Pathologic complete response to preoperative immunotherapy in a lung adenocarcinoma patient with bone metastasis: A case report.

Anti-programmed cell death 1 (PD-1) and its ligand (PD-L1) has emerged as a novel immunotherapy for non-small cell lung cancer (NSCLC). However, the proportion of patients who may benefit from immunotherapy is limited and the factors sensitive or resistant to immunotherapy are not completely clear. Therefore, to identify reliable biomarkers as predictors of clinical response and resistance to anti-PD-1/PD-L1 therapies have become increasingly important. Here, we report a case of a patient with bone metastatic NSCLC, who achieved a pathologic complete response after preoperative pembrolizumab treatment. Postoperative pathological examination found no viable cancer cells in the resected pulmonary nodules and lymph nodes. Several high-frequency DNA damage response and repair (DDR) gene mutations including two germline mutations were identified in the primary lesion. Moreover, high PD-L1 expression, Kirsten rat sarcoma viral oncogene homolog (KRAS) combined with tumor protein 53 (TP53) mutations without epidermal growth factor receptor (EGFR)/anaplastic lymphoma kinase (ALK) driver alterations, high infiltration level of CD8-positive cells and M1 macrophages were observed, which were favorable characteristics for immunotherapy. We explored the possible factors related to an excellent response to immune checkpoint inhibitor in this patient and determined that preoperative use of anti-PD-1 therapy might apply to late-stage lung adenocarcinoma patients with multidimensional advantageous biomarkers for treatment with immune checkpoint inhibitors (ICIs). KEY POINTS: We characterized the genomic features and immune microenvironment signature of a lung adenocarcinoma in a patient with bone metastasis who achieved pathologic complete response after pembrolizumab treatment. To evaluate multidimensional advantageous biomarkers for immunotherapy.