PD-L1 Axis Research Articles

Location matters: LAG3 levels are lower in renal cell carcinoma metastatic sites compared to primary tumors, and expression at metastatic sites only may have prognostic importance.

While great strides have been made in the treatment of advanced renal cell carcinoma (RCC) with the emergence of immune checkpoint inhibitors (ICIs) and VEGFR-targeting drugs, sizable proportions of patients still do not respond to upfront therapy and long-term responses only occur in a minority of patients. There is therefore a great need for the development of better predictors of response and an increased understanding of mechanisms of resistance to these therapies. Alternative immune checkpoints outside the PD-1/PD-L1 axis, such as LAG3, have been implicated as one mechanism of resistance to ICIs. These checkpoints thus represent attractive therapeutic targets, and indeed the LAG3 inhibitor relatlimab was recently approved for the treatment of metastatic melanoma in combination with anti-PD-1 therapy. LAG3 inhibitors are being evaluated for RCC as well. In this context, a better understanding of LAG3 expression patterns in RCC and how they relate to clinicopathologic features of disease and response to immunotherapy may give insight into mechanisms of resistance to PD-1 inhibitors and aid in the identification of subgroups of patients more likely to benefit from certain drug regimens. In this study, we assessed LAG3 protein levels in leukocytes in normal kidney adjacent to RCC, primary RCC tumors, and matched metastatic tumors, including large numbers of brain metastases. We found that LAG3 protein levels are on average lower at metastatic sites compared to matched primary tumors, and that the difference was more pronounced in patients with high-risk clinical characteristics, including those with larger primary tumor size, grade 4 tumors, IMDC poor-risk disease, and initial presentation with brain metastases. We further saw that the prognostic value of LAG3 levels varies depending on the tissue site queried (i.e., primary tumor versus metastases), and that relatively higher LAG3 levels at metastatic sites may predict a better response to immunotherapy and longer overall survival after the development of metastatic disease. These findings may have important implications for the design of future studies involving LAG3 or other immunotherapies in RCC.

PD-L1 antibodies-armed exosomal vaccine for enhanced cancer immunotherapy by simultaneously in situ activating T cells and blocking PD-1/PD-L1 axis

Tumor immunotherapy significantly rewards antigen-specific T-cell responses, which have been recognized as the foundation of adaptive immune responses. However, due to the immunosuppressive effects of the tumor microenvironment, it is still hard to activate T cells in situ. Especially, antigen-specific T cell activity is further limited as tumor cells can evade T cell attack via PD-1/PD-L1 axis. During this work, we used a dendritic cells (DCs)-derivate exosome vaccine to build an immunotherapeutic system that can simultaneously mediate antigenic T cell activity by carrying T cells activating CD80 and MHC to induce humoral immunity. More importantly, in order to interrupt tumor immune escape, we also engineered anti-PD-L1 antibodies (aPD-L1) to block PD-1/PD-L1 axis at the same time. Our antigens-feeding DCs-exosomes with aPD-L1 engineering represents a promising strategy for enhanced cancer immunotherapy by robust activating T cells. The outcomes demonstrated that Exo-OVA-aPD-L1 was successful in inhibiting the growth, recurrence, and metastasis of melanoma.

AAV-mediated gene transfer of a checkpoint inhibitor in combination with HER2-targeted CAR-NK cells as experimental therapy for glioblastoma

