Role Of Programmed Death-ligand 1 Research Articles

Immunohistochemical Expression of Programmed Death Ligand-1 and CD-8 in Glioblastoma

Background Glioblastoma (GBM) is the most common and most aggressive primary malignant brain tumor in adults. It is characterized by its extremely poor prognosis despite the available treatment strategies. Immune evasion is described in Glioblastoma via the PD-L1/ PD-1 interaction. Programmed death ligand 1 (PD-L1) is a cell surface ligand expressed on the surface of several tumors including GBM and its receptor is the PD-1 (Programmed deasth-1). Other malignant tumors including melanoma and non-small cell lung cancer, showed promising results using PD-L1/PD1 blockade treatment strategies where PD-L1 was described as a potential predictive biomarker for patient selection in these tumors. In our study we will shed the light on the expression and role of PD-L1 in glioblastoma, the presence of tumor infiltrating lymphocytes (TILs) and its interaction with PD-L1 in glioblastoma. The role of PD-L1, CD-8+ TILs, other clinicopathologic parameters and patient’s survival will be also discussed in relation to glioblastoma. Methods Paraffin embedded tissue blocks of thirty cases of GBN were retrieved, slides were prepared and stained via Hx& E for evaluation and confirmation of diagnosis according to the CNS WHO 2016. Immunohistochemistry using PD-L1 and CD-8 was performed on the 30 glioblastoma cases. Interpretation of the results and correlation between the expression of both markers and the clinicopathologic parameters was also done. Furthermore, survival analysis was done to correlate overall survival and progression free survival of the glioblastoma cases to the expression of PD-L1 and CD-8 markers and also the clinicopathologic parameters available. Results Diffuse/fibrillary PD-L1 was expressed in all cases (30/30) with variable percentages (16.7% in ≤ 25% of cases 5/30, 33.3% in > 25%- ≤ 50% of cases10/30, 16.7% in > 50%- ≤ 75% of cases 5/30 and 33.3% in > 75% of cases 10/30). The mean value of Diffuse/fibrillary PD-L1 expression was 57.6%. Membranous PD-L1 was expressed in 6/30 of the cases. TILs were set into two groups according to Han et al 2014; low infiltration group 17/30 (56.7%) of cases and high infiltration group 13/30 (43.3%) of cases. Expression of CD-8 was 10% (median percentage) and 14.3% (mean percentage). PD-L1 and CD-8 correlation was statistically significant (P 0.001) where high PD-L1 expression is associated with low CD-8 expression. PD-L1 expression was associated with worse overall survival (0.001) and worse progression free survival (P 0.026). CD-8expression did not affect the outcome. Correlation of age, sex, tumor site and laterality to outcome were statistically insignificant. In the results of our study PD-L1 expression was the only independent factor that affected the prognosis according to Cox variate analysis. Conclusion The incidence of PD-L1 expression in GBM patients is robust. Higher expression of PD-L1 is associated with lower TILs expression and worse prognosis.

Chemotherapy-induced PDL-1 expression in cancer-associated fibroblasts promotes chemoresistance in NSCLC

ObjectivesA cure for cancer is out of reach for most patients due to chemoresistance. Cancer-associated fibroblasts (CAFs) play a vital role in cancer chemoresistance, but detailed understanding of the process particularly in chemoresistant lung cancer is lacking. In this study, we investigated programmed death-ligand 1 (PDL-1) as a potential biomarker for CAF-induced chemoresistance and evaluated its role and the underlying mechanisms of chemoresistance in non-small cell lung cancer (NSCLC). Materials and MethodsA systemic search of gene expression profiles of multiple tissues in NSCLC was carried out to determine the expression intensities of traditional fibroblast biomarkers and CAF-secreted protumorigenic cytokines. PDL-1 expression in CAFs was analyzed by ELISA, Western blotting, and flow cytometry. Human cytokine array was used to identify specific cytokines secreted from CAFs. Role of PDL-1 in NSCLC chemoresistance was assessed using CRISPR/Cas9 knockdown and various functional assays including MTT, cell invasion, sphere formation, and cell apoptosis. In vivo experiments were conducted using a co-implantation xenograft mouse model with live cell imaging and immunohistochemistry. ResultsWe demonstrated that chemotherapy-stimulated CAFs promoted tumorigenic and stem cell-like properties of NSCLC cells, which contribute to their chemoresistance. Subsequently, we revealed that PDL-1 expression is upregulated in chemotherapy-treated CAFs and is associated with poor prognosis. Silencing PDL-1 expression suppressed CAFs’ ability to promote stem cell-like properties and invasiveness of lung cancer cells, favoring chemoresistance. Mechanistically, an upregulation of PDL-1 in chemotherapy-treated CAFs led to an increase in hepatocyte growth factor (HGF) secretion, which stimulates cancer progression, cell invasion, and stemness of lung cancer cells, while inhibiting apoptosis. ConclusionOur results show that PDL-1-positive CAFs modulate stem cell-like properties of NSCLC cells by secreting elevated HGF, thereby promoting chemoresistance. Our finding supports PDL-1 in CAFs as a chemotherapy response biomarker and as a drug delivery and therapeutic target for chemoresistant NSCLC.

