Programmed Cell Death Ligand 1 Protein Research Articles

Abstract 3625: MET signaling upregulates PD-L1 expression in human lung and gastric cancer

Abstract Background: Tyrosine kinase receptor, MET, plays an important role for the progression of tumor through diverse mechanisms. Cancer immunotherapy targeting PD-1/PD-L1 pathway shows clinical benefit in patient with PD-L1 expressing solid tumor. In our previous study on non-small cell lung cancer (NSCLC) using immunohistochemistry, MET overexpression was significantly associated with programmed cell death-ligand 1 (PD-L1) overexpression. Thus, we investigated if MET signaling pathway is involved in PD-L1 expression in tumor cells. Method and Result: Lung adenocarcinoma cell lines including H596 (harboring MET exon 14 skipping mutation), H1993 (harboring MET gene amplification), H23 and H522 (MET wild-type), and a gastric carcinoma cell line, Hs746T (harboring MET exon 14 skipping mutation and gene amplification) were used. Hs746T cells were treated with MET inhibitor or transfected with MET siRNA and subject to microarray analysis. MET inhibition or knockdown led to changes in expression level of variable immune-related molecules, of which PD-L1 was one of the most down-regulated molecules. Stimulation of H596, H23 and H522 cells with HGF, a MET ligand, increased PD-L1 expression at the mRNA and protein level. Treatment of H1993 and Hs746T cells with MET inhibitor or MET knockdown using siRNA resulted in down-regulation of PD-L1 at the mRNA, total protein, and surface expression levels. PI3K/Akt and MAPK/Erk signaling pathways were involved in MET-mediated PD-L1 up-regulation in H1993 and Hs746T cells. Finally, the Cancer Genome Atlas (TCGA) analysis showed that MET and PD-L1 expression are significantly positively correlates with each other in patients with lung cancer (in NSCLC, rho=0.219 [p<0.001]; in adenocarcinoma, r=0.401 [p<0.001]; in squamous cell carcinoma, r=0.144 [p=0.001]) and in patients with gastric cancer (r=0.137 [p=0.005]). Conclusion: This study demonstrates that MET signaling increases PD-L1 transcription and protein overexpression in lung and gastric cancer cells, which might contribute to immune escape of tumor via PD-1/PD-L1 pathway. MET-targeted therapy may be considered as combination therapy with PD-1/PD-L1 blockades. Citation Format: Hyunkyung Ahn, Sehui Kim, Ji Young Jang, Dohee Kwon, Jaemoon Koh, Young A Kim, Doo Hyung Chung, Yoon Kyung Jeon. MET signaling upregulates PD-L1 expression in human lung and gastric cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3625.

Abstract 4551: Thyroid hormone induces PD-L1 expression in oral cancer cells

Abstract Oral cancer is a fatal disease, which accounts for the fourth highest incidence of malignancy in males and the seventh highest in the general population of Taiwan. Oral cancer is increasing in Taiwan. About 95% of oral cancer in Taiwan is oral squamous cell carcinoma (OSCC). With the development of cancer molecular biology and immunology, targeted therapy for immune checkpoints of programmed cell death 1 (PD-1) and programmed cell death ligand 1 (PD-L1) has shown enormous development prospects for treatment of head and neck cancer. The PD-1/PD-L1 checkpoint is a critical regulator of activated T cell-cancer cell interactions which defend tumor cells against immune surveillance. Thyroid hormone induces PD-L1 expression in human oral cancer cells. Human oral cancer OEC-M1 and SCC-25 cells were treated with different concentrations of T4 (10-8 to 10-6M) for 24 h and cells were harvested and total RNA was extracted. qPCR of PD-L1 revealed that PD-L1 mRNA was significantly induced by thyroid hormone on a concentration-dependent basis. Parallel studies were conducted to study the effect of thyroid hormone on PD-L1 protein accumulation. Cancer cells were treated with different concentrations of T4 for 24 h. Total proteins were extracted and western blot analysis of PD-L1 was conducted. Thyroid hormone-activated ERK1/2 and STAT3 were companied with PD-L1 expression. Inhibition of ERK1/2 and consequently STAT3 activation also blocked PD-L1 induced by thyroid hormone. Knockdown of PD-L1 expression by siRNA also inhibits thyroid hormone-induced proliferation of oral cancer cells which indicated that PD-L1 expression is involved in thyroid hormone-induced cancer growth via an ERK1/2-STAT3 signal transduction pathway in oral cancer cells. Citation Format: Yu-Tang Chin, Kwan-Wei Su, Yee-Tang Lim, Ya-Jung Shih, Yi-Ru Chen, Sheng-Yang Lee, Paul J. Davis, Hung-Yun Lin, Earl Fu. Thyroid hormone induces PD-L1 expression in oral cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4551.

