I-4 Long-term follow-up effects on enzyme replacement treatment of adult form of acid maltase deficiency myopathy

We evaluated the clinical efficacy of alglucosidase alpha enzyme replacement therapy (ERT) in 77 patients with late-onset glycogen storage disease type 2 (GSDII) at various stages of disease progression. Previous studies on efficacy led to demonstrate ERT efficacy against placebo in a 18 months study (LOTS, van Der Ploeg, NEJM, 2010). Seventy-seven juvenile or adult patients were treated with ERT in a multi-centre open label non-randomized study with regular clinical assessment for up to 54 months. Recombinant human alpha glucosidase (rh-GAA) was injected by intravenous route at 20 mg/kg i.v. every second week. For analysis, patients were divided in three groups: one group received ERT treatment for 12-18 months, a second group received ERT treatment for 24-30 months, and a third group patients were treated for over 36 months. Clinical assessment included a 6-minute walk test (6MWT), the Walton and Gardner-Medwin scale, forced vital capacity (FVC) and blood creatine kinase (CK). All tests were performed at baseline and every three months thereafter. ERT was associated with a longer walking distance on the 6MWT. FVC was stabilized in most patients, and a significant decrease in number of hours off the ventilator was found in several patients. Few adverse effects were observed, leading to discontinuation of treatment in 1 patient. ERT appears a long term reasonable safe treatment for all patients examined. The response pattern in a single patient was variable and not always correlated with treatment duration.