Programmed Death-ligand 1 mRNA Levels Research Articles

The Clinicopathological and Prognostic Significance of the Expression of PD-L1 and MET Genes in Breast Cancer: Potential Therapeutic Targets.

The heterogeneity of breast cancer requires exploring novel prognostic biomarkers as well as therapeutic targets for the treatment of the disease. The METABRIC dataset was used to describe the gene expression of the programmed death-ligand 1 (PD-L1) and the hepatocyte growth factor receptor (MET) and their association with the tumor clinicopathologic characteristics and overall survival in breast cancer. The expression of the PD-L1 and MET genes correlated positively with the Nottingham Prognostic Index (NPI) (p=0.003 and p < 0.001, respectively). The expression of the two genes correlated inversely with luminal A and luminal B tumors (r= - 0.089, p= 0.021 and r= - 0.116, p= 0.013, respectively). The PD-L1 mRNA levels were significantly higher in hormone receptor-negative and HER2-positive tumors. MET mRNA expression levels were significantly higher in hormone receptor-negative, HER2-enriched, and non-luminal breast cancers. The PD-L1/MET double-high expression was associated with younger age of patients at diagnosis, higher NPI scores, larger tumors, advanced stage, high-grade, hormone receptor-negativity, HER2-positivity, and non-luminal tumors. None of the genes or their double expression status was significantly associated with overall survival in this analysis. The expression of the PD-L1 and MET genes is remarkably associated with worse tumor clinicopathologic features and poor prognosis in patients with breast cancer. Further investigations using combination drug regimens targeting PD-L1 and MET are important, particularly in breast tumors expressing high levels of both proteins.

PD-L1 mRNA and protein expression in canine mammary carcinomas: Correlation with histopathological grade and molecular markers.

Programmed death ligand 1 (PD-L1) is an immune checkpoint molecule that plays a crucial role in regulating antitumor immune responses. Canine mammary carcinomas (CMCs) are common tumors of dogs. Despite extensive studies on the heterogeneity of CMCs, there is still a lack of effective precision therapies for the treatment of CMCs. In this study, we aimed to investigate the correlation between PD-L1 mRNA and protein expression in CMCs and explore its association with histopathological grade and molecular markers, including the estrogen receptor, epidermal growth factor receptor 2, and cytokeratin 5/6 (CK5/6). Formalin-fixed paraffin-embedded samples were evaluated for PD-L1 mRNA expression using RNA in situ hybridization and PD-L1 protein expression using immunohistochemistry. We observed no substantial correlation between PD-L1 mRNA and protein expression in CMCs; however, PD-L1 mRNA levels were significantly higher in grade 3 than in grade 1 tumors (P = .001). In addition, we observed a positive correlation between PD-L1 protein expression and CK5/6 expression in CMCs (P = .032). These findings suggest that PD-L1 expression in CMCs is heterogeneous and may be regulated post-transcriptionally. Further studies are needed to explore the prognostic and therapeutic implications of PD-L1 expression in different molecular subtypes of CMCs and their potential as predictive biomarkers for immunotherapy.

The tumor promoter cysteinyl leukotriene receptor 1 regulates PD-L1 expression in colon cancer cells via the Wnt/β-catenin signaling axis

Immunotherapy targeting programmed death-ligand 1 (PD-L1) or PD-1 in solid tumors has been shown to be clinically beneficial. However, in colorectal cancer (CRC), only a subset of patients benefit from PD-1/PD-L1 treatment. Previously, we showed that high cysteinyl leukotriene receptor 1 (CysLT1R) levels are associated with poor prognosis in CRC patients. Recently, we have revealed the role of the tumor promoter CysLT1R in drug resistance and stemness in colon cancer (CC) cells. Here, we show the role of the CysLT1R/Wnt/β-catenin signaling axis in the regulation of PD-L1 using both in vitro and in vivo preclinical model systems. Interestingly, we found that both endogenous and IFNγ-induced PD-L1 expression in CC cells is mediated through upregulation of CysLT1R, which enhances Wnt/β-catenin signaling. Therapeutic targeting of CysLT1R with its antagonist montelukast (Mo), as well as CRISPR/Cas9-mediated or doxycycline-inducible functional absence of CysLT1R, negatively regulated PD-L1 expression in CC cells. Interestingly, an anti-PD-L1 neutralizing antibody exhibited stronger effects together with the CysLT1R antagonist in cells (Apcmut or CTNNB1mut) with either endogenous or IFNγ-induced PD-L1 expression. Additionally, mice treated with Mo showed depletion of PD-L1 mRNA and protein. Moreover, in CC cells with combined treatment of a Wnt inhibitor and an anti-PD-L1 antibody was effective only in β-catenin-dependent (APCmut) context. Finally, analysis of public dataset showed positive correlations between the PD-L1 and CysLT1R mRNA levels. These results elucidate a previously underappreciated CysLT1R/Wnt/β-catenin signaling pathway in the context of PD-L1 inhibition in CC, which might be considered for improving the efficacy of anti-PD-L1 therapy in CC patients.7T-oMpUEusLw1sD21V8GVPVideo