Abstract 4671: Rapid, no-wash measurement of immune checkpoint molecules expression induced by interaction with peripheral blood mononuclear cells in breast and cervical cancer cell models

Abstract The purpose of this study was to examine the pathways involved in the induction of immune checkpoint molecules in basal breast and cervical cancer cell lines by measuring classical biomarker expression using AlphaLISA no-wash homogeneous assays. Programmed cell death-ligand 1 (PD-L1) expression increases with tumor severity in basal-like breast cancer and is enhanced in intraepithelial neoplasia and cervical cancers. Basal-breast tumors can adapt to lymphocytic infiltration by responding to heightened concentrations of interferon gamma (IFN-y) secreted by Type 1 helper T cells with upregulation of PD-L1 protein allowing the tumors to evade immune targeting and reduce the immune response. We show here that human peripheral blood mononuclear cells (PBMCs) secrete IFN-y and other cytokines in response to stimulation with CD3/CD38 Dynabeads. We then examined modulation in expression of immune checkpoint molecules (PD-L1 and others) in HCC38 (basal breast cancer-derived) and HeLa (cervical cancer) cells in response to co-culturing with activated PBMCs, treatment with conditioned media collected from activated PBMCs, and direct treatment with recombinant IFN-y. As expected, IFN-y treatment induced dose-dependent upregulation of PD-L1 protein expression in both HCC38 and HeLa cell lines, whereas the effects of conditioned media and direct co-culturing with PBMCs resulted in more complex effects which are discussed. To determine if tumor cytoarchitecture influences responsiveness to the PBMCs, biomarker expression was measured from cultures grown in both traditional adherent monolayers and in 3D spheroid cultures using Ultra-Low Attachment (ULA) microplates. Cellular health and proliferation was assessed by measuring ATP concentration with ATPlite luminescence assays and cellular imaging with viability dyes. The upregulation of PD-L1 expression was observed to be largely independent of cellular proliferation and is further shown to be dependent on signaling through the JAK/STAT pathway by probing with AlphaLISA SureFire phosphorylation assays. These data illustrate and address some of the challenges in developing a biologically relevant culture system for examining the complex mechanisms involved in tumor evasion of the innate immune response. Citation Format: Jeanine M. Hinterneder, Jen Carlstrom, Adam Carlson, Dawn Nida. Rapid, no-wash measurement of immune checkpoint molecules expression induced by interaction with peripheral blood mononuclear cells in breast and cervical cancer cell models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4671.

Quantitative comparison of PD-L1 immuno-histochemical assays in hepatocellular carcinoma: The Blueprint-HCC study.

91 Background: Programmed cell death ligand 1 (PD-L1) expression by immunohistochemistry (IHC) enriches for responses to PD-1/PD-L1 inhibitors, however its role as a predictive biomarker in hepatocellular carcinoma (HCC) is inconclusive, with no consensus on any particular assay. We evaluated the performance of 4 different PD-L1 detection assays previously published in landmark clinical studies. Methods: PD-L1 IHC was performed on 4 serial sections from tissue microarray (TMA) blocks containing 100 archival cases of HCC that included tumour and surrounding non-tumorous tissue. Antibody clones E1LN3, 28-8, 22c3, SP263 were compared on the basis of percentage and intensity of staining in malignant cells (M) to generate an H-score (range 0-300). Immune cells infiltrating (ICI) and at the periphery, in non-tumorous tissue (ICP) were scored on a 4-tier system (0-3). Results: Patients were 76% males, 20% HCV-positive, 64% cirrhotic with a median age of 67 years. Median tumour size was 4 cm, 70% of patients had T1-T2 tumours and 48% were of grade 2. The proportion of PD-L1 positive cases according to M-ICI-ICP pattern was 2-6-2% for E1LN3, 10-18-19% for 28-8, 9-22-18% for 22c3 and 5-14-13% for SP263. Pairwise comparison of M H-scores revealed heterogeneity across antibodies, with highest concordance between E1L3N/SP263 (R2 = 0.95), E1L3N/22c3 (R2 = 0.65), 22c3/SP263 (R2 = 0.66) and increasing discordance for 28-8/22c3 (R2 = 0.44), E1L3N/28-8 (R2 = 0.29), and 28-8/SP263 (R2 = 0.26). Detection of PD-L1-positive immune infiltrates using a semi-quantitative scoring system revealed significantly different scores in pairwise non-parametric comparisons of ICI (p < 0.05) but not ICP (p > 0.05 for chi-square test). Conclusions: In the Blueprint-HCC study we demonstrated that quantification of PD-L1 protein levels in tumour cells, intra-tumoural and peri-tumoural infiltrate is characterised by inter-assay discordance in HCC. This has profound implications in the clinical development of predictive correlates of efficacy to immunotherapy in HCC. Sources of such discordance should be explored.

