Participants not interested in enrolling.

Hypothesis: the effectiveness of treatment of Pompe disease with rhGAA enzyme replacement therapy (ERT) is limited at least in part because patients develop antibodies against the provided rhGAA enzyme. Treatment with Zavesca® prior to infusion may dampen or eliminate the anti-rhGAA immune response in patients receiving ERT, thereby allowing for greater ERT efficacy.

Treatment with Zavesca® before a enzyme replacement therapy (ERT) may decrease the severity of, or eliminate infusion associated reactions (IAR) in people with Pompe Disease receiving ERT.

This Study is designed to assess the effects of Zavesca® as immunomodulatory therapy on anti-rhGAA immune responses in patients with Pompe disease, as well as their health and disease progression. Subjects will either receive Zavesca® at 100 mg or 300 mg dosing levels during study participation (n=3 @ 100 mg dosing; n=3 @ 300 mg dosing).

The first 3 subjects enrolled will be prescribed 100 mg Zavesca® 60 minutes prior to ERT infusion. The subsequent 3 subjects enrolled will be prescribed 300 mg Zavesca® 60 minutes to ERT infusion.

Eligible participants are on standard ERT for Pompe disease and have a history of infusion associated reaction. Travel to the study site in Gainesville, Florida is required for 3 visits. Participants are prescribed medication Zavesca® and have blood tests, punch muscle biopsy, physical exams, and answer questionnaires over 3 months study participation.

Inclusion Criteria:

Subjects will be patients between the ages of 18 years and 65 years who have been diagnosed with Pompe Disease, confirmed by mutational analysis and/or GAA enzyme activity assay.

• Receiving rhGAA ERT
• Willing to travel to the study site for study assessments
• Willingness of local medical treatment provider to continue treating study participant with addition of Zavesca® to treatment plan.
• Willingness of study participant to modify dietary intake on day of infusion *All Subjects will continue enzyme replacement therapy as standard of care, as prescribed by local medical treatment provider during the course of the Study.

Exclusion Criteria:

• Subject is unable to meet the study requirements
• Subject's medical condition contraindicates participation or Study Investigators feel that participation is otherwise not in the Subject's best interest
• Subject does not receive ERT treatment
• Participation in other interventional studies at the time of enrollment that may interfere with this study (at the investigator's discretion)
• Unable to travel to the University of Florida for study visits