A Study to Assess Safety and Efficacy of Avalglucosidase Alfa Administered Every Other Week in Pediatric Patients With Infantile-onset Pompe Disease Previously Treated With Alglucosidase Alfa

Prior treatment

• The participant has high antibody titer to alglucosidase alfa.
• The participant requires any prohibited concomitant medications (e.g., immune modulatory treatment) for the duration of the study.
• The participant has previously participated in any ACT14132 study cohort.

Other illness

• The participant has a high risk for a severe allergic reaction to neoGAA (avalglucosidase alfa).

Other

• Participants are excluded from the study if any of the following criteria apply:
• Female participant of childbearing potential not protected by highly effective contraceptive method of birth control and/or who is unwilling or unable to tested for pregnancy.
  • The above information is not intended to contain all considerations relevant to a participant's potential participation in a clinical trial.

• The participants has confirmed acid alpha-glucosidase (GAA) enzyme deficiency from any tissue source.
• The participants who has reached legal age of majority as defined by local regulation, or the participant's legal guardian(s) must provide signed informed consent prior to performing any study-related procedures. If the participant is legally minor per local regulations, assent shall be obtained from participants, if applicable.
• The participants (and participant's legal guardian if participant is legally minor as defined by local regulation) must have the ability to comply with the clinical protocol.
• The participants is less than 18 years old.
• The participants, if female and of childbearing potential, must have a negative serum pregnancy test (beta-human chorionic gonadotropin) and must not breastfeeding at screening/Baseline.
• The participant has cardiomyopathy at the time of diagnosis: i.e., left ventricular mass index (LVMI) equivalent to mean age specific LVMI plus 2 standard deviations.
• The participant has been receiving a stable dose of alglucosidase alfa regularly for a minimum of 6 months immediately prior to study entry.
• For participants in Stage 1: The participant has documented evidence of clinical decline in at least 1 of the following parameters related to Pompe Disease and not related to intercurrent illness as assessed by the Investigator: respiratory function, motor skills, and/or cardiac parameters.
• For participants in Stage 2: The participant has documented evidence of suboptimal clinical response in at least 1 of the following parameters related to Pompe Disease and not related to intercurrent illness as assessed by the Investigator: respiratory function, motor skills, and/or new onset of ptosis.