Effect of MiR-424-5p on the Drug Resistance of Diffuse Large B-Cell Lymphoma Cells by Regulating PD-1/PD-L1 Signaling Pathway

To explore the effect of microRNA-424-5p (miR-424-5p) on the drug resistance of diffuse large B-cell lymphoma (DLBCL) cells by regulating the programmed death receptor-1 (PD-1)/programmed death ligand-1 (PD-L1) signaling pathway. Human DLBCL cell line CRL2631 cells were induced to construct CRL2631-CHOP resistant cell line. RT-qPCR and Western blot were used to detect the expression levels of MiR-424-5p, PD-L1 mRNA and protein, and multidrug resistance gene-1 (MDR-1) protein in CRL2631 cells and CRL2631-CHOP cells, respectively. The target genes of MiR-424-5p was verified by dual luciferase reporter assay. The miRNA simulation/interference technology and thiazole blue (MTT) method were used to detect the resistance of CRL2631 cells and CRL2631-CHOP cells to CHOP. Compared with CRL2631 cells, the drug resistance of CRL2631-CHOP cells to CHOP and the levels of MDR-1 protein (P<0.05), PD-L1 mRNA and protein in the cells were significantly increased (both P<0.001), while the relative level of MiR-424-5p was significantly reduced (P<0.001). The result of the dual luciferase reporter assay showed that PD-L1 was the direct downstream target gene of MiR-424-5p (P<0.001). After transfection of MiR-424-5p inhibitor, the resistance of CRL2631 cells to CHOP drugs increased, and the expression level of MDR-1 protein (P<0.01), PD-L1 mRNA and protein also increased significantly (both P<0.01). After transfection of MiR-424-5p mimics, the resistance of CRL2631-CHOP cells to CHOP drugs decreased, and the expression level of MDR-1 protein (P<0.001), PD-L1 mRNA and protein also decreased significantly (both P<0.001). Overexpression of PD-L1 could reverse the inhibitory effect of upregulating MiR-424-5p on PD-L1 (P<0.001). Down-regulation of MiR-424-5p enhances the drug resistance of DLBCL cells by regulating the PD-1/PD-L1 signaling pathway.

Programmed Death-Ligand 1 and Programmed Death-Ligand 2 mRNAs Measured Using Closed-System Quantitative Real-Time Polymerase Chain Reaction Are Associated With Outcome and High Negative Predictive Value in Immunotherapy-Treated NSCLC

IntroductionImmune checkpoint inhibitors (ICIs) have become standard of care in lung cancer management, but only a relatively small percentage of patients treated respond. Current predictive biomarkers, including immunohistochemical detection of programmed death-ligand 1 (PD-L1), are insufficient for determining who will respond or, more importantly in the adjuvant setting, who will not respond to ICI therapy. Here, we investigate an alternative method of assessment of PD-L1 to predict nonresponse. MethodsThis study uses a research use only quantitative real-time reverse transcription polymerase chain reaction assay on the GeneXpert system, to test for the association between four target immune genes, CD274 (PD-L1), PDCD1LG2 (programmed death-ligand 2 [PD-L2]), CD8A, and IRF1, and response to ICI therapy. Tissues were collected from 122 patients with advanced NSCLC before ICI therapy in a retrospective cohort, macrodissected, and analyzed using the GeneXpert. ResultsBoth high PD-L1 and PD-L2 mRNA expression levels were associated with improved long-term benefit at 24 months (p = 0.047 for both PD-L1 and PD-L2) and overall survival (PD-L1, p = 0.048; PD-L2, p = 0.049). Both PD-L1 and PD-L2 mRNA levels were higher in patients with KRAS mutations. Most importantly, low PD-L1 mRNA level had a high negative predictive value of 0.92 for absence of long-term benefit. ConclusionsWith further validation of this assay in low-stage patients, an assessment of PD-L1 mRNA rather than protein, could be a method to determine which low-stage patients that should not be treated with ICIs in the adjuvant setting. This approach may also be a useful objective method for selecting patients for treatment in the advanced setting.

