LAUSR

Objectives: Anti–programmed cell death 1 (PD‐1)/programmed death ligand 1 (PD‐L1) immunotherapy has demonstrated success in the treatment of advanced NSCLC. Recently, PD‐1/PD‐L1 blockade also has demonstrated interesting results in small trials of neoadjuvant treatment in stage IB to IIIA NSCLC. In addition, several clinical trials using anti–PD‐1/PD‐L1 immunotherapy as an adjuvant or neoadjuvant treatment in patients with resectable stage NSCLC are ongoing. However, few analyses of anti–PD‐1/PD‐L1 immunotherapy–related biomarkers in early‐stage squamous cell lung carcinoma (SqCLC) have been reported. In this study, we evaluated PD‐L1 protein expression, tumor mutation burden, and expression of an immune gene signature in early‐stage SqCLC, providing data for identifying the potential role for patients with anti–PD‐1/PD‐L1 treatment in early‐stage SqCLC. Methods: A total of 255 specimens from patients with early‐stage SqCLC were identified within participating centers of the Strategic Partnering to Evaluate Cancer Signatures program. PD‐L1 protein expression by immunohistochemistry was evaluated by using the Dako PD‐L1 22C3 pharmDx kit on the Dako Link 48 auto‐stainer (Dako, Carpinteria, CA). Tumor mutation burden (TMB) was calculated on the basis of data from targeted genome sequencing. The T‐effector and interferon gamma (IFN‐&ggr;) gene signature was determined from Affymetrix gene chip data (Affymetrix, Santa Clara, CA) from frozen specimens. Results: The prevalence of PD‐L1 expression was 9.8% at a tumor proportion score cutoff of at least 50%. PD‐L1 mRNA and programmed cell death 1 ligand 2 mRNA positively correlated with PD‐L1 protein expression on tumor cells (TCs) and tumor‐infiltrating immune cells. PD‐L1 protein expression on tumor‐infiltrating immune cells was correlated with the T‐effector and IFN‐&ggr; gene signature (p < 0.001), but not with TMB. For TCs, all of these biomarkers were independent of each other and neither PD‐L1 protein expression, TMB, or T‐effector and IFN‐&ggr; gene signatures were independently prognostic for patient outcomes. Conclusions: Evaluation of PD‐L1 expression, TMB, and T‐effector and IFN‐&ggr; gene signatures in the cohort with early‐stage SqCLC found them to be independent of each other, and none was associated with overall survival. Our results also support the hypothesis that PD‐L1 expression is regulated by an intrinsic mechanism on TCs and an adaptive mechanism on immune cells.