Early-onset meningitis associated with atezolizumab treatment for non-small cell lung cancer: case report and literature review.

Immune checkpoint inhibitors (ICIs) have improved the overall survival of many patients with advanced cancers. However, unlike cytotoxic and targeted drugs, ICIs may cause various immune-related adverse events (irAEs). Among these irAEs, autoimmune meningitis is very rare. Here, we report a case of early-onset, atezolizumab-induced meningitis after administration of one dose of atezolizumab. A 56-year-old man with lung adenocarcinoma had received seventh-line treatment with atezolizumab when he experienced dysarthria. Blood examinations, including the measurement of electrolytes, glucose, and organ functions, were unremarkable, but enhanced head magnetic resonance imaging T1-weighted images showed meningeal enhancement. Although cerebral spinal fluid (CSF) examinations revealed elevated lymphocyte and protein levels, no cancer cells were detected in the CSF. CSF cultures and serological tests, including polymerase chain reaction for herpes simplex virus, were negative. The patient was therefore diagnosed with atezolizumab-triggered autoimmune meningitis. With steroid treatment, the patient's clinical and neurological state improved immediately and he recovered to baseline conditions. Prompt diagnosis and therapeutic intervention are essential for the effective treatment of autoimmune meningitis.