In this 52-week, phase I/II double-blind, randomized, placebo-controlled study, the authors investigated the novel use of clenbuterol in eleven participants with late-onset Pompe disease (LOPD) stably treated with ER (NCT01942590).. At week 52, the 6-min walk test distance increased by a mean of 16 m (p = 0.08), or a mean of 3% of predicted performance (p = 0.03), and the maximum inspiratory pressure increased 8% (p = 0.003) for the clenbuterol group. The quick motor function test score improved by a mean of seven points (p = 0.007); and the gait, stairs, gower, chair test improved by a mean of two points (p = 0.004). Clenbuterol decreased glycogen content in the vastus lateralis by 50% at week 52. Transcriptome analysis revealed more normal muscle gene expression for 38 of 44 genes related to Pompe disease following clenbuterol. No serious adverse events were related to clenbuterol, and transient minor adverse events included mild elevations of creatine kinase, muscle spasms, and tremors. The placebo group demonstrated no significant changes over the course of the study.
