Programmed death ligand-1 (pd-l1) expression in either tumor cells or tumor-infiltrating immune cells correlates with solid and high-grade lung adenocarcinomas

Programmed death ligand-1 (PD-L1) expression in non-small cell lung carcinoma (NSCLC) is heterogeneous and known to be underestimated on small biopsies. Correlation of PD-L1 expression with clinicopathologic features may provide additional useful information. To our knowledge, the clinicopathologic features of NSCLC have not been reported for subsets defined by PD-L1 expression in either tumor cells or tumor-infiltrating immune cells. Objective.-To investigate the clinicopathologic characteristics of NSCLC subsets defined by PD-L1 expression in either tumor cells or tumor-infiltrating immune cells. Design.-PD-L1 immunohistochemistry with the SP142 clone was performed on whole-tissue sections and given semiquantitative scores (0/1/2/3) according to percent of PD-L1+ tumor cells (TCs) and percent tumor area with PDL1+ tumor-infiltrating immune cells (ICs). Results.-Adenocarcinoma cases that were scored either TC 1/2/3 or IC 1/2/3 included most (22 of 34; 65%) high- histologic grade cases and most (25 of 36; 69%) solid subtype cases. Compared with the adenocarcinoma TC 0 and IC 0 subset, the TC 1/2/3 or IC 1/2/3 subset correlated with higher histologic grade (P .005, v2 test for trend) and solid subtype (P , .001, Fisher exact test). Compared with the adenocarcinoma TC 0/1 or IC 0/1 subset, the TC 2/3 or IC 2/3 subset correlated with higher histologic grade (P.002, v2 test for trend), solid subtype (P , .001, Fisher exact test), and higher smoking pack-years (P .01, Mann-Whitney test). Conclusions.-Lung adenocarcinoma subsets defined by PD-L1 expression in either tumor cells or tumor-infiltrating immune cells correlated with high histologic grade, solid subtype, and high smoking pack-years.