Autopsy case: Pathological complete response in an advanced lung cancer patient with severe immune related adverse events and COVID-19.

A 51-year-old man with advanced lung cancer underwent chemotherapy including an immune checkpoint inhibitor (ICI). Subsequently, he developed ICI-related pneumonitis and colitis, followed by a ten-month treatment course of high doses of steroids. An infection with the SARS-CoV-2 Omicron BA.5 variant caused lethal respiratory failure. Autopsy examination revealed no evidence of viable lung cancer cells in the evaluated organs including the lungs, suggesting that pathological complete response (pCR) could be successfully achieved by ICI treatment in advanced lung cancer patients. Recognizing steroid-resistant ICI-related adverse events as critical factors in severe COVID-19 emphasizes the need for appropriate assessment of ICI-induced pCR.