Poliovirus Receptor Research Articles

Neuroendocrine subtypes of small cell lung cancer differ in terms of immune microenvironment and checkpoint molecule distribution.

Small cell lung cancer (SCLC) has recently been subcategorized into neuroendocrine (NE)‐high and NE‐low subtypes showing ‘immune desert’ and ‘immune oasis’ phenotypes, respectively. Here, we aimed to characterize the tumor microenvironment according to immune checkpoints and NE subtypes in human SCLC tissue samples at the protein level. In this cross‐sectional study, we included 32 primary tumors and matched lymph node (LN) metastases of resected early‐stage, histologically confirmed SCLC patients, which were previously clustered into NE subtypes using NE‐associated key RNA genes. Immunohistochemistry (IHC) was performed on formalin‐fixed paraffin‐embedded TMAs with antibodies against CD45, CD3, CD8, MHCII, TIM3, immune checkpoint poliovirus receptor (PVR), and indoleamine 2,3‐dioxygenase (IDO). The stroma was significantly more infiltrated by immune cells both in primary tumors and in LN metastases compared to tumor nests. Immune cell (CD45+ cell) density was significantly higher in tumor nests (P = 0.019), with increased CD8+ effector T‐cell infiltration (P = 0.003) in NE‐low vs NE‐high tumors. The expression of IDO was confirmed on stromal and endothelial cells and was positively correlated with higher immune cell density both in primary tumors and in LN metastases, regardless of the NE pattern. Expression of IDO and PVR in tumor nests was significantly higher in NE‐low primary tumors (vs NE‐high, P < 0.05). We also found significantly higher MHC II expression by malignant cells in NE‐low (vs NE‐high, P = 0.004) tumors. TIM3 expression was significantly increased in NE‐low (vs NE‐high, P < 0.05) tumors and in LN metastases (vs primary tumors, P < 0.05). To our knowledge, this is the first human study that demonstrates in situ that NE‐low SCLCs are associated with increased immune cell infiltration compared to NE‐high tumors. PVR, IDO, MHCII, and TIM3 are emerging checkpoints in SCLC, with increased expression in the NE‐low subtype, providing key insight for further prospective studies on potential biomarkers and targets for SCLC immunotherapies.

Tracing the evolution of nectin and nectin-like cell adhesion molecules

Nectin and nectin-like cell adhesion molecules (collectively referred as nectin family henceforth) are known to mediate cell-cell adhesion and related functions. While current literature suggests that nectins are prevalent in vertebrates, there are no in-depth analyses regarding the evolution of nectin family as a whole. In this work, we examine the evolutionary origin of the nectin family, using selected multicellular metazoans representing diverse clades whose whole genome sequencing data is available. Our results show that this family may have appeared earlier during metazoan evolution than previously believed. Systematic analyses indicate the order in which various members of nectin family seem to have evolved, with some nectin-like molecules appearing first, followed by the evolution of other members. Furthermore, we also found a few possible ancient homologues of nectins. While our study confirms the previous grouping of the nectin family into nectins and nectin-like molecules, it also shows poliovirus receptor (PVR/nectin-like-5) to possess characteristics that are intermediate between these two groups. Interestingly, except for PVR, the other nectins show surprising sequence conservations across species, suggesting evolutionary constraints due to critical roles played by these proteins.

Oncolytic poliovirus immunotherapy for breast cancer

Abstract Oncolytic poliovirus PVSRIPO is a recombinant, non-pathogenic polio:rhinovirus chimera that enters cells via the poliovirus receptor CD155. CD155 expression is virtually universal in solid cancers, including breast cancer. CD155 is also expressed on myeloid cells. PVSRIPO infection of antigen-presenting cells (APC), including dendritic cells (DC) and macrophages, induces type I interferon and APC activation. Intratumor injection of PVSRIPO results in robust T cell infiltration and generates an immune-engaged tumor microenvironment. PVSRIPO is therefore an ideal therapeutic complement to immune checkpoint inhibitors, such as anti-PD1/PDL1. We tested the hypothesis that blocking PD1/PDL1 in conjunction with PVSRIPO will potentiate durable antitumor immunity in the murine E0771 orthotopic breast cancer immunotherapy model. Intratumor injection of PVSRIPO in 5–7 mm orthotopic tumors induces rapid recruitment of neutrophils followed by infiltration of DC, T cells and B cells. Next, we investigated PVSRIPO with PD1/PDL1 blockade. All treatment groups significantly inhibited tumor growth compared to PBS. There were no significant differences in tumor growth inhibition between PVSRIPO and anti-PD1/PDL1 monotherapies. Combination PVSRIPO+PD1/PDL1 blockade was significantly more effective than the monotherapies at controlling tumor growth. We also tested neoadjuvant PVSRIPO in E0771-tumor bearing mice. We observed that intratumor PVSRIPO followed by surgery effectively controls tumor growth and prevents tumor regrowth following tumor rechallenge, suggesting induction of a systemic immune response. We are now testing neoadjuvant PVSRIPO with anti-PD1/PDL1 in murine models of cancer.

