T cell major histocompatibility complex class II molecules down-regulate CD4+ T cell clone responses following LAG-3 binding

Cutting Edge: LAG3 Dimerization Is Required for TCR/CD3 Interaction and Inhibition of Antitumor Immunity

Lymphocyte activation gene 3 (LAG3) is an inhibitory receptor that plays a critical role in controlling T cell tolerance and autoimmunity and is a major immunotherapeutic target. LAG3 is expressed on the cell surface as a homodimer but the functional relevance of this is unknown. In this study, we show that the association between the TCR/CD3 complex and a murine LAG3 mutant that cannot dimerize is perturbed in CD8+ T cells. We also show that LAG3 dimerization is required for optimal inhibitory function in a B16-gp100 tumor model. Finally, we demonstrate that a therapeutic LAG3 Ab, C9B7W, which does not block LAG3 interaction with its cognate ligand MHC class II, disrupts LAG3 dimerization and its association with the TCR/CD3 complex. These studies highlight the functional importance of LAG3 dimerization and offer additional approaches to therapeutically target LAG3.

A novel LAG3 neutralizing antibody improves cancer immunotherapy by dual inhibition of MHC-II and FGL1 ligand binding

LAG3 is an inhibitory immune checkpoint expressed on activated T and NK cells. Blocking the interaction of LAG3 with its ligands MHC-II and FGL1 renders T cells improved cytotoxicity to cancer cells. Current study generated a panel of LAG3 monoclonal antibodies (mAbs) through immunization of mice followed by phage display. Some of them bound to the D1-D2 domain of LAG3, which is known for the engagement of its ligands FGL1 and MHC-II. Three outperformers, M208, M226, and M234, showed stronger blocking activity than Relatlimab in the FGL1 binding. Furthermore, M234 showed dual inhibition of FGL1 (IC50 of 20.6 nM) and MHC-II binding (IC50 of 6.2 nM) to LAG3. In vitro functional tests showed that M234 significantly stimulated IFN-γ secretion from activated PBMC cells. In vivo studies in a mouse model of hepatocellular carcinoma xenografts demonstrated that combining M234 IgG with GPC3-targeted bispecific antibodies significantly improved efficacy. In addition, GPC3-targeted CAR-T cells secreting IL-21-M234 scFv fusion protein exhibited enhanced activity in inhibiting tumor growth and greatly increased the survival rate of mice. Taken together, M234 has potential in cancer immunotherapy and warrants further clinical trial.

Soluble immune checkpoints: implications for cancer prognosis and response to immune checkpoint therapy and conventional therapies

Longitudinal sampling of tumor tissue from patients with solid cancers, aside from melanoma and a few other cases, is often unfeasible, and thus may not capture the plasticity of interactions between the tumor and immune system under selective pressure of a given therapy. Peripheral blood analyses provide salient information about the human peripheral immunome while offering technical and practical advantages over traditional tumor biopsies, and should be utilized where possible alongside interrogation of the tumor. Some common blood-based biomarkers used to study the immune response include immune cell subsets, circulating tumor DNA, and protein analytes such as cytokines. With the recent explosion of immune checkpoint inhibitors (ICI) as a modality of treatment in multiple cancer types, soluble immune checkpoints have become a relevant area of investigation for peripheral immune-based biomarkers. However, the exact functions of soluble immune checkpoints and their roles in cancer for the most part remain unclear. This review discusses current literature on the production, function, and expression of nine soluble immune checkpoints - sPD-L1, sPD-1, sCTLA4, sCD80, sTIM3, sLAG3, sB7-H3, sBTLA, and sHVEM - in patients with solid tumors, and explores their role as biomarkers of response to ICI as well as to conventional therapies (chemotherapy, radiotherapy, targeted therapy, and surgery) in cancer patients.

Checkpoint Inhibitors in Dogs: Are We There Yet?

