A Study of S-606001 as Monotherapy in Participants With Late-onset Pompe Disease (LOPD)

Prior treatment

• Has received any investigational therapy or pharmacological treatment for Pompe disease, within 30 days or 5 half-lives of the therapy or treatment, whichever is longer, before day 1 or is anticipated to do so during the study
• Has received gene therapy for Pompe disease within 2 years of screening or small interfering RNA therapy for Pompe disease within 6 months of screening

Other illness

• Has a medical condition or any other extenuating circumstance that may, in the opinion of the investigator or medical monitor, pose an undue safety risk to the participant or may compromise his/her ability to comply with or adversely impact protocol requirements
• Has active infections at screening
• Malignancy within the past 5 years except for basal cell or squamous epithelial carcinomas of the skin that have been resected with no evidence of metastatic disease for 3 years
• Current or chronic history of liver disease

Other

• Known biallelic loss of function mutations whether in the muscle glycogen synthase gene or in the glycogen phosphorylase muscle associated gene
• Participant, if female, is pregnant or breastfeeding at screening
• Participant, whether male or female, is planning to conceive a child during the study
  • Note: Other protocol-specified inclusion and exclusion criteria may apply.

• Participant must be ≥40 kilograms of body weight at the time of signing the informed consent form
• Participant must have a diagnosis of LOPD based on documentation of the following: deficiency of acid alpha-glucosidase (GAA) enzyme; GAA genotype
• Participant has a %FVC ≥30% and ≤80% in an upright position without mechanical ventilation at screening or participant has \>80% FVC in upright position and ≥10% %FVC drop from upright position to supine position and %FVC ≥20% in a supine position
• Participant performs the 6MWT at screening, as determined by the clinical evaluator, and meets all of the following criteria: screening values of 6-minute walk distance (6MWD) are ≥75 meters; screening values of 6MWD are ≤90% of the predicted value for healthy adults
• Participant must not have received enzyme replacement therapy (ERT) for at least 3 months prior to providing informed consent and enrollment and agrees not receive any type of ERT while participating in the study