Abstract P6-14-15: PD-L1 expression regulated by JAK/STAT signaling pathway contributes to cell migration and invasion in breast cancer

Abstract Background: Programmed death-ligand 1 (PD-L1) implicated in tumor immune evasion and predictive biomarker in immunotherapy is widely recognized, however, the role of PD-L1 in modulating tumor invasion remains largely unexplored. PD-L1 expression on tumor tissue is usually limited by the invasiveness, tumor heterogeneity as well as insufficient tumor tissue samples, while PD-L1 expression on circulating tumor cells (CTCs) might overcome the limitation. In the present study, we aimed to investigate the role and mechanism of PD-L1 in regulating the migration and invasion of breast cancer cells and to evaluate PD-L1 expression on CTCs in metastatic breast cancer patients. Methods: The expression level of PD-L1 in MCF-7 cells and MDA-MB-231 cells was assessed by quantitative real-time RT-PCR and Western Blot. Gain-of-function and loss-of-function study on cell migration and invasion abilities were carried out by overexpression of PD-L1 or silencing PD-L1. PD-L1 expression on CTCs in thirty-six metastatic breast cancer patients were detected. A novel staining procedure which included fluorescent glucose analog staining for CTC enumeration and immunostaining targeting CD45, vimentin and PD-L1 were analyzed. Survival curves were estimated by the Kaplan-Meier method and the log-rank test was used to compare between groups. All tests were two-sided, and p values were considered significant at the 0.05 level. Results: Compared with MCF-7 cells, PD-L1 mRNA and PD-L1 protein expression were significantly increased in MDA-MB-231 cells. Down-regulation of PD-L1 expression in MDA-MB-231 cells inhibited the migration and invasion of MDA-MB-231 cells, while overexpression of PD-L1 in MCF-7 cells increased the migration and invasion of MCF-7 cells. In addition, we found that PD-L1 expression was regulated by JAK/STAT signaling pathway. PD-L1 expression on CTCs in metastatic breast cancer patients was associated with triple negative breast cancers subtype (P=0.013). High expression of PD-L1 on CTCs in metastatic breast cancer patients was correlated to poor overall survival (HR=3.165, 95%CI: 1.121-8.938, P=0.029). Conclusion: Our results indicate that high expression of PD-L1 contributes to cell migration and invasion in breast cancer cell possibly partially through JAK/STAT signaling pathway. The PD-L1 expression on CTCs might serve as a promising non-invasive prognostic biomarker in patients with metastatic breast cancer. Citation Format: Junqing Chen. PD-L1 expression regulated by JAK/STAT signaling pathway contributes to cell migration and invasion in breast cancer [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P6-14-15.

Abstract C050: The role of PD-L1, ACKR/DARC, Livin and Annexin A5 in malignant tumours of the bone, prostate, breast, eye/orbit, nasopharynx, and metastatic carcinomas to the brain, neck and lymph node among West Africans in Zaria, Nigeria

Abstract Cancer ranks as a leading cause of death and an important barrier to increasing life expectancy worldwide. Globally, there are estimated 19.3 million new cancer cases and about 10 million cancer mortality in 2020. Should current cancer trends continue, Africa’s cancer burden is projected to reach an alarming 1.4 million new cases and 1 million deaths by 2030. Thus, racial/ethnic disparities in cancer morbidity and mortality continue to widen globally but molecular biology and genomic studies rarely interrogate cancer in diverse disadvantaged populations. Effective control of tumour growth in cancer microenvironment is facilitated by cellular interaction between innate and adaptive immune cells. The programmed death ligand-1 (PD-L1), an immune checkpoint expressed on tumour cells, facilitates the escape of immunosurveillance in cancer by interacting with programmed death-1 (PD-1) to initiate apoptosis of the immune cells. The interaction between these immune cells may be mediated by atypical chemokine receptor 1 (ACKR1)/Duffy antigen receptor for chemokines (DARC) towards activation of tumour-specific immune response by chemoattraction of leukocytes to the inflammatory sites. Livin/BIRC7 protein overexpression is a key component of evasion of apoptosis in cancer cells. Interestingly, Annexin A5, an important member of Annexin family of proteins with high affinity to phosphatidylserine, has been reported to serve as an important component of apoptosis by stimulating immunogenicity of tumor cells. In this pilot study, we report using immunohistochemistry, RNA-seq and whole exome sequencing the expression pattern and functional significance of PD-L1, ACKR/DARC, Livin/BIRC7 and Annexin A5 in malignant tumours of the bone, prostate, breast, eye/orbit, nasopharynx, and metastatic carcinomas to the brain, neck and lymph node among West Africans in Zaria, Nigeria. In osteosarcoma and osteogenic sarcoma of the bone, we observed negative expression of ACKR/DARC and PD-L1, and overexpression of Livin and Annexin A5 proteins. However, a mucoepidermoid carcinoma of the index finger shows strong expression of ACKR/DARC, PD-L1 and Annexin A5 with poor expression of Livin protein. The results also show negative expression of ACKR/DARC, PD-L1 and Livin proteins from retinoblastoma, nasopharyngeal carcinoma, metastatic adenosquamous carcinoma to the parietal lobe of the brain, Metastatic squamous neck cancer, metastatic carcinoma of the lymph nodes and invasive breast carcinoma no special type (NST) grade 3. Prostate adenocarcinomas with Gleason grade 9 show negative expression of ACKR/DARC and PD-L1 proteins. All the tumours studied are strongly positive for Annexin A5 expression. The diverse expression pattern of ACKR/DARC, PD-L1, Livin and Annexin A5 in malignant tumours of the bone, retina, nasopharynx, breast, prostate and metastatic carcinomas to the brain, neck and lymph may be of significant importance in tumour behaviour and prognosis. Citation Format: Faruk Mohammed, Melissa B. Davis, Clayton C. Yates, Halimatu Sadiya Musa. The role of PD-L1, ACKR/DARC, Livin and Annexin A5 in malignant tumours of the bone, prostate, breast, eye/orbit, nasopharynx, and metastatic carcinomas to the brain, neck and lymph node among West Africans in Zaria, Nigeria [abstract]. In: Proceedings of the 15th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2022 Sep 16-19; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2022;31(1 Suppl):Abstract nr C050.

