Nevertheless, the response rate of ALK-positive lung cancer to ICI monotherapy ranges between 0 and 8%; therefore, it is generally considered to be ineffective.[11,12] Regarding ALK-positive lung cancer, median progression-free survival (PFS) for ALK-tyrosine kinase inhibitor-treatment-naive and posttreatment patients were 3.9 and 1.5 months, respectively, with limited efficacy when ICIs were administered.[13] We herein report a rare case of ALK-positive lung adenocarcinoma that responded to pembrolizumab monotherapy as the 8th-line treatment. The gene discussed is ALK; the disease is lung cancer.