Prognostic significance of tumor poliovirus receptor and CTLA4 expression in patients with surgically resected non-small-cell lung cancer.

Poliovirus receptor (PVR) is a tumor promoter and a regulatory checkpoint that enhances immunosuppression. We investigated PVR expression by applying immunohistochemistry (IHC) staining. A positive association existed between PVR expression and cytotoxic T lymphocyte-associated antigen 4 (CTLA4) expression in patients with surgically resected non-small-cell lung cancer (NSCLC). PVR expression is a prognosis predictor of lung adenocarcinoma. To investigate the prognostic significance of PVR expression and CTLA4 expression for surgically resected NSCLC. The medical records of 108 Chinese patients with primary NSCLC who underwent surgery were retrospectively reviewed. The expression of PVR and CTLA4 were measured through IHC. Clinical characteristics, the association between PVR and CTLA4, and the prognostic significance of PVR were analyzed. A significant positive association was observed between PVR and CTLA4 expression in NSCLC (P = 0.016). PVR had a high positive rate among females, nonsmokers, and patients with adenocarcinoma and advanced lung cancer. The overall survival (OS) of patients with negative PVR expression was significantly longer than that of patients with positive PVR expression (P = 0.049), especially among females (P = 0.03) and nonsmokers (P = 0.025). Multivariate analysis results showed that advanced tumor stage and PVR expression were independent prognosis predictors of poor OS. PVR can potentially serve as a prognostic predictor and biomarker for NSCLC and cancer anti-CTLA4 immunotherapy response.

Poliovirus Non-Permissive CD155 Knockout Cells Derived from RD Cell Line Using CRISPR Technology for Handling Poliovirus Potentially Infectious Materials in Virology Laboratories

Background: Destruction of all poliovirus containing materials, and safe and secure handling of retained polioviruses for vaccine production and research will be obligatory to eliminate facility-associated risks. As defined in WHO-GAPIII, poliovirus potentially infectious materials (PIM) include fecal or respiratory samples collected for any purpose in time and geographic area of wild poliovirus or during OPV use and products of such materials from poliovirus permissive cells or animals. Non-polio laboratories culturing viruses from PIM are most affected as cell cultures of human and monkey origin are also poliovirus permissive. Methods: CRISPR gene editing technology was used to knockout poliovirus receptor (PVR/CD155) gene in RD cell line. Poliovirus non-permissive cells were identified by resistance to poliovirus infection, cell surface immunofluorescence and DNA sequencing. PVR knockout RD cell susceptibility was tested using known non-polio enterovirus types. A selected clone (RD-SJ40) was field evaluated for virus isolation from 626 stool samples of AFP cases. Findings: Poliovirus non-permissive cells derived from RD cell line did not show CD155-specific cell surface immunofluorescence. CD155 gene sequencing confirmed nucleotide base pair deletions within exon2 and exon3. The CD155 knockout RD-SJ40 cells did not support growth of poliovirus from positive stool samples. All NPEV types isolated in parental RD cells were also isolated in RD-SJ40. Interpretation: CRISPR correctly edited CD155 gene of RD cells to render them poliovirus non-permissive while susceptibility to NPEV remained unchanged. RD-SJ40 cells are safe for NPEV isolation from poliovirus PIM without derogating GAPIII containment requirements. Funding: Department of Health Research, Govt. of India. Project Grant No.R.12020/08/2018-HR Declaration of Interests: SSN, SS and JD have IPR interests. Other authors have no conflict of interests.

CD96 functions as a co-stimulatory receptor to enhance CD8+ Tcell activation and effector responses.

