Abstract
The effect of chemotherapy on programmed cell death-ligand 1 (PD-L1) expression has been previously studied in lung cancer, while the results remain controversial. The aim of this study was to investigate the variation of PD-L1 expression after neoadjuvant chemotherapy and explore the association between chemotherapy response, prognosis and the variation of PD-L1 expression in lung cancer patients. A total of 63 lung cancer patients who received platinum-based neoadjuvant chemotherapy and subsequently underwent surgical resection were selected. PD-L1 expression on tumor cells (TC) and tumor-infiltrating immune cells (IC) was assessed by immunohistochemistry using 22C3 monoclonal antibody in these 63 matched lung cancer specimens before and after neoadjuvant chemotherapy. The positivity of PD-L1 on TC changed from 17.5% to 39.7% after neoadjuvant chemotherapy and the positivity of PD-L1 on IC changed from 19.0% to 71.4% after neoadjuvant chemotherapy. The elevation of PD-L1 expression on TC after neoadjuvant chemotherapy was more frequently observed in patients achieving stable disease or progressive disease than in patients achieving partial response (P=0.026). Patients with elevated PD-L1 expression on TC after neoadjuvant chemotherapy showed a trend to have a shorter progression-free survival than patients without elevated PD-L1 expression on TC, although the difference was not statistically significant in multivariate analysis (hazard ratio=2.38, 95% confidence interval=0.99-5.73, P=0.053). PD-L1 expression can be elevated by chemotherapy in lung cancer. Furthermore, elevation of PD-L1 expression on TC after neoadjuvant chemotherapy was associated with reduced chemotherapy response and inferior progression-free survival in patients with lung cancer.