Abstract-Background:Pompe disease is a progressive metabolic neuromuscular disorder resulting from deficiency of lysosomal acid ␣-glucosidase (GAA). Infantile-onset Pompe disease is characterized by cardiomyopathy, respiratory and skeletal muscle weakness, and early death. The safety and efficacy of recombinant human (rh) GAA were evaluated in 18 patients with rapidly progressing infantile-onset Pompe disease. Methods: Patients were diagnosed at 6 months of age and younger and exhibited severe GAA deficiency and cardiomyopathy. Patients received IV infusions of rhGAA at 20 mg/kg (n ϭ 9) or 40 mg/kg (n ϭ 9) every other week. Analyses were performed 52 weeks after the last patient was randomized to treatment. Results: All patients (100%) survived to 18 months of age. A Cox proportional hazards analysis demonstrated that treatment reduced the risk of death by 99%, reduced the risk of death or invasive ventilation by 92%, and reduced the risk of death or any type of ventilation by 88%, as compared to an untreated historical control group. There was no clear advantage of the 40-mg/kg dose with regard to efficacy. Eleven of the 18 patients experienced 164 infusion-associated reactions; all were mild or moderate in intensity. Conclusions: Recombinant human acid ␣-glucosidase is safe and effective for treatment of infantile-onset Pompe disease. Eleven patients experienced adverse events related to treatment, but none discontinued. The young age at which these patients initiated therapy may have contributed to their improved response compared to previous trials with recombinant human acid ␣-glucosidase in which patients were older.

Objective-To conduct an open-label, multinational, multicenter study examining the safety and efficacy of recombinant human acid α-glucosidase (rhGAA) in treatment of infantile-onset Pompe disease.Study design-We enrolled 8 infant patients who had Pompe disease with GAA activity <1% of normal, cardiomyopathy, and hypotonia. In the 52-week initial phase, rhGAA was infused intravenously at 10 mg/kg weekly; an extension phase continued survivors' treatment with 10 to 20 mg/kg of rhGAA weekly or 20 mg/kg every 2 weeks for as long as 153 weeks. Safety measurements included adverse events, laboratory tests, and anti-rhGAA antibody titers. Efficacy evaluations included survival, ventilator use, echo-cardiograms, growth, and motor and cognitive function.Result-After 52 weeks of treatment, 6 of 8 patients were alive, and 5 patients were free of invasive ventilator support. Clinical improvements included ameliorated cardiomyopathy and improved growth and cognition. Five patients acquired new motor milestones; 3 patients walked independently. Four patients died after the initial study phase; the median age at death or treatment withdrawal for all patients was 21.7 months, significantly later than expected for patients who were not treated. Treatment was safe and well tolerated; no death was drug-related. Patients with infantile-onset Pompe disease typically present before 12 months of age with progressive, hypertrophic cardiomyopathy that may obstruct left ventricular outflow; profound muscle weakness and hypotonia; non-attainment or loss of motor milestones; difficulty feeding; and failure to thrive. These patients have a dramatically shortened life span. In patients who are not treated, the median age of death ranges from 6.0 to 8.7 months. 4,7 In the most rapidly progressive form, also termed "classic" infantile Pompe disease, the mortality rate is as high as 92% to 95% in the first year of life. 7 In an historical cohort of patients manifesting Pompe disease in the first year of life, irrespective of phenotype, 74% died by 1 year of age, 91% by 2 years of age, and 93% by 3 years of age. 7 Death generally results from cardiac and respiratory failure. 1,3,7No approved specific treatment for Pompe disease currently exists. However, recombinant human GAA (rhGAA) has shown physiological activity both in animal disease models and in early clinical trials. 8-15 In 3 pilot studies in severely affected infants, rhGAA (purified from transgenic rabbit milk 11-14 or from Chinese hamster ovary [CHO] cell cultures 8 ) markedly ameliorated cardiomyopathy and prolonged all patients' survival beyond 1 year. One of 6 patients given rhGAA from rabbit milk (a preparation that is no longer available) and 1 of 3 patients given CHO cell-derived rhGAA walked independently and remained ventilator-free. The remaining 7 patients from these 3 studies showed lesser degrees of motor improvement and eventually required ventilation. As of January 2006, 3 of the 9 patients in these pilot studies had died and 6 remained alive (unpublished data)...