Immune checkpoint inhibitors (ICIs) have become an important milestone in the treatment of non-small cell lung cancer (NSCLC). High expression of protein ligand 1 (PD-L1) and tumor mutation burden (TMB) can help to select the dominant population for immunotherapy, but the expression of PD-L1 does not seem to be unchanged. A 61-year-old man with adenocarcinoma of the lung experienced postoperative recurrence. PD-L1 expression was negative before recurrence, and TMB was stable by next-generation sequencing (NGS) test. However, after radiotherapy and chemotherapy, PD-L1 positive expression was found in a re-biopsy specimen, and NGS detection indicated the loss of immune negative predictive genes. The patient achieved a durable response to a posterior-line immunotherapy combined chemotherapy. The tumor microenvironment maybe changed after chemoradiotherapy, which provides an opportunity for patients to benefit from immunotherapy. The use of NGS in dynamic detection and PD-L1 expression may help monitor this change in the tumor microenvironment, the transition from cold to hot tumor. This case maybe provides new clinical evidence that a non-immuno-dominant population in the initial state can be converted to a population with the benefit of immunotherapy after chemoradiotherapy. However, patients who are initially unsuitable for immunotherapy may still need to undergo combined immunotherapy to achieve a clinical benefit.
Keywords: Non-small cell lung cancer (NSCLC); case report; chemoradiotherapy; immunotherapy; next-generation sequencing (NGS); protein-ligand 1 (PD-L1).