Astellas Gene Therapies licensed a MyoAAV capsid‑based gene therapy (ASP2957) for X‑linked myotubular myopathy (XLMTM) via a deal tied to Kate Therapeutics’ technology. ASP2957 encodes human MTM1 under a muscle‑specific promoter and uses an engineered capsid designed to boost muscle uptake and permit lower systemic AAV doses. The program follows previous safety setbacks with AAV‑based XLMTM candidate AT132; Astellas emphasised the newer capsid profile aims to reduce required vector dose and improve tolerability. The company is recruiting the Phase I/II VALOR trial (NCT07052929) to evaluate safety and early activity. Astellas framed ASP2957 as an example of iterative vector engineering intended to address dosing and safety concerns in systemic muscle gene therapies.