CD96 is a member of the poliovirus receptor (PVR, CD155)-nectin family that includes Tcell Ig and ITIM domain (TIGIT) and CD226. While CD96, TIGIT, and CD226 have important roles in regulating NK cell activity, and TIGIT and CD226 have also been shown to regulate Tcell responses, it is unclear whether CD96 has inhibitory or stimulatory function in CD8+ Tcells. Here, we demonstrate that CD96 has co-stimulatory function on CD8+ Tcells. Crosslinking of CD96 on human or mouse CD8+ Tcells induced activation, effector cytokine production, and proliferation. CD96 was found to transduce its activating signal through the MEK-ERK pathway. CD96-mediated signaling led to increased frequencies of NUR77- and T-bet-expressing CD8+ Tcells and enhanced cytotoxic effector activity, indicating that CD96 can modulate effector Tcell differentiation. Antibody blockade of CD96 or genetic ablation of CD96 expression on CD8+ Tcells impaired expression of transcription factors and proinflammatory cytokines associated with CD8+ Tcell activation in in vivo models. Taken together, CD96 has a co-stimulatory role in CD8+ Tcell activation and effector function.

Abstract P1-09-05: Overexpression of CD155 in breast cancer microenvironment, associated with higher counts of tumor-infiltrating lymphocytes and increased risk of relapse and death

Abstract Background: CD155 is poliovirus receptor and has an overexpression in malignant tissues. However the expression status and the association with prognosis and clinical characteristics were seldom reported in breast cancer patients. This study aimed to investigate the expression of CD155 and the association with prognosis and pathological features of breast cancer. Methods: 126 patients were recruited this cohort study consecutively and CD155 expression on tumor cells were detected by immunohistochemistry. Kaplan-Meier survival curve and Cox Hazard Regression model were used to estimate the association. Results: 38.1% patients had an overexpression of CD155 and the percentage of tumor cells overexpressing CD155 was 17%, 39%, 37% and 62% among Luminal A, Luminal B, HER2-positive and TNBC cases, respectively (p&amp;lt;0.05). The percentage was higher in Luminal B and TNBC cases than that in Luminal A patients. Among patients with low expression of CD155, Ki-67 index was 26%, significantly lower than patients with CD155 overexpression (42%).Cell count of TILs was 144/HPF among patients with CD155 overexpression, in comparison of 95/HPF among patients with low expression of CD155 (p&amp;lt;0.05). However, the percentage of PD-1+ TILs was significantly higher (17% vs. 13%) in patients with CD155 overexpression than that of patients with low expression of CD155 (p&amp;lt;0.01) and the cell count of PD-1+ TILs was 52/HPF and 25/HPF among patients with overexpression and low expression of CD155, respectively (p&amp;lt;0.01). The median follow-up time was 75 months and the rate of loss of follow-up was 7.1% and 10.3% for relapse and overall survival respectively. The mean DFS length was 86 months among patients with low expression of CD155, significantly longer than patients (73 months) with CD155 overexpression. The mean OS length was 87 months among patients with low expression of CD155, significantly longer than patients (78 months) with CD155 overexpression. The disease-free survival and overall survival rate was 88.5% and 87.2% among patients with low expression of CD155, however the survival rate reduced to 56.3% and 62.5% among patients with overexpression of CD155. The study power was 97.7% and 87.3% for disease-free and overall survival rate. In COX-Hazard regression analysis, the overexpression of CD155 was associated with a 5.41-fold high risk of relapse (95%CI 1.93, 15.20) and a 3.74-fold high risk of death (95%CI 1.25, 11.16); under further adjustment, the HR of relapse increased to 13.93 (2.82, 68.91) and the HR of death increased to 5.47 (95%CI 1.42, 20.99) (Table 1). Conclusions: Overexpression of CD155 was correlated with more proliferative cancer cells and a dysfunctional immune microenvironment. CD155 overexpression introduced a worse relapse-free and overall survival and might be a potential immunotherapy target for breast cancer. Table 1. Cox-Hazard regression on association between CD155 expression and prognosisCD155 expressionHRcrude95%CIHR*95%CIHR**95%CILow expression (n=78)Overexpression (n=48)Disease-free survival, n (%)Relapse6 (7.7)15 (31.3)5.411.93, 15.205.682.01, 16.0213.932.82, 68.91Survival69 (88.5)27 (56.3)Overall survival, n (%)Death6 (7.7)9 (18.8)3.741.25, 11.164.511.50, 13.635.471.42, 20.99Survival68 (87.2)30 (62.5)*further adjusting age, ** further adjusting age, histological grade and molecular subtype. Citation Format: Qingkun Song, Shuzhen Lv. Overexpression of CD155 in breast cancer microenvironment, associated with higher counts of tumor-infiltrating lymphocytes and increased risk of relapse and death [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P1-09-05.

Bone Marrow Stromal Cell-Derived IL-8 Upregulates PVR Expression on Multiple Myeloma Cells via NF-kB Transcription Factor.

