Long-term effects of enzyme replacement therapy in an elderly cohort of late-onset Pompe disease.

Enzyme replacement therapy (ERT) with recombinant human acid alpha-glucosidase (rhGAA) in late-onset Pompe disease (LOPD) shows beneficial effects in the first years often followed by a decline. We aimed to examine long-term ERT effects in an elderly LOPD cohort. Patients with age at diagnosis/start of ERT >50 years and ERT duration > seven years were included. Outcome parameters were MRC sum-score, 6 Minute Walk Test 6MWT, Quick Motor Function Test QMFT, forced vital capacity FVC sitting/supine, CK levels and rhGAA IgG antibody titers. We retrospectively analysed six patients with a median age at diagnosis/start of ERT of 63 years (range 52-69), and a median ERT duration of eight years (range 7-12). 6MWT improved in 4/6, and 2/6 each showed an improvement or stabilization in muscle strength and FVC supine. In contrast, FVC showed a decline in all patients in a sitting position, and QMFT worsened in 5/6. CK levels decreased in all patients. Antibody titers were not associated with treatment effects. Highest titers were present in best responders who were female, still ambulatory and without ventilatory support at follow-up. ERT effects were very heterogeneous and showed best results in 6MWT, followed by muscle strength in manual testing and FVC supine.