Immune checkpoint inhibitors (ICI) have revolutionised cancer treatment in people. Immune checkpoints are important regulators of the body's reaction to immunological stimuli. The most studied immune checkpoint molecules are programmed death (PD-1) with its ligand (PD-L1) and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) with its ligands CD80 (B7-1) and CD86 (B7-2). Certain tumours can evade immunosurveillance by activating these immunological checkpoint targets. These proteins are often upregulated in cancer cells and tumour-infiltrating lymphocytes, allowing cancer cells to evade immune surveillance and promote tumour growth. By blocking inhibitory checkpoints, ICI can help restore the immune system to effectively fight cancer. Several studies have investigated the expression of these and other immune checkpoints in human cancers and have shown their potential as therapeutic targets. In recent years, there has been growing interest in studying the expression of immune checkpoints in dogs with cancer, and a few small clinical trials with ICI have already been performed on these species. Emerging studies in veterinary oncology are centred around developing and validating canine-targeted antibodies. Among ICIs, anti-PD-1 and anti-PD-L1 treatments stand out as the most promising, mirroring the success in human medicine over the past decade. Nevertheless, the efficacy of caninized antibodies remains suboptimal, especially for canine oral melanoma. To enhance the utilisation of ICIs, the identification of predictive biomarkers for treatment response and the thorough screening of individual tumours are crucial. Such endeavours hold promise for advancing personalised medicine within veterinary practice, thereby improving treatment outcomes. This article aims to review the current research literature about the expression of immune checkpoints in canine cancer and the current results of ICI treatment in dogs.

Tissue biomarkers of immune checkpoint inhibitor therapy

Cancer immunotherapy has been rejuvenated by the growing understanding of the immune system's role in tumor activity over the past two decades. During cancer initiation and progression, tumor cells employ various mechanisms that resemble peripheral immune tolerance to evade the antitumor responses of the immune system. Immune checkpoint molecules are the major mechanism of immune resistance that are exploited by tumor cells to inhibit T-cell activation and suppress immune responses. The targeting of immune checkpoint pathways has led to substantial improvements in survival rates in a number of solid cancers. However, a lack of understanding of the heterogeneity of the tumor microenvironment (TME) has resulted in inefficient therapy responses. A greater understanding of the TME is needed to identify patients likely to respond, and those that will have resistance to immune checkpoint inhibitors (ICIs). Advancement in spatial single-cell technologies has allowed deeper insight into the phenotypic and functional diversities of cells in the TME. In this review, we provide an overview of ICI biomarkers and highlight how high-dimensional spatially resolved, single-cell approaches provide deep molecular insights into the TME and allow for the discovery of biomarkers of clinical benefit.

Novel immune checkpoint targets: A promising therapy for cancer treatments

The immune system frequently comprises immunological checkpoints. They serve as a barrier to keep the immune system from overreacting and damaging cells that are robust. Immune checkpoint inhibitors (ICIs) are utilized in immunotherapy to prevent the synergy of partner proteins of checkpoint proteins with auxiliary proteins. Moreover, the T cells may target malignant cells since the "off" signal cannot be conveyed. ICIs, which are mostly composed of monoclonal antibodies (mAbs) against cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) and anti- programmed death-1/programmed ligand 1 (anti-PD-1/PD-L1), might transform the context of cancer therapy. Further, more patients continued to exhibit adaptive resistance, even though several ICIs demonstrated convincing therapeutic benefits in selective tumor types. Immune checkpoint therapy's overall effectiveness is still lacking at this time. A popular area of study involves investigating additional immune checkpoint molecules. Recent research has found a number of fresh immune checkpoint targets, including NKG2A ligands, TIGIT, B7-H6 ligands, Galectin 3, TIM3, and so on. These targets have been focus of the study, and recent investigational approaches have shown encouraging outcomes. In this review article, we covered the development and present level understanding of these recently identified immune checkpoint molecules, its effectiveness and limitations.

Mechanisms of immune checkpoint inhibitors: insights into the regulation of circular RNAS involved in cancer hallmarks