Novel Mechanism of Post-Transcriptional Regulation of PD-L1 Expression By 3'-UTR Binding Proteins

Programmed cell death ligand 1 (PD-L1) plays a key role in tumor immune escape by negatively regulating cytotoxic T-cells (CTLs) via PD-1 receptors. Thus, those tumors with high PD-L1 expression are thought to be sensitive to PD-1/PD-L1 blockade, reactivating CTL reactions to tumors. However, the mechanism that regulates PD-L1 expression in tumor cells has not been fully elucidated, understanding of which would help to develop effective anti-tumor immunotherapy.Recently, we reported that disruption of 3'-UTR of PD-L1 led to a remarkably enhanced expression of PD-L1 in a wide variety of human cancers, particularly adult T-cell leukemia/lymphoma (ATL) and diffuse large B-cell lymphoma. In these cancers, stability of PD-L1 transcripts is negatively regulated via their 3'-UTR sequence, whose disruption thus, results in markedly elevated PD-L1 expression and immune evasion (Kataoka et al., Nature, 2016). It has been well established that non-coding regions (i.e., 5'- and 3'-untranslated regions (UTRs)) play important roles in the regulation of mRNA expression, which is accomplished by several transacting factors that bind to cis-regulatory elements within the UTR. Based on this knowledge, we investigated the mechanism that controls PD-L1 expression through 3'-UTR sequence, primarily focusing on those transacting RNA-binding proteins (RNA-BPs).To determine the relevant regions within the 3'-UTR which are capable of repressing PD-L1, several cell lines were transfected with luciferase reporter vectors, in which a luciferase coding sequence was concatenated to various deletion mutants of the PD-L1 3'-UTR (Panel A). We identified two critical sequences, segment 5 and 2 within the PD-L1 3'-UTR, whose existence significantly decreased luciferase expression (Panel B; 293T data, mean ± SD, * denotes t-test p < .05). Importantly, the deletion of these sequences showed a similar effect on gene expression in various cell lines derived from different tissues. To confirm this finding, we used a CRISPR-mediated tiled 3'-UTR editing in situ technique. We designed all possible single-guide (sg) RNAs in the PD-L1 3'-UTR. The library was virally infected into cells and those with high expression of PD-L1 were concentrated by FACS, and the enrichment of each sgRNA was evaluated by high-throughput sequencer. The enriched sgRNAs localized to positions compatible with the luciferase assay, confirming that the two regions are actually responsible for the regulation of PD-L1 expression.Next, we searched RNA-BPs that bind to these regions in mass spectrometry, utilizing flag-peptide-tagged RNA pull-down method (Panel C). In brief, we synthesized PD-L1 3'-UTR RNA segments along with β-actin mRNA as control in vitro, and conjugated a flag-peptide to their 3'-ends. Using these RNA-baits, an immunoprecipitation experiment was performed in 293T cells and the co-immunoprecipitated proteins were analyzed by mass spectrometry. The data obtained from different segments were compared to each other. In addition to those proteins binding to multiple regions within the PD-L1 3'-UTR, we found proteins that specifically interacted with the repressive segments (segment 5 and 2) identified through luciferase assays.Finally, to confirm that the proteins detected by mass spectrometry actually suppress PD-L1 expression, we performed knock-down experiments using siRNA designed for the RNA-BPs that are presumed to interact with the segment 5 and 2. Three siRNA constructs per gene were transfected to 293T cells and their effect on PD-L1 expression was evaluated by RQ-PCR. Panel D shows relative PD-L1 expressions for each siRNA targets with median line, which are grouped according to relevant PD-L1 3'-UTR segments. The negative regulatory effect of these RNA-PBs on PD-L1 expression was largely confirmed. PD-L1 protein level was also increased, when these genes were knocked out by CRISPR/Cas9 system. Expression of these genes in ATL and other lymphomas was also evaluated.In summary, we identified critical sequences within the PD-L1 3'-UTR and RNA-BPs that bind to these sequences and negatively regulate PD-L1 expression. Our findings should not only provide novel insight into the molecular mechanisms by which PD-L1 expression in tumor cell is regulated but also help to identify potential targets for immune therapy. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

P1.07-002 The Expression of PD-L1 Protein as a Prognostic Factor in Lung Squamous Cell Carcinoma

Programmed cell death-1 (PD-1)/programmed cell death-ligand 1 (PD-L1) pathway-targeted immunotherapy has become the standard option of care in the management of lung cancer. The expression of the PD-L1 protein in lung cancer is expected to be a prognostic factor or to predict the response to PD-1-blocking antibodies. However, the association between PD-L1 positivity and the clinicopathological features and patient outcomes in lung squamous cell carcinoma (SCC) remains unclear because the definitive cut-off value for the expression of PD-L1 protein remains to be established.

Programmed Cell Death Ligand 1 Expression in Primary Central Nervous System Lymphomas: A Clinicopathological Study.