AXL/PLCγ1/PKCα as a Central Axis for PD‐L1 Regulation in Triple‐Negative Breast Cancer

Breast cancer is the most prevalent malignancy in women globally, accounting for 12% of all new annual cancer cases worldwide. Triple-negative breast cancer (TNBC), which is ER, PR and HER2 negative, represents 10-15% of breast cancers and displays an aggressive metastatic phenotype, with limited treatment options and poor patient prognosis. TNBC is associated with high expression levels of immune checkpoint programmed-death ligand 1 (PD-L1) compared with other breast cancer subtypes, and it is therefore amenable to immune checkpoint therapy. In this study, we analyzed the role of diacylglycerol (DAG)-regulated protein kinase C alpha (PKCα) in the control of PD-L1 expression in TNBC. Dataset analysis of 50 breast cancer cell lines revealed a prominent up-regulation of PKCα in TNBC, particularly in TNBC-B subtype, with a concomitant down-regulation of protein kinase C delta (PKCδ). This finding was authenticated in the TCGA-BRCA database. A significant correlation was found between PKCα expression and EMT markers, i.e., up-regulation of vimentin, Zeb1, TWIST1, SNAI2 and AXL, and E-cadherin down-regulation. High PKCα expression was also observed in TNBC patient-derived xenografts (PDXs). Immunofluorescence analysis revealed significant PKCα endogenous levels in the TNBC B cell line BT549, with strong "peripheral staining", a hallmark of its activated state. Conversely, a tenuous PKCα staining was detected in luminal breast cancer cells. Notably, TNBC-B cell lines express high levels of phosphorylated (active)-phospholipase C gamma 1 (PLCγ1), an enzyme responsible for DAG generation and PKCα activation. We also found a significant positive correlation between PKCα and PD-L1 expression in breast cancer cell lines. Notably, both RNAi silencing and pharmacological inhibition of PKCα or PLCγ1 reduced PD-L1 mRNA and protein levels in TNBC cells. We also show that AXL and PKCα mutually and positively control their expression in addition to up-regulating PD-L1, and they share a common gene expression signature that is highly enriched in cytokine, extracellular matrix, and motility pathways. Mechanistic analysis showed that inhibition of AXL, PLCγ1 or PKCα significantly reduced PD-L1 promoter activity in TNBC cells, suggesting a transcriptional control of the PDL1 (CD274) gene by this pathway. In summary, our results indicate that aberrant overactivation of AXL/PLCγ1/PKCα represents a cancer cell intrinsic mechanism for PD-L1 up-regulation in TNBC, suggesting a potential role for this axis in the control of tumor immunosurveillance. PKCα and AXL may be promising candidates for integrated targeted therapy in TNBC treatment.

Interferon‐γ Induced PD‐L1 Expression in Ovarian Cancer Cells is Regulated by IRF1 Signaling

The immune checkpoint programmed death ligand‐1 (PD‐L1) is highly expressed in cancer cells, including ovarian cancer (OC) cells. High PD‐L1 expression in ovarian cancer correlates with poor prognosis, but the mechanisms that regulate the PD‐L1 expression in OC remain poorly understood. We have recently shown that IFNγ induces the PD‐L1 expression in OC cells, resulting in their increased proliferation and invasion. Here, we show that the IFNγ‐induced PD‐L1 expression in OC cells is associated with increased levels of STAT1, Tyr‐701 pSTAT1 and Ser‐727 pSTAT1 in OC cells. JAK1 and STAT1 suppression significantly decreases the IFNγ‐induced PD‐L1 mRNA and protein levels in OC cells. In addition, IRF1 suppression significantly decreases the IFNγ‐induced gene and protein levels of PD‐L1, indicating that the IFNγ‐induced PD‐L1 expression in OC cells is dependent on IRF1 signaling. Chromatin immunoprecipitation data demonstrate that IFNγ induces occupancy of STAT1, Ser‐727 pSTAT1 and IRF1 at STAT1 and IRF1 binding sites in human PD‐L1 promoter. Together, these results show that the IFNγ‐induced PD‐L1 expression in OC cells is regulated by IRF1/JAK1/STAT1 signaling, and suggest that targeting the IRF1/JAK1/STAT1 pathway may provide leverage to regulate the PD‐L1 levels in ovarian cancer.

MicroRNA-378a-3p regulates the progression of hepatocellular carcinoma by regulating PD-L1 and STAT3

ABSTRACT Programmed death ligand 1 (PD-L1) plays an essential role in the development or progression of hepatocellular carcinoma (HCC). MicroRNAs (miRNAs) are small RNA molecules that regulate gene expression during normal and pathophysiological events. Here, we explored the functions and detailed mechanisms of miR-378a-3p and PD-L1 in HCC progression. First, miR-378a-3p was selected by analyzing miRNA levels in two HCC Gene Expression Omnibus datasets. We found that miR-378a-3p levels exhibited a downward trend in HCC and were negatively correlated with PD-L1 levels. Additionally, a dual luciferase assay predicted that miR-378a-3p directly targets PD-L1. Moreover, the transfection of miR-378a-3p mimics into Li-7 and HuH-7 cells effectively decreased the PD-L1 mRNA and protein expression levels, and inhibited Treg differentiation in co-culture models by modulating the expression levels of certain cytokines. Furthermore, the overexpression of miR-378a-3p hindered cell proliferation and migration but facilitated apoptosis by repressing STAT3 signaling in HCC cells. In conclusion, miR-378a-3p appears to inhibit HCC tumorigenesis by regulating PD-L1 and STAT3 levels. Thus, miR-378a-3p may be a potential target for HCC therapy.

