Abstract
Programmed death ligand 1 (PD-L1) expression is a predictive biomarker of the success of PD-1/PD-L1 inhibitor therapy for patients with advanced non-small cell lung cancer (NSCLC) but its role as a prognostic marker for early stage resectable NSCLC remains unclear. Here, we studied PD-L1 expression and tumor infiltrating lymphocytes (TILs) in surgically resectable NSCLC and correlate the finding with clinicopathological features and patient outcomes. Total of 170 archival samples of resectable NSCLC were probed for PD-L1 expression using the clone 22C3 pharmDx kit. The PD-L1 expression was determined by the Tumor Proportion Score (TPS) and classified into TPS <1%, TPS 1 to 49% and TPS ≥50%. The scoring of TILs was from hematoxylin & eosin stained tissue sections using a system for standardized evaluation of TILs in breast cancer. PD-L1 expression was compared with clinical pathological characteristics and survival outcome. Expression of PD-L1 scores of TPS ≥50%, TPS 1 to 49% and TPS <1% were observed in 10.6%, 24.7% and 64.7% of the 170 archival samples, respectively. Positive PD-L1 expression was significantly higher in patients with squamous carcinoma, in those with higher TNM stage and with the presence of TILs. Neither the PD-L1 expression, TIL status, nor their combination was an independent prognosis biomarker of survival when the data was subjected to either univariate or multivariate analysis. The incidence of PDL1 expression appears to be lower in patient with early stage resectable lung cancer. PD-L1 expression and TILs are not prognostic indicators of survival outcome in this population.
Highlights
Blockade of immune checkpoints has recently emerged as a novel treatment for various cancers
We investigate association with clinicopathologic characteristics and the prognostic value of Programmed death ligand 1 (PD-L1) expression measured by a commercial 22C3-PD-L1 immunohistochemistry diagnostic assay with a Dako platform in patients with surgically resectable non-small cell lung cancer (NSCLC)
We have explored the immune microenvironment by studying the association between PD-L1 expression and tumor lymphocyte infiltration
Summary
Blockade of immune checkpoints has recently emerged as a novel treatment for various cancers. The recent clinical series had reported various degrees of PD-L1 expression in lung cancers ranging from 7.4% to 72.7%, which was well reviewed by MinoKenudson [8]. Among the PD-L1 antibodies, only the PDL1 IHC 22C3 pharmDx assay has obtained regulatory approval as a companion diagnostic, which is linked to the use of pembrolizumab [1, 2, 7]. Clinical application of the 22C3-PD-L1 biomarker was essentially confined to patients with advanced NSCLC and there is only limited information on patients with early stage resectable lung cancer. To our knowledge, the clinical data linked to clinicopathologic factors and survival are very limited and the results inconsistent, even using the FDA approved standard 22C3 PD-L1 antibody [12, 14, 15]
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