Autoimmune Myasthenia, Primary Adrenal Insufficiency, and Progressive Hypothyroidism Due to Pembrolizumab and Axitinib Combination Regimen

Immune checkpoint inhibitors (ICI) and tyrosine kinase inhibitors (TKI) have been among the increasingly used antineoplastic agents for advanced cancers including renal cell carcinoma (RCC). Although these antineoplastic agents have broad range of efficacy, rare adverse events - mild and fatal, acute and chronic, immune and non-immune mediated - have been reported. We report a case of a 73-year-old Caucasian male patient with stage IV right-sided clear cell RCC who was treated with a pembrolizumab-axitinib combination regimen and suffered life-threatening, acute onset immune-related myasthenia gravis (MG), subsequently progressive hypothyroidism, and primary adrenal insufficiency.