Bone marrow stromal cells (BMSCs) strongly contribute to multiple myeloma (MM) progression, promoting the survival and growth of malignant plasma cells (PCs). However, the possible impact of these cells on the immune-mediated recognition of MM cells remains largely unknown. DNAM-1 activating receptor plays a prominent role in NK cell anti-MM response engaging the ligands poliovirus receptor (PVR) and nectin-2 on malignant PCs. Here, we analysed the role of MM patient-derived BMSCs in the regulation of PVR expression. We found that BMSCs enhance PVR surface expression on MM cells and promote their NK cell-mediated recognition. PVR upregulation occurs at transcriptional level and involves NF-kB transcription factor activation by BMSC-derived soluble factors. Indeed, overexpression of a dominant-negative mutant of IKBα blocked PVR upregulation. IL-8 plays a prominent role in these mechanisms since blockade of CXCR1/2 receptors as well as depletion of the cytokine via RNA interference prevents the enhancement of PVR expression by BMSC-derived conditioned medium. Interestingly, IL-8 is associated with stromal microvesicles which are also required for PVR upregulation via CXCR1/CXCR2 signaling activation. Our findings identify BMSCs as regulators of NK cell anti-MM response and contribute to define novel molecular pathways involved in the regulation of PVR expression in cancer cells.

A phase I study evaluating COM701 monotherapy and in combination with nivolumab in patients with advanced solid malignancies.

TPS23 Background: COM701 is a novel 1st-in-class monoclonal antibody that binds with high affinity to poliovirus receptor related immunoglobulin domain containing (PVRIG) blocking its interaction with its ligand, PVRL2. In preclinical experiments inhibition of PVRIG alone and in combination with a PD-1 inhibitor leads to activation of T cells in the tumor microenvironment generating an anti-tumor immune response leading to tumor growth inhibition. Novel checkpoint therapies are needed for the treatment of patients with advanced malignancies. We hypothesized that COM701 monotherapy and in combination with nivolumab will be safe and tolerable and demonstrate preliminary antitumor activity in pts with advanced solid malignancies. Methods: This ongoing phase 1 study (NCT03667716) is evaluating the safety and tolerability of escalating doses of COM701 monotherapy IV Q3 or Q4 weekly and in combination with nivolumab 360 mg IV Q3 weekly or 480 mg IV Q4 weekly. Key Inclusion Criteria: Age ≥18 yrs, histologically or cytologically confirmed advanced solid malignancy and has exhausted all available standard therapy, ECOG performance status 0-1, prior ICI permissible. Key Exclusion Criteria: Symptomatic interstitial lung disease or inflammatory pneumonitis, untreated or symptomatic central nervous system metastases. Primary outcome measures are the incidence of adverse events and dose-limiting toxicities (21-day or 28-day DLT window), pharmacokinetics of COM701 and to identify the maximum tolerated dose and/or the recommended dose for expansion. Key secondary outcome measures are to characterize the immunogenicity and preliminary antitumor activity of COM701 as monotherapy and in combination with nivolumab. Study Design: Hybrid accelerated titration and 3+3 study design. Statistical Considerations: Adverse events graded as per CTCAE v4.03, responses as per RECIST v1.1. Analyses of all study objectives are descriptive and hypothesis generating. As of the date of this submission dose level 8 of COM701 monotherapy and dose level 3 of the combination arm are open to enrollment. Updated data will be presented at the conference. Clinical trial information: NCT03667716.

The interaction of Multiple Sclerosis risk loci with Epstein-Barr virus phenotypes implicates the virus in pathogenesis

Translating the findings of genome wide association studies (GWAS) to new therapies requires identification of the relevant immunological contexts to interrogate for genetic effects. In one of the largest GWAS, more than 200 risk loci have been identified for Multiple Sclerosis (MS) susceptibility. Infection with Epstein-Barr virus (EBV) appears to be necessary for the development of Multiple Sclerosis (MS). Many MS risk loci are associated with altered gene expression in EBV infected B cells (LCLs). We have interrogated this immunological context to identify interaction between MS risk loci and EBV DNA copy number, intrinsic growth rate and EBV encoded miRNA expression. The EBV DNA copy number was associated with significantly more risk alleles for MS than for other diseases or traits. EBV miRNAs BART4-3p and BART3-5p were highly associated with EBV DNA copy number and MS risk loci. The poliovirus receptor (PVR) risk SNP was associated with EBV DNA copy number, PVR and miRNA expression. Targeting EBV miRNAs BART4-3p and BART3-5p, and the gene PVR, may provide therapeutic benefit in MS. This study also indicates how immunological context and risk loci interactions can be exploited to validate and develop novel therapeutic approaches.

