Effect of AT2220 on ERT-Related Immunogenicity Measured ex vivoBy stabilizing the folded and active form of the rhGAA enzyme, AT2220 may mitigate ERT-induced immunogenicity since unfolded and aggregated proteins are generally more antigenic than properly folded proteins. Recent published studies show that approximately 40% of the administered ERT can be captured by circulating antibodies and infusion associated reactions occur in approximately 50% of Pompe patients receiving ERT infusions. 2 Initial ex vivo studies using T cells derived from blood from 50 healthy donors demonstrated that the addition of AT2220 may significantly reduce the immunogenicity of Myozyme and Lumizyme. The studies utilized Antitope Ltd.'s EpiScreen™ assay and are being repeated in samples from the Pompe patients in Study 010. Results from these ex vivo studies may help to guide the clinical investigation of the effects of AT2220 on ERT-related immunogenicity. Study 010 Design Study 010 is a Phase 2 open-label, multi-center study to evaluate the safety and PK effects of four increasing oral doses of AT2220 (50 mg, 100 mg, 250 mg, or 600 mg) co-administered with ERT (Myozyme ®/Lumizyme ®) versus ERT alone in males and females with Pompe disease. The study enrolled male and female patients who had been on a stable dose and regimen of ERT for at least three months. All patients were given a regularly scheduled ERT infusion. One hour prior to the initiation of the next ERT infusion, patients received a single oral dose of AT2220. Plasma rhGAA activity and protein levels were evaluated during each infusion. Each patient underwent muscle biopsies three or seven days after each infusion to measure tissue GAA enzyme activity with and without the chaperone, as well as to measure the level of AT2220 in the muscle. More information about Study 010 can be obtained by visiting www.clinicaltrials.gov : NCT1380743 or www.pompestudy.com . About Amicus Therapeutics Amicus Therapeutics (Nasdaq:FOLD) is a biopharmaceutical company at the forefront of developing therapies for rare diseases. The Company is developing orally-administered, small molecule drugs called pharmacological chaperones, a novel, first-in-class approach to treating a broad range of human genetic diseases. Amicus' late-stage programs for lysosomal storage disorders include migalastat HCl monotherapy in Phase 3 for Fabry disease; migalastat HCl co-administered with enzyme replacement therapy (ERT) in Phase 2 for Fabry disease; and AT2220 co-administered with ERT in Phase 2 for Pompe disease.