Glycogen storage disease type II or Pompe disease is characterized by muscle weakness, cardiomyopathy and frequent respiratory failure. It is due to the lack of an enzyme, alpha-glucosidase (GAA) or acid maltase, responsible for the degradation of glycogen to glucose in cells. This results in excessive accumulation of glycogen in the lysosomes of cells of different organs. Enzyme replacement therapy is currently the main treatment. In this study, Dutch researchers describe the results of a randomized, placebo-controlled Phase III clinical trial conducted by Genzyme. The trial assessed the efficacy of a recombinant human GAA (alglucosidase alfa or Myozyme) for the treatment of late forms of Pompe disease. Ninety patients aged 10-70 years, ambulatory and without invasive ventilation, received intravenous Myozyme (20mg/kg body weight) or placebo every two weeks for 78 weeks in eight centres in the U.S. and Europe. The two main criteria for evaluating the effectiveness of treatment were the distance covered during a 6-minute walking test and the value of the vital capacity. After 78 weeks, treated patients showed an improvement of 28.1 m (+ / -13.1 m) in the 6-minute walking test and an improvement of 3.4% (+ / -1.2%) in the vital capacity, despite the advanced stage of the disease, while placebo patients continued to deteriorate. The number of reported side effects was similar in both groups (treated and placebo).

Références : van der Ploeg AT, Clemens PR, Corzo D, Escolar DM, Florence J, Groeneveld GJ, Herson S, Kishnani PS, Laforet P, Lake SL, Lange DJ, Leshner RT, Mayhew JE, Morgan C, Nozaki K, Park DJ, Pestronk A, Rosenbloom B, Skrinar A, van Capelle CI, van der Beek NA, Wasserstein M, Zivkovic SA. A randomized study of alglucosidase alfa in late-onset Pompe's disease. N Engl J Med. 2010 Apr 15;362(15):1396-406.