Programmed cell death ligand 1 (PD-L1)/programmed cell death 1 (PD-1) have been shown to predict response to PD-L1/PD-1-targeted therapy. We analyzed PD-L1 expression in primary central nervous system lymphomas (PCNSLs). PD-L1 protein and mRNA expression were evaluated in 64 PCNSL tissue samples. IFN-γ, IL-10, CD4, and CD8 mRNA expression was also evaluated. PD-L1 protein was detected in tumor cells in 2 (4.1%) cases and in tumor microenvironments in 25 (52%) cases. PD-L1 mRNA positively correlated with IFN-γ (p=0.0024) and CD4 (p=0.0005) mRNA expression. IFN-γ mRNA positively correlated with CD8 mRNA expression (p=0.0001). Furthermore, tumor cell PD-L1 expression correlated positively with overall survival (p=0.0177), whereas microenvironmental PD-L1 expression exhibited an insignificant negative trend with overall survival (p=0.188). PD-L1 was expressed on both tumor and/or tumor-infiltrating immune cells in PCNSL. The biological roles of this marker warrant further investigation.

Abstract 5623: A comparative study of four PD-L1 immunohistochemical assay in non-small cell lung cancer and evaluation of scoring system

Abstract Background: Clinical trials of immune checkpoints modulators, including both programmed cell death-1 (PD-1) and programmed cell death-ligand 1 (PD-L1) inhibitors, have recently shown promising activity and tolerable toxicity in pre-treated and first line NSCLC patients. At least five PD-L1 IHC assays with custom reagents and scoring-criteria are evaluated in clinical trials. However, current assays for the prognostic and/or predictive role of tumor PD-L1 expression are not standardized and the role of PD-L1 expression as a biomarker is still controversial. Materials and Methods: Retrospectively collected formalin-fixed paraffin-embedded whole-tissue sections (WTS) from 97 NSCLC cases from Seoul National University Bundang Hospital were obtained. We tested the samples divided “training set” and “validation set”: A set of 50 NSCLC WTS (32 adenocarcinoma and 18 squamous cell carcinoma) resected from 2010 to 2011 was designated “training set” and the other set of 47 NSCLC WTS (32 adenocarcinoma, 14 squamous cell carcinoma, and 1 pleomorphic carcinoma) resected from 2015 to 2016 was designated “validation set”. We examined PD-L1 protein expression using four different antibodies (Clone E1L3N, SP142, SP263 and 22C3) using Ventana XT platform with optiview detection kit for E1L3N, SP142 and SP263, and DAKO link 46 platform with pharmDx kit for 22C3 by immunohistochemical analysis. Staining of tumor cells (Tumor proportion score, TPS) and immune cells were evaluated. Results: PD-L1 protein expression was observed in 18 %, 16%, 11% and 12% of total tumors with E1L3N with Ventana optiview kit (5% cutoff), SP142 with Ventana optiview kit with amplification (1% cutoff), SP263 with Ventana optiview kit (25% cutoff) and 22C3 with DAKO PharmDx kit (50% cufoff), respectively. There was no different positive rate between “training” and “validation” set, which means there was no effect of the age of paraffin block on PD-L1 expression. Regarding staining proportion of tumor cells, 22C3 yields more stained tumor cells (highest TPS) and SP142 consistently labels fewer tumor cells (lowest TPS). Among 38 cases which were positive in one or more assays, 28.9% showed discrepant results for PD-L1 expression between the assays according to each criterion. When the same criterion applied for all assays, discrepant rate is higher (63.1 % with 1% cutoff, 71.0% with 5% cutoff). Conclusion: Although comparative determination of PD-L1 protein levels in NSCLC reveals inter-assay variability of tumor cell staining, positive rate is similar under each criterion. Therefore, there is a potential for different diagnostic results according to the key clinical cut-offs if assays and algorithms are mismatched and we should be careful when interpret the PD-L1 expression with different assays. Citation Format: Hyojin Kim, Hyun Jung Kwon, Soo Young Park, Eunhyang Park, Jin-Haeng Chung. A comparative study of four PD-L1 immunohistochemical assay in non-small cell lung cancer and evaluation of scoring system [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5623. doi:10.1158/1538-7445.AM2017-5623

Targeting programmed cell death ligand 1 by CRISPR/Cas9 in osteosarcoma cells.

Programmed cell death ligand 1 (PD-L1) is a transmembrane protein that is expressed on tumor cells that suppresses the T cell-mediated immune response. Therapies targeting the PD-L1 pathway promote anti-tumor immunity and have shown promising results in some types of cancers. However, the functional and therapeutic roles of PD-L1 in osteosarcoma remain largely unknown. In this study, we found that PD-L1 protein was expressed in osteosarcoma cell lines and tissue microarray of patient tumors. Tissue microarray immunohistochemistry analysis showed that the overall and five-year survival rates of patients with high levels of PD-L1 expression were significantly shorter than patients with low levels. High levels of PD-L1 expression were also associated with metastasis in osteosarcoma patients. Furthermore, we applied the Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/Cas9 system to target PD-L1 gene at the DNA level in osteosarcoma cell lines. We found that the expression of PD-L1 could be efficiently disrupted by CRISPR/Cas9 system and PD-L1 knockdown increased drug sensitivities for doxorubicin and paclitaxel. These results suggest that PD-L1 is an independent prognostic factor in osteosarcoma and that PD-L1 knockout by CRISPR/Cas9 may be a therapeutic approach for the treatment of osteosarcoma.

