Gene Transfer Study in Patients With Late Onset Pompe Disease

This study (FORTIS) will evaluate the safety and efficacy of an investigational gene replacement therapy, AT845, in adult subjects with LOPD. Subjects will receive a single dose of AT845 delivered via intravenous (IV) infusion. Up to 3 nominal dose levels of AT845 are planned to be evaluated in this study. A single AT845 administration via IV infusion is planned for each subject. The initial dosing cohort received a single dose of 3x10\^13 vg/kg of AT845. The second dose cohort will receive a single dose of 6×10\^13 vg/kg. The third dose cohort will receive a single dose of 1×10\^14 vg/kg. Dose escalation between cohorts will be based on evaluations of safety and in consultation with the independent DMC. There will be a core observation period of 48 weeks with scheduled visits and assessments. Following the conclusion of the core observation period, subjects will be seen every 6 months for a safety follow-up visit for up to 10 years postdose.