PD-L1 expression and its relationship with oncogenic drivers in non-small cell lung cancer (NSCLC)

Abstract

In order to explore the potential patient population who could benefit from anti PD-1/PD-L1 mono or combination therapies, this study aimed to profile a panel of immunotherapy related biomarkers (PD-1, PD-L1, CTLA-4 and CD8) and targeted therapy biomarkers (EGFR, KRAS, ALK, ROS1 and MET) in NSCLC.Tumor samples from 297 NSCLC patients, including 156 adenocarcinomas (AD) and 129 squamous cell carcinomas (SCC), were analyzed using immunohistochemistry, immunofluorescence, sequencing and fluorescence in situ hybridization.43.1% of NSCLC patients had PD-L1 positive staining on ≥ 5% tumor cells (TC). Furthermore, dual color immunofluorescence revealed that the majority of PD-L1/CD8 dual positive tumor infiltrating lymphocytes (TIL) had infiltrated into the tumor core. Finally, combined analysis of all eight biomarkers showed that tumor PD-L1 positivity overlapped with known alterations in NSCLC oncogenic tumor drivers in 26% of SCC and 76% of AD samples.Our illustration of the eight biomarkers' overlap provides an intuitive overview of NSCLC for personalized therapeutic strategies using anti-PD-1/PD-L1 immune therapies, either as single agents, or in combination with targeted therapies. For the first time, we also report that PD-L1 and CD8 dual positive TILs are predominantly located within the tumor core.

Keywords: PD-L1; biomarker; non-small cell lung cancer (NSCLC); oncogenic driver; tumor-infiltrating immune cells.

Conflict of interest statement

CONFLICTS OF INTEREST

The authors with the AstraZeneca affiliation are full time employees and/or have stock in AstraZeneca. AstraZeneca sponsored this study. The remaining authors declare no conflict of interest.

Figures

Figure 1. PD-L1 expression on tumor cells (TC) and tumor infiltrating immune cells (IC) in Chinese NSCLC patients

(A) representative images on adenocarcinomas (a & b) and squamous carcinomas (c &d) showed PD-L1 negative staining (a), positive staining on TC (b), IC (c) and both on TC and IC (d) respectively by IHC. The arrows indicate PD-L1 positivity on TC, the triangle indicates PD-L1 positivity on IC; (B) Correlation between PD-L1 expression on TC and PD-L1 positivity in IC in 182 patients. Median (solid red lines) and the 1st and 3rd quantile (dashed red lines) are reported.

Figure 2. Association between PD-L1 expression (%+ve) on tumor cells (TC) and clinical parameters in the whole patient cohort, adenocarcinoma (AD) and squamous cell carcinoma (SCC) subgroups in the first, second and third column, respectively

Each row signifies a clinical parameter.

Figure 3. Association between PD-L1 positive staining on tumor cells (TC) and other biomarkers of lung cancer drivers

(A) representative images of lung cancer drivers including (a) MET IHC positive, (b) MET FISH positive, (c) ALK and (d) ROS1 rearrangement positive. For FISH images, the red signals represent C-termini of ALK or ROS1 genes, the green signals represent N-termini of ALK or ROS1 genes, nucleus of tumor cells were stained as blue by DAPI; (B) the relationship of PD-L1 on TC and lung cancer driver genes in AD and SCC patients respectively. The largest black circles represent 91 AD and 77 SCC patients respectively. The size of each circle reflects the patient number.

Figure 4. Location of CD8+ lymphocytes in Chinese NSCLC tumors

(A and F) are representative images showing CD8+ lymphocytes locating in the stroma and tumor center respectively. The black square indicates the same tissue location for fluorescent images. (B–E) showed that at stroma CD8 and PD-L1 were not co-localized, while (G–J) showed colocalization of CD8 and PD-L1 on lymphocytes which mainly occurred in the tumor center (as indicated by arrows). PD-L1 was stained as green, CD8 was stained as red and the nucleus was counterstained as blue by DAPI.