Expression of PD-L1 and prognosis in breast cancer: a meta-analysis.

The associations between programmed cell death ligand 1 (PD-L1) and the prognosis of various cancers have always been a research topic of considerable interest. However, the prognostic value of PD-L1 in breast cancer patients remains a controversial subject. We aimed to assess the association between PD-L1 protein expression and clinicopathological features and the impact of this relationship on breast cancer survival. We performed a systematic search of the PubMed, EMBASE, and Cochrane Library databases to determine the correlations among PD-L1 expression, clinicopathological features and overall survival (OS). A total of 5 studies containing 2,546 cases were included in the analysis. The combined hazard ratio (HR) and its 95% confidence interval (CI) for OS were 1.76 (95% CI 1.09–2.82; P=0.02) for patients with tumors exhibiting PD-L1 overexpression. The pooled odds ratios (ORs) indicated that PD-L1 expression was associated with positive lymph node metastasis, higher histological grades, estrogen receptor (ER)-negativity, and triple-negative breast cancer (TNBC). Our findings indicate that PD-L1 expression is a promising biomarker for the prognosis of breast cancer, and may be helpful to clinicians aiming to select the appropriate immunotherapy for breast cancer.

The expression of PD-L1 protein as a prognostic factor in lung squamous cell carcinoma

BackgroundProgrammed cell death-1 (PD-1)/programmed cell death-ligand 1 (PD-L1) pathway-targeted immunotherapy has become the standard option of care in the management of lung cancer. The expression of the PD-L1 protein in lung cancer is expected to be a prognostic factor or to predict the response to PD-1-blocking antibodies. However, the association between PD-L1 positivity and the clinicopathological features and patient outcomes in lung squamous cell carcinoma (SCC) remains unclear because the definitive cut-off value for the expression of PD-L1 protein remains to be established. Materials and methodsThe expression of PD-L1 protein in 205 surgically resected primary lung SCC patients was evaluated by immunohistochemistry with the antibody clone SP142. We generated a histogram to show the proportion of PD-L1-positive carcinoma cells, and set the cut-off values as 1%, 5%, 10% and 50%. Moreover, we examined the proliferative capacity of these tumors using Ki-67 immunohistochemistry. ResultsThe samples from 106 (51.7%), 72 (35.1%), 61 (29.7%) and 37 (18.0%) patients were positive for the expression of PD-L1 protein at cut-off values of 1%, 5%, 10% and 50%, respectively. Fisher’s exact test showed that, for almost all of the factors, PD-L1 positivity was not associated with the clinicopathological features with any of the four cut-off values. Univariate and multivariate survival analyses revealed that the PD-L1-positive patients only had a poorer prognosis than the PD-L1-negative patients at the 1% cut-off value. The Ki-67 labeling index in the PD-L1-positive patients was higher than that in the PD-L1-negative patients. ConclusionsThe expression of PD-L1 protein was associated with a poor prognosis in lung SCC patients. The 1% cut-off value for PD-L1 might become a better predictive marker than the other cut-off values.

Expression of PD-1/PD-L1 in lung adenocarcinoma and correlation with epidermal growth factor receptor mutation status

Objective: To investigate the expression of programmed cell death-1(PD-1) and programmed cell death-ligand 1(PD-L1) in lung adenocarcinoma in correlation with clinical pathological parameters, especially with regard to different epidermal growth factor receptor (EGFR) mutation status. Methods: One hundred and nine cases of lung adenocarcinoma were collected during the period from Aug. 2010 to Jan. 2016, including 51 cases of EGFR wild type and 58 cases of EGFR mutations. Immunohistochemistry was used to detect PD-1/PD-L1 protein expression. Chi-square test was used to analyze the correlation between PD-1 and PD-L1 expression, and in correlation with clinicopathological parameters. All statistical analyses run by SAS 9.1 software. Results: The positive rates of PD-1 and PD-L1 expression were 68.8% (75/109) and 27.5% (30/109), respectively, with significant correlation between the two (P<0.05). PD-1 and PD-L1 expression rates were higher in 51 cases with EGFR wild type status (74.5% and 39.2%) than those in 58 EGFR mutation cases (63.8% and 17.2%); PD-1 expression was significantly associated with age (P<0.05); that of PD-L1 was closely correlated with histological type, tumor size, lymph node metastasis and EGFR status (P<0.05). Conclusions: PD-1 and PD-L1 expression profiles and their correlation with EGFR mutations are different from those with native EGFR. PD-L1 overexpression is closely correlated with larger tumor size and lymph node metastasis, suggesting it is a high-grade marker for lung adenocarcinoma.