Current treatment strategies for cancer, especially advanced cancer, are limited and unsatisfactory. One of the most substantial advances in cancer therapy, in the last decades, was the discovery of a new layer of immunotherapy approach, immune checkpoint inhibitors (ICIs), which can specifically activate immune cells by targeting immune checkpoints. Immune checkpoints are a type of immunosuppressive molecules expressed on immune cells, which can regulate the degree of immune activation and avoid autoimmune responses. ICIs, such as anti-PD-1/PD-L1 drugs, has shown inspiring efficacy and broad applicability across various cancers. Unfortunately, not all cancer patients benefit remarkably from ICIs, and the overall response rates to ICIs remain relatively low for most cancer types. Moreover, the primary and acquired resistance to ICIs pose serious challenges to the clinical application of cancer immunotherapy. Thus, a deeper understanding of the molecular biological properties and regulatory mechanisms of immune checkpoints is urgently needed to improve clinical options for current therapies. Recently, circular RNAs (circRNAs) have attracted increasing attention, not only due to their involvement in various aspects of cancer hallmarks, but also for their impact on immune checkpoints in shaping the tumor immune microenvironment. In this review, we systematically summarize the current status of immune checkpoints in cancer and the existing regulatory roles of circRNAs on immune checkpoints. Meanwhile, we also aim to settle the issue in an evidence-oriented manner that circRNAs involved in cancer hallmarks regulate the effects and resistance of ICIs by targeting immune checkpoints.

Immunotherapy and biomarkers in patients with lung cancer with tuberculosis: Recent advances and future Directions

Lung cancer (LC) and tuberculosis (TB) are two major global public health problems, and the incidence of LC-TB is currently on the rise. Therefore effective clinical interventions are crucial for LC-TB. The aim of this review is to provide up-to-date information on the immunological profile and therapeutic biomarkers in patients with LC-TB. We discuss the immune mechanisms involved, including the immune checkpoints that play an important role in the treatment of patients with LC-TB. In addition, we explore the susceptibility of patients with LC to TB and summarise the latest research on LC-TB. Finally, we discuss future prospects in this field, including the identification of potential targets for immune intervention. In conclusion, this review provides important insights into the complex relationship between LC and TB and highlights new advances in the detection and treatment of both diseases.

Targeting LAG-3, TIM-3, and TIGIT for cancer immunotherapy

In one decade, immunotherapy based on immune checkpoint blockades (ICBs) has become a new pillar of cancer treatment following surgery, radiation, chemotherapy, and targeted therapies. However, not all cancer patients benefit from single or combination therapy with anti-CTLA-4 and anti-PD-1/PD-L1 monoclonal antibodies. Thus, an increasing number of immune checkpoint proteins (ICPs) have been screened and their effectiveness evaluated in preclinical and clinical trials. Lymphocyte activation gene-3 (LAG-3), T cell immunoglobulin and mucin-domain-containing-3 (TIM-3), and T cell immunoreceptor with immunoglobulin and tyrosine-based inhibitory motif (ITIM) domain (TIGIT) constitute the second wave of immunotherapy targets that show great promise for use in the treatment of solid tumors and leukemia. To promote the research and clinical application of ICBs directed at these targets, we summarize their discovery, immunotherapy mechanism, preclinical efficiency, and clinical trial results in this review.

Immune Checkpoints in Recurrent Pregnancy Loss: New Insights into a Detrimental and Elusive Disorder

Recurrent pregnancy loss (RPL) refers to two or more miscarriages before 20 weeks gestation. Its prevalence is 1-2%; its pathogenesis remains unexplained in more than 50% of cases, in which the cause is thought to be abnormal immune activity during placentation leading to a lack of pregnancy-induced immune tolerance. It is unknown whether immune activity is deranged in the endometrium of women with RPL. We studied the gene expression and the quantitative tissue protein levels of three immune checkpoints (CD276, which enhances cytotoxic T-cell activity, cytotoxic T-lymphocyte-associated antigen-4 [CTL-4], which reduces Th1 cytokine production, and lymphocyte activation gene-3 [LAG-3], which shows suppressive activity on Tregs and CD4+ T-cells) in endometrial samples from 27 women with unexplained RPL and in 29 women with dysfunctional uterine bleeding and previous uneventful pregnancies as controls. RNA isolation, real-time PCR, protein isolation, and ELISA were performed. CD276 gene expression and protein tissue levels were significantly lower in the endometrium of the RPL group than in the controls, whereas both CTL-4 and LAG-3 were significantly higher. This difference suggests defective endometrial immune regulation and overactivation of immune response in women with a history of RPL, at least in relation to controls with dysfunctional uterine bleeding and previous normal reproductive history.