ABSTRACT Glioblastoma (GB) is the most common primary brain tumor, which is characterized by low immunogenicity of tumor cells and prevalent immunosuppression in the tumor microenvironment (TME). Targeted local combination immunotherapy is a promising strategy to overcome these obstacles. Here, we evaluated tumor-cell specific delivery of an anti-PD-1 immunoadhesin (aPD-1) via a targeted adeno-associated viral vector (AAV) as well as HER2-specific NK-92/5.28.z (anti-HER2.CAR/NK-92) cells as components for a combination immunotherapy. In co-culture experiments, target-activated anti-HER2.CAR/NK-92 cells modified surrounding tumor cells and bystander immune cells by triggering the release of inflammatory cytokines and upregulation of PD-L1. Tumor cell-specific delivery of aPD-1 was achieved by displaying a HER2-specific designed ankyrin repeat protein (DARPin) on the AAV surface. HER2-AAV mediated gene transfer into GB cells correlated with HER2 expression levels, without inducing anti-viral responses in transduced cells. Furthermore, AAV-transduction did not interfere with anti-HER2.CAR/NK-92 cell-mediated tumor cell lysis. After selective transduction of HER2+ cells, aPD-1 expression was detected at the mRNA and protein level. The aPD-1 immunoadhesin was secreted in a time-dependent manner, bound its target on PD-1-expressing cells and was able to re-activate T cells by efficiently disrupting the PD-1/PD-L1 axis. Moreover, high intratumoral and low systemic aPD-1 concentrations were achieved following local injection of HER2-AAV into orthotopic tumor grafts in vivo. aPD-1 was selectively produced in tumor tissue and could be detected up to 10 days after a single HER2-AAV injection. In subcutaneous GL261-HER2 and Tu2449-HER2 immunocompetent mouse models, administration of the combination therapy significantly prolonged survival, including complete tumor control in several animals in the GL261-HER2 model. In summary, local therapy with aPD-1 encoding HER2-AAVs in combination with anti-HER2.CAR/NK-92 cells may be a promising novel strategy for GB immunotherapy with the potential to enhance efficacy and reduce systemic side effects of immune-checkpoint inhibitors.

Content of PD-1+ and PD-L1+ peripheral blood lymphocytes in individuals with pollen sensitization before and after allergen-specific immunotherapy

The available data on the contribution of the PD-1 and its ligands to immunoregulatory processes suggest their involvement into development of tolerance during immunotherapy. Currently, allergen-specific immunotherapy (ASIT) is the single treatment option that can influence the outcome of allergic diseases. Our purpose was to evaluate the PD-1/PD-L1 expression on the immune cells in patients with confirmed sensitization to plant pollen allergens in comparison with healthy controls before and after ASIT. The patients with bronchial asthma (BA) (n = 5, age 33.82.7), allergic rhinitis (AR) (n = 7, age 31.62.8), and healthy donors (n = 12, age 32.81.8) were included. Venous blood samples were obtained from the patients three times: before starting ASIT, upon completion of the ASIT course, and during the period of seasonal exacerbation. In patients with AR, the number of B lymphocytes was decreased, and the expression of PD-L1 by B lymphocytes increased after ASIT in comparison with donor parameters. At the same time, B lymphocyte counts were increased in BA patients before ASIT and returned to normal after ASIT. In AR, the CD8+PD-1+T lymphocyte count was reduced before ASIT, however, returning to normal values after ASIT was completed. Meanwhile, the reduced number of CD4+PD-1+T lymphocytes returned to normal only during the pollination season following ASIT. In BA patients, both before or after ASIT, PD-1 and PD-L1 expression on CD4+ and CD8+T lymphocytes did not differ from the donor parameters. The PD-1 expression in the T regulatory cells (Tregs) was decreased comparing with donors before ASIT in BA, and in the patients with AR, both before and after treatment. It was shown earlier that low PD-1 expression in the circulating CD4+ T cells is associated with high specific IgE concentrations. Thus, low PD-1 levels on CD4+ and CD8+T lymphocytes and regulatory T cells may indicate their functional disorders in allergic pathology. In summary, our results show a regulatory role of PD-1/PD-L1 axis in the immune response during ASIT and reflect differences in pathogenesis of allergic disorders, which are associated with imbalance of the cell activation and suppression. Further studies are required to establish the role of PD-1/PD-L1 interactions in the process of ASIT-induced modification of allergic responses.