Analysis of poliovirus receptor, CD155, expression in patients with adult acute myeloid leukemia and its relation to clinical outcome

Background CD155 is called poliovirus receptor owing to its function as the receptor for poliovirus. The role of CD155 in hematological malignancies is limited.Aim To measure CD155 level in serum of adult patients with acute myeloid leukemia (AML) using enzyme-linked immunosorbent assay and to correlate the level with clinical outcome.Patients and methods The study was conducted on 30 adult patients with AML and 30 healthy controls from the Clinical Hematology Unit, Department of Internal Medicine, Ain Shams University Hospital, Cairo, Egypt.Results Serum CD155 was significantly higher in patients with AML than in controls (mean=66.067±30.172 vs. 11.067±5.021 ng/l, P<0.001). After a median duration of follow-up of about 6 months, the cut-off value for serum CD155 at diagnosis in predicting patient survival was 75 ng/l. The median overall survival and disease-free survival were found to be significantly higher in cases with CD155 level less than or equal to 75 ng/l (P=0.004, and P<0.001, respectively).Conclusion Adult patients with AML have elevated CD155 levels, which are associated with an inferior overall survival, disease-free survival, and poor prognosis.

A Platform for Extracellular Interactome Discovery Identifies Novel Functional Binding Partners for the Immune Receptors B7-H3/CD276 and PVR/CD155

Receptors expressed on the plasma membrane and their interacting partners critically regulate cellular communication during homeostasis and disease, and as such represent main therapeutic targets. Despite its importance for drug development, receptor-ligand proteomics has remained a daunting field, in part because of the challenges associated to the study of membrane-expressed proteins. Here, to enable sensitive detection of receptor-ligand interactions in high throughput, we implement a new platform, the Conditioned Media AlphaScreen, for interrogation of a library consisting of most single transmembrane human proteins. Using this method to study key immune receptors, we identify and further validate the interleukin receptor IL20RA as the first binding partner for the checkpoint inhibitor B7-H3. Further, KIR2DL5, a natural killer cell protein that had remained orphan, is uncovered as a functional binding partner for the poliovirus receptor (PVR). This interaction is characterized using orthogonal assays, which demonstrate that PVR specifically engages KIR2DL5 on natural killer cells leading to inhibition of cytotoxicity. Altogether, these results reveal unappreciated links between protein families that may importantly influence receptor-driven functions during disease. Applicable to any target of interest, this technology represents a versatile and powerful approach for elucidation of receptor-ligand interactomes, which is essential to understand basic aspects of the biology of the plasma membrane proteins and ultimately inform the development of novel therapeutic strategies.

Targeting the TIGIT-PVR immune checkpoint axis as novel therapeutic option in breast cancer

ABSTRACTImmune checkpoints are intensively investigated as targets in cancer therapy. T-cell immunoreceptor with immunoglobulin (Ig) and ITIM domains (TIGIT) and its ligand poliovirus receptor (PVR) are recently emerging as novel promising targets in immunotherapy. Here, we show that high expression of PVR represents an independent prognostic marker being associated with poor outcome for breast cancer patients. Furthermore, PVR mRNA, as well as protein expression, is associated with more aggressive breast cancer subtypes such as HER2 positive and triple-negative breast cancer. In vitro, blocking TIGIT or PVR resulted in enhanced immune cell-mediated lysis of breast cancer cell lines SKBR-3, MDA-MB-231, MDA-MB-468, and BT549 and additionally increased the cytotoxic effects of a bispecific T cell engager BiTE® antibody construct targeting EGFR. Taken together, our data identify the immune checkpoint factor PVR as a novel prognostic marker in breast cancer and indicate that blocking the TIGIT-PVR axis might represent a novel therapeutic option for the treatment of breast cancer patients.

Expression of TIGIT/CD155 and correlations with clinical pathological features in human hepatocellular carcinoma.

