Overall safety summary of patients experiencing Adverse Events (AEs), Serious Adverse Events (SAEs), treatment-related AEs, and Infusion Associated Reactions (IARs). Summary is based on Treatment-emergent AEs (TEAEs), defined as AEs that occurred following the initiation of study treatment, i.e., alglucosidase alfa or placebo.

All patients who received any amount of study treatment comprise the safety population. Patients were considered, for safety analysis, to be in the treatment group of the treatment they actually received.

Missing or invalid safety or resource utilization data were not replaced.

Mean distance walked gives an indication of functional endurance. The greater the distance, the greater the endurance. Mean values of distance walked in a six-minute walk test are offered for baseline, week 78 (or last available observation), and the mean change from baseline (at week 78 or last available post-baseline observation).

Intent-to-Treat (ITT) population. Last observation carried forward. The last available distance walked for one patient was the Baseline visit; therefore, this patient was excluded from the change from baseline calculation.

Forced vital capacity is a standard pulmonary function test used to quantify respiratory muscle weakness. Forced vital capacity (FVC) is the volume of air that can forcibly be blown out after full inspiration in the upright position, measured in liters. Predicted forced vital capacity is based on a formula using sex, age and height of a person, and is an estimate of healthy lung capacity. Percent of predicted FVC = (observed value)/(predicted value) * 100%.

ITT population. Last observation carried forward.

Quantitative muscle testing (QMT) is a standardized system to measure muscle force production during maximal voluntary isometric contraction. QMT data were collected directly from sensors into laptop computers. Predicted normal values for QMT are based on a formula using sex, age and body mass index of a person, and is an estimate of healthy muscle force. Percent of predicted QMT = (observed value)/(predicted value) * 100%. The QMT Leg Score is the average of the bilateral means for percent predicted knee flexors and extensors. A value of 100% indicates 'normal' muscle strength.

ITT population. Last observation carried forward.

The Medical Outcomes Study Short Form (MOS SF)-36 questionnaire consists of 36 items grouped into 8 domains designed to assess generic health-related quality of life in healthy and ill adult populations. Physical Component Scores (PCS) report the four domains of physical functioning, role-physical, bodily pain, and general health. Higher scores are associated with better quality of life. All questions are scored on a scale from 0 to 100, with 100 representing the highest level of functioning possible. The PCS scores are reported.

ITT population. Last observation carried forward.

Area under the plasma concentration versus time curve from time zero (pre-dose) to 16 hours after the end of infusion. Blood sample time points were 0 (before the start of the infusion), 1 and 2 hours after the start of infusion, end of the infusion, and then 0.25, 0.5, 1, 2, 3, 4, 8, 12,and 16 hours after the end of the infusion (with a 5-minute window for time-points after the start of infusion). Pooled figures combine the values for the three timeframes.

The subgroup of patients for whom pharmacokinetic samples were obtained was based on those study sites that could accommodate pharmacokinetic sampling needs.

Maximum plasma concentration observed in blood samples taken at the following time points: 0 (before the start of the infusion), 1 and 2 hours after the start of infusion, end of the infusion, and then 0.25, 0.5, 1, 2, 3, 4, 8, 12,and 16 hours after the end of the infusion (with a 5-minute window for time-points after the start of infusion). Pooled figures combine the values for the three timeframes.

The subgroup of patients for whom pharmacokinetic samples were obtained was based on those study sites that could accommodate pharmacokinetic sampling needs.

Time to maximum plasma concentration observed in blood samples taken at the following time points: 0 (before the start of the infusion), 1 and 2 hours after the start of infusion, end of the infusion, and then 0.25, 0.5, 1, 2, 3, 4, 8, 12,and 16 hours after the end of the infusion (with a 5-minute window for time-points after the start of infusion). Pooled figures combine the values for the three timeframes.

The subgroup of patients for whom pharmacokinetic samples were obtained was based on those study sites that could accommodate pharmacokinetic sampling needs.