Co-inhibitory Immune Checkpoint Research Articles

Immune Checkpoints in Endometriosis-A New Insight in the Pathogenesis.

Endometriosis (EMS) is an oestrogen-dependent, chronic disease affecting women of a reproductive age. One of the important factors involved in the development of this disease is the complex disorders associated with the functioning of the immune system. Recent evidence has shown that EMS development is associated with changes in systemic and local immunity, including functional disturbances of effector and antigen-presenting cells. One of the reasons for immune imbalance can be the improper expression of immune checkpoints (ICPs). ICPs and their ligands are responsible for maintaining self-tolerance and the modulation of the initiation, duration, and magnitude of the immune response of effector cells in normal tissues to avoid tissue damage. Considering the complex nature of co-stimulatory or co-inhibitory ICPs and the signalling between effector cells and APCs, we hypothesise that changes in cells' activity caused by ICPs may lead to serious immune system disturbances in patients with endometriosis. Moreover, both upregulation and downregulation in the expression of ICPs may be implicated in this process, including the reduced activity of effector cells against endometrial implants and disturbances in the antigen-presenting process. In this narrative review, we discuss, for the first time, key findings from the emerging literature, describing the associations between ICPs and their possible implication in the pathogenesis of endometriosis.

Targeting Histone 3 Variants Epigenetic Landscape and Inhibitory Immune Checkpoints: An Option for Paediatric Brain Tumours Therapy.

Despite little progress in survival rates with regular therapies, which do not provide complete care for curing pediatric brain tumors (PBTs), there is an urgent need for novel strategies to overcome the toxic effects of conventional therapies to treat PBTs. The co-inhibitory immune checkpoint molecules, e.g., CTLA-4, PD-1/PD-L1, etc., and epigenetic alterations in histone variants, e.g., H3K27me3 that help in immune evasion at tumor microenvironment have not gained much attention in PBTs treatment. However, key epigenetic mechanistic alterations, such as acetylation, methylation, phosphorylation, sumoylation, poly (ADP)-ribosylation, and ubiquitination in histone protein, are greatly acknowledged. The crucial checkpoints in pediatric brain tumors are cytotoxic T lymphocyte antigen-4 (CTLA-4), programmed cell death protein-1 (PD-1) and programmed death-ligand 1 (PDL1), OX-2 membrane glycoprotein (CD200), and indoleamine 2,3-dioxygenase (IDO). This review covers the state of knowledge on the role of multiple co-inhibitory immunological checkpoint proteins and histone epigenetic alterations in different cancers. We further discuss the processes behind these checkpoints, cell signalling, the current scenario of clinical and preclinical research and potential futuristic opportunities for immunotherapies in the treatment of pediatric brain tumors. Conclusively, this article further discusses the possibilities of these interventions to be used for better therapy options.

Development of small molecule drugs targeting immune checkpoints.

Immune checkpoint inhibitors (ICIs) are used to relieve and refuel anti-tumor immunity by blocking the interaction, transcription, and translation of co-inhibitory immune checkpoints or degrading co-inhibitory immune checkpoints. Thousands of small molecule drugs or biological materials, especially antibody-based ICIs, are actively being studied and antibodies are currently widely used. Limitations, such as anti-tumor efficacy, poor membrane permeability, and unneglected tolerance issues of antibody-based ICIs, remain evident but are thought to be overcome by small molecule drugs. Recent structural studies have broadened the scope of candidate immune checkpoint molecules, as well as innovative chemical inhibitors. By way of comparison, small molecule drug-based ICIs represent superior oral bioavailability and favorable pharmacokinetic features. Several ongoing clinical trials are exploring the synergetic effect of ICIs and other therapeutic strategies based on multiple ICI functions, including immune regulation, anti-angiogenesis, and cell cycle regulation. In this review we summarized the current progression of small molecule ICIs and the mechanism underlying immune checkpoint proteins, which will lay the foundation for further exploration.

GITR and TIGIT immunotherapy provokes divergent multicellular responses in the tumor microenvironment of gastrointestinal cancers