PD-L1, PD-1, CD4, and CD8 expression in neoplastic and nonneoplastic thymus

The checkpoint protein programmed cell death ligand-1 protein (PD-L1) binds to its receptor (PD-1) activating the PD-L1/PD-1 pathway, an important therapeutic target. There is limited information regarding PD-L1 and PD-1 expression in thymic lesions. Sections from nonneoplastic thymi (n = 20), thymomas World Health Organization types A, AB, B1, B2, and B3 (n = 38) and thymic squamous cell carcinoma (n = 8) were stained for PD-L1 (clone SP142; Spring BioScience), PD-1 (MRQ22; Cell Marque), CD4 (clone SPO32; Cell Marque), and CD8 (JCB117; Ventana). Immunoreactivity for each antibody was classified as focal or diffuse and scored as follows: 0, negative; 1%-5%, 1+; 6%-20%, 2+; and >20%, 3+. The proportions of cases expressing PD-L1, PD-1, CD4, and C8 at score ≥1+ were compared by diagnosis, using χ2 statistics. PD-L1 was expressed in 90% of nonneoplastic thymi, 92% of thymomas, and 50% of carcinomas, with significantly higher scores (P < .01) in B2 and B3 thymomas and carcinomas than in AB and B1 thymomas; PD-L1 was diffuse in most B2 and B3 thymomas and focal in carcinomas. PD-1 was focally expressed, and mostly with scores 1+, in 55% of nonneoplastic thymi, 63% of thymomas, and 37.5% of carcinomas. CD4+ and CD8+ cells were diffusely distributed with scores 3+ in all lesions other than B3 thymomas and carcinomas. The latter showed CD4+ cells mostly at the interface between neoplastic cells and stroma. PD-L1 and PD-1 are not expressed in similar locations and cellular proportions in thymic lesions, raising a question as to whether the PD-L1/PD-1 pathway is an actionable therapeutic target in these lesions.

Validated programmed cell death ligand 1 immunohistochemistry assays (E1L3N and SP142) reveal similar immune cell staining patterns in melanoma when using the same sensitive detection system.

Tumour cell and/or immune cell programmed cell death ligand 1 (PD-L1) expression is considered as a potential biomarker for anti-PD1 and anti-PD-L1 immunotherapy. Currently, different PD-L1 assays are used. This study aims to compare the staining patterns of two PD-L1 antibody clones in melanoma metastases and correlate them with PD-L1 mRNA expression. The immunohistochemistry assays were optimized and validated independently on a Ventana Benchmark Ultra (Ventana Medical Systems Inc., Tucson, AZ, USA) (E1L3N) and XT (SP142), using the same detection system. In total, 46 melanoma metastases were stained with both validated immunohistochemistry assays. Stained slides were digitized for qualitative and semi-quantitative evaluation; done by pathologist and semi-automated software analysis. A subset of 21 melanoma metastases was selected for quantification of the PD-L1 mRNA expression. Accuracy and precision criteria were met for both assays. PD-L1 protein and mRNA expression showed remarkably good Spearman's coefficients of 0.90 (E1L3N) and 0.87 (SP142). Despite the remarkable correlation between both PD-L1 assays in expression patterns and quantification values (ρ > 0.90), E1L3N showed significantly more tumour cell staining than SP142. E1L3N and SP142 IHC assays were optimized and validated successfully and independently for sensitive and accurate PD-L1 detection. Concordance was best for immune cell scoring, while E1L3N tended to detect more tumour cells. Determination of the clinically relevant cut-off values for immune cell versus tumour cell detection requires further research.

Abstract 2223: Membranous expression of programmed cell death-ligand 1 (PDL1) on cancer cells is induced by cisplatin in an ATR dependent manner

Abstract Cancer cells frequently develop strategies allowing to escape potential immune attacks by the host. One central component of this defense mechanism is the PDL1-PD1 axis with PDL1 expression on the surface of antigen presenting cells. DNA damaging chemotherapeutic are known to have suppressive effect on the immune system. Possible effects on immune checkpoints, however, are poorly understood. We investigated if Cisplatin, a widely used chemotherapeutic for treatment of ovarian and lung carcinomas, might influence expression of PDL1 on cancer cells of these pathologies. Treatment of cell lines as well as precision-cut tissue slices from patient tumors with clinically relevant dosages of cisplatin led to a significant induction of PDL1 protein in cancer cells as revealed by Western Blot and IHC analyses. This effect was independent on ATR or ATM activity since pre-treatment with ATR or ATM inhibitors had no significant effect on cisplatin induced total PDL1 protein levels. Interestingly, however, we observed an almost complete inhibition of cisplatin-induced membranous PDL1 upon ATR but not ATM inhibition as revealed by FACS analysis in unfixed cells. The role of the ATR axis was further corroborated by the finding that presentation of PDL1 at the cell surface was paralleled by phosphorylation of CHK1. Together our data indicate an important role of DNA damage induced ATR/CHK1 activity on the localization of PDL1 at the surface of cancer cells. These data implicate that combination of cisplatin with either anti-PD1 or anti-PDL1 antibodies or ATR/CHK1 inhibitors should reduce immunosuppressive mechanisms and enhance chemotherapy efficacy. Citation Format: Lea Schaaf, Meng Dong, Simon Heine, Heiko van der Kuip, Walter E. Aulitzky. Membranous expression of programmed cell death-ligand 1 (PDL1) on cancer cells is induced by cisplatin in an ATR dependent manner. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2223.