Expression of PD‑L1 and CD4+ tumor‑infiltrating lymphocytes predict survival in head and neck squamous cell carcinoma

The clinical efficacy of immune checkpoint blockade has been recently demonstrated in a variety of cancer types. The aim of the present study was to characterize the expression profile of tumor-infiltrating lymphocytes (TILs) and programmed death-ligand 1 (PD-L1) in head and neck squamous carcinoma (HNSCC). A total of 63 patients with HNSCC were enrolled in the present study. CD3+ and CD4+ TILs and the expression of PD-L1 were detected by immunohistochemistry. PD-L1 mRNA levels were evaluated by reverse transcription-quantitative PCR analysis. The association of TILs and PD-L1 with patient clinicopathological characteristics was also assessed. CD3+ and CD4+ TILs were detected in 100% of the samples. CD3+ was the predominant subset of TILs. PD-L1 was expressed in 53 of 61 (86%) patients when a score of ≥1 on tumor cells was considered positive and in 28 patients (45.2%) when a score of >5 on tumor cells was considered positive. PD-L1 mRNA levels were determined to be significantly correlated with PD-L1 protein expression. Survival analysis demonstrated that high CD4+ TILs were associated with improved overall survival (OS) and disease-free survival (DFS), and furthermore, the association of high PD-L1 expression with unfavorable OS and DFS was statistically significant. Multivariate analysis identified CD4+ TILs and PD-L1 as prognostic markers for HNSCC. The results of the present study suggested that increased CD4+ TILs in HNSCC may be associated with improved outcomes, while high expression of PD-L1 may indicate unfavorable OS and DFS; thus, these factors may serve as predictors of the response to immune checkpoint therapy.

Anti-Tumor Effects of Carrimycin and Monomeric Isovalerylspiramycin I on Hepatocellular Carcinoma in Vitro and in Vivo.

Hepatocellular carcinoma results in a high risk of second primary malignancies and has prominent morbidity and mortality. There is a lack of effective treatment and prognosis is poor. Therefore, effective drugs need to be discovered. Carrimycin is a 16-member macrolide antibiotic with anticancer activity, and monomeric isovalerylspiramycin I is a main component. The aim of this study was to determine the anti-tumor effects of carrimycin and monomeric isovalerylspiramycin I on hepatocellular carcinoma through in vivo and in vitro experiments. In vitro, changes in cellular proliferation, migration, invasion, and apoptosis were analyzed by MTT, colony formation, EdU labeling, wound-healing, matrigel transwell invasion, and flow cytometric assays using SK-Hep1, Hep3B, SNU-354, SNU-387 hepatocellular carcinoma cell lines. Western blotting and RT-PCR were used to detect the effects of carrimycin and monomeric isovalerylspiramycin I on the expression levels of vascular endothelial growth factor (VEGF) and programmed death ligand 1 (PD-L1). Nude mice were subcutaneously transplanted with SK-Hep1 cells or C57BL/6J mice were orthotopically transplanted with hepatocarcinoma H22 cells. Tumor volume, pathological changes in tumor tissues, and the concentration of VEGF in mouse serum were measured after treatments. Carrimycin and monomeric isovalerylspiramycin I dose-dependently inhibited hepatocellular carcinoma cell viability, colony formation, and DNA replication. These agents markedly suppressed migration and invasion and promoted apoptosis of the cell lines. Western blotting and RT-PCR demonstrated that carrimycin and monomeric isovalerylspiramycin I reduced VEGF and PD-L1 protein and mRNA levels in a dose-dependent manner. In vivo studies further confirmed that carrimycin and monomeric isovalerylspiramycin I could significantly inhibit tumor growth, tumor histopathological alterations, and the concentration of VEGF in both mouse tumor models. These results show that carrimycin and monomeric isovalerylspiramycin I promoted apoptosis and inhibited proliferation, migration, and invasion of hepatocellular carcinoma cells. Therefore, our discovery suggests anti-tumor capacity for carrimycin and monomeric isovalerylspiramycin I and provides data on potential new drugs for inhibiting hepatocellular carcinoma.

