A Study of AT132 in Young Children With X-Linked Myotubular Myopathy (XLMTM)

This study evaluated safety and efficacy of gene transfer in X-Linked Myotubular Myopathy. Participants received a single dose of resamirigene bilparvovec delivered intravenously. ASPIRO was being conducted in two parts. Part 1 was a dose escalation phase that was evaluating the preliminary safety and efficacy of Resamirigene bilparvovec at doses of 1.3x10\^14 vg/kg and 3.5x10\^14 vg/kg. Part 2 of ASPIRO was a pivotal expansion cohort designed to confirm the safety and efficacy of resamirigene bilparvovec at a dose of 3.5x10\^14 vg/kg. The pivotal expansion cohort enrolled eight participants, consisting of four age-matched pairs (within +/- 6 months of age). One participant from each pair was randomized to receive a single dose of resamirigene bilparvovec at 3.5x10\^14 vg/kg, and the other served as a delayed treatment control. Eligible delayed treatment control participants administered resamirigene bilparvovec after that individual participant completed the Week 24 visit as a delayed treatment control. The primary efficacy endpoint measures assessed at Week 24. Participants were followed for a total of 10 years after administration of resamirigene bilparvovec. Only Part 1 of the study was reported. This study utilized an independent Data Monitoring Committee (DMC) that monitored participant safety and provided recommendations to Astellas regarding dose escalation, dose expansion, and safety matters.