How do I qualify? Study participant must meet all of the inclusion criteria and none of the exclusion criteria to participate in the study.
- Male or female participants (ERT-naïve [have never received a dose of alglucosidase alfa] or ERT-experienced [have received at least 1 dose of alglucosidase alfa]), diagnosed with late-onset Pompe disease who are aged 12 to < 18 years at screening
- Participant's parent or legally authorized representative is willing and able to provide written informed consent and authorization for use and disclosure of personal health information or research-related health information, and participant provides assent, if applicable based on site and local regulations
- Participant must have a diagnosis of LOPD based on documentation of one of the following:
- Deficiency of GAA enzyme
- GAA genotyping
- If of reproductive potential, both male and female participants agree to use a highly effective method of contraception throughout the duration of the study and for up to 90 days after their last dose of the investigational treament, ATB200/AT2221
- Participant has a sitting Forced Vital Capacity (FVC) ≥ 30% of the predicted value for healthy adolescents (Global Lung Function Initiative [GLI]) at screening
- Participant performs two 6MWTs at screening that are valid, as determined by the clinical evaluator, and that meet all of the following criteria:
- Both screening values of 6-Minute Walk Distance (6MWD) are ≥ 75 meters
- Both screening values of 6MWD are ≤ 90% of the predicted value for healthy adolescents
- The lower value of 6MWD is within 20% of the higher value of 6MWD
- Participant has received any investigational/experimental drug, biologic or device within 30 days or 5 half-lives of the therapy1 or treatment, whichever is longer, before screening
- Participant has received treatment with prohibited medications2 within 30 days of screening
- Participant has received any gene therapy at any time
- Participant has any intercurrent illness or condition at screening or baseline that may preclude the participant from fulfilling the protocol requirements or suggests to the investigator and/or the medical monitor that the potential participant may have an unacceptable risk by participating in this study
- Participant has a hypersensitivity to any of the excipients in ATB200, alglucosidase alfa, or AT2221
- Female participant is pregnant or breast-feeding at screening
- Participant requires the use of ventilation support for > 6 hours per day while awake
- None of these medications have a half-life that, when multiplied by 5, is longer than 30 days.
Use of the following medications is prohibited during this study: miglitol (e.g. Glyset®), non-study miglustat (e.g. Zavesca®), Myozyme® or Lumizyme® after treatment with ATB200/AT2221 has begun, acarbose (e.g. Precose® or Glucobay®), voglibose (e.g. Volix®, Vocarb®, or Volibo®), any investigational/experimental drug.