The effect of hypoxia on PD-L1 expression in bladder cancer

IntroductionRecent data has demonstrated that hypoxia drives an immunosuppressive tumour microenvironment (TME) via various mechanisms including hypoxia inducible factor (HIF)-dependent upregulation of programmed death ligand 1 (PD-L1). Both hypoxia and an immunosuppressive TME are targetable independent negative prognostic factors for bladder cancer. Therefore we sought to investigate whether hypoxia is associated with upregulation of PD-L1 in the disease.Materials and methodsThree human muscle-invasive bladder cancer cell lines (T24, J82, UMUC3) were cultured in normoxia (20% oxygen) or hypoxia (1 and 0.1% oxygen) for 24 h. Differences in PD-L1 expression were measured using Western blotting, quantitative polymerase chain reaction (qPCR) and flow cytometry (≥3 independent experiments). Statistical tests performed were unpaired t tests and ANOVA. For in silico work an hypoxia signature was used to apply hypoxia scores to muscle-invasive bladder cancers from a clinical trial (BCON; n = 142) and TCGA (n = 404). Analyses were carried out using R and RStudio and statistical tests performed were linear models and one-way ANOVA.ResultsWhen T24 cells were seeded at < 70% confluence, there was decreased PD-L1 protein (p = 0.009) and mRNA (p < 0.001) expression after culture in 0.1% oxygen. PD-L1 protein expression decreased in both 0.1% oxygen and 1% oxygen in a panel of muscle-invasive bladder cancer cells: T24 (p = 0.009 and 0.001), J82 (p = 0.008 and 0.013) and UMUC3 (p = 0.003 and 0.289). Increasing seeding density decreased PD-L1 protein (p < 0.001) and mRNA (p = 0.001) expression in T24 cells grown in both 20 and 1% oxygen. Only when cells were 100% confluent, were PD-L1 protein and mRNA levels higher in 1% versus 20% oxygen (p = 0.056 and p = 0.037). In silico analyses showed a positive correlation between hypoxia signature scores and PD-L1 expression in both BCON (p = 0.003) and TCGA (p < 0.001) cohorts, and between hypoxia and IFNγ signature scores (p < 0.001 for both).ConclusionTumour hypoxia correlates with increased PD-L1 expression in patient derived bladder cancer tumours. In vitro PD-L1 expression was affected by cell density and decreased PD-L1 expression was observed after culture in hypoxia in muscle-invasive bladder cancer cell lines. As cell density has such an important effect on PD-L1 expression, it should be considered when investigating PD-L1 expression in vitro.

Sorting nexin 6 interacts with Cullin3 and regulates programmed death ligand 1 expression.

Programmed death ligand 1 (PD-L1) is critical for the ability of cancer cells to evade attacks by the host immune system. However, the molecular mechanisms controlling PD-L1 expression have not been fully understood. Here, we demonstrate that sorting nexin 6 (SNX6) is a novel regulator of PD-L1 expression. Knockdown of SNX6 in cancer cells significantly decreases PD-L1 protein levels. In contrast, loss of SNX6 does not reduce PD-L1 mRNA levels. Instead, SNX6 interacts with Cullin3, an E3 ubiquitin ligase responsible for PD-L1 ubiquitination and subsequent degradation. By binding with Cullin3, SNX6 decreases the interaction between the adaptor protein speckle-type POZ protein and Cullin3, which in turn downregulates Cullin3-mediated PD-L1 ubiquitination. This research reveals a novel molecular nexus in modulating PD-L1.

LPS stimulates gingival fibroblasts to express PD-L1 via the p38 pathway under periodontal inflammatory conditions

ObjectiveThe overall aim of this research was to investigate the differences in the expression of programmed death ligand 1 (PD-L1) in human gingival fibroblasts (HGFs) between a periodontal healthy group and a periodontal inflammatory group. and explore the possible mechanism involved. MethodsDifferences in PD-L1 mRNA and protein expression in HGFs from a periodontal healthy group and a periodontal inflammatory group were examined by qPCR and western blotting, respectively, and were further tested after lipopolysaccharide (LPS) stimulation in both groups. The effects of a p38 pathway inhibitor on the changes in p38 phosphorylation levels and PD-L1 expression after LPS stimulation were investigated in both groups. ResultsPD-L1 mRNA and protein levels in HGFs in the periodontal inflammatory group were significantly higher than those in the periodontal healthy group (p < 0.05). After 10 μg/mL LPS stimulation, PD-L1 mRNA levels in HGFs from both groups increased significantly (p < 0.05), peaking at 4 h, and the peak was significantly higher in the periodontal inflammatory group than in the periodontal healthy group (p < 0.05). However, PD-L1 protein expression was upregulated only in the inflammatory group (p < 0.05). Inhibition of the p38 pathway in HGFs decreased p38 phosphorylation in both groups (p < 0.05) but this treatment reversed the LPS-induced increase in PD-L1 mRNA and protein levels only in the inflammatory group (p < 0.05). ConclusionIn the periodontal inflammatory state, the expression of PD-L1 in HGFs is more easily activated, and may be influenced by the p38 pathway.