PD-L1 evaluation in the gastrointestinal tract: from biological rationale to its clinical application.

Immune-checkpoint inhibitors targeting the PD-1/PD-L1 axis have brought significant clinical benefit in many solid cancer types, including gastrointestinal malignancies. However, it has been estimated that only 20-40% of patients respond to treatment. The pattern of expression and potential predictive value of PD-L1 as an immunohistochemical biomarker has been extensively studied in gastrointestinal neoplasms. Until now, its predictive value has been demonstrated, and is currently in use only in upper gastrointestinal malignancies (gastroesophageal adenocarcinoma and esophageal squamous cell carcinoma).In this Review, we describe the technical aspects and challenges related to PD-L1 immunohistochemical assays, the current role of PD-L1 as a biomarker in clinical practice and we outline the main studies and clinical trials analyzing the prognostic and predictive value of PD-L1 in gastrointestinal cancers.

CTLA-4-Ig internalizes CD80 in fibroblast-like synoviocytes from chronic inflammatory arthritis mouse model

CD80 interact with CD28 and CTLA-4 on antigen-presenting cells, and function in the co-stimulatory signaling that regulates T cell activity. CTLA-4-Ig is used to treat RA by blocking co-stimulatory signaling. Chronic inflammatory arthritis was induced in D1BC mice using low-dose arthritogenic antigens and treated with CTLA-4-Ig. We performed histopathology of the joints and lymph nodes, serological examination for rheumatoid factors, and flow cytometric analysis of isolated synovial cells, including CD45− FLSs and CD45+ synovial macrophages. CTLA-4-Ig treatment ameliorated the chronic inflammatory polyarthritis. There was a decrease in the number of infiltrating lymphoid cells in the joints as well as in the levels of RF-IgG associated with a decrease in the number of B cells in the lymph nodes; more than 15% of CD45− FLSs expressed CD80, and a small number of them expressed PD-L1, indicating the presence of PD-L1/CD80 cis-heterodimers in these cells. CTLA-4-Ig internalized CD80, but not PD-L1, in isolated synovial cells. Gene ontology analysis revealed that CTLA-4-Ig internalization did not significantly alter the expression of inflammation-related genes. The therapeutic effect of CTLA-4-Ig appears to extend beyond the lymph nodes into the inflamed synovial compartment through the synergistic inactivation of T cells by the CD80 and PD-L1 axes.

Lymphopenic condition enhanced the antitumor immunity of PD-1-knockout T cells mediated by CRISPR/Cas9 system in malignant melanoma

BackgroundAdoptive transfer of PD-1 knockout T cells mediated by CRISPR/Cas9 technology has been used in various cancers and got satisfactory treatment effectiveness. However, the effectiveness was limited due to the low proliferation ability, antigen recognition ability and short lifetime of T cells in vivo. MethodIn this study, PD-1 knockout T cells mediated by CRISPR/Cas9 system were transferred into lymphopenic mice after sub-lethal dose of total body irradiation. The antitumor effects of PD-1 knockout T cells were comprehensively analyzed by flow cytometry. Moreover, PD-L1 knockout B16 cells were inoculated subcutaneously in lymphopenic mice receiving infusion of naïve T cells to value the role of PD-1/PD-L1 axis on lymphopenia-induced antitumor immunity ResultIn this study, we found that the PD-1-knockout T cells underwent several rounds of homeostatic proliferation in vivo when they were transferred into lymphopenic mice. The number of IFN-γ-releasing CTL was significantly increased and the tumor growth was remarkably inhibited in lymphopenic mice receiving infusion of PD-1 knockout T cells. The expression of PD-L1 on tumor cells rose smartly in lymphopenic mice undergoing homeostatic proliferation. PD-L1 gene knockout on B16 melanoma cells could effectively enhance the antitumor immunity mediated by the homeostatic proliferation of T cells and significantly inhibited the growth of tumor ConclusionThese findings suggested that lymphopenic condition after total body irradiation might be able to create an environment to promote the PD-1 knockout T cells to recognize tumor antigen and undergo homeostatic proliferation, thus induced a more powerful antitumor immunity than adoptively transferring into immunocompetent hosts.

