Neuromuscular Weakness Syndromes from Immune Checkpoint Inhibitors: A Case Series and Literature Review

Abstract Immune checkpoint inhibitors (CPIs) (anti-cytotoxic T-lymphocyte antigen-4, anti-programmed death 1, and anti-programmed death-ligand 1) have transformed the landscape of cancer therapy. However, their increasing use has unleashed immune-related adverse events in various organs, among which neurologic ones, while rare, are increasingly being recognized and remain incompletely characterized. Herein, we report five patients with nonmelanoma cancers who developed weakness after receiving CPIs. The etiology was attributed to radiculoneuritis (one patient), myositis (one patient), Miller Fisher/myasthenia gravis (MG) (one patient), neuropathy/myositis/MG (one patient), and myositis/MG (one patient). Weakness developed after a median of two doses (range: 1–3) and 4 weeks (range: 3–10) from initiation of therapy. Two patients had severe manifestations without improvement while the other three experienced partial improvement despite discontinuation of the CPI (s) and initiation of immunosuppressive therapy. A review of literature identified 62 similar cases. This report highlights the challenges in the diagnosis and management of neurologic adverse events related to the use of CPIs. It also addresses the crucial need for early recognition, proper workup, and better biomarkers to help improve the outcomes of these adverse events.