Rituximab in the Treatment of LRP4-Antibody-Positive Myasthenia Gravis: A Case Report

Abstract

Antibodies against LRP4 were found in 2-4% of patients with myasthenia gravis (MG). LRP4-antibody-positive (LRP4+) MG presents with more severe disease with bulbar involvement. No standard treatment guideline has been established for this subtype. We identified a LRP4+MG patient with severe symptoms including bulbar dysfunction that were refractory to standard therapy. Rituximab was started due to treatment failure with standard therapy. At the time of initiation of rituximab, patient was on plasmapheresis every 1-2 weeks. Her work and quality of life were greatly compromised. Six weeks after initiating rituximab therapy, remarkable improvements in dyspnea, dysphagia, ptosis, and proximal limb muscle strength were reported without adverse events. Improvements in 3 standardized Myasthenia Gravis scoring systems were observed. The maintenance plasmapheresis was discontinued and pyridostigmine dose decreased by 50% because of sufficient symptom control. Stable improvement was achieved with rituximab maintenance therapy spaced 5 months apart. Our case demonstrates rapid onset of efficacy of rituximab in patient with refractory LRP4+MG. This response and the proposed mechanism of action of LPR4-Ab suggest that the efficacy of rituximab in LRP4+MG may parallel that in MuSK+MG. Further exploration of this treatment option is warranted.