Real-world assessment of ipilimumab plus nivolumab in anti-PD-L1/PD-1- refractory Merkel Cell Carcinoma

Background and aims: Merkel cell carcinoma (MCC) is a rare and aggressive cutaneous neuroendocrine carcinoma. Immune checkpoint inhibitors (ICIs) have emerged as the new standard of care in the treatment of advanced MCC, offering durable clinical benefit. Currently, two ICIs targeting the PD-1/PD-L1 axis- avelumab, an anti-PD-L1 agent, and pembrolizumab, an anti-PD-1 agent- are approved by the U.S. Food and Drug Administration (FDA) for the treatment of advanced MCC. Despite these advances in effective treatment options, approximately 50% of patients with unresectable/locally advanced or metastatic MCC have primary or acquired resistance to ICIs.

Merkel polyomavirus specific transgenic T cell receptor therapy in PD-1 inhibitor refractory Merkel cell carcinoma

Background and aims: Patients with advanced Merkel cell carcinoma that do not respond or develop resistance to PD-1/PD-L1 axis blockade may lack sufficient tumor specific T cell responses. We sought to ask whether adoptive transfer of autologous T cells transduced with Merkel polyomavirus (MCPyV) specific T cells could lead to clinical responses in PD-1 inhibitor refractory patients. Methods: Five MCPyV positive, HLA-A02 patients with PD-1 inhibitor refractory metastatic Merkel cell carcinoma were treated with adoptive transfer of CD62L+ CD8+ and CD4+ autologous T cells transduced with a T cell receptor (TCR) targeting an HLA-A0201 restricted MCPyV epitope.

PD-1 expression on mouse intratumoral NK cells and its effects on NK cell phenotype

SummaryAlthough PD-1 was shown to be a hallmark of T cells exhaustion, controversial studies have been reported on the role of PD-1 on NK cells. Here, we found by flow cytometry and single cell RNA sequencing analysis that PD-1 can be expressed on MHC class I-deficient tumor-infiltrating NK cells in vivo. We also demonstrate distinct alterations in the phenotype of PD-1-deficient NK cells and a more mature phenotype which might reduce their capacity to migrate and kill in vivo. Tumor-infiltrating NK cells that express PD-1 were highly associated with the expression of CXCR6. Furthermore, our results demonstrate that PD-L1 molecules in membranes of PD-1-deficient NK cells migrate faster than in NK cells from wild-type mice, suggesting that PD-1 and PD-L1 form cis interactions with each other on NK cells. These data demonstrate that there may be a role for the PD-1/PD-L1 axis in tumor-infiltrating NK cells in vivo.

Discovery of the first PD-1 ligand encoded by a pathogen.

Large double-stranded DNA viruses deploy multiple strategies to subvert host immune defenses. Some of these tactics are mediated by viral gene products acquired by horizontal gene transfer from the corresponding hosts and shaped throughout evolution. The programmed death-1 (PD-1) receptor and its ligands, PD-L1 and PD-L2, play a pivotal role attenuating T-cell responses and regulating immune tolerance. In this study, we report the first functional PD-L1 homolog gene (De2) found in a pathogen. De2, captured by a γ-herpesvirus from its host during co-evolution around 50 million years ago, encodes a cell-surface glycoprotein that interacts with high affinity and stability with host PD-1. We also find that mutations evolved by the viral protein result in a significant loss of its ability to interact in cis with CD80, an interaction that for PD-L1:CD80 has been reported to block PD-1 inhibitory pathways. Furthermore, we demonstrate that the viral protein strongly inhibits T-cell signaling. Our observations suggest that PD-L1 homologs may enable viruses to evade T cell responses, favor their replication, and prevent excessive tissue damage. Altogether, our findings reveal a novel viral immunosuppressive strategy and highlight the importance of the modulation of the PD-1/PD-L1 axis during viral infections.

