• Muscle funtion improved in 17 of 19 patients at month 12
• Treatment with AT-GAA resulted in persistent and durable reductions in key biomarkers of muscle damage across all patient cohorts out to month 18
• Amicus anticipates initiation of a pivotal study to support full approval in U.S. and EU, as well as other geographies (2H18)

Amicus Therapeutics (Nasdaq: FOLD)  announced on 10/5/18 additional positive results from a global Phase 1/2 clinical study (ATB200-02) to investigate AT-GAA in patients with Pompe disease, an inherited lysosomal storage disorder caused by an enzyme deficiency that leads to accumulation of glycogen (disease substrate) in cells. Patients treated with AT-GAA for up to 18 months showed improvements in six-minute walk test (6MWT) distance and other measures of motor function and muscle strength, stability or increases in forced vital capacity (FVC), and durable reductions in biomarkers of muscle damage and disease substrate. These clinical results are being featured at the 23rd International Annual Congress of the World Muscle Society in an oral platform presentation today, Friday October 5, 2018 at 12:20am ART (11:20am EDT). The presentation will be given by Professor Benedikt Schoser, senior consultant at the Friedrich-Baur-Institute, Dept. of Neurology at the Ludwig-Maximilians-University of Munich, Germany and Principal Investigator in the ATB200-02 study.

John F. Crowley, Chairman and Chief Executive Officer of Amicus Therapeutics stated, “The clinical data for our investigational therapy for Pompe disease AT-GAA are very compelling and consistent across patients and in multiple endpoints now for up to 18 months on treatment. These latest data continue to show meaningful and very durable improvements in functional outcomes in nearly all patients, in addition to persistent and durable reductions in key biomarkers of muscle damage and disease substrate. These new results further support our strategy to significantly enhance the body of clinical data for AT-GAA through our ongoing clinical and natural history studies, as well as our upcoming pivotal study, as we seek to deliver this potential new therapy to as many people living with Pompe disease as soon as possible.”

Data on functional outcomes are available for 19 of the 20 patients enrolled (one patient dropped out of the extension study due to travel burden and family considerations). Muscle function improved in 17 of 19 patients at month 12. Muscle function improved in 17 out of 18 patients with available data at month 18.

Treatment with AT-GAA resulted in persistent and durable reductions in key biomarkers of muscle damage (creatine kinase, or CK) and disease substrate (urine hexose tetrasaccharide, or Hex4) across all patient cohorts out to month 18 and continue to suggest a positive effect on muscle tissue.

Amicus anticipates the following upcoming milestones:

• Initiation of pivotal study to support full approval in U.S. and EU, as well as other geographies (2H18)
• Complete a retrospective natural history study in approximately 100 ERT-treated Pompe patients (2H18)
• Additional ATB200-02 study data from up to 10 additional ERT-switch patients in a new Cohort 4 (2019)
• Initiation of studies in additional patient populations, including pediatric patients (2019)

AT-GAA is an investigational therapy that consists of ATB200, a unique recombinant human acid alpha-glucosidase (rhGAA) enzyme with optimized carbohydrate structures, particularly mannose-6 phosphate (M6P), to enhance uptake, co-administered with AT2221, a pharmacological chaperone. In preclinical studies, AT-GAA was associated with increased tissue enzyme levels, reduced glycogen levels in muscle, and improvements in muscle strength. Amicus Therapeutics is currently conducting a global Phase 1/2 study (ATB200-02) to evaluate the safety, tolerability, pharmacokinetics (PK) and pharmacodynamics of AT-GAA.

Pompe disease is an inherited lysosomal storage disorder caused by deficiency of the enzyme acid alpha-glucosidase (GAA). Reduced or absent levels of GAA leads to accumulation of glycogen in cells, which is believed to result in the clinical manifestations of Pompe disease. Pompe disease can be debilitating, and is characterized by severe muscle weakness that worsens over time. Pompe disease ranges from a rapidly fatal infantile form with significant impacts to heart function to a more slowly progressive, late-onset form primarily affecting skeletal muscle. It is estimated that Pompe disease affects approximately 5,000 to 10,000 people worldwide.