P.67 - Effect of enzyme replacement therapy with alglucosidase alfa (Myozyme®) in 12 patients with advanced late-onset Pompe disease

Abstract

Glycogen storage disease type II (Pompe disease) is a lysosomal disorder caused by deficiency in acid α-glucosidase. Enzyme replacement therapy (ERT) with recombinant human alglucosidase alfa (Myozyme®, Genzyme) is available since 2006. So far, treatment benefit in adults has been mostly evaluated in patients who maintained ability to walk, and without permanent ventilator assistance. The aim of this study is to evaluate ERT efficacy in twelve patients with advanced Pompe disease, identified from the French Pompe registry. Inclusion criteria were wheelchair dependency and ventilation support (>12 h/24) upon ERT initiation. Home mechanical ventilation hours, forced vital capacity (FVC), maximal inspiratory pressure (MIP), maximal expiratory pressure (MEP), ability to walk a few steps and motor function measure (MFM) scale prior and after ERT were studied, where available. Age at ERT initiation ranged from 20 to 73 years (mean = 49.3) and disease duration from 13 to 40 years (mean = 23.9). Years on ventilation varied from 4 to 40 (mean = 15.4) and of wheelchair use from 1 to 20 (mean = 9). ERT duration ranged from 9 to 111 months (mean 54.4). During follow-up, one patient reduced his daily time of ventilatory support, 9 remained fully dependant (24 h/24) and two became fully dependant of assisted ventilation. Values of FVC, MIP and MEP did not change significantly. At ERT initiation, 3 patients could walk a few meters with aid. Two of them increased their walking distance, while a decrease was observed in the third one. There were no significant changes of MFM values between start of ERT and last follow-up. Moreover, 5 patients died, after a treatment period ranging from 9 to 64 months (mean = 33.4). In our series of 12 patients who started ERT in an advanced stage of Pompe disease, we observed a clinically meaningful improvement of respiratory or muscle functions in two patients. Five patients died and five remained wheelchair bound and fully dependant of ventilatory support.