T cell immunoglobulin and ITIM domain (TIGIT) is a recently identified T cell coinhibitory receptor. Studies have shown that TIGIT is expressed in colon adenocarcinoma, uterine corpus endometrioid carcinoma, breast carcinoma and kidney renal clear cell carcinoma. However, the role of the TIGIT/human poliovirus receptor (CD155) pathway in the pathogenesis of hepatocellular carcinoma (HCC) remains to be elucidated. In the present study, the expression of TIGIT and CD155 in HCC tissues and peripheral blood were determined, and correlations among TIGIT, CD155, TIGIT+ CD4+ T cells, TIGIT+ regulatory T (Treg) cells and α-fetoprotein (AFP) were investigated in order to identify a potential target for diagnosing and treating HCC. Immunohistochemistry, reverse transcription-quantitative PCR analysis and western blotting were used to examine the expression of TIGIT and CD155 in cancerous tissues and peripheral blood collected from patients with HCC. The frequency of TIGIT+ CD4+ T cells and TIGIT+ Treg cells and the concentration of inflammatory cytokines secreted by T cell subsets were analyzed by flow cytometry and a Merck Milliplex assay. Correlations between the frequency of TIGIT+ CD4+ T and TIGIT+ Treg cells and AFP were analyzed using Spearman's rank correlation test. With the degree of cancerous differentiation from high to low, the expression levels of TIGIT and CD155 were upregulated in the cancerous tissues from patients with HCC. TIGIT+ CD4+ T cell and TIGIT+ Treg cell frequencies were decreased in peripheral blood from postoperative patients with HCC. The increased expression of TIGIT was positively correlated with the level of AFP. These results indicate that co-inhibitory receptor TIGIT may be involved in the pathogenesis of HCC and represent a novel target for the diagnosis and treatment of HCC.

Poliovirus receptor CD155 is up-regulated in muscle-invasive bladder cancer and predicts poor prognosis

ObjectiveTo investigate the expression pattern of CD155 and evaluate the prognostic value of CD155 in muscle-invasive bladder cancer (MIBC). Patients and methodsImmunohistochemical staining of CD155 and survival analysis were conducted on 228 nonmetastatic MIBC patients underwent radical cystectomy in cohorts from Fudan University Shanghai Cancer Center and Zhongshan Hospital. Association of CD155 gene expression with tumor stage and survival were analyzed in TCGA and GSE13507 dataset. ResultsCD155 was significantly up-regulated in MIBC compared to matched normal urothelium and majorly stained on the membrane of tumor cells. In Fudan MIBC cohort, CD155 high expression was significantly correlated with shorter recurrence-free survival (HR = 2.13, P < 0.001) and overall survival (HR = 2.49, P < 0.001). CD155 expression, T stage, and lymph node status were independent factors for predicting survival in multivariate analysis. In TCGA dataset, CD155 high expression was independently associated with shorter overall survival (HR = 1.74, P = 0.001) beyond age, T stage, and lymph node status. Further, explorative analysis in Fudan MIBC cohort showed that adjuvant chemotherapy was associated with longer recurrence-free survival and overall survival in stage III and IV disease with CD155-high tumors. ConclusionsThese findings suggest that CD155 is a robust prognostic factor and may help predict the benefit of adjuvant chemotherapy in MIBC.

High expression of soluble CD155 in estrogen receptor-negative breast cancer

BackgroundThe poliovirus receptor (CD155) is expressed ubiquitously at low levels on both hematopoietic and nonhematopoietic cells, but its expression is upregulated in various tumor cells. An activating receptor DNAM-1 expressed on cytotoxic T lymphocytes (CTLs) and natural killer (NK) cells binds to CD155 and mediates the cytotoxic activity of CTLs and NK cells against tumors. Unlike mouse tissues, human tissues express a soluble form of CD155 (sCD155), which is a splicing isoform of CD155 lacking the transmembrane region. We previously reported that the serum levels of sCD155 were higher in lung, gastrointestinal, breast, and gynecologic cancer patients than in healthy donors. Here, we focus on breast cancer patients.MethodsTo analyze the association between serum level of sCD155 and clinicopathological parameters of breast cancer, we quantified sCD155 in the sera of 153 breast cancer patients by sandwich ELISA.ResultssCD155 levels in the sera of breast cancer patients were positively correlated with patient age, disease stage, and invasive tumor size. Moreover, they were higher in patients with estrogen receptor (ER)-negative cancers than in those with ER-positive tumors, and higher in those with Ki-67-high cancers than in those with Ki-67-low cancers.ConclusionsThe serum level of sCD155 is correlated with high risk factors in breast cancer.

