NCMP-28. CASE REPORT: REFRACTORY MYASTHENIA GRAVIS FLARE INDUCED BY IMMUNE CHECK POINT INHIBITOR

Abstract Immune checkpoint inhibitors (ICIs) are used for treating many types of cancers. Neurological adverse effects are uncommon (incidence of 7.2%), however these effects can have life-threatening outcomes when they occur. We present a case of a 78-year-old male with an existing diagnosis of Myasthenia Gravis (MG) with metastatic Basal Cell Carcinoma (BCC). He was diagnosed in 2015 with ocular myasthenia gravis that was acetylcholine receptor antibody positive. He developed an exacerbation with double vision, fatigue, and upper extremity weakness that resolved with intravenous immunoglobulin (IVIG). During this year, he also had a thymectomy and he was controlled on Mestinon. Five months after his MG diagnosis, he was diagnosed with BCC and was given Vismodegib, however he had metastasis to the spine and lymph nodes. Unfortunately, he had no other treatment options besides immunotherapy, thus Cemiplimab was given in 2023. Ten days after receiving his 2nd dose, he developed left eye ptosis, neck weakness, shortness of breath, dysphagia, bilateral lower extremity weakness, and urinary retention. Workup additionally revealed concern for myocarditis and myositis. He received IVIG and intravenous methylprednisolone initially, and then had maintenance IVIG 1g/kg every 2 weeks with a prednisone taper. Due to ongoing symptoms, he got Rituximab which improved most of the symptoms except for dysphagia. He then received Efgartigimod alfa-fcab (Vyvgart) but had no improvement in dysphagia. Later, plasmapheresis (PLEX) was trialed but there was a partial response. Unfortunately, he obtained a PEG tube for dysphagia and declined significantly due to disease progression and multiple medical comorbidities. Myasthenia Gravis crisis from ICI therapy is a rare but serious treatment complication. In addition to the challenging nature of treating this condition, our case highlights the importance of a comprehensive work up to include consideration of overlap syndromes, such as myocarditis and myositis as identified in this case.