Rituximab as treatment for anti-MuSK myasthenia gravis: Multicenter blinded prospective review
OBJECTIVE: To evaluate the efficacy of rituximab in treatment of anti-muscle-specific kinase (MuSK) myasthenia gravis (MG). METHODS: This was a multicenter, blinded, prospective review, comparing anti-MuSK-positive patients with MG treated with rituximab to those not treated with rituximab. The primary clinical endpoint was the Myasthenia Gravis Status and Treatment Intensity (MGSTI), a novel outcome that combines the Myasthenia Gravis Foundation of America (MGFA) postintervention status (PIS) and the number and dosages of other immunosuppressant therapies used. A priori, an MGSTI of level ≤2 was used to define a favorable outcome. Secondary outcomes included modified MGFA PIS of minimal manifestations or better, mean/median prednisone dose, and mean/median doses of other immunosuppressant drugs. RESULTS: Seventy-seven of 119 patients with anti-MuSK MG evaluated between January 1, 2005, and January 1, 2015, at 10 neuromuscular centers were selected for analysis after review of limited clinical data by a blinded expert panel. An additional 22 patients were excluded due to insufficient follow-up. Baseline characteristics were similar between the rituximab-treated patients (n = 24) and the controls (n = 31). Median follow-up duration was >3.5 years. At last visit, 58% (14/24) of rituximab-treated patients reached the primary outcome compared to 16% (5/31) of controls ( = 0.002). Number needed to treat for the primary outcome is 2.4. At last visit, 29% of rituximab-treated patients were taking prednisone (mean dose 4.5 mg/day) compared to 74% of controls (mean dose 13 mg/day) ( 0.001 and = 0.005). CLASSIFICATION OF EVIDENCE: This study provides Class IV evidence that for patients with anti-MuSK MG, rituximab increased the probability of a favorable outcome.
Medical Subject Headings
Adult; Anti-Inflammatory Agents (therapeutic use); Autoantibodies (metabolism); Female; Follow-Up Studies; Humans; Immunologic Factors (therapeutic use); Male; Middle Aged; Myasthenia Gravis (drug therapy, immunology); Prednisone (therapeutic use); Prospective Studies; Receptor Protein-Tyrosine Kinases (immunology); Receptors, Cholinergic (immunology); Rituximab (therapeutic use); Severity of Illness Index; Single-Blind Method; Treatment Outcome
Digital Object Identifier (DOI)
Hehir, Michael K.; Hobson-Webb, Lisa D.; Benatar, Michael; Barnett, Carolina; Silvestri, Nicholas J.; Howard, James F.; Howard, Diantha; Visser, Amy; Crum, Brian A.; Nowak, Richard; Beekman, Rachel; Kumar, Aditya; Ruzhansky, Katherine; Chen, I-Hweii Amy; Pulley, Michael T.; LaBoy, Shannon M.; Fellman, Melissa A.; Greene, Shane M.; Pasnoor, Mamatha; and Burns, Ted M., "Rituximab as treatment for anti-MuSK myasthenia gravis: Multicenter blinded prospective review" (2017). Neurology. 1674.