PD-L1 negatively regulates antifungal immunity by inhibiting neutrophil release from bone marrow

Programmed death ligand 1 (PD-L1) has been shown to be inducibly expressed on neutrophils to suppress host immunity during polymicrobial sepsis, virus and parasite infections. However, the role of PD-L1 on neutrophil-mediated antifungal immunity remains wholly unknown. Here, we show that the expression of PD-L1 on murine and human neutrophils was upregulated upon the engagement of C-type lectin receptor Dectin-1 with its ligand β-glucans, exposed on fungal pathogen Candida albicans yeast. Moreover, β-glucan stimulation induced PD-L1 translocation into nucleus to regulate the production of chemokines CXCL1 and CXCL2, which control neutrophil mobilization. Importantly, C. albicans infection-induced expression of PD-L1 leads to neutrophil accumulation in bone marrow, through mediating their autocrine secretion of CXCL1/2. Furthermore, neutrophil-specific deficiency of PD-L1 impaired CXCL1/2 secretion, which promoted neutrophil migration from bone marrow into the peripheral circulation, thereby conferring host resistance to C. albicans infection. Finally, either PD-L1 blockade or pharmacological inhibition of PD-L1 expression significantly increased neutrophil release from bone marrow to enhance host antifungal immunity. Our data together indicate that activation of Dectin-1/PD-L1 cascade by β-glucans inhibits neutrophil release from bone marrow reserve, contributing to the negative regulation of antifungal innate immunity, which functions as a potent immunotherapeutic target against life-threatening fungi infections.

Abstract 5624: PD-L1 mediates IFNγ-regulation of glucose but not of tryptophan metabolism in clear cell renal cell carcinoma

Abstract The immune checkpoint programmed death-ligand 1 (PD-L1) is expressed on the cell surface of tumor cells and is key for maintaining an immunosuppressive microenvironment through its interaction with the programmed cell death 1 (PD-1). Clear cell renal cell carcinoma (ccRCC) is a highly immunogenic cancer characterized by an aberrant aerobic glycolytic metabolism and is known to overexpress PD-L1. Multiple immunotherapies have been approved for the treatment of ccRCC, including cytokines and immune checkpoint inhibitors. Recently the intrinsic role of PD-L1 and interferon gamma (IFNγ) signaling have been studied in several types of tumor cells, yet it remains unclear how they affect the metabolism and signaling pathways of ccRCC. Using metabolomics, metabolic assays and RNAseq, we showed that IFNγ enhanced aerobic glycolysis and tryptophan metabolism in ccRCC cells in vitro and induced the transcriptional expression of signaling pathways related to inflammation, cell proliferation and cellular energetics. These metabolic and transcriptional effects were partially reversed following PD-L1 transient silencing. Aerobic glycolysis as well as signaling pathways related to inflammation were not induced by IFNγ when PD-L1 was silenced, however tryptophan metabolism and activation of Jak2 and STAT1 were maintained. Our data demonstrate that PD-L1 expression is required to mediate some of IFNγ’s effect in ccRCC cells and highlight the importance of PD-L1 signaling in regulating the metabolism of ccRCC cells in response to inflammatory signals. Citation Format: Mamatha Garige, Susmita Ghosh, ALexis Norris, Guangyuan Li, Carole Sourbier. PD-L1 mediates IFNγ-regulation of glucose but not of tryptophan metabolism in clear cell renal cell carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5624.