Evaluation of PD-L1 expression in a large set of gastroenteropancreatic neuroendocrine tumours and correlation with clinicopathological data

BackgroundTargeting programmed death protein 1 (PD-1) or its ligand PD-L1 is a promising therapeutic approach for many types of cancer in which PD-L1 is overexpressed. However, data on PD-L1 expression levels in gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) are limited and contradictory. MethodsWe evaluated PD-L1 expression in 457 archived, formalin-fixed, paraffin-embedded GEP-NEN samples from 175 patients by immunohistochemistry using the highly sensitive monoclonal anti-PD-L1 antibody 73-10. The immunostaining was semiquantitatively evaluated using a 12-point immunoreactivity score (IRS) taking both PD-L1-positive tumour cells and immune cells into account. Tumour samples with an IRS ≥ 3 were considered PD-L1-positive. Results were correlated with clinicopathological data and with the expression of several typical markers and receptors for neuroendocrine tumours. ResultsOf the GEP-NEN samples, 73% were PD-L1-positive. The median IRS value across all samples was 4.0, corresponding to low expression. PD-L1 immunostaining was predominantly localised at the plasma membrane of the tumour cells. Positive correlations were observed between PD-L1 expression and tumour grading or Ki-67 index, between PD-L1 expression and the expression of chromogranin A, and between PD-L1 expression and the expression of each of the five somatostatin receptors. PD-L1 expression was lower in tumours with lymph node metastases at diagnosis than in those without regional metastasis and lower in high-stage than in earlier-stage tumours. No association was noted between PD-L1 expression and patient survival. ConclusionsPD-L1 expression is common in GEP-NENs and increases with malignancy. Therefore, especially in high-grade GEP-NENs, targeting the PD-1/PD-L1 axis could be a promising additional therapeutic strategy.

619O shRNA-mediated PD1 gene knock-down anti-CD19 CAR-T cell therapy for relapsed/refractory b cell malignancies

PD-1 is expressed on CD4+ and CD8+ T lymphocytes,PD-L1 is mainly expressed on tumor cells. The PD-1/PD-L1 binding can inhibit T cell activation. Many studies have proved that blockade of PD-1/ PD-L1 axis is effective to enhance the function of CAR-T cells. However, this strategy has mainly been studied in vitro and the antitumor properties of CAR-T cells that continuously knock down PD-1 in vivo have not been thoroughly investigated.

1150P Progression of advanced non-small cell lung cancer after durable clinical benefit on anti-PD-1/PD-L1 monotherapy: Prolonged post-progression survival and interest of tumor growth rate

Immunotherapy blocking the PD-1/PD-L1 axis has been used as monotherapy for barely a decade in advanced non-small cell lung cancers (aNSCLC). Tumor progression can occur even after durable clinical benefit (DCB), defined as a minimum of 6 month of responsive/stable disease (per RECIST 1.1). It is qualified as oligo-progression (OPD) if occurring in ≤3 lesions. Clinical and radiological data in this situation is still scarce and heterogeneous, but needed to optimize care and understand the underlying biological processes.

The Oncolytic Adenovirus XVir-N-31, in Combination with the Blockade of the PD-1/PD-L1 Axis, Conveys Abscopal Effects in a Humanized Glioblastoma Mouse Model.