BackgroundUnderstanding the mechanistic effects of novel immunotherapy agents is critical to improving their successful clinical translation. These effects need to be studied in preclinical models that maintain the heterogenous tumor microenvironment (TME) and dysfunctional cell states found in a patient’s tumor. We investigated immunotherapy perturbations targeting co-stimulatory molecule GITR and co-inhibitory immune checkpoint TIGIT in a patient-derived ex vivo system that maintains the TME in its near-native state. Leveraging single-cell genomics, we identified cell type-specific transcriptional reprogramming in response to immunotherapy perturbations.MethodsWe generated ex vivo tumor slice cultures from fresh surgical resections of gastric and colon cancer and treated them with GITR agonist or TIGIT antagonist antibodies. We applied paired single-cell RNA and TCR sequencing to the original surgical resections, control, and treated ex vivo tumor slice cultures. We additionally confirmed target expression using multiplex immunofluorescence and validated our findings with RNA in situ hybridization.ResultsWe confirmed that tumor slice cultures maintained the cell types, transcriptional cell states and proportions of the original surgical resection. The GITR agonist was limited to increasing effector gene expression only in cytotoxic CD8 T cells. Dysfunctional exhausted CD8 T cells did not respond to GITR agonist. In contrast, the TIGIT antagonist increased TCR signaling and activated both cytotoxic and dysfunctional CD8 T cells. This included cells corresponding to TCR clonotypes with features indicative of potential tumor antigen reactivity. The TIGIT antagonist also activated T follicular helper-like cells and dendritic cells, and reduced markers of immunosuppression in regulatory T cells.ConclusionsWe identified novel cellular mechanisms of action of GITR and TIGIT immunotherapy in the patients’ TME. Unlike the GITR agonist that generated a limited transcriptional response, TIGIT antagonist orchestrated a multicellular response involving CD8 T cells, T follicular helper-like cells, dendritic cells, and regulatory T cells. Our experimental strategy combining single-cell genomics with preclinical models can successfully identify mechanisms of action of novel immunotherapy agents. Understanding the cellular and transcriptional mechanisms of response or resistance will aid in prioritization of targets and their clinical translation.

The co-inhibitory immune checkpoint proteins B7-H1(PD-L1) and B7-H4 in high grade glioma: From bench to bedside

Co-inhibitory immune checkpoints play a crucial role in tumor progression, and PD-1/PD-L1 inhibitor has been a breakthrough for treating multiple refractory tumors in last decade. Nevertheless, results of several phase III clinical trials of PD-1/PD-L1 inhibitor are unsatisfactory in high grade gliomas recently. This article reviews the promising biomarkers which can predict the efficacy of PD-1/PD-L1 blockade immunotherapy and current status of emerging strategies involving PD-1/PD-L1 inhibitors, especially the combination treatment and neoadjuvant PD-1 therapy in gliomas. In addition, B7-H4, one of the most promising immune checkpoints, is also briefly reviewed here for its clinical significance, regulatory mechanism and developing immunotherapeutic strategies in pre-clinical glioma models.

Charting new frontiers: Co-inhibitory immune checkpoint proteins in therapeutics, biomarkers, and drug delivery systems in cancer care

Cancer remains a major health concern globally. Immune checkpoint inhibitors (ICIs) target co-inhibitory immune checkpoint molecules and have received approval for treating malignancies like melanoma and non-small cell lung cancer. While CTLA-4 and PD-1/PD-L1 are extensively researched, additional targets such as LAG-3, TIGIT, TIM-3, and VISTA have also demonstrated effective in cancer therapy. Combination treatments, which pair ICIs with interventions such as radiation or chemotherapy, amplify therapeutic outcomes. However, ICIs can lead to diverse side effects, and their varies across patients and cancers. Hence, identifying predictive biomarkers to guide therapy is essential. Notably, expression levels of molecules like PD-1, CTLA-4, and LAG-3 have been linked to tumor progression and ICI therapy responsiveness. Recent advancements in drug delivery systems (DDSs) further enhance ICI therapy efficacy. This review explores predominant DDSs for ICI delivery, such as hydrogel, microparticle, and nanoparticle, which offer improved therapeutic effects and reduced toxicity. In summary, we discuss the future of immune therapy focusing on co-inhibitory checkpoint molecules, pinpoint challenges, and suggest avenues for developing efficient, safer DDSs for ICI transport.

1150P Transforming growth factor-beta-1 and soluble co-inhibitory immune checkpoints as putative drivers of immune suppression in advanced basal cell carcinoma

1150P Transforming growth factor-beta-1 and soluble co-inhibitory immune checkpoints as putative drivers of immune suppression in advanced basal cell carcinoma

Developments in targeted therapy & immunotherapy-how non-small cell lung cancer management will change in the next decade: a narrative review.