Clinicopathological and prognostic significance of programmed cell death ligand1 (PD-L1) expression in patients with non-small cell lung cancer: a meta-analysis.

Programmed cell death 1 (PD-1) and one of its ligands, PD-L1, are key immune checkpoint proteins. Evidences showed PD-L1 is an emerging biomarker for immunotherapy by anti-PD-1 and anti-PD-L1 antibody in non-small cell lung cancer (NSCLC). To investigate the association of PD-L1 protein expression with clinicopathological features and its impact on survival outcome, we conducted a meta-analysis. A comprehensive literature search of electronic databases (up to July 10, 2014) was performed. Correlation between PD-L1 expression and clinicopathological features and overall survival (OS) was analyzed by synthesizing the qualified data. Publication biases were examined. A total of 1,550 NSCLC patients from 9 studies were included. The pooled odds ratios (ORs) indicated high PD-L1 expression was associated with poor tumor differentiation [OR =0.53, 95% confidence interval (CI): 0.39-0.72, P<0.0001]. Whereas, none of other clinicopathological characteristics [gender, smoking status, histological type, invasive depth of tumor, status of lymph node metastasis and tumor node metastasis (TNM) stage] were correlated with PD-L1 expression in current analysis. The combined hazard ratio (HR) for OS showed high expression of PD-L1 impaired the OS in NSCLC (HRpositive/negative =1.47, 95% CI: 1.19-1.83, P=0.0004). Our meta-analysis indicated PD-L1 protein expression in NSCLC was not associated with common clinicopathological characteristics, except tumor differentiation. It was a poor prognostic biomarker for NSCLC. Further research should be performed to investigate the precise clinicopathological and prognostic significance of PD-L1 in NSCLC under uniform testing standard.

Expression of programmed cell death ligand 1 (PD-L1) and prevalence of tumor-infiltrating lymphocytes (TILs) in chordoma

Chordomas are primary malignant tumors of the notochord that are resistant to conventional chemotherapy. Expression of programmed cell death ligand 1 (PD-L1), prevalence of tumor-infiltrating lymphocytes (TILs), and their clinical relevance in chordoma remain unknown. We evaluated PD-L1 expression in three chordoma cell lines and nine chordoma tissue samples by western blot. Immunohistochemical staining was performed on a chordoma tissue microarray (TMA) that contained 78 tissue specimens. We also correlated the expression of PD-L1 and TILs with clinical outcomes. PD-L1 protein expression was demonstrated to be induced by IFN-γ in both UCH1 and UCH2 cell lines. Across nine human chordoma tissue samples, PD-L1 protein was differentially expressed. 94.9% of chordoma samples showed positive PD-L1 expression in the TMA. The expression score of PD-L1 for metastatic chordoma tumors was significant higher as compared with non-metastatic chordoma tumors. Expression of PD-L1 protein significantly correlates with the presence of elevated TILs, which correlates with metastasis. In summary, our study showed high levels of PD-L1 are expressed in chordoma, which is correlated with the prevalence of TILs. The current study suggests targeting PD-L1 may be a novel immunotherapeutic strategy for chordoma clinical trials.

Abstract 3750: Targeting PD-L1 sensitizes head and neck squamous cell carcinoma to cisplatin

Abstract Platinum-based chemotherapy agents such as Cisplatin (CDDP) are commonly used as first-line treatment for several types of human cancers including ovarian, lung, testicular, and head and neck squamous cell carcinomas (HNSCC). Unfortunately, CDDP monotherapy is often ineffective due to inherent or acquired tumor resistance to therapy, also known as chemoresistance. This contributes to a need for the administration of larger, more toxic doses, as well as failure of chemotherapy and tumor recurrence. Despite the clinical significance of chemoresistance, the mechanisms driving this phenomenon are not completely understood. Programmed cell death ligand 1 (PD-L1), a membrane-bound glycoprotein responsible for modulating the immunological response through the induction of T-Cell anergy and apoptosis, has been shown to be overexpressed in many cancers, including HNSCC. While PD-L1 overexpression has been directly related to the immunoevasion of cancer cells allowing for tumor progression, recent reports suggest that PD-L1 also plays an important role in the tumor response to doxorubicin-based chemotherapy independent of its immune function. The present study investigates the role of PD-L1 in response to CDDP in HNSCC. In vitro experiments were performed using four well-characterized human HNSCC cell lines. Quantitative polymerase chain reaction (qPCR) and western blot were conducted to determine the baseline and post-CDDP-treatment PD-L1 gene expression. The results demonstrated that PD-L1 mRNA transcription and protein expression are upregulated in response to CDDP, suggesting that PD-L1 is involved in the chemoresponse. Conversely, knockdown of PD-L1 using siRNA resulted in chemosensitization of HNSCC cells to CDDP. Together, these findings implicate PD-L1 in the CDDP-chemoresponse in HNSCC. In conclusion, we propose a role for PD-L1 that is distinct from the classic immunoevasion pathway. Our findings demonstrate that disruption of this protein leads to increased sensitivity of HNSCC cells to CDDP, suggesting a potential combination therapeutic strategy for patients with CDDP-resistant HNSCC. Citation Format: Peter Qiao, Shayanne A. Lajud, Danish A. Nagda, Nobuaki Tanaka, Alyssa Civantos, Bert W. O'Malley, Daqing Li. Targeting PD-L1 sensitizes head and neck squamous cell carcinoma to cisplatin. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3750. doi:10.1158/1538-7445.AM2014-3750