Expression and Role of PD-L1 in a Mouse Model of Necrotizing Enterocolitis

To investigate the expression and role of programmed death ligand-1 (PD-L1) in a mouse model of necrotizing enterocolitis (NEC). A total of 20 wild-type C57 BL/6 J mice were randomly assigned to the control and the model groups. Mice in the control group were breastfed, while mice in the model group were given lipopolysaccharide, formula feeding, hypoxia, and cold stimulation for NEC induction. Then, the intestines of the mice were collected in order to assess the pathological changes through HE staining, to examine PD-L1 expression and localization with immunofluorescence co-localization, and to evaluate intestinal PD-L1 expression with Western blot. Peripheral blood was collected for flow cytometry to examine leukocyte subpopulations and their PD-L1 expression. On the other hand, 14 PD-L1 (+/+) mice and 14 PD-L1 (-/-) mice were randomly divided into their respective genotype control groups and model groups. The same induction method as was already mentioned was adopted for the model groups. The intestines of the mice were collected for HE staining to evaluate the pathological change and peripheral blood was collected to examine the expression of inflammatory factors. The NEC mouse model was successfully constructed. PD-L1 was widely expressed in enterocytes and inflammatory cells in the mouse intestines and in T cells, monocytes, and neutrophils in peripheral blood. The expression of PD-L1 in NEC mouse intestines increased in comparison with that of the control group. In the peripheral blood of NEC mice, the proportion of T cells and monocytes and their PD-L1 expression showed no significant changes compared with those of the control group, while the proportion of neutrophils and their PD-L1 expression increased by about 140% and 150%, respectively, in comparison with those of the control group ( P<0.05). According to the results of the PD-L1 gene mouse experiment, the control groups of PD-L1 (+/+) mice and PD-L1 (-/-) mice showed no significant difference in their intestinal conditions and serum inflammatory factor levels, while the PD-L1 (-/-) NEC mouse had worse intestinal pathological changes and increased mean pathological scores compared with those of PD-L1 (+/+) NEC mouse ( P<0.05). In addition, serum interleukin (IL)-10 in PD-L1 (-/-) NEC mouse decreased by about 44% compared with that of PD-L1 (+/+) NEC mice, and chemokine (C-X-C motif) ligand 1/IL-6/IL-1β all increased by more than 25% (all P<0.05). PD-L1 is widely expressed in inflammatory cells and enterocytes in mice. Knocking out PD-L1 aggravates the degree of NEC inflammation and intestinal pathological changes. PD-L1 plays a protective role by reducing inflammation in the pathogenesis of NEC, the mechanism of which may be related to the regulation of neutrophils/enterocytes.

Innate PD-L1 limits T cell-mediated adipose tissue inflammation and ameliorates diet-induced obesity.

Obesity has become a major health problem in the industrialized world. Immune regulation plays an important role in adipose tissue homeostasis; however, the initial events that shift the balance from a noninflammatory homeostatic environment toward inflammation leading to obesity are poorly understood. Here, we report a role for the costimulatory molecule programmed death-ligand 1 (PD-L1) in the limitation of diet-induced obesity. Functional ablation of PD-L1 on dendritic cells (DCs) using conditional knockout mice increased weight gain and metabolic syndrome during diet-induced obesity, whereas PD-L1 expression on type 2 innate lymphoid cells (ILC2s), T cells, and macrophages was dispensable for obesity control. Using in vitro cocultures, DCs interacted with T cells and ILC2s via the PD-L1:PD-1 axis to inhibit T helper type 1 proliferation and promote type 2 polarization, respectively. A role for PD-L1 in adipose tissue regulation was also shown in humans, with a positive correlation between PD-L1 expression in visceral fat of people with obesity and elevated body weight. Thus, we define a mechanism of adipose tissue homeostasis controlled by the expression of PD-L1 by DCs, which may be a clinically relevant finding with regard to immune-related adverse events during immune checkpoint inhibitor therapy.

Inhibition of myeloid PD-L1 suppresses osteoclastogenesis and cancer bone metastasis.

Programmed death-ligand 1 (PD-L1) is predominantly expressed in the antigen-presenting cells (APCs) that are originated and are abundant in the bone marrow. The roles of PD-L1 in bone cell differentiation and cancer bone metastasis remain unclear. Here we show that PD-L1 antibody or PD-L1 conditional knockout in the hematopoietic or myeloid lineage suppresses osteoclast differentiation in vitro and in vivo. Bone metastases of breast cancer and melanoma are diminished by PD-L1 antibody or PD-L1 deletion in the myeloid lineage. Transcriptional profiling of bone marrow cells reveals that PD-L1 deletion in the myeloid cells upregulates immune-stimulatory genes, leading to increased macrophage M1 polarization, decreased M2 polarization, enhanced IFNγ signaling, and elevated T cell recruitment and activation. All these alterations result in heightened anti-tumor immunity in the cancer microenvironment. Our findings support PD-L1 antibody as a potent therapy for bone metastasis of breast cancer and melanoma by simultaneously suppressing osteoclast and enhancing immunity.

PD-L1 promotes myofibroblastic activation of hepatic stellate cells by distinct mechanisms selective for TGF-β receptor I versus II.

