Assessment Of PD-L1 Research Articles

Immune microenvironment in mesothelioma: Looking beyond PD-L1.

8515 Background: Studies using immune checkpoint inhibitors in mesothelioma (MM) have shown promise. Differences in response to PD-L1 and PD-1 inhibitors (10% vs 25%) have been reported. Also, expression of PD-L1 alone appears to be a limited predictor. As the roles of the multiple check point receptors and their ligands become defined, an understanding of their expression and interplay in the mm tumour microenvironment, which could affect suitability for checkpoint inhibition therapy, has become necessary. Methods: Tissue microarrays were constructed and stained with PD-L2, LAG3 and TIM3 antibodies. Tumour infiltrating lymphocytes (TILs) were assessed in the stroma and expressed as a % of stromal area within invasive tumour. These data were combined with PD-L1 expression, CD4+ and CD8+ infiltration in the same cohort reported previously. To quantify the immunosuppressive milieu, we combined our assessment of PD-L1, PD-L2 and TIM3 expression to derive an “Immune checkpoint score (ICS)” and explored its correlation with the tumour microenvironment and clinicopathological covariates. We are also exploring its predictive value in an independent cohort of mm patients who have received anti-PD-1 treatment. Results: Amongst 329 patients evaluated, PD-L1 was positive (+) in 41.7% and PD-L2+ in 24.5%. TIM3+ lymphocytes were found in 99.4% but LAG3+ lymphocytes in only 0.2%. 28/173 (16%) of PD-L1- patients were PD-L2+ and 31/136 (22%) PD-L1 and PD-L2 negative patients had high infiltration with TIM3+ lymphocytes. High ICS was associated with non-epithelioid histology, increased TILs and poorer survival. On multivariate analysis, high TILs, non-epithelioid histology and poor physiological status remained significantly associated with poorer survival. Data on the predictive role of ICS score will also be reported. Conclusions: While co-expression of PD-L1, PD-L2 and TIM3 can occur, their expression is mutually exclusive in a large proportion of patients. The expression of PD-L2 may explain differences in responses seen between PD-1 compared to PD-L1 inhibitors. A comprehensive assessment of these multiple immunosuppressive pathways may be necessary to truly gauge the immunosuppressive environment and tailor immunotherapy for individual cases.

Enumeration of circulating tumor cells and assessment of immunotherapy biomarker PD-L1 in patients with colorectal cancer.

e23029 Background: Circulating tumor cells (CTC) play a prognostic role in patients with metastatic colorectal cancer (mCRC). Studies investigating detection of CTC in peripheral blood (PB) showed limited clinical sensitivity. This study compares clinical sensitivity of CTC analysis in mesenteric venous blood (MVB) vs PB. PD-L1 expression on isolated CTCs was also characterized in various stages of CRC patients. Methods: 8mL PB and MVB samples were collected into K2EDTA-containing vacationer tubes and subsequently performed CTC enumeration and PD-L1 analysis by MiSelect R system. CTC is defined as EpCAM+, cytokeratin+ and CD45- with intact nuclei. CTC and PD-L1+ CTC number were counted and correlated to the patients’ clinical manifestations. Results: Blood samples were collected from 75 CRC patients with various stages. In MVB, CTC detection rate was 20%, 33%, 44% and 58% for stage I, II, III, and IV respectively, and the overall detection rate is 41%. In PB, CTC only detected in sporadic cases (7%). Also, the amount of CTC detected in MVB was more abundant than that in PB ( P < 0.001) In addition, preoperative serum CEA levels were significantly associated with presence of CTC in MVB ( P= 0.011). PD-L1 expression was detected in 32% of the isolated CTCs, and was more abundant in those from late stage patients. The expression level of PD-L1 showed heterogeneity among CTCs. Conclusions: CTC enumeration in MVB could potentially increase the clinical sensitivity for CTC analysis in CRC. The CTC level in MVB significantly correlated with CEA levels which could serve as an important biomarker information for post-operative management. In additions, using MiSelect R System to determine PD-L1 expression on CTC could provide a promising approach for both patient selection or therapeutic monitoring of immunotherapies for CRC.

Image Analysis-based Assessment of PD-L1 and Tumor-Associated Immune Cells Density Supports Distinct Intratumoral Microenvironment Groups in Non-small Cell Lung Carcinoma Patients.