The adoption of targeted therapy and immunotherapy has revolutionised the treatment landscape of non-small cell lung cancer. For early staged disease, incorporation of targeted therapy and immunotherapy has recently been demonstrated to reduce recurrence. Development of targeted therapies in advanced lung cancer is driven by advanced genomic sequencing techniques, better understanding of drug resistance mechanisms, and improved drug designs. The list of targetable molecular alteration is continuously expanding, and next generation molecular therapies have shown promise in circumventing drug resistance. Lung cancer patients may achieve durable disease control with immune checkpoint inhibitors however most patients develop immunotherapy resistance. A wide spectrum of resistance mechanisms, ranging from impaired T-cell activation, presence of coinhibitory immune checkpoints, to immunosuppressive tumour microenvironment, have been proposed. A multitude of novel immunotherapy strategies are under development to target such resistance mechanisms. This review aims to provide a succinct overview in the latest development in targeted therapy and immunotherapy for NSCLC management. We searched all original papers and reviews on targeted therapy and immunotherapy in non-small cell lung cancer (NSCLC) using PubMed in June 2022. Search terms included "non-small cell lung cancer", "targeted therapy", "immunotherapy", "EGFR", "ALK", "ROS1", "BRAF V600E", "MET", "RET", "KRAS", "HER2", "ERBB2", "NRG1", "immune checkpoint", "PD-1", "PD-L1", "CTLA4", "TIGIT", "VEGF", "cancer vaccine", "cellular therapy", "tumour microenvironment", "cytokine", and "gut microbiota". We first discuss the incorporation of targeted therapy and immunotherapy in early staged NSCLC. This includes the latest clinical data that led to the approval of neoadjuvant immunotherapy, adjuvant immunotherapy and adjuvant targeted therapy for early staged NSCLC. The second section focuses on targeted therapy in metastatic NSCLC. The list of targetable alteration now includes but is not limited to EGFR, ALK, ROS1, BRAF V600E, MET exon 14 skipping, RET, KRAS G12C, HER2 and NRG1. Potential drug resistance mechanisms and novel therapeutics under development are also discussed. The third section on immunotherapy in metastatic NSCLC, covers immunotherapy that are currently approved [anti-PD-(L)1 and anti-CTLA4], and agents that are under active research (e.g., anti-TIGIT, cancer vaccine, cellular therapy, cytokine and other TME modulating agents). This review encompasses the latest updates in targeted therapy and immunotherapy in lung cancer management and discusses the future direction in the field.

Transforming growth factor-b1 and soluble co-inhibitory immune checkpoints as putative drivers of immune suppression in advanced basal cell carcinoma.

9567 Background: BCC rarely metastasizes and the mortality rate is low; however, the disease is associated with substantial morbidity. Transforming growth factor-b1 (TGF-b1) is a key player in cell proliferation, differentiation, apoptosis, and immune regulation. TGF-b1 is associated with immunosuppression and resistance to immunotherapeutic drugs. Immune checkpoint proteins (ICMs) maintain self-tolerance and modulate the immune responses of effector cells. The current study compared the levels and possible associations between systemic soluble ICMs (sICMs) and a group of humoral modulators of immune suppressor cells in a cohort of patients with advanced basal cell carcinoma (BCC, n = 40) and a group of healthy control subjects (n = 20). Methods: We measured sICMs and immunosuppressive humoral modulators by using multiplex bead array or ELISA procedures, with plasma as the matrix. The sICMs comprised seven co-inhibitory (CTLA-4, BTLA, LAG-3, PD-1, PDL-1, PDL-2, and TIM-3) and eight co-stimulatory (CD27, CD28, CD40, CD80, CD86, GITR, GITRL, and ICOS) proteins, as well as the two dual-active sICPs, HVEM and TLR2. The seven humoral modulators of immunosuppressor cells included arginase 1, fibroblast activation protein (FAP), RANTES (Regulated upon Activation Normal T Cell Expressed and Presumably Secreted) also known as CCL5, interleukin-10 (IL-10), TGF-b1, and the M2-type macrophage biomarkers, soluble CD163 (sCD163) and sCD206. Ethics approval was granted by The Research Ethics Committee, Faculty of Health Sciences, University of Pretoria (Ethics Committee Approval Numbers 356/2020. Results: The plasma levels of six co-inhibitory sICPs, sCTLA-4, sLAG-3, sPD-1, sPD-L1, and sTIM-3 and sPD-L2 were significantly elevated in the cohort of BCC patients ( p< 0.001- p< 0.00001), while that of sBTLA was significantly decreased ( p< 0.006). Of the co-stimulatory sICPs, sCD27 was significantly increased ( p <0.0002) in the cohort of BCC patients, with the levels of the others essentially comparable with those of the control patients; of the dual active sICPs, sHVEM, sTLR2 was significantly elevated ( p< 0.00001) and TLR2 comparable with the control group. Although the plasma levels of the seven modulators of immune suppressor function were not significantly different between the BCC and control groups, correlation heat maps revealed selective, strong associations of TGF-b1 with seven co-stimulatory (z = 0.618468-0.768131) and 4 co-inhibitory (z = 0.674040-0.808365) sICPs, as well as with sTLR2 (z = 0.696431). Conclusions: Notwithstanding the association of BCC with selective elevations in the levels of a large group of co-inhibitory sICPs, our novel findings also imply the probable involvement of TGF-b1 in driving immunosuppression in this malignancy, possibly via activation of regulatory T cells.