Abstract PR004: Genetic ablation of adipocyte PD-L1 reduces tumor growth but accentuates obesity-associated inflammation

Abstract The programmed death-ligand 1 (PD-L1)-dependent immune checkpoint attenuates host immunity and maintains self-tolerance. Imbalance between protective immunity and immunopathology due to altered PD-L1 signaling can lead to autoimmunity or tumor immunosuppression. The role of the PD-L1-dependent checkpoint in non-immune system is less reported. We previously found that white adipocytes highly express PD-L1. Here we show that adipocyte-specific PD-L1 knockout mice exhibit enhanced host anti-tumor immunity against mammary tumors and melanoma with low or no tumor PD-L1. However, adipocyte PD-L1 ablation in tumor-free mice also exacerbates diet-induced body weight gain, pro-inflammatory macrophage infiltration into adipose tissue, and insulin resistance. Low PD-L1 mRNA levels in human adipose tissue correlate with high body mass index and presence of type 2 diabetes. Therefore, our mouse genetic approach unequivocally demonstrates a cell-autonomous function of adipocyte PD-L1 in promoting tumor growth and inhibiting anti-tumor immunity. In addition, our work uncovers a previously unrecognized role of adipocyte PD-L1 in mitigating obesity-related inflammation and metabolic dysfunction. This abstract is also being presented as PO031. Citation Format: Bogang Wu, Huai-Chin Chiang, Xiujie Sun, Bin Yuan, Payal Mitra, Yanfen Hu, Tyler J. Curiel, Rong Li. Genetic ablation of adipocyte PD-L1 reduces tumor growth but accentuates obesity-associated inflammation [abstract]. In: Abstracts: AACR Virtual Special Conference: Tumor Immunology and Immunotherapy; 2020 Oct 19-20. Philadelphia (PA): AACR; Cancer Immunol Res 2021;9(2 Suppl):Abstract nr PR004.

The Progress of Immunotherapy in Refractory Pituitary Adenomas and Pituitary Carcinomas

Most pituitary adenomas (PAs) are considered benign tumors, but approximately 0.2% can present metastasis and are classified as pituitary carcinomas (PCs). Refractory PAs lie between benign adenomas and true malignant PC and are defined as aggressive-invasive PAs characterized by a high Ki-67 index, rapid growth, frequent recurrence, and resistance to conventional treatments, including temozolomide. It is notoriously difficult to manage refractory PAs and PC because of the limited therapeutic options. As a promising therapeutic approach, cancer immunotherapy has been experimentally used for the treatment of many tumors, including pituitary tumors. The purpose of this review is to report the progress of immunotherapy in pituitary tumors, including refractory PAs and PCs. The tumor immune microenvironment has been recognized as a key contributor to tumorigenesis, progression, and prognosis. One study indicated that the number of CD68+ macrophages was positively correlated with tumor size and Knosp classification grade for tumor invasiveness. The infiltration of CD4+ and CD8+ T cells was relatively scant in these adenomas, but pituitary growth hormone (GH) adenomas exhibited significantly more CD4+ and CD8+ T cells than non-GH adenomas. These results suggest an association of CD68+ macrophage infiltration with an increase in pituitary tumor size and invasiveness. Another study suggested that a lower number of CD8+ lymphocytes is associated with cavernous sinus invasion and resistance to treatment with first-generation somatostatin analogs in acromegaly patients, highlighting a potential role of the tumor immune microenvironment in determining the prognosis of somatotroph pituitary tumors. Preclinical studies have indicated that widely varying degrees of programmed death-ligand 1 (PD-L1) expression and tumor-infiltrating lymphocytes (TILs) are found among different subtypes. Functional PAs and aggressive PAs express significantly higher levels of PD-L1 and TILs than other subtypes, indicating that PD-1 blockade might be a promising alternative therapy for patients with aggressive PAs. PD-L1 transcript and protein levels were found to be significantly increased in functioning (GH and prolactin-expressing) pituitary tumors compared to nonfunctioning (null cell and silent gonadotroph) adenomas. Moreover, primary pituitary tumors harbored higher levels of PD-L1 mRNA than recurrent tumors. These findings suggest the possibility of considering checkpoint blockade immunotherapy for functioning pituitary tumors refractory to conventional management. Animal models of Cushing’s disease also demonstrated PD-L1 and TIL expression in cultured tumors and murine models, as well as the effectiveness of checkpoint blockade therapy in reducing the tumor mass, decreasing hormone secretion, and increasing the survival rate. Clinical studies show that immunotherapy may be an effective treatment in patients with pituitary tumors. One corticotroph carcinoma patient showed a significant reduction in hormone levels and shrinkage of the tumor size of primary and metastatic lesions immediately after investigational treatment with ipilimumab and nivolumab. However, another patient with corticotroph adenoma progressed rapidly after four cycles of anti-PD-1 (pembrolizumab) treatment. To date, there are two registered clinical trials of immunotherapy for pituitary tumors. One of them is the phase II clinical trial of nivolumab combined with ipilimumab for patients with aggressive pituitary tumors (NCT04042753). The other one is also a phase II clinical trial of the combination of nivolumab and ipilimumab for rare tumors, including pituitary tumors (NCT02834013). Both clinical trials are in the stage of recruiting patients and have not been completed. In summary, the results from preclinical research and clinical studies indicated that immunotherapy might be a promising alternative therapy for PCs and refractory PAs resistant to conventional treatments. The combination of immunotherapy and radiotherapy or temozolomide may have synergistic effects compared to a single treatment. More preclinical and clinical studies are needed to further indicate the exact efficacy of immunotherapy in pituitary tumors.

