Study to Compare the Efficacy and Safety of Enzyme Replacement Therapies Avalglucosidase Alfa and Alglucosidase Alfa Administered Every Other Week in Patients With Late-onset Pompe Disease Who Have Not Been Previously Treated for Pompe Disease

Primary Objective: To determine the effect of avalglucosidase alfa treatment on respiratory muscle strength measured by percent (%) predicted forced vital capacity (FVC) in the upright position, as compared to alglucosidase alfa. Secondary Objective: To determine the safety and effect of avalglucosidase alfa treatment on functional endurance (6-minute walk test, inspiratory muscle strength (maximum inspiratory pressure), expiratory muscle strength (maximum expiratory pressure), lower extremity muscle strength (hand-held dynamometry), motor function (Quick Motor Function Test), and health-related quality of life (Short Form-12).

The duration of the study per participant will be up to approximately 6 years that will consist of a 14-day screening period (may be extended up to 8 weeks in pre-specified situations), a 49-week blinded treatment period (except for the subgroup of pediatric patients aged 3 to less than (\<) 18 years enrolling directly in the open-label long-term follow-up phase), a 240-week open-label treatment period, and a 4-week post-treatment observation period.