Abstract 5712: Anti-TIGIT antibody tiragolumab leverages myeloid cells and regulatory T cells to improve PD-L1 checkpoint blockade

Abstract Background: TIGIT is a co-inhibitory receptor and immune checkpoint associated with T cell and natural killer (NK) cell dysfunction in cancer. Tiragolumab is an anti-TIGIT antibody with an active IgG1/kappa Fc. In a randomized double-blind phase 2 clinical trial in non-small cell lung cancer (NSCLC), tiragolumab + atezolizumab (anti-PD-L1) combination treatment demonstrated significant improvement relative to atezolizumab alone. However, the mechanisms underlying the efficacy of this combination are not well understood. Methods: In CITYSCAPE (phase 2, NCT03563716), chemotherapy-naïve patients with locally advanced/metastatic NSCLC received either placebo + 1200 mg atezolizumab or 600 mg tiragolumab + 1200 mg atezolizumab q3w IV. We collected tumor pretreatment samples and serum samples (baseline and on-treatment) from patients enrolled in the trial, which were subject to bulk RNA-seq and proteomics, respectively. In the mouse tumor model, BALB/c mice were implanted with syngeneic CT26 tumors. After tumor establishment, mice were randomized by tumor volume and then treated with control IgG2a, anti-PD-L1, anti-TIGIT IgG2a-LALAPG (Fc-inactive) ± anti-PD-L1, anti-TIGIT IgG2b ± anti-PD-L1, or anti-TIGIT IgG2a ± anti-PD-L1. Three days after treatment, CD45+ immune cells were collected from the peripheral blood and tumor from selected treatment groups and underwent single cell RNA sequencing or flow cytometry profiling. Tumor growth was also monitored to determine efficacy. Results: Here, we show that tiragolumab functions as both a conventional checkpoint inhibitor and, via Fc gamma receptor engagement, as a modulator of immunosuppressive myeloid cells and T regulatory (Treg) cells. Gene expression analysis of patient tumor samples revealed high levels of these cell subsets, were instead associated with treatment benefit in the tiragolumab + atezolizumab arm but not atezolizumab arm. Analysis of patient serum proteins suggested an association of myeloid cell activation with clinical benefit mediated by the combination therapy. In mouse tumor models, treatment with anti-PD-L1 + anti-TIGIT IgG2a (but not anti-TIGIT IgG2b or Fc-silent anti-TIGIT) led to effective tumor control in mice, suggesting a pivotal role for activating Fc receptors. Phenotypic profiling by single cell RNAseq and flow cytometry revealed that Fc-active anti-TIGIT remodels the tumor microenvironment, most prominently by inducing antigen presentation machinery in myeloid cells, counteracting of anti-PDL1-enforced CD8+ T cell exhaustion, and reducing Treg suppressive capacity. Conclusions: These findings reveal that FcR engagement is one of several distinct mechanisms by which tiragolumab unleashes antitumor immune responses, and inform further clinical development of anti-TIGIT therapies. Citation Format: Namrata S. Patil, Shyam Srivats, Yoonha Choi, Xiangnan Guan, Barzin Nabet, Lisa McGinnis, Eugene Chiang, Alexis Dunkle, Bill O’Gorman, Patrick S. Chang, Ruozhen Hu, John Silva, Joy Han, Amelia Au-Yeung, Chikara Takahashi, Nandini Molden, Pallavi Daggumati, Wendy Connolly, Melissa Johnson, Delvys Rodriguez Abreu, Byoung Chul Cho, Antoine Italiano, Ignacio Gil-Bazo, Enriqueta Felip, Ira Mellman, Raymond Meng, Sanjeev Mariathasan, Robert Johnston, David S. Shames. Anti-TIGIT antibody tiragolumab leverages myeloid cells and regulatory T cells to improve PD-L1 checkpoint blockade. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5712.

What do we know about co-stimulatory and co-inhibitory immune checkpoint signals in ankylosing spondylitis?