Obesity and metabolic syndrome related macrophage promotes PD-L1 expression in TNBC through IL6/JAK/STAT pathway and can be reversed by telmisartan

ABSTRACT Breast cancer is the most common malignant tumor in women. Its incidence is associated with obesity and metabolic syndrome (MetS), which are highly prevalent world widely and have been identified as poorer prognosis factors in breast cancer including triple-negative breast cancer (TNBC), which has poorer response to chemotherapy, radiotherapy, and endocrine therapy. Programmed death ligand 1 (PD-L1) is one of the immune checkpoints ligands that facilitates tumor escape and progress. Obesity/MetS could cause systemic inflammation and immune disorders, however, whether and how obesity/MetS affect PD-L1 expression in breast cancer had not been clarified. In the present study, we examined the PD-L1 expression profile in breast cancer either in online database or cell lines. We found higher PD-L1 mRNA level but not DNA copy number in breast cancer than normal breast tissue, and higher PD-L1 expression in TNBC than other subtypes. Moreover, we found a positive relationship between PD-L1 expression in TNBC and metabolic complications in patients. Next, obesity/MetS related M1 macrophage was found to promote the expression of PD-L1 in breast cancer cells cocultured with polarized macrophages derived from either monocyte-like cell line THP-1 or Wistar rat models. IL6/JAK/STAT pathway was further identified to be involved in the process. In addition, we discovered that the PD-L1 expression promoted by obesity/MetS could be restored by telmisartan, one of the angiotensin II receptor blockers (ARBs) and could affect macrophage polarization, through its selective peroxisome proliferator-activated receptor-gamma (PPARG) activation and NFKB p65 inhibition and therefore downregulates IL6 secretion from M1 macrophage.

PD-1 blockade in recurrent or metastatic cervical cancer: Data from cemiplimab phase I expansion cohorts and characterization of PD-L1 expression in cervical cancer

ObjectivesTo characterize the safety, tolerability, and anti-tumor activity of cemiplimab as monotherapy or in combination with hypofractionated radiation therapy (hfRT) in patients with recurrent or metastatic cervical cancer. To determine the association between histology and programmed death-ligand 1 (PD-L1) expression. MethodsIn non-randomized phase I expansion cohorts, patients (squamous or non-squamous histology) received cemiplimab 3 mg/kg intravenously every 2 weeks for 48 weeks, either alone (monotherapy cohort) or with hfRT during week 2 (combination cohort). Due to insufficient tissue material, PD-L1 protein expression was evaluated in commercially purchased samples and mRNA expression levels were analyzed from The Cancer Genome Atlas (TCGA). ResultsTwenty patients enrolled in both cohorts in total; 10 had squamous histology. The most common adverse events of any grade were diarrhea, fatigue, and hypokalemia, occurring in 35%, 25%, and 25%, respectively. Objective response rate was 10% in each cohort; responders had squamous histology. Duration of response was 11.2 months and 6.4 months for the responder in the monotherapy and combination cohort, respectively. Irradiated lesions were not included in the response assessments. In separate archived specimens (N = 155), PD-L1 protein expression in tumor and immune cells was negative (<1%) more commonly in adenocarcinoma than in squamous tumors. PD-L1 mRNA levels were lower in adenocarcinoma than squamous cell tumors (1.2 vs 5.0 mean transcripts per million, respectively) in TCGA. ConclusionsCemiplimab has activity in cervical squamous cell carcinoma. The phase I results, combined with results from other anti–PD-1 trials in cervical cancer and our biomarker analyses have informed the design of the ongoing phase III trial, with the primary overall survival hierarchical analyses being done first in patients with squamous histology.

Abstract 6011: Mesenchymal stem cells promote PD-L1 expression in lung cancer cells