Anticancer activity of emodin is associated with downregulation of CD155

Emodin is a Chinese herb-derived compound that exhibits a variety of pharmacological benefits. Although emodin has been shown to inhibit growth of cancer cells, its antineoplastic function is incompletely understood. CD155 is a member of poliovirus receptor–related (PRR) family of adhesion molecules; it is constitutively expressed on many tumor cell lines and tissues and has diverse functions. CD155 has been reported to mediate activation of T cells via CD226 or inhibition of T cells via T-cell immunoreceptor with Ig and ITIM domains (TIGIT). In addition, CD155 may play a critical role through non-immunological mechanisms in cancer. In this study, we tested the ability of emodin to modulate CD155 expression in cancer cells. We found that emodin significantly decreased the expression of CD155 in tumor cells and inhibited tumor cell proliferation and migration, and induced cell-cycle arrest at G2/M phase. The tumor inhibitory effects of emodin were lost with CD155 knockdown. Furthermore, emodin was used to treat mice bearing B16 melanoma. It was shown that emodin attenuated tumor growth accompanied by suppressing CD155 expression. Therefore, we propose that emodin could inhibit tumor growth, and the antineoplastic properties of emodin are at least partially CD155 dependent. Our study provides new insights into the mechanisms by which emodin inhibits tumor growth.

Abstract 4844: A novel anti-TIGIT antibody (YH29143) enhances T cell activity and suppresses Treg cell activity and synergizes with anti-PD-L1 antibody

Abstract TIGIT (T cell immunoreceptor with Ig and ITIM domains) is a T cell coinhibitory receptor, highly expressed on regulatory and memory CD4+, CD8+ T cells and natural killer (NK) cells. TIGIT binding of PVR (poliovirus receptor) on the surface of antigen presenting cells leads to downregulation of CD8+ T cell and NK cell responses in tumors. In this study, we sought to determine the efficacy of TIGIT blockade in antitumor immunity and demonstrate the synergistic effect of treatment with other checkpoint blockade such as anti-PD-L1. We generated anti-TIGIT monoclonal antibody that binds TIGIT with high affinity and blocks ligand binding. Anti-TIGIT antibody YH29143 was shown to increase T cell activities and suppress Treg cell activities from in vitro cell-based assays. We determined the crystal structure of YH29143 Fab fragment in complex with TIGIT and identified its epitope that overlaps with the PVR-binding interface. We also studied in vivo efficacy of YH29143 whether to inhibit the growth of tumor in two syngeneic colon tumor-bearing mouse models (CT26 and MC38). YH29143 reduced growth of both tumors compared to that of control IgG. In addition to these results, YH29143 showed synergistic efficacy for inhibition of tumor growth in combination with anti-PD-L1 antibody. From these tumor tissues, the ratio of CD8+ T cells to Treg cells was increased by treatment of anti-TIGIT antibody. Taken together, we evaluated the efficacy of YH29143, a potent anti-TIGIT monoclonal antibody, which enhanced T cell activation and suppressd Treg cell function in vitro, and efficiently inhibited tumor growth in vivo having synergistic effect with anti-PD-L1 antibody. These data also provide the rationale for YH29143 as a potential combination candidate for cancer immunotherapy with other immune checkpoint blockades. Citation Format: Kwang-Hoon Lee. A novel anti-TIGIT antibody (YH29143) enhances T cell activity and suppresses Treg cell activity and synergizes with anti-PD-L1 antibody [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4844.

Abstract CT168: Phase I study of COM701 (a novel checkpoint inhibitor of PVRIG) in patients with advanced solid tumors