Insights into anti-tumor immunity via the polyomavirus shared across human Merkel cell carcinomas

Understanding and augmenting cancer-specific immunity is impeded by the fact that most tumors are driven by patient-specific mutations that encode unique antigenic epitopes. The shared antigens in virus-driven tumors can help overcome this limitation. Merkel cell carcinoma (MCC) is a particularly interesting tumor immunity model because (1) 80% of cases are driven by Merkel cell polyomavirus (MCPyV) oncoproteins that must be continually expressed for tumor survival; (2) MCPyV oncoproteins are only ~400 amino acids in length and are essentially invariant between tumors; (3) MCPyV-specific T cell responses are robust and strongly linked to patient outcomes; (4) anti-MCPyV antibodies reliably increase with MCC recurrence, forming the basis of a standard clinical surveillance test; and (5) MCC has one of the highest response rates to PD-1 pathway blockade among all solid cancers. Leveraging these well-defined viral oncoproteins, a set of tools that includes over 20 peptide-MHC class I tetramers has been developed to facilitate the study of anti-tumor immunity across MCC patients. Additionally, the highly immunogenic nature of MCPyV oncoproteins forces MCC tumors to develop robust immune evasion mechanisms to survive. Indeed, several immune evasion mechanisms are active in MCC, including transcriptional downregulation of MHC expression by tumor cells and upregulation of inhibitory molecules including PD-L1 and immunosuppressive cytokines. About half of patients with advanced MCC do not persistently benefit from PD-1 pathway blockade. Herein, we (1) summarize the lessons learned from studying the anti-tumor T cell response to virus-positive MCC; (2) review immune evasion mechanisms in MCC; (3) review mechanisms of resistance to immune-based therapies in MCC and other cancers; and (4) discuss how recently developed tools can be used to address open questions in cancer immunotherapy. We believe detailed investigation of this model cancer will provide insight into tumor immunity that will likely also be applicable to more common cancers without shared tumor antigens.

Tackling of Immunorefractory Tumors by Targeting Alternative Immune Checkpoints

Physiologically, well known or traditional immune checkpoints (ICs), such as CTLA-4 and PD-1, are in place to promote tolerance to self-antigens and prevent generation of autoimmunity. In cancer, the ICs are effectively engaged by the tumor cells or stromal ells from the tumor microenvironment through expression of cognate ligands for the ICs present on the cell surface of CD8+ T lymphocytes. The ligation of ICs on CD8+ T lymphocytes triggers inhibitory signaling pathways, leading to quiescence or an exhaustion of CD8+ T lymphocytes. This results in failure of immunotherapy. To overcome this, several FDA-approved therapeutic antibodies are available, but the clinical outcome is quite variable due to the resistance encountered through upregulated expression of alternate ICs such as VISTA, LAG-3, TIGIT and TIM-3. This review focuses on the roles played by the traditional as well as alternate ICs and the contribution of associated signaling pathways in generating such resistance to immunotherapy. Combinatorial targeting of traditional and alternate ICs might be beneficial for immune-refractory tumors.

LAG3+ erythroid progenitor cells inhibit HBsAg seroclearance during finite pegylated interferon treatment through LAG3 and TGF-β

HBsAg seroclearance, the ideal aim of anti-hepatitis B virus (HBV) treatment, cannot be achieved easily. Anemia is another common issue for chronic hepatitis B (CHB) patients, which leads to elevation of erythroid progenitor cells (EPCs) and immune suppression in cancer. This study investigated the role of EPCs in HBsAg seroclearance following PEGylated interferon-α (PEG-IFN) treatment. CD45⁺EPC accumulation in CHB patients and an AAV/HBV mice model was found in the circulation and liver by flow cytometry and immunofluorescence tests. Wright-Giemsa staining showed that these pathological CD45⁺EPCs presented elevated erythroid cells with relative immature morphologies and atypical cells compared with the control cells. CD45⁺EPCs were associated with immune tolerance and decreased HBsAg seroclearance during finite PEG-IFN treatment. CD45⁺EPCs suppressed antigen non-specific T cell activation and HBV-specific CD8⁺T cells, partially through transforming growth factor β (TGF-β). RNA-seq revealed that CD45⁺EPCs in patients with CHB presented a distinct gene expression profile compared with CD45^-EPCs and CD45⁺EPCs from cord blood. Notably, CD45⁺EPCs from patients with CHB expressed high level of Lymphocyte-activation gene 3 (LAG3), an immune checkpoint molecule, and were then defined as LAG3⁺EPCs. LAG3⁺EPCs diminished the function of antigen presenting cells through LAG3, which was another mechanism by which LAG3⁺EPCs' suppressed HBV-specific CD8⁺T cells. Anti-LAG3 and anti-TGF-β combination treatment decreased serum HBeAg, HBV DNA levels and HBsAg level, as well as HBsAg-expression in hepatocytes during PEG-IFN treatment in the AAV/HBV mice model. Conclusions: LAG3⁺EPCs inhibited the efficacy of PEG-IFN treatment on HBsAg seroclearance induced by LAG3 and TGF-β. Anti-LAG3, anti-TGF-β and PEG-IFN combination treatment might facilitate HBV clearance.

