High Dose or High Dose Frequency Study of Alglucosidase Alfa

Pompe disease (also known as glycogen storage disease Type II) is caused by a deficiency of a critical enzyme in the body called acid alpha-glucosidase (GAA). Normally, GAA is used by the body's cells to break down glycogen (a stored form of sugar) within specialized structures called lysosomes. In patients with Pompe disease, an excessive amount of glycogen accumulates and is stored in various tissues, especially heart and skeletal muscle, which prevents their normal function. The objective of this exploratory study is to evaluate the safety and efficacy of alternative dosing regimens of alglucosidase alfa in patients with Pompe disease who have not demonstrated an optimal response to the standard dosing regimen of 20 mg/kg every other week after a minimum of 6 months treatment immediately prior to study entry.