Clinical characterizations, management, and prognosis in immune checkpoint inhibitor-induced myelitis.

The expanding clinical application of immune checkpoint inhibitors (ICIs) has led to increasing recognition of neurological immune-related adverse events, among which myelitis represents a rare but clinically significant complication. Currently, most available data come from case reports or small case series, highlighting the need for comprehensive characterization. Our study systematically analyzed the clinical features of ICI-induced myelitis to improve diagnostic and therapeutic approaches. Through a comprehensive literature review up to February 28, 2025, we identified and analyzed 36 cases of ICI-associated myelitis from 27 publications. The study cohort had a median age of 58 years (range 16-81) with male predominance (58.3%). Clinical presentations included isolated myelitis (63.9%) and multifocal neurological involvement (36.1%), most commonly manifesting meningoencephalomyelitis/encephalomyelitis. The median time to symptom onset was 2 months (range 0.3-8) after treatment initiation, with a median of 4 treatment cycles (range 1-51). The most frequently associated malignancies were melanoma and lung cancer, with programmed cell death protein-1 inhibitor being the most commonly used regimen (69.4%). Diagnostic evaluation revealed longitudinally extensive spinal cord lesions (≥ 3 vertebral segments) in 75.0% of patients, along with frequent inflammatory cerebrospinal fluid abnormalities. Neural autoantibodies were detected in 33.3% of cases. Treatment strategies predominantly involved corticosteroids (97.2%) and ICI discontinuation (91.7%). While most patients (72.2%) showed improvement, relapses occurred in 30.6% of cases. These findings emphasize the importance of early recognition and prompt immunosuppressive therapy for ICI-induced myelitis.