Abstract Background Effects of mesenchymal stem cells (MSCs) on tumors have been extensively studied in recent years, but results still remain controversial. In this study we investigated the roles of MSCs on the expression of programmed death-ligand 1 (PD-L1) in lung cancer cells. Since overexpression of PD-L1 has been found to attenuate body's immune system against tumor cells, PD-1/PD-L1 blockages have become the most effective immunotherapy to the late stage non-small cell lung cancer (NSCLC). Therefore, understanding the effects of MSCs on PD-L1 expression is critical in managing immunotherapy for NSCLC patients. Method PD-L1 expressions were tested in two NSCLC cell lines, A549 and H1299 using qRT-PCR and Western Blot to qualitatively measure mRNA and protein levels, respectively. MSCs were isolated from umbilical cord blood and co-cultured with A549 and H1299 cells in complete medium using Transwell filters for 24-h, 48-h and 72-h. Then both A549 and H1299 cells were collected and PD-L1 expressions were tested. MSC-Conditioned Medium (MSC-CM) was generated by culturing 80% confluence of MSCs with serum-free medium. After 48 h, the medium was collected as MSC-CM. Both A549 and H1299 were then cultured in MSC-CM for 24-h, 48-h and 72-h, and PD-L1 expressions were measured from these two cell lines separately. Result Both MSCs and MSC-CM significantly increased the PD-L1 mRNA levels in the two NSCLC cells, while the MSC-CM had stronger stimulation to PD-L1 expressions (P &amp;lt; 0.0001) comparing to MSCs treatment (P&amp;lt;0.01). A549 cells reached the most significant effect at 48-h, while H1299 cells attended the same effect at 24-h treatment. The similar results were observed with PD-L1 protein levels. Both cell lines showed increased PD-L1 protein expressions after treating with MSCs and MSC-CM, but the augmented scales were smaller than the mRNA levels. The PD-L1 protein expressions in A549 cells increased significantly (p &amp;lt; 0.05) at 48-h when treating with MSCs, while increased much higher when treating with MSC-CM (P &amp;lt; 0.01). H1299 cells also showed the similar increase in PD-L1 protein expressions after 24-h treatment. Conclusion Both MSCs and MSC-CM significantly increase PD-L1 expressions in lung cancer cells, which ultimately attenuate the immune system against tumor cells. Citation Format: Hui Zhao, Hui Yang, Jinqiu Sun, Guoqiang Liang, Qianqian Zhao, Xiufang Zhang, Shengxian Liang, Rui Guo, Li Zhong. Mesenchymal stem cells promote PD-L1 expression in lung cancer cells [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 6011.

PD-L1 over-expression is driven by B-cell receptor signaling in diffuse large B-cell lymphoma

Targeting the programmed death 1 (PD-1)/programmed death ligand 1 (PD-L1) pathway represents a milestone in cancer therapy. However, the biologic features of diffuse large B-cell lymphoma (DLBCL) with PD-L1 expression remains unknown. We evaluated the correlation between pSYK and PD-L1 mRNA levels with RNAscope in situ hybridization and protein levels with immunohistochemistry in 108 cases of DLBCL, 25 of which featured loss of B-cell receptor (BCR), and investigated the effects of BCR signaling and MYC on PD-L1 mRNA and protein level with qPCR, immunoblotting and flow cytometery in DLBCL cell lines. PD-L1 amplification was detected with fluorescent in situ hybridization. Animal studies were applied to validate the in vitro findings. pSYK and MYC correlated with both PD-L1 mRNA and protein level. Genetic aberrations involving PD-L1 were rare in DLBCL. BCR signaling and MYC increased PD-L1 mRNA and protein expression. Inhibition of BCR signaling and BCR knockdown down-regulated PD-L1. DLBCL with a loss of loss of BCR showed low levels of PD-L1 mRNA and protein. PD-L1 was down-regulated by ibrutinib in a xenograft mouse model and correlated with slower tumor growth. In conclusion, this study demonstrates that DLBCL with PD-L1 expression features an activated B-cell receptor signal pathway, and that BCR inhibition and PD-L1 blockage may potentially synergize to targeting DLBCL.

Neddylation inhibition upregulates PD-L1 expression and enhances the efficacy of immune checkpoint blockade in glioblastoma.

Pevonedistat (MLN4924), a specific NEDD8-activating enzyme inhibitor, has been considered as a promising treatment for glioblastoma, which is currently in Phase I/II clinical trials. On the other hand, inhibition of neddylation pathway substantially upregulates the expression of T cell negative regulator programmed death-ligand 1 (PD-L1), which might account for the potential resistance via evasion of immune surveillance checkpoints. Whether administration of anti-PD-L1 enhances the efficacy of pevonedistat through a cytotoxic T cell-dependent mechanism in glioblastoma needs to be investigated. Here, we report that depletion of neddylation pathway key enzymes markedly elevates PD-L1 expression in glioblastoma cancer cells. Consistently, neddylation inhibitor pevonedistat significantly enhances PD-L1 expression in both glioblastoma cancer cell lines and animal models. Mechanistically, pevonedistat increases PD-L1 mRNA levels mainly through inhibiting Cullin1-F-box and WD repeat domain-containing 7 E3 ligase activity and accumulating c-MYC proteins, a direct transcriptional activator of PD-L1 gene expression. In addition, inhibition of Cullin3 activity by pevonedistat also blocks PD-L1 protein degradation. Importantly, pevonedistat attenuates T cell killing through PD-L1 induction, and blockade of PD-L1 restores the sensitivity of pevonedistat-treated glioblastoma cancer cells to T cell killing. The combination of pevonedistat and anti-PD-L1 therapy compared to each agent alone significantly increased the therapeutic efficacy in vivo. Our study demonstrates inhibition of neddylation pathway suppresses cancer-associated immunity and provides solid evidence to support the combination of pevonedistat and PD-L1/programmed cell death protein 1 immune checkpoint blockade as a potential therapeutic strategy to treat glioblastoma.