We investigated the correlation between immunohistochemical PD-L1 expression and tumor-associated immune cells (TAICs) density in non-small cell lung carcinoma (NSCLC) and correlated them with clinicopathologic variables. Tumor tissue specimens from 254 stage I-III NSCLCs [146 adenocarcinomas; 108 squamous cell carcinomas (SCCs)] were examined. PD-L1 expression in malignant cells and macrophages and the density of TAICs expressing CD3, CD4, CD8, CD57, granzyme B, CD45RO, PD-1, FOXP3, and CD68 were evaluated using immunohistochemistry and image analysis. Malignant cells PD-L1 H-score > 5 was detected in 23% of adenocarcinomas and 31% of SCCs, and no significant differences were detected comparing both histologies; the median H-score in macrophages was significantly higher in SCC than in adenocarcinoma (P < 0.001). In adenocarcinoma, high malignant cells PD-L1 expression and high TAIC density correlated with solid histology, smoking history, and airflow limitation. Multivariate analysis demonstrated that high CD57-positive cell density correlated with better recurrence-free survival (RFS; P = 0.0236; HR, 0.457) and overall survival (OS; P = 0.0261; HR, 0.481) rates for SCC. High CD68-positive cell density in intratumoral compartment correlated with better RFS (P = 0.0436; HR, 0.553) for adenocarcinoma. The combination of low CD4/CD8/C68-positive cell density and PD-L1 H-score >5 in malignant cells identified small subset of adenocarcinomas with worse outcomes (RFS: P = 0.036; HR, 4.299; OS: P = 0.00034; HR, 5.632). We detected different PD-L1 expression and TAIC density patterns in NSCLC. Distinct groups of tumor microenvironment correlated with NSCLC clinicopathologic features, including outcome. Clin Cancer Res; 22(24); 6278-89. ©2016 AACR.

10PD - Assessment of PD-L1 and CD47 expression together with tumor-associated TILs in resectable early stage NSCLC

Aim/Background: Solid tumors have been shown to evade host antitumor immunity through upregulation of the immune checkpoint PD-1/PD-L1 pathway. However, CD47, an antiphagocytic ligand expressed on tumor cells, represents another cell surface molecule promoting tumor immune evasion via targeting the innate immune system. We investigated whether PD-L1 and CD47 are co-expressed in early stage non-small cell lung cancer (NSCLC). Methods: Resected tumor and matched adjacent normal tissue from 84 stage I-III NSCLCs (42 adenocarcinomas [Adeno]; 42 squamous cell carcinomas [SqCC]) were processed to single cell suspensions, stained with a panel of antibodies (CD45, CD31, CD14, EpCAM, CD73, CD90, PD-L1, CD47) and subjected to multicolor flow cytometric analysis. In parallel, the phenotype of tumor infiltrating lymphocytes (TILs) was also performed using CD19, CD45RO, CD3, CD4, CD8, PD-1, CD127 and CD107a. In a subset of patients, expression of PD-L1 and CD47 was confirmed via immunohistochemistry. Results: PD-L1 expression on tumor epithelium (EpCAM+) was increased in both Adeno (p = 0.0295) and SqCC (p = 0.0016) patients. CD47 was also upregulated on the tumor EpCAM+ fraction in SqCC (p = 0.05) but not in Adeno patients (p = 0.124). An increase in the tumor mesenchymal fraction in both Adeno (p = 0.015) and SqCC (p = 0.027) patients was found that showed an enhanced expression of PD-L1 but not CD47. Immunohistochemical analysis confirmed coexpression of PD-L1 and CD47 in a subset of patients. Finally, there was an increase in CD4+PD-1hi TILs in Adeno patients, whereas a decrease in CD127 expression was found on CD8+ TILs (p < 0.0001) with a CD107aloPD1hi phenotype in both histological subtypes. Conclusions: We detected PD-L1 expression in different compartments in a subset of patients with early stage Adeno and SqCC, whereas CD47 expression was restricted to the tumor epithelial compartment in SqCC patients only. These differences may be related to the intragraft immune priming inside the tumor microenvironment. Further study is required to determine whether dual targeting of PD-L1 and CD47 in the perioperative setting represents a promising therapeutic strategy to reinvigorate TILs in affected patients. Legal entity responsible for the study: N/A Funding: Inselspital, University Hospital of Bern, Division of Thoracic Surgery Disclosure: All authors have declared no conflicts of interest.

Measurement of spatial and antibody-based PD-L1 heterogeneity in non-small cell lung cancer.

9040Background: Assessment of PD-L1 is not yet standardized and is based largely on “assay performance” rather than protein measurement; with each assay requiring its own specialized platform and a...

Assays for predicting and monitoring responses to lung cancer immunotherapy.

Immunotherapy has become a key strategy for cancer treatment, and two immune checkpoints, namely, programmed cell death 1 (PD-1) and its ligand (PD-L1), have recently emerged as important targets. The interaction blockade of PD-1 and PD-L1 demonstrated promising activity and antitumor efficacy in early phase clinical trials for advanced solid tumors such as non-small cell lung cancer (NSCLC). Many cell types in multiple tissues express PD-L1 as well as several tumor types, thereby suggesting that the ligand may play important roles in inhibiting immune responses throughout the body. Therefore, PD-L1 is a critical immunomodulating component within the lung microenvironment, but the correlation between PD-L1 expression and prognosis is controversial. More evidence is required to support the use of PD-L1 as a potential predictive biomarker. Clinical trials have measured PD-L1 in tumor tissues by immunohistochemistry (IHC) with different antibodies, but the assessment of PD-L1 is not yet standardized. Some commercial antibodies lack specificity and their reproducibility has not been fully evaluated. Further studies are required to clarify the optimal IHC assay as well as to predict and monitor the immune responses of the PD-1/PD-L1 pathway.