SUMMARYIntrahepatic cholangiocarcinoma (ICC) contains abundant myofibroblasts derived from hepatic stellate cells (HSCs) through an activation process mediated by TGF-β. To determine the role of programmed death-ligand 1 (PD-L1) in myofibroblastic activation of HSCs, we disrupted PD-L1 of HSCs by shRNA or anti-PD-L1 antibody. We find that PD-L1, produced by HSCs, is required for HSC activation by stabilizing TGF-β receptors I (TβRI) and II (TβRII). While the extracellular domain of PD-L1 (amino acids 19–238) targets TβRII protein to the plasma membrane and protects it from lysosomal degradation, a C-terminal 260-RLRKGR-265 motif on PD-L1 protects TβRI mRNA from degradation by the RNA exosome complex. PD-L1 is required for HSC expression of tumor-promoting factors, and targeting HSC PD-L1 by shRNA or Cre/loxP recombination suppresses HSC activation and ICC growth in mice. Thus, myofibroblast PD-L1 can modulate the tumor microenvironment and tumor growth by a mechanism independent of immune suppression.

Impact of hyperthermic intraperitoneal chemotherapy on genomic heterogeneity of peritoneal metastases in stage IV gastroesophageal adenocarcinoma.

312 Background: Programmed death ligand 1 (PD-L1) expression and tumor mutational burden (TMB) are potential biomarkers for response to therapy. Heterogeneity of PD-L1 and TMB has been demonstrated in gastroesophageal adenocarcinoma (GEA) in response to systemic chemotherapy. With the increased use of hyperthermic intraperitoneal chemotherapy (HIPEC) for GEA peritoneal metastases (PM), we aimed to determine the effects of HIPEC on genomic heterogeneity of PM. Methods: This is a retrospective review of a prospectively maintained database of patients with stage IV GEA who underwent iterative laparoscopic HIPEC (mitomycin C 30 mg + cisplatin 200 mg, 60 minutes) between 2017 and 2021. PD-L1 status and TMB levels were reviewed from peritoneal tumor specimens collected prior to each HIPEC. PD-L1 status was defined as positive if combined positive score (CPS) was 1 or greater using the 22C3 pharmDx assay. TMB levels were defined as low, intermediate, or high for up to 5, 5 to 15, or over 15 mutations per megabase (m/MB), respectively. Potentially actionable and biologically relevant variants were reviewed, as well as overall survival, defined as time from diagnosis with stage IV disease to death from any cause. Results: 16 patients completed at least one HIPEC during the study period. Median age was 55.5 years (range 43-79), 50% were female, and 62.5% were Caucasian. All patients received at least one line of systemic chemotherapy after stage IV diagnosis and prior to first HIPEC. Median peritoneal cancer index at first HIPEC was 15 (range 3-39). Three patients completed only one HIPEC. Of the 13 who completed at least two HIPECs, 5 had sufficient tumor tissue for genomic analysis at two timepoints. Of those 5 patients, one exhibited a change in PD-L1 expression from positive to negative after HIPEC, and one exhibited an increase in TMB from low to intermediate. All 5 patients exhibited a change in the profile of potentially actionable or biologically relevant genetic variants, including gain or loss of mutations in DNA repair genes (RAD51), proto-oncogenes (MET), and tumor suppressor genes (ERBB3, IRS2). Median overall survival amongst the full cohort was 27.4 months, with median follow-up of 26.1 months. Overall survival was higher amongst those who underwent at least 2 HIPECs compared to only one, but this was not statistically significant. Conclusions: Amongst our cohort, only one patient exhibited a change in PD-L1 expression and one in TMB after HIPEC. However, HIPEC was associated with a change in genetic variant profiles in all evaluable patients. If confirmed in larger studies, this temporal genomic heterogeneity could inform the role of PD-L1, TMB, and other genetic variants as predictive biomarkers for therapy after HIPEC. Iterative laparoscopic HIPEC warrants further investigation as a treatment option after systemic therapy for GEA with peritoneal metastases.

Profile of PD-L1 mRNA Expression in Childhood Acute Leukemia

Background: Programmed Death Ligand 1 (PD-L1) expression was used to determine type of patients who respond to immunotherapy using immune checkpoint inhibitor in several solid malignancies. However, the role of PD-L1 in hematological malignancies is less explored. Therefore, we aim to investigate PD-L1 mRNA expression in childhood leukemia patients. Association between PD-L1 expression and clinicopathological features was also analyzed. Method: Blood samples of 17 childhood leukemia patients and 12 healthy individuals as control were used in this study. The samples were collected in Dharmais Cancer Hospital. Real time PCR was used to analyze PD-L1 expression with GAPDH as internal control. Result: PD-L1 mRNA expression is significantly lower in childhood leukemia patients (medians: 0.0012) compared to healthy individuals (medians: 0.0041) (p=0.017). PD-L1 mRNA expressions were not correlated with age (p=1.000), sex (p=1.000), outcome (p=1.000), type of leukemia (p=1.000), hyperleukocytosis (p=1.000), and syndrome down (p=0.426). Conclusion: PD-L1 expression is lower in leukemia patients compared to healthy controls. PD-L1 expressions were not correlated with all clinicopathological features. Our result provides preliminary data of PD-L1 expression in Indonesian childhood leukemia patients.

