The purpose of this study is to evaluate the safety, pharmacodynamics (PD), and exploratory clinical efficacy of S-606001 in adult participants with LOPD as an add-on to ERT.
Participant must be ≥18 years of age and ≥40 kilograms (kg) of body weight at the time of signing the informed consent.
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 ≥10% %FVC drop from upright position to supine position and %FVC ≥20% in a supine position.
Has a medical condition or any other extenuating circumstance that may 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.