Using PD‐L1 to Induce Chemosensitization of Head and Neck Squamous Cell Carcinoma

Objectives: (1) Investigate the impact of programmed cell death ligand 1 (PD-L1) on the response to Cisplatin (CDDP) therapy in head and neck squamous cell carcinoma (HNSCC). (2) Quantify the effect of CDDP treatment on the expression of PD-L1 in HNSCC cells. (3) Evaluate the impact of PD-L1 down-regulation on the chemosensitivty of HNSCC cells. (4) Describe the implications of PD-L1 modulation on the efficacy of current platinum-based chemotherapeutic agents in HNSCC. Methods: In vitro experiments were performed from November 2013 to January 2014 at the University of Pennsylvania Gene and Molecular Therapy Laboratory with 4 well-characterized human HNSCC cell lines. Quantitative polymerase chain reaction (qPCR) and western blot were conducted to determine the baseline and post-CDDP treatment PD-L1 gene expression. Knockdown of PD-L1 expression using siRNA was then performed to induce chemosensitization of HNSCC cells to CDDP. Cells treated with CDDP were compared with untreated controls to evaluate cytotoxicity. Results: Treatment of HNSCC cells with CDDP resulted in increased transcription and translation of PD-L1 compared with baseline levels. Subsequent knockdown of PD-L1 expression in HNSCC cells using siRNA resulted in increased CDDP cytotoxicity compared with control HNSCC cells. Conclusions: Increased PD-L1 expression in response to CDDP therapy and improved chemosensitization with its down-regulation are significant findings that highlight the role of PD-L1 in determining the efficacy of chemotherapeutic agents. Our findings demonstrate that disruption of the PD-L1 protein leads to increased sensitivity of HNSCC cells to CDDP, suggesting a potential combination therapeutic strategy for patients with CDDP-resistant HNSCC.

PD-L1 Expression Is Characteristic of a Subset of Aggressive B-cell Lymphomas and Virus-Associated Malignancies

Programmed cell death ligand 1 (PD-L1) is an immunomodulatory molecule expressed by antigen-presenting cells and select tumors that engages receptors on T cells to inhibit T-cell immunity. Immunotherapies targeting the PD-1/PD-L1 pathway have shown durable antitumor effects in a subset of patients with solid tumors. PD-L1 can be expressed by Reed-Sternberg cells comprising classical Hodgkin lymphoma (CHL) and by malignant B cells comprising EBV-positive posttransplant lymphoproliferative disorders (PTLD). We sought to determine whether the expression of PD-L1 represents a general strategy of immune evasion among aggressive B-cell lymphomas and virus- and immunodeficiency-associated tumors. Using novel antibodies and formalin-fixed, paraffin-embedded (FFPE) tissue biopsies, we examined 237 primary tumors for expression of PD-L1. Robust PD-L1 protein expression was found in the majority of nodular sclerosis and mixed cellularity CHL, primary mediastinal large B-cell lymphoma, T-cell/histiocyte-rich B-cell lymphoma, EBV-positive and -negative PTLD, and EBV-associated diffuse large B-cell lymphoma (DLBCL), plasmablastic lymphoma, extranodal NK/T-cell lymphoma, nasopharyngeal carcinoma, and HHV8-associated primary effusion lymphoma. Within these tumors, PD-L1 was highly expressed by malignant cells and tumor-infiltrating macrophages. In contrast, neither the malignant nor the nonmalignant cells comprising nodular lymphocyte-predominant Hodgkin lymphoma, DLBCL-not otherwise specified, Burkitt lymphoma, and HHV8-associated Kaposi sarcoma expressed detectable PD-L1. Certain aggressive B-cell lymphomas and virus- and immunodeficiency-associated malignancies associated with an ineffective T-cell immune response express PD-L1 on tumor cells and infiltrating macrophages. These results identify a group of neoplasms that should be considered for PD-1/PD-L1-directed therapies, and validate methods to detect PD-L1 in FFPE tissue biopsies.