First-In-Human Study to Evaluate Safety, Tolerability, and PK of Intravenous ATB200 Alone and When Co-Administered With Oral AT2221

Key Inclusion Criteria:

1. Male and female subjects between 18 and 75years of age, inclusive
2. Diagnosis of Pompe disease

Enzyme Replacement Therapy (ERT)-experienced subject (ambulatory):

1. Has received ERT with alglucosidase alfa for the previous 2-6 years, inclusive
2. Subject is currently receiving alglucosidase alfa (Myozyme/Lumizyme), at a frequency of once every other week
3. Must be able to walk 200-500 meters on the 6-Minute Walk Test (6MWT )
4. Has upright Forced Vial Capacity (FVC) 30% to 80% of predicted normal value

ERT-experienced subjects (non-ambulatory):

1. Has received ERT with alglucosidase alfa (Myozyme/Lumizyme) for ≥2 years
2. Is wheelchair-bound

ERT-naïve subjects (ambulatory):

1. Must be able to walk 200-500 meters on the 6MWT
2. Has upright FVC must be 30% to 80% of predicted normal value
3. Subject has never received alglucosidase alfa

Enzyme Replacement Therapy (ERT)-experienced subject (ambulatory):

1. Has received ERT with alglucosidase alfa for >7years, inclusive
2. Subject is currently receiving alglucosidase alfa (Myozyme/Lumizyme), at a frequency of once every other week
3. Must be able to walk 200-500 meters on the 6-Minute Walk Test (6MWT )
4. Has upright Forced Vial Capacity (FVC) 30% to 80% of predicted normal value

Exclusion Criteria:

1. Subject has received treatment with prohibited medications within 30 days of Baseline Visit
2. Subject, if female, is pregnant or breastfeeding at screening
3. Subject, whether male or female, planning to conceive a child during the study
4. Subject has a medical or any other extenuating condition or circumstance that may, in opinion of investigator, pose an undue safety risk to the subject or compromise his/her ability to comply with protocol requirements
5. Subject has a history of allergy or sensitivity to miglustat or other iminosugars
6. Subjects with active systemic autoimmune disease such as lupus, scleroderma, or rheumatoid arthritis. All subjects with autoimmune disease must be discussed with the Amicus Medical Monitor
7. Subjects with active bronchial asthma. All subjects with bronchial asthma must be discussed with the Amicus Medical Monitor