Ankylosing Spondylitis is the main entity of a family of inflammatory diseases affecting many musculoskeletal (sacroiliac joints, spine, peripheral joints) and extra-musculoskeletal sites, termed spondyloarthritis. While it is debated whether disease onset is primarily driven by autoimmune or autoinflammatory processes, what is certain is that both innate and adaptive immune responses orchestrate local and systemic inflammation, which leads to chronic pain and immobility. Immune checkpoint signals are one key player for keeping the immune system in check and in balance, but their role in disease pathogenesis is still rather elusive. Therefore, we ran a MEDLINE search utilizing the PubMed platform for a variety of immune checkpoint signals in regard to ankylosing spondylitis. In this review, we summarise the experimental and genetic data available and evaluate the relevance of immune checkpoint signalling in the pathogenesis of ankylosing spondylitis. Markers such as PD-1 and CTLA-4 have been extensively studied and facilitate the concept of an impaired negative immune regulation in ankylosing spondylitis. Other markers are either neglected completely or insufficiently examined, and the data is conflicting. Still, some of those markers remain interesting targets to decipher the pathogenesis of ankylosing spondylitis and to develop new treatment strategies.

PRRSV-1 induced lung lesion is associated with an imbalance between costimulatory and coinhibitory immune checkpoints.

Porcine reproductive and respiratory syndrome virus (PRRSV) induces a dysregulation on the innate and adaptive immune responses. T-cell activation requires a proper interaction and precise balance between costimulatory and coinhibitory molecules, commonly known as immune checkpoints. This study aims to evaluate the expression of immune checkpoints in lung and tracheobronchial lymph node from piglets infected with two PRRSV-1 strains of different virulence during the early stage of infection. Seventy 4-week-old piglets were grouped into three experimental groups: (i) control, (ii) 3249-infected group (low virulent strain), and (iii) Lena-infected group (virulent strain) and were euthanized at 1, 3, 6, 8, and 13 days post-infection (dpi). Lung and tracheobronchial lymph node were collected to evaluate histopathological findings, PRRSV viral load and mRNA expression of costimulatory (CD28, CD226, TNFRSF9, SELL, ICOS, and CD40) and coinhibitory (CTLA4, TIGIT, PD1/PDL1, TIM3, LAG3, and IDO1) molecules through RT-qPCR. Our findings highlight a mild increase of costimulatory molecules together with an earlier and stronger up-regulation of coinhibitory molecules in both organs from PRRSV-1-infected animals, especially in the lung from virulent Lena-infected animals. The simultaneous expression of coinhibitory immune checkpoints could work in synergy to control and limit the inflammation-induced tissue damage. Further studies should be addressed to determine the role of these molecules in later stages of PRRSV infection.

When three is not a crowd: trispecific antibodies for enhanced cancer immunotherapy.

Despite the clinical success of the first bispecific antibody approved by the FDA against B cell malignancies (blinatumomab), many obstacles remain such as dosing, treatment resistance, and modest efficacy in solid tumors. To overcome these limitations, considerable efforts have been dedicated to the development of multispecific antibodies, opening up new avenues to address both the complex biology of cancer and the onset of anti-tumoral immune responses. Simultaneous targeting of two tumor-associated antigens is presumed to enhance cancer cell selectivity and reduce immune escape. Co-engagement of CD3, along with agonists of co-stimulatory molecules or antagonists of co-inhibitory immune checkpoint receptors in a single molecule, may revert T cell exhaustion. Similarly, targeting of two activating receptors in NK cells may improve their cytotoxic potency. And these are only examples of the potential of antibody-based molecular entities engaging three (or more) relevant targets. From the perspective of health care costs, multispecific antibodies are appealing, since a similar (or superior) therapeutic effect could be obtained with a single therapeutic agent as with a combination of different monoclonal antibodies. Despite challenges in production, multispecific antibodies are endowed with unprecedented properties, which may render them more potent biologics for cancer therapy.

KLRG1 Depletion Is a Novel Therapeutic Strategy for Patients with Mature T and NK/T-Cell Lymphomas