Classic and new strategies for the treatment of advanced melanoma and non-melanoma skin cancer

Advanced melanoma and non-melanoma skin cancers (NMSCs) are burdened with a dismal prognosis. To improve the survival of these patients, studies on immunotherapy and target therapies in melanoma and NMSCs are rapidly increasing. BRAF and MEK inhibitors improve clinical outcomes, and anti-PD1 therapy demonstrates better results than chemotherapy or anti-CTLA4 therapy in terms of the survival of patients with advanced melanoma. In recent years, the combination therapy of nivolumab plus ipilimumab has gained ground in studies for its survival and response rate benefits in patients with advanced melanoma. In addition, neoadjuvant treatment for stages III and IV melanoma, either as monotherapy or combination therapy, has recently been discussed. Another promising strategy evaluated in recent studies is the triple combination of anti-PD-1/PD-L1 immunotherapy and anti-BRAF plus anti-MEK targeted therapy. On the contrary, in advanced and metastatic BCC, successful therapeutic strategies, such as vismodegib and sonidegib, are based on the inhibition of aberrant activation of the Hedgehog signaling pathway. In these patients, anti-PD-1 therapy with cemiplimab should be reserved as the second-line therapy in case of disease progression or poor response. In patients with locally advanced or metastatic SCC, who are not candidates for surgery or radiotherapy, anti-PD1 agents such as cemiplimab, pembrolizumab, and cosibelimab (CK-301) have shown significant results in terms of response rate. PD-1/PD-L1 inhibitors, such as avelumab, have also been used in Merkel carcinoma, achieving responses in half of the patients with advanced disease. The latest prospect emerging for MCC is the locoregional approach involving the injection of drugs that can stimulate the immune system. Two of the most promising molecules used in combination with immunotherapy are cavrotolimod (a Toll-like receptor 9 agonist) and a Toll-like receptor 7/8 agonist. Another area of study is cellular immunotherapy with natural killer cells stimulated with an IL-15 analog or CD4/CD8 cells stimulated with tumor neoantigens. Neoadjuvant treatment with cemiplimab in CSCCs and nivolumab in MCCs has shown promising results. Despite the successes of these new drugs, the new challenges ahead will be to select patients who will benefit from these treatments based on biomarkers and parameters of the tumor microenvironment.

A more novel and robust gene signature predicts outcome in patients with esophageal squamous cell carcinoma

BACKGROUND

Esophageal squamous cell carcinoma (ESCC) is a life-threatening thoracic tumor with a poor prognosis. The tumor microenvironment (TME) mainly comprises tumor cells and tumor-infiltrating immune cells mixed with stromal components. The latest research has displayed that tumor immune cell infiltration (ICI) is closely connected with the ESCC patients' clinical prognosis. This study was designed to construct a gene signature based on the ICI of ESCC to predict prognosis.

METHODS

Based on the selection criteria we set, the eligible ESCC cases from the GSE53625 and TCGA-ESCA datasets were chosen for the training cohort and the validation cohort, respectively. Unsupervised clustering detailed grouped ESCC cases of the training cohort based on the ICI profile. We determined the differential expression genes (DEGs) between the ICI clusters, and, subsequently, we adopted the univariate Cox analysis to recognize DEGs with prognostic potential. These screened DEGs underwent a Lasso regression, which then generated a gene signature. The harvested signature's predictive ability was further examined by the Kaplan-Meier analysis, Cox analysis, ROC, IAUC, and IBS. More importantly, we listed similar studies in the most recent year and compared theirs with ours. We performed the functional annotation, immune relevant signature correlation analysis, and immune infiltrating analysis to thoroughly understand the functional mechanism of the signature and the immune cells' roles in the gene signature's predicting capacity.

