Enzyme Replacement Therapy Can Reverse Pathogenic Cascade in Pompe Disease

Pompe disease, a deficiency of glycogen-degrading lysosomal acid alpha-glucosidase (GAA), is a disabling multisystemic illness that invariably affects skeletal muscle in all patients. The patients still carry a heavy burden of the disease, despite the currently available enzyme replacement therapy. We have previously shown that progressive entrapment of glycogen in the lysosome in muscle sets in motion a whole series of “extra-lysosomal” events including defective autophagy and disruption of a variety of signaling pathways. Here, we report that metabolic abnormalities and energy deficit also contribute to the complexity of the pathogenic cascade. A decrease in the metabolites of the glycolytic pathway and a shift to lipids as the energy source are observed in the diseased muscle. We now demonstrate in a pre-clinical study that a recently developed replacement enzyme (recombinant human GAA; AT-GAA; Amicus Therapeutics) with much improved lysosome-targeting properties reversed or significantly improved all aspects of the disease pathogenesis, an outcome not observed with the current standard of care. The therapy was initiated in GAA-deficient mice with fully developed muscle pathology but without obvious clinical symptoms; this point deserves consideration. [Display omitted] Muscle damage is a prominent feature of Pompe disease, a deficiency of the enzyme acid alpha-glucosidase (GAA), which is required to metabolize glycogen to glucose in the lysosome. Unlike the current enzyme replacement therapy (ERT), the recently developed recombinant GAA (AT-GAA) reverses or significantly improves various aspects of the disease pathogenesis and holds promise for patients suffering from this debilitating disorder.