Rituximab for Immune Checkpoint Inhibitor Myasthenia Gravis

The use of immune checkpoint inhibitors (iCPI) in the treatment of multiple cancers has gained prominence due to their high efficacy. However, neurological immune-related adverse events (irAEs) such as myasthenia gravis (MG) have been associated with iCPI therapy. Most of these neurological irAEs are rare, and in many cases, their diagnoses and management can be challenging.  We present a case of a 70-year-old woman with stage IIIC melanoma who developed a new onset of gradually progressive dyspnea, diplopia, and bilateral ptosis following treatment with one cycle of nivolumab and ipilimumab (Nivo+Ipi). She was diagnosed with MG via positive serum acetylcholine receptor (AChR) antibodies. She had developed a severe dyspnea at rest, which was refractory to multiple immune-suppressive therapies including prednisone, pyridostigmine, and intravenous immunoglobulin (IVIG). Subsequently, she was treated with rituximab 375 mg/m² monthly every four weeks with significant improvement of her symptoms within 48 hours each time. As the implementation of immunotherapy increases in medical practice, irAEs may become more apparent. When first-line therapies are not adequate, other alternative therapies should be explored. This case of MG as an irAE shows that rituximab can provide a potential benefit to treating patients with immunotherapy-induced MG who are refractory to other standard treatments. Prospective studies are needed to further evaluate the efficacy of rituximab in the management of irAEs.