Glioblastoma (GBM) is an obligatory lethal brain tumor with a median survival, even with the best standard of care therapy, of less than 20 months. In light of this fact, the evaluation of new GBM treatment approaches such as oncolytic virotherapy (OVT) is urgently needed. Based on our preliminary preclinical data, the YB-1 dependent oncolytic adenovirus (OAV) XVir-N-31 represents a promising therapeutic agent to treat, in particular, therapy resistant GBM. Preclinical studies have shown that XVir-N-31 prolonged the survival of GBM bearing mice. Now using an immunohumanized mouse model, we examined the immunostimulatory effects of XVir-N-31 in comparison to the wildtype adenovirus (Ad-WT). Additionally, we combined OVT with the inhibition of immune checkpoint proteins by using XVir-N-31 in combination with nivolumab, or by using a derivate of XVir-N-31 that expresses a PD-L1 neutralizing antibody. Although in vitro cell killing was higher for Ad-WT, XVir-N-31 induced a much stronger immunogenic cell death that was further elevated by blocking PD-1 or PD-L1. In vivo, an intratumoral injection of XVir-N-31 increased tumor infiltrating lymphocytes (TILs) and NK cells significantly more than Ad-WT not only in the virus-injected tumors, but also in the untreated tumors growing in the contralateral hemisphere. This suggests that for an effective treatment of GBM, immune activating properties by OAVs seem to be of greater importance than their oncolytic capacity. Furthermore, the addition of immune checkpoint inhibition (ICI) to OVT further induced lymphocyte infiltration. Consequently, a significant reduction in contralateral non-virus-injected tumors was only visible if OVT was combined with ICI. This strongly indicates that for an effective eradication of GBM cells that cannot be directly targeted by an intratumoral OV injection, additional ICI therapy is required.

Abstract PO002: Pretreatment immune cell composition and checkpoint ligand expression define the response to immunotherapy in advanced HCC: a study using single-cell sequencing

Abstract The novel combination of atezolizumab/bevacizumab has demonstrated unprecedented response rates in a subgroup of advanced hepatocellular carcinoma (aHCC) patients. In order to understand why only a subset of aHCC patients respond to immunotherapy targeting the PD-1/PD-L1 axis, we subjected pre-treatment tissue biopsies from 31 aHCC patients, with mainly non-viral etiologies, to simultaneous single-cell transcriptome (scRNAseq) and T-cell receptor (scTCRseq) sequencing, providing an integrative view of the tumor-microenvironment of aHCC (n=91 169 cells). The therapeutic targets, PD-1 and PD-L1 are expressed in tumor-infiltrating T-cells versus myeloid cells and tumor cells, respectively. Myeloid cells in tumors responding to immunotherapy (according to mRECIST) express significantly higher levels of PD-L1 (p=0.014) compared to non-responders and this is driven by pro-inflammatory PD-L1 expressing CXCL10+ macrophages, involved in T-cell recruitment. In contrast, non-responding tumors are infiltrated by immature CX3CR1+ macrophages and CCR2+ ‘monocyte-like’ macrophages (p=0.009 and p=0.01, respectively). Interestingly, the composition of tumor-infiltrating T-cells did not differ significantly between patient groups. However, responding tumors were characterized by a more clonal baseline T-cell receptor repertoire (p=0.007). Single-cell T-cell receptor sequencing revealed that this clonality was present in activated, effector T-cells, while non-responders had a higher proportion of non-clonal T-cells (p=0.01) concentrated within naïve and memory-like T-cell phenotypes. In conclusion, this is the first and largest aHCC cohort to correlate single-cell sequencing data with clinical outcomes. Prior to treatment, differences in abundancy and ligand expression in small clusters of immune cells as well as difference in baseline T-cell clonality drive response to checkpoint inhibition in aHCC. Citation Format: Sarah Cappuyns, Gino Philips, Vincent Vandecaveye, Chris Verslype, Eric Van Cutsem, Diether Lambrechts, Jeroen Derkervel. Pretreatment immune cell composition and checkpoint ligand expression define the response to immunotherapy in advanced HCC: a study using single-cell sequencing [abstract]. In: Proceedings of the AACR Special Conference: Advances in the Pathogenesis and Molecular Therapies of Liver Cancer; 2022 May 5-8; Boston, MA. Philadelphia (PA): AACR; Clin Cancer Res 2022;28(17_Suppl):Abstract nr PO002.