Programmed Death Ligand 1 Expression as a Prognostic Marker in Patients with Advanced Biliary Tract Cancer

Background: Biliary tract cancer (BTC) is associated with poor prognosis because of its aggressive and heterogeneous nature. Programmed death ligand 1 (PD-L1) has been considered a novel biomarker for prognosis and response of immune checkpoint inhibitors in various tumors. However, there are limited data reporting on the role of PD-L1 in advanced BTC patients. Patients and Methods: We analyzed 186 patients with advanced BTC who received palliative gemcitabine and platinum between May 2010 and December 2019. All patients were evaluated for PD-L1 expression by combined positive score positivity. Results: Of the 186 patients, the primary tumor location was intrahepatic cholangiocarcinoma (IHCC) in 72 (38.7%), extrahepatic cholangiocarcinoma (EHCC) in 90 (48.4%), and gallbladder (GB) cancer in 24 (12.9%). Among all the patients, 53 (28.5%) had PD-L1 positivity. The median overall survival (OS) of patients with PD-L1 positivity or negativity was 12.1 and 15.4 months, respectively. The median progression-free survival (PFS) in patients with PD-L1 positivity or negativity was 5.7 and 7.1 months, respectively. OS and PFS were not statistically different between groups. In subgroup analysis, EHCC patients with PD-L1 negativity had more favorable OS (17.2 vs. 11.6 months, p = 0.002) and PFS (7.8 vs. 5.4 months, p = 0.005) than those who were PD-L1-positive. However, this finding was not reproduced in patients with IHCC or GB cancer. Conclusion: This study demonstrated that PD-L1 expression might be a novel prognostic biomarker in patients with EHCC but not in patients with IHCC or GB cancer.

Diffuse Large B Cell Lymphoma and Programmed Death-Ligand 1 Expression. a Clinical and Pathological Study of Patients Seen in Tawam Hospital UAE

Introduction: Diffuse Large B Cell Lymphoma (DLBL) is the most common type of Non-Hodgkin's Lymphoma (NHL) seen in Tawam hospital UAE. DLBL is a heterogenous disease arising either from a Germinal center (GC) or non- GCB cells. Molecular signature has identified 3 different groups of DLBL with significantly different prognosis (Primary mediastinal, Germinal center and Activated B Cell type). The therapy for DLBL has been without innovation since introduction of Rituximab more than 20 years ago and using R-CHOP. Attempts at improving the outcome has been uniformly unsatisfactory either by adding additional drugs, increasing the dose of drugs or deceasing the frequency of each cycle. New biomarkers and or targets are needed to improve the prognosis of patients with DLBL. Programmed Death-Ligand 1 (PDL1) has been shown to protect tumor cells by inducing T cell apoptosis (Dong et al., 2002). PDL1 targeting agents have been approved for many different types of malignancies including Hodgkin's Lymphoma. The role of PDL1 in DLBL is still under intense study. We report our findings of PDL1 expression in DLBL patients in UAE. Methods: Patients diagnosed with DLBL between December 1, 2019 till July 15th 2020. Patient records were reviewed in this study. Data was collected regarding patient demographics, clinical stage, International prognostic index (IPI), pathology and cell of origin {using immunohistochemistry (IHC) and Han's criteria}. PDL1 testing was performed by using FDA approved PharmaDx Dako Ab 22C3 kit for IHC on the gold standard Link 48 Dako platform. PDL1 expression was reported as Tumor proportion score (TPS). TPS in this assay was the percentage of viable tumor cells showing any perceptible partial or complete linear membranous (or membranous &amp; cytoplasmic) staining, in the large lymphoma cells. The specimen was considered PDL1 positive if the TPS was greater than or equal to 30%(Xu-Monette et al Blood 2018). All scores were reported by single pathologist Results Twenty-six patients were diagnosed with DLBL in the study period. The median age was 44 years (range 18-90 years). Majority of patients (75%) were less than sixty years of age. Advanced stage disease was seen in preponderance (66%) as compared to early stage (34%) while the LDH was elevated in 65 % patients (institutional normal &amp;lt; 225 IU per liter). Majority of patients (60%) were poor risk with IPI 3 or higher. Pathology review showed a uniformly elevated Ki 67 with the majority of specimens showing greater than 80 %. Molecular classification showed GCB type 50 % (n=13) as compared to non-GCB 42 % (n=11), data was not available for 2 patients. Epstein-Barr virus encoded small RNA (EBER) CISH was positive in only 3 patients (data was not available for 8 patients). PDL1 expression was tested in eighteen (GCB n=8, ABC n=10) patients. PDL1 expression was elevated in ABC type (90%) as compared GCB type (50 %) Fig 1. Conclusion The median age (44 years) is at least 2 decades less than the reported western cohort. Majority of the patients had high risk disease with advanced stage and IPI. Ki 67 was uniformly elevated (&amp;gt;80 % in 90 % of patients). There was a slight preponderance of GCB type (50 % vs 42%). PDL1 expression in ABC type DLBL was higher as compared to GCB. This observation needs to be validated in a larger cohort. Recent literature makes it very clear that ABC type DLBL has a poor outcome as compared to GCB type. PDL1 may offer an attractive target for treatment evaluation in ABC type DLBL. Figure Disclosures Alam: Pfizer:Honoraria;Roche:Honoraria.McCarthy:Karyopharm:Consultancy, Honoraria;Magenta:Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Advisory Board;Janssen:Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Advisory Board;Takeda:Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Advisory Board;Juno Therapeutics, a Bristol-Myers Squibb Company:Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Advisory Board , Research Funding is to Roswell Park, Research Funding;AbbVie:Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Advisory Board;Genentech:Consultancy, Honoraria;Starton:Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Advisory Board.

