Pearls & Oy-sters: Pembrolizumab-induced myasthenia gravis

Myasthenia gravis (MG) is an uncommon autoimmune, postsynaptic neuromuscular disorder, characterized clinically by variable and fluctuating weakness of ocular, bulbar, respiratory, and limb muscles.c Targeted immunotherapies, directed against immune checkpoint modulators such as cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), programmed cell death protein 1 (PD-1), and the PD-1 ligand (PD-L1), have become an important treatment modality for malignancies; while effective, these novel therapies have been associated with autoimmunerelated adverse events.c Exacerbations of preexisting MG, as well as de novo presentations of MG, have been reported after the initiation of these agents; to date in the literature, pembrolizumab (Keytruda) has been associated with 3 exacerbations and 7 de novo presentations of MG. cIt is imperative to be acquainted with immune checkpoint modulator complications, as while they are effective in otherwise treatment-resistant malignancies, they may also produce severe adverse effects including exacerbation or induction of autoimmune disorders including devastating neurologic diseases and endocrinopathies.