Rituximab in refractory myasthenia gravis: Extended prospective study results.

ABSTRACT

INTRODUCTION: Rituximab appears to be beneficial in treatment-refractory myasthenia gravis (MG); however, prospective, long-term durability data are lacking. METHODS: In this prospective, open-label study of rituximab in refractory MG, 22 patients (10 nicotinic acetylcholine receptor, 9 muscle-specific tyrosine kinase, 3 seronegative) received rituximab at baseline, with repeat cycles driven by clinical worsening. Manual muscle testing (MMT) scores and CD19/CD20+ B-cell counts were serially monitored. RESULTS: At mean follow-up of 28.8 ± 19.0 months (range, 6-66), mean MMT scores declined from 10.6 ± 5.4 to 3.3 ± 3.1 (P < 0.0001). Mean prednisone dosage declined from 25.2 ± 15.1 to 7.3 ± 7.1 mg/d (P = 0.002). Ten relapses occurred, with average time to first relapse of 17.1 ± 5.5 months (range, 9-23). CD19/CD20+ count recovery did not predict relapse. Three patients experienced prolonged B-cell depletion (range, 24-45 months) after 1 cycle. DISCUSSION: Sustained clinical improvement was associated with rituximab after 1 cycle, with prolonged time to relapse and reduction in steroid dosage. Muscle Nerve 58 453-456, 2018.