Abstract PR03: Pretreatment immune cell composition and checkpoint ligand expression define the response to immunotherapy in advanced HCC: a study using single-cell sequencing

Abstract The novel combination of atezolizumab/bevacizumab has demonstrated unprecedented response rates in a subgroup of advanced hepatocellular carcinoma (aHCC) patients. In order to understand why only a subset of aHCC patients respond to immunotherapy targeting the PD-1/PD-L1 axis, we subjected pre-treatment tissue biopsies from 31 aHCC patients, with mainly non-viral etiologies, to simultaneous single-cell transcriptome (scRNAseq) and T-cell receptor (scTCRseq) sequencing, providing an integrative view of the tumor-microenvironment of aHCC (n=91 169 cells). The therapeutic targets, PD-1 and PD-L1 are expressed in tumor-infiltrating T- cells versus myeloid cells and tumor cells, respectively. Myeloid cells in tumors responding to immunotherapy (according to mRECIST) express significantly higher levels of PD-L1 (p=0.014) compared to non-responders and this is driven by pro-inflammatory PD-L1 expressing CXCL10+ macrophages, involved in T-cell recruitment. In contrast, non-responding tumors are infiltrated by immature CX3CR1+ macrophages and CCR2+ ‘monocyte-like’ macrophages (p=0.009 and p=0.01, respectively). Interestingly, the composition of tumor-infiltrating T-cells did not differ significantly between patient groups. However, responding tumors were characterized by a more clonal baseline T-cell receptor repertoire (p=0.007). Single-cell T-cell receptor sequencing revealed that this clonality was present in activated, effector T-cells, while non-responders had a higher proportion of non-clonal T-cells (p=0.01) concentrated within naïve and memory-like T-cell phenotypes. In conclusion, this is the first and largest aHCC cohort to correlate single-cell sequencing data with clinical outcomes. Prior to treatment, differences in abundancy and ligand expression in small clusters of immune cells as well as difference in baseline T-cell clonality drive response to checkpoint inhibition in aHCC. Citation Format: Sarah Cappuyns, Gino Philips, Vincent Vandecaveye, Chris Verslype, Eric Van Cutsem, Diether Lambrechts, Jeroen Derkervel. Pretreatment immune cell composition and checkpoint ligand expression define the response to immunotherapy in advanced HCC: a study using single-cell sequencing [abstract]. In: Proceedings of the AACR Special Conference: Advances in the Pathogenesis and Molecular Therapies of Liver Cancer; 2022 May 5-8; Boston, MA. Philadelphia (PA): AACR; Clin Cancer Res 2022;28(17_Suppl):Abstract nr PR03.

EP08.01-100 Unlocking Primary Resistance to Checkpoint Inhibitors in Non-small Cell Lung Cancer by Metagenomic and Metabolomic

Immune checkpoint inhibitors (ICIs) targeting the PD-1/PD-L1 axis generate sustained therapeutic responses in a sizable minority of advanced non-small-cell lung cancer (NSCLC) patients. Several studies have shown that abnormal gut microbiome composition which may influence antitumor immune responses via metabolome led to primary resistance to ICIs, and therapeutic responses can be improved via its modulation. But functions of antitumor gut microbiome strains and metabolomic characteristics for advanced NSCLC have not been fully elucidated.