RESULTS

A sixteen-gene signature (ARSD, BCAT1, BIK, CLDN11, DLEU7-AS1, GGH, IGFBP2, LINC01037, LINC01446, LINC01497, M1AP, PCSK2, PCSK5, PPP2R2A, TIGD7, and TMSB4X) was generated from the Lasso model. We then confirmed the signature as having solid and stable prognostic capacity by several statistical methods. We revealed the superiority of our signature after comparing it to our predecessors, and the GSEA uncovered the specifically mechanism of action related to the gene signature. Two immune relevant signatures, including GZMA and LAG3 were identified associating with our signature. The immune-infiltrating analysis identified crucial roles of resting mast cells, which potentially support the sixteen-gene signature's prognosis ability.

CONCLUSIONS

We discovered a robust sixteen-gene signature that can accurately predict ESCC prognosis. The immune relevant signatures, GZMA and LAG3, and resting mast cells infiltrating were closely linked to the sixteen-gene signature's ability.

Approaches for development of LAG-3 inhibitors and the promise they hold as anticancer agents

INTRODUCTION

LAG-3 is considered to be the third point of immunological control in relation to clinical trials that address cancer treatment, only behind PD-1 and CTLA-4, due to its role as a suppressor of the immune response and enhancer of differentiation of Treg cells.

AREAS COVERED

The authors focus on emphasizing the strategy of development of LAG-3 inhibitors to develop anticancer therapeutics, especially from the perspective of designing new monoclonal and bispecific antibodies against LAG-3. This article also covers details of patents and clinical trials of LAG-3 inhibitors reported in the literature. In addition, we highlight as future research challenges the design and development of peptides and small molecules as inhibitors of LAG-3 function.

EXPERT OPINION

Three approaches have been used for the development of LAG-3 inhibitors, and they include inhibitory LAG-3 binding peptides and antagonist monoclonal and multispecific antibodies. These approaches include more than 100 clinical trials of 21 molecules that bind to LAG-3 and block its binding to MHC II. However, these approaches do not cover the design and development of peptides and small molecules that could inhibit the function of LAG-3, for which it is necessary to develop new alternatives that cover this gap.

The Role of TIM-3 and LAG-3 in the Microenvironment and Immunotherapy of Ovarian Cancer

Ovarian cancer has the highest mortality rate among gynecologic malignancies. The main treatment options are surgical removal of the tumor and chemotherapy. Cancer treatment has been revolutionized by immunotherapy, which has developed explosively over the past two decades. Clinical anticancer strategies used in immunotherapy include therapies based on the inhibition of PD-1, PD-L1 or CTLA-4. Despite encouraging results, a large proportion of cancer patients are resistant to these therapies or eventually develop resistance. It is important to perform research that will focus on immunotherapy based on other immune checkpoint inhibitors. The aim of the review was to analyze studies considering the expression of TIM-3 and LAG-3 in the ovarian cancer microenvironment and considering immunotherapy for ovarian cancer that includes antibodies directed against TIM-3 and LAG-3. As the data showed, the expression of the described immune checkpoints was shown in different ways. Higher TIM-3 expression was associated with a more advanced tumor stage. Both TIM-3 and LAG-3 were co-expressed with PD-1 in a large proportion of studies. The effect of LAG-3 expression on progression-free survival and/or overall survival is inconclusive and certainly requires further study. Co-expression of immune checkpoints prompts combination therapies using anti-LAG-3 or anti-TIM-3. Research on immune checkpoints, especially TIM-3 and LAG-3, should be further developed.

The relationship between soluble lymphocyte activation gene-3 and coronary artery disease

Background

Soluble lymphocyte activation gene 3 (sLAG3) may be used for diagnosis or prognosis in various diseases. However, the relationship between sLAG3 and coronary artery disease (CAD) are still unclear. This study aimed to investigate the levels of sLAG3 in patients with CAD, and its potential clinical association with the disease.

Methods

A total of 66 subjects (49 patients with CAD and 17 control subjects without CAD) were enrolled. The sLAG3 level was measured using enzyme-linked immunosorbent assay (ELISA) kits. Clinical variables included demographics, biochemical markers, coronary angiography status, and ejection fraction of the heart (EF) were collected, and Gensini scores were calculated. LAG3 gene data was extracted from three datasets (GSE23561, GSE61144, GSE60993) in Gene Expression Omnibus (GEO) to compare differential expression between CAD and control subjects.