Outcomes for patients with aggressive T-cell lymphomas (TCLs) remain dismal. Killer cell lectin-like receptor G1 (KLRG1) is a co-inhibitory immune checkpoint receptor expressed on late differentiated CD8+ T effector memory (TEM) and TEMRA cells. Monotherapy with KLRG1 neutralizing antibodiesextended survival in solid tumor models. Here, we report the therapeutic potential of a novel and distinct strategy characterized by depletion of KLRG1+ malignant cells in hematologic malignancies and specifically in TCLs. We defined the molecular epidemiology of KLRG1 by determining tumor cell-specific RNA and protein expression on T cell subsets from 8 healthy donors, 26 TCL lines, 15 patient-derived xenografts (PDXs), and 165 tumor and blood specimens representing various subtypes of T and NK/TCLs. Microarray andRNA-seqdata demonstrated highertranscript levels of KLRG1 in patients with T-LGLL and PDXs of T-PLL and HSTCL relative to other subtypes, which were corroborated by protein expression. We quantified tumor cell-specific protein expression of KLRG1 by IHC by generating H scores (% of KLRG1+ tumor cells × measure of staining intensity) ranging from 0-300 across 141 primary TCL biopsies. PTCL-NOS and AITL had heterogeneous KLRG1 expression, whereas ALCL, CTCL, and EATL demonstrated none. The majority of patients with T-PLL (median 180), δ/γ TCLs (median 140), and NK/TCLs (median 100) exhibited higher H scores relative to other subtypes. Up to 99% of the CD3+/CD8+/CD57+ and up to 97% of the CD3-/CD56+/CD57+/CD16+/CD94+ leukemic cells in the blood of patients with T-LGLL (n=12) and CLPD-NK (n=12) respectively expressed KLRG1 protein (Fig.1). None of the TCL cell lines expressed surface KLRG1. Therefore, SMZ1 cells (TP63 rearranged PTCL-NOS line) were stably transduced to express KLRG1. We utilized two human KLRG1 binding antibodies, 13F12F2 (a commercial mIgG2a Ab) and mAb208 (a humanized afucosylated mIgG2a Ab) for in vitro and in vivo studies. Antibody binding capacity assays confirmed a higher number of KLRG1 receptors per cell on SMZ1 KLRG1+ (175,800), HSTCL (23,586), and CD8+ T cells (16,326) compared with B-cell lymphoma cells (242). Competition binding assays demonstrated that concentrations of 0.1 ug/ml of mAb208 saturated receptors on SMZ1 KLRG1+ cells. mAb208 induced a 2-5-fold dose-dependent increase in antibody-dependent cellular cytotoxicity (ADCC), antibody-dependent cellular phagocytosis (ADCP), and complement-dependent cytotoxicity (CDC), but not apoptosis of SMZ1 KLRG1+ cells relative to SMZ1 KLRG1- WT and isotype control (CTL). This was exhibited across a variety of human and murine effectors such as human PBMCs, human and murine macrophages, and human and murine complements. Reporter-based murine FcγRIV ADCC bioassay demonstrated a dose-dependent 2-6 fold induction of bioluminescence by mAb208 in SMZ1 KLRG1+ cells relative to WT (p=<0.0001). In 4/4 tested T-LGLL patient samples, mAb208 induced ADCC of CD8+/CD57+ LGLs with autologous PBMCs (p=0.03) relative to CTL. Finally, mAb208 induced selective ADCC of KLRG1+ CD8+ TEM and TEMRA cells while sparing KLRG1- naive and central memory T cells in 3 healthy donors (p=0.06). Duvelisib (Duv), a dual PI3K-δ/γ inhibitor (PI3Ki), has demonstrated a high ORR of 50% in phase II trials in TCLs and its ability to reprogram macrophages to an M1 phenotype in TCL PDXs. Thus, we hypothesized that the combination of PI3Ki with anti-KLRG1 mAbs would enhance the clearance of apoptotic and opsonized KLRG1+ TCL cells by proinflammatory macrophages in several PTCL subtypes. We tested this combination in vivo using SMZ1 KLRG1+ subcutaneous xenografts in NSG mice. After 17 days of treatment, combination (mAb208 + Duv)- treated mice had a marked reduction in their mean tumor volumes (159 mm3) relative to mAb208 (1003 mm3 ; p=0.03), Duv (465.6 mm3 ; p=0.03) and CTL (2104 mm3 ; p=0.03) mice resulting in prolonged survival (Fig. 2). Studies in PDX models of T-PLL and HSTCL with varying levels of KLRG1 expression (30% and 80% respectively) have been initiated and will be reported at the meeting. Selective depletion of tumor cells with an anti-KLRG1 depleting mAb in specific subtypes of TCLs, T-LGLL, and CLPD-NK is effective in vitro and in vivo, and its combination with Duv has marked activity in an aggressive PTCL-NOS xenograft model. A multicenter phase I/II trial of the KLRG1 depleting antibody ABC008 (Abcuro) in patients with R/R T-LGLL has been initiated. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Cancer cell intrinsic TIM-3 induces glioblastoma progression

