Japanese Society of Internal Medicine Acta Medica Okayama 0918-2918 63 9 2024 Severe Cytokine Release Syndrome and Immune Effector Cell-associated Neurotoxicity Syndrome in a Man Receiving Immune Checkpoint Inhibitors for Lung Cancer 1261 1267 EN Takaaki Tanaka Department of Respiratory Medicine, Okayama University Hospital Masataka Taoka Department of Respiratory Medicine, Okayama University Hospital Go Makimoto Department of Respiratory Medicine, Okayama University Hospital Kiichiro Ninomiya Center for Comprehensive Genomic Medicine, Okayama University Hospital Hisao Higo Department of Respiratory Medicine, Okayama University Hospital Masanori Fujii Department of Respiratory Medicine, Okayama University Hospital Eiki Ichihara Department of Respiratory Medicine, Okayama University Hospital Kadoaki Ohashi Department of Respiratory Medicine, Okayama University Hospital Katsuyuki Hotta Center for Innovative Clinical Medicine, Okayama University Hospital Masahiro Tabata Center for Clinical Oncology, Okayama University Hospital Yoshinobu Maeda Department of Hematology, Oncology, and Respiratory Medicine, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences A 55-year-old man with stage IV lung adenocarcinoma was treated with cisplatin, pemetrexed, nivolumab, and ipilimumab. Approximately 100 days after treatment initiation, he became disoriented and presented to the emergency department with a high fever. Blood tests revealed liver and kidney dysfunctions. Subsequently, the patient developed generalized convulsions that required intensive care. He was clinically diagnosed with cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS). Organ damage was gradually controlled with immunosuppressive drugs, including steroids, and the patient was discharged. Successful treatment is rare in patients with CRS, including ICANS, during immune checkpoint inhibitor treatment for solid tumors. No potential conflict of interest relevant to this article was reported.