Role of PD-L1 Expression during the Progression of Submucosal Gastric Cancer

Introduction: Programmed death-ligand 1 (PD-L1) expression is a prognostic marker for gastric cancer that correlates with tumor diameter and depth of penetration. But the role of PD-L1 and mechanism(s) employed in the initial phase of invasion in early gastric cancer is yet to be understood. Objective: This study aims to elucidate the role of PD-L1 during the progression of gastric cancer, specifically invading the submucosa beyond the lamina muscularis mucosa. Methods: Using 107 patients with pathological submucosal gastric cancer, we determined the expression of PD-L1 based on the staining of the cell membrane or cytoplasm of tumor cells in the central and invasive front of the tumor. Samples were categorized into 3 groups based on the intensity of PD-L1 expression. CD8⁺ lymphocytes expressing PD-1 and CD163⁺ macrophages were used to determine the number of cell nuclei at the invasive front, similar to PD-L1. CMTM6 levels were determined and used to stratify samples into 3 groups. Results: PD-L1 expression was higher in the invasive front (26.2%) than in the central portion of the tumors (7.4%; p < 0.001). Moreover, lymphatic and vascular invasion were more frequently observed in samples with high levels of PD-L1 (lymphatic invasion: 60.7 vs. 35.4%, p = 0.0026, and vascular invasion: 39.3 vs. 16.5%, p = 0.0018). There was no correlation between PD-L1 expression and the levels of PD-1, CD8, CD163, and CMTM6. Conclusions: PD-L1-expressing cancer cells at the invasive front of gastric cancer influence the initial stages of tumor invasion and lymphovascular permeation in early-stage gastric cancers. Immune checkpoint signaling may be the driving force in the invasive front during the invasion of the submucosa beyond the lamina muscularis mucosa.

Novel PD-L1 mAb HC16 reveals upregulation of PD-L1 in BAC subtype.

Programmed death-ligand 1 (PD-L1) is an inhibitory transmembrane protein that can prevent autoimmune response. Upregulated PD-L1 serves as a predictive biomarker for patients who may respond well to immune checkpoint therapies. However, variable associations of PD-L1 level with prognoses have been reported. In this study, a short peptide sequence corresponding to PD-L1 amino acids 172-187 (from the extracellular Ig-like C-type domain, and with high predicted antigenicity and hydrophilicity) was used to generate a monoclonal antibody (mAb). The resultant PD-L1 mAb, clone HC16, was examined for binding specificity and reactivity in cancer cell-lines, as assessed by immunocytochemical, immunoblotting, and co-immunoprecipitation. The potential diagnostic and clinical applicability of clone HC16 was further tested using malignant tissue arrays derived from various cancer types analyzed with an automated immunohistochemical (IHC) staining platform. Additionally, tumor samples from patients diagnosed with non-small cell lung cancer (NSCLC) were analyzed by western blotting. Clone HC16 showed obvious staining activity in lung and breast cancer tissues. Interestingly, we observed that PD-L1 level was negatively associated with clinical stage in NSCLC. Strong PD-L1 expression tended to be found in patients diagnosed with bronchioloalveolar carcinoma (BAC). These results demonstrate that clone HC16 harbors good target specificity and is suitable for further development in diagnostic tools to assess PD-L1 expression in human tissues. In addition, our findings also suggest a role for PD-L1 in a non-invasive subtype of lung cancer.

Pentamethylquercetin Inhibits Hepatocellular Carcinoma Progression and Adipocytes-induced PD-L1 Expression via IFN-γ Signaling.