Glioblastoma (GBM) is identified to share common signal pathways between glioma and immune cells. Here, we find that Tcell immunoglobulin domain and mucin domain protein 3 (TIM-3) is one of the most common co-inhibitory immune checkpoints in GBM shared by tumor and non-tumor cells. Glioma cell-intrinsic TIM-3 is involved in not only regulating malignant behaviors of glioma cells but also inducing macrophage migration and transition to anti-inflammatory/pro-tumorigenic phenotype by a TIM-3/interleukin 6 (IL6) signal. In mechanism, as one of the major regulators of IL6, TIM-3 regulates its expression through activating NF-κB. Blocking this feedback loop by Tocilizumab, an IL6R inhibitor, inhibited the above effects and repressed the tumorigenicity of GBM invivo. Our work identifies glioma cell-intrinsic functions of TIM-3/IL6 signal mediating the crosstalk feedback loop between glioma cells and tumor-associated macrophages (TAMs). Blocking this feedback loop may provide a novel therapeutic strategy for GBM.

Glioma Shapes Blood-Brain Barrier Integrity and Remodels the Tumor Microenvironment: Links with Clinical Features and Prognosis.

Background: The presence of the blood–brain barrier (BBB) uniquely distinguishes the brain from other organs, and various brain pathologies, including cancer, can disrupt or breach the BBB. The specific implications of BBB alterations in glioma have not been sufficiently clarified. Methods: In this study, statistical analysis of the TCGA pan-glioma dataset and four other validation cohorts was used to investigate the infiltration of BBB constituent cells (endothelial cells, pericytes and astrocytes) in the glioma tumor microenvironment (TME). Results: We found that the infiltration proportions of the three BBB constituent cell types were highly collinear, which implied alteration of the BBB. Hence, we developed an index, the BBB score, which is calculated based on the infiltration proportion of BBB constituent cells. Furthermore, we observed that patients with higher BBB scores were more likely to be diagnosed with more malignant entities in the TCGA database according to significant molecular features, such as IDH mutation status and 1p/19q deletion. The BBB score was also strikingly positively correlated with WHO grade in other cohorts. More importantly, a higher BBB score correlated with shorter survival time and unfavorable prognosis in glioma patients. Finally, we showed that TME-related pathways may regulate BBB alterations and that coinhibitory immune checkpoints were enriched in samples with higher BBB scores. Conclusions: We showed that TME-related pathways may regulate BBB alterations and that coinhibitory immune checkpoints were enriched in samples with higher BBB scores. Assessing BBB alterations may help elucidate the complex role of the glioma TME and suggest new combination treatment strategies.

870P Systemic levels of the soluble co-inhibitory and co-stimulatory immune checkpoint molecules in basal cell carcinoma

Although co-inhibitory immune checkpoint proteins are primarily involved in promoting inhibitory cell-cell interactions in adaptive immunity, especially tumor immunity, the soluble cell-free variants of these molecules are also detectable in the circulation of cancer patients where they retain immunosuppressive activity. Nevertheless, little is known about the systemic levels of these soluble co-inhibitory immune checkpoints in patients with various subtypes of basal cell carcinoma (BCC), which is the most invasive and treatment-resistant type of this most commonly occurring malignancy.

1194TiP AdvanTIG-205: Phase II trial of ociperlimab (OCI) + tislelizumab (TIS) + chemotherapy (chemo) in first line (1L) treatment of patients (pts) with locally advanced (LA), unresectable, or metastatic non-small cell lung cancer (mNSCLC)

T-cell immunoreceptor with immunoglobulin and immunoreceptor tyrosine-based inhibitory motif domains (TIGIT) is a co-inhibitory immune checkpoint receptor upregulated on T cells and natural killer cells in multiple solid tumors. Early phase clinical trials have shown antitumor activity of anti-TIGIT monoclonal antibodies (mAbs) + anti-programmed cell death protein 1 (PD-1) mAbs in pts with mNSCLC. OCI is a humanized mAb designed to bind to Fc-intact TIGIT with high affinity and specificity. In China, TIS, an anti-PD-1 mAb, is approved for 2/3L treatment of LA/mNSCLC, and 1L treatment of NSCLC with chemo.