Abstract Background: A high unmet medical need exists for the treatment of patients who are unresponsive to or relapse following treatment with checkpoint inhibitors. Therefore, novel checkpoint inhibitors that can demonstrate clinical activity in this patient population are urgently needed. COM701 is a novel first-in-class humanized IgG4 monoclonal antibody that binds with high affinity to PVRIG (poliovirus receptor related immunoglobulin domain containing) blocking its interaction with its ligand, PVRL2. Both PVRIG and PVRL2 are part of the DNAM axis. In nonclinical experiments using in vitro and animal models we have demonstrated that inhibition of PVRIG leads to enhanced activation of T and NK cells, and that knockout of PVRIG results in tumor growth inhibition in mouse tumor models. We hypothesize that COM701 will be safe and tolerable and demonstrate antitumor activity in pts with advanced solid tumors. Methods: NCT03667716 is an ongoing open-label first-in-human phase 1 study in pts with advanced solid tumors. The initial part of this study (Arm A) will evaluate the safety and tolerability of escalating doses of COM701 monotherapy IV Q3 weekly. Dose-limiting toxicities will be assessed within 21 days in cycle 1 of administration of COM701. Key Inclusion Criteria: Age ≥18 yrs, histologically or cytologically confirmed, locally advanced or metastatic solid malignancy and has exhausted all the available standard therapy or is not a candidate for the available standard therapy, ECOG performance status 0-1, prior anti-PD-1, anti-PD-L1, anti-CTLA-4, OX-40, CD137. Key Exclusion Criteria: Active autoimmune disease requiring systemic therapy in the last 2 years prior to the first dose of COM701, symptomatic interstitial lung disease or inflammatory pneumonitis, untreated or symptomatic central nervous system metastases. Primary outcome measures are the incidence of adverse events and dose-limiting toxicities (21-day DLT window), pharmacokinetics of COM701 and to identify the maximum tolerated dose and/or the recommended dose for expansion. Secondary outcome measures are to characterize the immunogenicity and preliminary antitumor activity of COM701. Study Design: Single subject dose cohorts in initial 4 dose cohorts and 3+3 study design for subsequent cohorts. Statistical Considerations: Adverse events graded as per CTCAE v4.03, responses as per RECIST v1.1. The analyses of all study objectives will be descriptive and hypothesis generating. As of the date of this submission no DLTs have been reported in the initial 4 dose cohorts. Enrollment in cohort 5 is ongoing. Citation Format: Dan Vaena, Amita Patnaik, Erika Hamilton, Judy Olweny, John Hunter, Adeboye Henry Adewoye, Adam ElNaggar, Drew Rasco. Phase I study of COM701 (a novel checkpoint inhibitor of PVRIG) in patients with advanced solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr CT168.

Abstract 4969: TIGIT pathway phenotyping sheds light on promising strategies to restore anti-tumor immunity

Abstract TIGIT is a T cell co-inhibitory receptor recently described as a key checkpoint driving tumor cell immunosuppression. It is predominantly expressed on CD4+ Tregs, CD8+ T cells and NK cells from healthy individuals but further upregulated in cancer patients where it frequently co-expresses with exhaustion markers such as PD-1. TIGIT cognate receptors are members of the poliovirus receptors, among which CD155 has the highest affinity for TIGIT. They are expressed on antigen presenting cells but also on tumor cells which provides a strong rationale for blocking TIGIT as a therapeutic approach to reverse T or NK cell dysfunction linked with cancer progression. To substantiate the importance of TIGIT as an immunotherapy target, we used flow cytometry and immunohistochemistry (IHC) to extensively characterize TIGIT and CD155 expression in both healthy donors and cancer patients. We initially confirmed TIGIT expression on multiple immune subsets from healthy donors. Similar flow cytometry analysis performed on matched circulating and tumor-infiltrating immune populations from 15 cancer patients highlighted the global overexpression of TIGIT associated with cancer. Interestingly, ex vivo polyfunctional analysis of cytokine release strongly supported the immunosuppressed character of infiltrated TIGIT positive CD4+ and CD8+ T cells. Finally, combining receptor density with frequency of positive cells led to the interesting observation that tumor-infiltrating Tregs represents the population with the highest TIGIT expression, confirming the opportunity to preferentially target that suppressive population within the tumor microenvironment. These findings on Tregs were further confirmed by IHC. TIGIT was expressed in 10 out of the 11 lung adenocarcinoma tissues analysed. Both Tregs and CD8+ T cells express TIGIT, with Tregs showing a higher proportion of TIGIT+ cells. Finally, direct expression of TIGIT on tumor cells was also found on several haematological malignancies, opening the door for anti-TIGIT therapies to act directly on tumor cells besides revigoration of the immune system. The presence of TIGIT ligands within the tumor microenvironment was also assessed and confirmed using both flow cytometry and IHC. CD155 expression was analysed by IHC in both normal individuals (n=90) and cancer patient tissues from 9 different cancer indications (n=284). In cancer tissues, CD155 is mostly expressed by tumor cells, ranging from a median percentage of 50 % for pancreatic cancer to 2 % for cervix cancer. Cancer samples with the highest CD155 expression are pancreatic, prostate, kidney, gastric and colon cancers. CD155 expression is always lower in normal tissues compared to their cancer counterparts except for lung. Together, these data strongly support the relevance of targeting TIGIT in immuno-oncology and pave the way to select the ideal indications where patients could benefit from such a therapy. Citation Format: Noémie Wald, Marjorie Mercier, Julia Cuende, Florence Nyawouame, Shruthi Prasad, Margreet Brouwer, Erica Houthuys, Anne Marie-Cardine, Martine Bagot, Grégory Driessens, Véronique Bodo, Catherine Hoofd. TIGIT pathway phenotyping sheds light on promising strategies to restore anti-tumor immunity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4969.