Obesity is a significant risk factor for the development of types of cancer. Programmed death 1 and its ligand programmed death-ligand 1 (PD-L1) play a crucial role in tumor immune escape. Although, the role of PD-L1 in obesity-associated hepatocellular carcinoma (HCC) remains unknown. We previously showed that the natural flavonoid pentamethylquercetin (PMQ) possesses anti-obesity properties. This study was designed to investigate the effects of PMQ on the development of HCC in obese mice and whether PMQ regulates PD-L1 and expression in HCC. Monosodium glutamate-induced obese mice were inoculated with H22 tumor cells. Tumor volumes and weights were measured. In vitro, 3T3-L1 preadipocytes were differentiated and lipid accumulation was measured by oil-red staining, and IFN-γ level was detected by Elisa. Hepatoma HepG2 cells were treated with conditional media from 3T3-L1 adipocytes (adi-CM). Western blotting was applied to detect PD-L1 protein levels in tumor tissue and HepG2 cells. Compared with control mice, H22 tumors grew faster and exhibited higher PD-L1 protein levels in obese mice. PMQ inhibited H22 tumor growth and reduced PD-L1 expression in tumor tissues. PD-L1 protein level was elevated in adi-CM-treated HepG2 cells. IFN-γ was detectable in adi-CM and exogenous IFN-γ induced PD-L1 expression in HepG2 cells. PMQ affected the differentiation of 3T3-L1 preadipocytes, decreased the level of IFN-γ secreted by adipocytes and downregulated adi-CM-induced PD-L1 expression in HepG2 cells. PMQ could inhibit HCC progression in obese mice at least in part through down-regulating adipocytes-induced PD-L1 expression via IFN-γ signaling.

Role of PD-L1 in Oral Cancer: From the Perspective of Immuno-oncology

Oral cancers are prevalent in our region and their management requires an upgrade in terms of advanced techniques. Immunotherapy is a novel therapeutic approach across the world that has shown significance in the sphere of oncology. Tumor cells escape detection from the immune surveillance mechanism resulting in proliferation. Through cancer immunotherapy, body’s own immune defense mechanism is stimulated with the aid of immunomodulating drugs. Scientists are underway studying the tumor microenvironment where immune editing takes place resulting in tumor escape and evasion. Many immune checkpoint proteins are being studied for clinical implications, however, the immune checkpoint blockade of Programmed death ligand-1(PD-L1) has proven to be successful and FDA approved in certain tumors. Role of increased expression of PD-L1 in oral cancer has been explored with variable results. Most researches have related it with tumor progression and prognosis. This review focuses on the importance of PD-L1 as an emerging immune checkpoint inhibitor, emphasizing its expression in cancers, particularly in oral cancer. The information was retrieved from reliable search engines e.g. PubMed, Medline, Google scholar and others, through original research papers and reviews published hitherto, from 2010-2019. It is essential to explore advanced treatment modalities for oral cancer especially via immunotherapy. Furthermore, additional studies on PD-L1 expression in OSCC are required including standardized protocols to reach definitive conclusions for clinical implications.

The role of PD-L1 in the prediction of treatment responses to neoadjuvant chemotherapy in breast carcinoma

Aims: To assess programmed death ligand 1 (PD-L1) expression and its correlation with prediction of response to neoadjuvant chemotherapy (NACT) in invasive breast carcinoma (IBC). Introduction: NACT is being increasingly utilised in IBC management with pathologic complete response (pCR) strongly correlated with excellent disease-free and overall survival. PD-L1 has recently gained attention in breast carcinomas as a potential therapeutic target as well as a prognostic indicator. PD-L1 is expressed in response to inflammation and has been found to be expressed on a number of tumours. The presence of tumour infiltrating lymphocytes has been found to be strongly associated with pathological complete response (pCR) and a relationship between PD-L1 and pCR has been suggested in recent studies. Methods: Pretreatment core biopsies and their matched subsequent surgical excision from 74 consecutive patients with IBC from the PathWest pathology database, Fiona Stanley Hospital, in 2013–2016 were assessed for TILs and PD-L1 expression. Results: Eighteen cases achieved pCR while 56 cases did not. When comparing these groups, there was a greater likelihood of pCR in patients with higher TILs scores (p=0.006) and higher PD-L1 scores (p=0.018). Conclusion: Our study demonstrates a significant association between PD-L1 expression with pCR in NACT.

Programmed death ligand-1 expression is associated with stage and histological grade of parotid carcinoma

Background: The immune checkpoint ligand programmed death ligand-1 (PD-L1) is expressed by various cancers, including those of the head and neck. However, the role of PD-L1 is still unknown.Objectives: To investigate the relationship between PD-L1 expression and survival rate in parotid carcinoma.Methods: PD-L1 expression was investigated by immunohistochemical analysis in 127 patients with parotid carcinoma. The relationship between PD-L1 expression and stage, histological grade, and survival was assessed.Results: PD-L1 expression was found in 28.3% of parotid carcinomas, with the expression being higher in tumors with a higher stage, a higher-grade, and node positive cases. However, the 5-year disease-specific survival rate was 82.2% for the patients with PD-L1 positive and 86.9% for those with PD-L1 negative tumors, showing no significant difference.Conclusions: PD-L1 expression was positive in approximately 50% of high- grade carcinomas, which was similar to the level in head and neck squamous cell carcinoma. In patients with other cancers, it has been reported that an anti-PD-1 monoclonal antibody was more effective against tumors with higher PD-L1 expression. Therefore, it could be a possible new therapeutic option for patients with highly malignant parotid tumors that have a poor prognosis.