Abstract 5080: Age- and pregnancy-related impact on soluble immune checkpoint protein profiles in mice as analyzed by a novel multiplex immunoassay

Abstract Immune checkpoint proteins are key regulators of the immune system and drug targets of cancer immunotherapy. There is extensive literature on the use of various types of mouse models for biomarker discovery and drug testing. Only a few studies have examined the association between soluble immune checkpoint proteins and the immune status. Following the development of multiplex immunoassay panels for profiling human co-inhibitory and co-stimulatory immune checkpoint proteins, here we report the development of a novel magnetic bead-based Luminex multiplex assay for the quantitative detection of 28 mouse immune checkpoint proteins and immune regulators in 25 μL of sample (PD-1, PD-L1, PD-L2, CTLA-4/CD152, TIM-3, LAG-3, B7-H2/ICOSL, B7-H3/CD276, BTLA, GITR, HVEM, CD27, CD40, CD80/B7-1, CD226/DNAM-1, 4-1BBL/TNFSF9, CD137/4-1BB, 5’-NT/CD73, BCA-1/CXCL13, CD25/IL-2Rα, Granzyme B, E-cadherin, Galectin-1, Galectin-3, IFNγ, IL-10, TLR-2, and TNFα). Immune function declines with age, while the incidence of cancer rises. In this study, we examined age-related serum samples by quantitative profiling soluble checkpoint proteins from young (age of 8-month-old, n=8) and old-aged mice (48-month-old, n=8) of C57BL/6 strain. A significant age effect was observed on the levels of soluble checkpoint proteins in mouse serum samples tested. Comparing with the young mice, decreased levels of circulating HVEM, Granzyme B, LAG-3, PD-L1, CD73, B7-H2, CD25, and CD27; and increased levels of circulating TIM-3, PD-1, PD-L2, CD40, Galectin-3, IL-10, BCA-1, and TLR-2 were observed in aged C57BL/6 mice (Mann Whitney test, P value &amp;lt;0.05). The immune system also changes during pregnancy. We used the similar multiplex array approach to profile the soluble checkpoint proteins in non-pregnant (n=16) and pregnant CD-1 mice (n=9). Significant decreased levels of soluble LAG-3, B7-H2, B7-H3, CD25, CD27, and Galectin-1; and significant increase of soluble CD137, Galectin-3, and CD73 expression levels were detected in the serum samples of pregnant mice, as compared to the samples from the non-pregnant mice (Mann Whitney test, P value &amp;lt;0.05). Altogether, using bead-based quantitative multiplex analysis, our results demonstrate that the changes on circulating immune checkpoint protein profiles occur in the immunologic adaptations with age and during pregnancy in mice. Citation Format: Wen-Rong Lie, Christine Kornmeier, Ling Zeng, James Hoberg. Age- and pregnancy-related impact on soluble immune checkpoint protein profiles in mice as analyzed by a novel multiplex immunoassay [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5080.

Abstract 4248: HFB200603, a novel anti-BTLA monoclonal antibody that provides therapeutic potential for immune escape and synergizes with anti-PD-1 treatment

Abstract BTLA is a co-inhibitory immune checkpoint molecule sharing sequence and structural homology with PD-1 and CTLA4. Ligation of HVEM with BTLA induces recruitment of SHP1 and SHP2, and triggers inhibition of T cell proliferation and cytokine production. In melanoma, HVEM is described to have a broader expression than PD-L1 and constituted a negative prognostic marker; in PD-L1 negative NSCLC, the expression of HVEM has been shown to contribute to immune escape. Therefore BTLA-HVEM axis could play an important role in the immune escape, thus BTLA blockade in combination with PD-1/PD-L1 blockade could represent an effective therapeutic option. Using our proprietary microfluidic-based single cell platform CelliGO™, we identified a series of anti-human BTLA antibodies that were characterized for their binding affinity, cross-reactivity, selectivity and functional activity. Amongst them, HFB200603 was identified as a single-digit nanomolar binder to human and cynomolgus BTLA, capable of reversing HVEM-mediated immune suppression in a BTLA-HVEM reporter system and in a primary CD4+ T cell proliferation assay. HFB200603 showed synergistic effect with anti-PD-1 to enhance IFN-γ production in an MLR assay, and demonstrated favorable developability and pharmacokinetic profiles. Profiling of tumor infiltrating lymphocytes demonstrated that BTLA+PD-1+ T cells are present in melanoma, NSCLC, and HCC. Blockade of the BTLA-HVEM interaction with HFB200603 alone or in combination with anti-PD-1 led to increases in IFN-γ, CXCL9, IP-10 and other proinflammatory cytokines in primary dissociated tumor cultures. Based on its favorable pharmacological activity and excellent developability, HFB200603 is currently being developed as a potential novel immunotherapy coupled with a patient biomarker strategy derived from HiFiBiO’s Drug Intelligent Science (DIS™) single-cell immune profiling platform. Citation Format: Juying Li, Qian Zhang, Bingqing Shen, Manan Shah, Mingjie Chen, Sharon Li, Ling Dong, Francisco Adrian, Liang Schweizer. HFB200603, a novel anti-BTLA monoclonal antibody that provides therapeutic potential for immune escape and synergizes with anti-PD-1 treatment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 4248.