Defining the Immune Checkpoint Landscape in Human Colorectal Cancer Highlights the Relevance of the TIGIT/CD155 Axis for Optimizing Immunotherapy

Simple SummaryOne promising avenue for the treatment of colorectal cancer is the reinvigoration of pre-existing anti-tumor T-cell responses by overcoming inhibitions that arise from the T-cell expression of immune checkpoints. This study aims to perform an in-depth assessment of human colorectal cancer, the immune checkpoint landscape in tumor-infiltrating T cells and their respective ligands in tumor cells and myeloid cells; this is achieved using multiparametric flow cytometry on dissociated fresh tumors from 40 patients and in situ immunohistochemistry. Our results highlight the strong expression of TIGIT and its ligand, CD155, in tumors, suggesting the role of the TIGIT/CD155 axis in colorectal cancer. Moreover, unsupervised clustering allowed us to identify two distinct subgroups of colorectal cancer patients according to the co-expression of several immune checkpoints on T-lymphocyte subpopulations. Altogether, our findings support the development of colorectal cancer immunotherapies targeting TIGIT, which could be used in combination immune checkpoint therapy in colorectal cancer.While immune checkpoint (IC) therapies, particularly those targeting the PD-1/PD-L1 axis, have revolutionized the treatment of melanoma and several other cancers, their effect remains very limited in colorectal cancer (CRC). To define a comprehensive landscape of ICs in the human CRC tumor microenvironment (TME), we evaluated, using multiparametric flow cytometry, their ex vivo expression via tumor-infiltrating lymphocytes (TILs) (n = 40 CRCs) as well as that of their respective ligands on tumor and myeloid cells (n = 29). Supervised flow cytometry analyses showed that (i) most CD3+ TILs expressed PD-1 and TIGIT and, to a lesser extent, Tim-3, Lag3 and NKG2A, and (ii) EpCAM+ tumor cells and CD11b+ myeloid cells differed in their IC ligand expression profile, with a strikingly high expression of CD155 by tumor cells. An in situ analysis of IC and their ligands using immunohistochemistry on paraffin sections of CRC confirmed the overexpression of TIGIT and its ligand, CD155, in the TME. Most interestingly, an unsupervised clustering analysis of IC co-expression on CD4+ and CD8+ TILs identified two tumor subgroups, named IChigh and IClow. Altogether, our findings highlight the TIGIT/CD155 axis as a potential target that could be used in combination IC therapy in CRC.

Computational design of PD-L1 small molecule inhibitors for cancer therapy.

Drug repurposing opens new avenues in cancer therapy. Drug repurposing, or finding new uses for existing drugs, can substantially reduce drug discovery time and costs. Cheminformatics, genetics, and systems biology advances enable repositioning drugs. Clinical usage of PD-1/PD-L1 blocking has been approved because of its efficacy in improving prognosis in select groups. The PD-1/PD-L1 axis was considered to represent a mechanism for tumour evasion of host tumour antigen-specific T-cell immunity in early preclinical research. The expression of PD-L1 in cancer cells causes T lymphocytes to become exhausted by transmitting a co-inhibitory signal. A better understanding of how PD-L1 is regulated in cancer cells could lead to new therapeutic options. In this view, the study was aimed to repurpose the existing FDA-approved drugs as a potential PD-L1 inhibitor through e-Pharmacophore modelling, molecular docking and dynamic simulation. e-Pharmacophore screening retrieved 324 FDA-approved medications with the fitness score ≥ 1. The top 10-docked FDA candidates were compared with IN-35 (Clinical trial candidate) for its interaction pattern with critical amino acid residues. Mirabegron and Indacaterol exhibited a greater affinity for PD-L1 with docking scores of - 9.213kcalmol-1 and - 8.023kcalmol-1, respectively. Mirabegron retain interactions at all three major hotspots in the PD-L1 dimer interface similar to IN-35. MM-GBSA analyses indicated that Mirabegron uses less energy to create a more stable complex and retains all of the inhibitor's positive interactions found in clinical trial ligand IN-35. Molecular dynamics simulation analysis of the Mirabegron complex showed a similar pattern of deviation in correlation with IN-35, and it retains the interaction with the active key amino acids throughout the simulation time. Our present study has shown Mirabegron as a powerful inhibitor of PD-L1 expression in cancer cells using a drug-repurposing screen.