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CRANBURY, N.J., May 15, 2017 —Amicus Therapeutics today announced positive functional data from initial patients in a global Phase 1/2 study (ATB200-02) to investigate ATB200/AT2221 in patients with Pompe disease. Patients who completed six months of treatment with ATB200/AT2221 showed improvements in the six-minute walk test (6MWT) distance and other measures of motor function, in addition to stability or improvements in forced vital capacity (FVC). Consistent with previous results1 presented at the 2017 WORLDSymposium™, patients treated with ATB200/AT2221 continue to show improvements in biomarkers of muscle damage and disease substrate.

“We are very pleased to see improvements in six minute walk distance and other measures of motor function in both naïve and ERT-switch patients, as well as stability or improvements in forced vital capacity. The consistency and magnitude of improvements exceeded our expectations and follow the initial improvements seen on key biomarkers of muscle damage and disease substrate,” said John F. Crowley, Chairman and Chief Executive Officer of Amicus Therapeutics, Inc. “These preliminary functional results are very encouraging and suggest a clinically meaningful improvement for patients. We look forward to additional data from all patients in the third quarter as we continue in our mission to develop an improved treatment option for people living with Pompe disease.”

ATB200-02 Study – Updated Data Highlights in Initial ERT-Switch and Naive Patients

Safety, Tolerability & Pharmacokinetics (PK)
Safety and tolerability data are currently available for all 20 patients enrolled in the study (maximum 48 weeks). To date, adverse events have been generally mild and transient. Importantly, ATB200/AT2221 has also shown no infusion-associated reactions following 200+ infusions. As previously reported, the clinical PK profile has been consistent with previously reported preclinical data.

Pharmacodynamic (PD) Data on Muscle Damage and Disease Substrate Biomarkers (n=16)
PD data are currently available for 11 ERT-switch patients and five ERT-naïve patients. Improvements in key biomarkers of muscle damage and disease substrate continue to suggest a positive effect of ATB200/AT2221 on muscle cells after up to 34 weeks of treatment.

Muscle damage biomarkers: Creatine kinase (CK) enzyme, alanine aminotransferase (ALT), and aspartate aminotransferase (AST) continue to show a decrease in a majority of patients. Across the three biomarkers, mean reductions from baseline were approximately 15-20% and 50-55% for the ERT-switch and ERT-naïve patients, respectively.

Disease substrate biomarker: Urine hexose tetrasaccharide (Hex4) continues to show decreases in a majority of ERT-switch patients and all ERT-naïve patients, with mean reductions from baseline of approximately 40% and 50% for the ERT-switch and ERT-naïve patients, respectively.

Functional Outcomes at Month 6 (n=10)
Functional outcomes data from baseline to Month 6 are currently available for 10 patients (seven ambulatory ERT-switch, two ERT-naïve and one non-ambulatory ERT-switch). Motor function improved and pulmonary function was stable in ambulatory ERT-switch patients; motor and pulmonary function both improved in ERT-naïve patients. Muscle strength data are available from the first non-ambulatory ERT-switch patient and showed improvement.

Muscle Function:

– Motor function: Six-minute walk test (6MWT) distance, a primary measure of motor function in Pompe patients, increased in both ERT-switch patients (mean +38 meters; improvement in 6/7 patients) and ERT-naïve patients (mean +52 meters; improvement in 2/2 patients). Other motor function tests also showed mean improvements, consistent with 6MWT distance.

– Muscle Strength: In the first non-ambulatory ERT-switch patient, improvements in four out of four muscle groups on the quantitative muscle testing (QMT) and two of three muscle groups on the manual muscle testing (MMT) were observed.

Pulmonary Function: Forced vital capacity (FVC), the primary measure of pulmonary function, was stable in ERT-switch patients (mean absolute change in percent predicted FVC +0.3%) and improved in ERT-naïve patients (mean absolute change +3.0%). Other pulmonary tests included maximal inspiratory pressure (MIP), a measure of inhalation, and maximal expiratory pressure (MEP), a measure of exhalation. MIP and MEP both showed mean increases in ERT-switch patients. MIP showed a mean increase and MEP showed a mean decrease in ERT-naïve patients.

Prof. Dr. Benedikt Schoser of the Friedrich-Baur Institute in Munich, Germany stated, “These preliminary data from the first clinical study of ATB200/AT2221 are very positive and suggest that this could become a significant and different treatment paradigm for Pompe disease. There have been considerable improvements in functional measures, especially the six-minute walk test, among both naïve patients and in ambulatory patients who switched from standard of care. To my knowledge, no other investigational agents show similar positive results across such a broad range of patients at this stage of development. If the full data set is according to these functional measures, then it could be very meaningful for our patients.”

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