efficacy. Company comments stress dose reduction and capsid engineering as the key differentiators versus earlier candidates.