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