Results

The sLAG3 level was significantly lower in the CAD vs. the controls (P < 0.05), and negatively associated with CAD [odds ratio (OR): 0.212, 95% confidential interval (CI): 0.060–0.746, P < 0.05]. Furthermore, the area under the curve (AUC) of sLAG3 level was significant (P < 0.05). The sLAG3 level in subjects with body mass index (BMI) ≥ 24 kg/m² was lower compared to those with BMI < 24 kg/m² (P < 0.05). The sLAG3 level was also negatively associated with BMI and diabetes mellitus (P < 0.05), though not associated with the Gensini scores or EF (P > 0.05). Lastly, the LAG3 gene expression in peripheral whole blood of patients with CAD were down-regulated compared to healthy controls (P < 0.05).

Conclusion

The sLAG3 level was negatively associated with the occurrence but not severity of CAD. Meanwhile, the sLAG3 was negatively associated with BMI and diabetes mellitus, suggesting the reduced sLAG3 might be a novel risk factor for developing CAD.

Immune checkpoint modulators in cancer immunotherapy: recent advances and emerging concepts

The discovery of immune checkpoint inhibitors (ICIs) has now been universally acknowledged as a significant breakthrough in tumor therapy after the targeted treatment of checkpoint molecules: anti-programmed cell death protein 1/programmed cell death ligand 1 (PD-1/PD-L1) and anti-cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) on several cancer types achieved satisfying results. However, there are still quite a lot of patients suffering from severe side effects and ineffective treatment outcomes. Although the current ICI therapy is far from satisfying, a series of novel immune checkpoint molecules with remarkable preclinical and clinical benefits are being widely investigated, like the V-domain Ig suppressor of T cell activation (VISTA), which can also be called PD-1 homolog (PD-1H), and ectonucleotidases: CD39, CD73, and CD38, which belong to the ribosyl cyclase family, etc. In this review, we systematically summarized and discussed these molecules' biological structures, molecular features, and the corresponding targeted drugs, aiming to help the in-depth understanding of immune checkpoint molecules and promote the clinical practice of ICI therapy.

Immune checkpoint modulators in cancer immunotherapy: recent advances and emerging concepts

The discovery of immune checkpoint inhibitors (ICIs) has now been universally acknowledged as a significant breakthrough in tumor therapy after the targeted treatment of checkpoint molecules: anti-programmed cell death protein 1/programmed cell death ligand 1 (PD-1/PD-L1) and anti-cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) on several cancer types achieved satisfying results. However, there are still quite a lot of patients suffering from severe side effects and ineffective treatment outcomes. Although the current ICI therapy is far from satisfying, a series of novel immune checkpoint molecules with remarkable preclinical and clinical benefits are being widely investigated, like the V-domain Ig suppressor of T cell activation (VISTA), which can also be called PD-1 homolog (PD-1H), and ectonucleotidases: CD39, CD73, and CD38, which belong to the ribosyl cyclase family, etc. In this review, we systematically summarized and discussed these molecules' biological structures, molecular features, and the corresponding targeted drugs, aiming to help the in-depth understanding of immune checkpoint molecules and promote the clinical practice of ICI therapy.

Cutting-Edge: Preclinical and Clinical Development of the First Approved Lag-3 Inhibitor

Immune checkpoint inhibitors (ICIs) have revolutionized medical practice in oncology since the FDA approval of the first ICI 11 years ago. In light of this, Lymphocyte-Activation Gene 3 (LAG-3) is one of the most important next-generation immune checkpoint molecules, playing a similar role as Programmed cell Death protein 1 (PD-1) and Cytotoxic T-Lymphocyte Antigen 4 (CTLA-4). 19 LAG-3 targeting molecules are being evaluated at 108 clinical trials which are demonstrating positive results, including promising bispecific molecules targeting LAG-3 simultaneously with other ICIs. Recently, a new dual anti-PD-1 (Nivolumab) and anti-LAG-3 (Relatimab) treatment developed by Bristol Myers Squibb (Opdualag), was approved by the Food and Drug Administration (FDA) as the first LAG-3 blocking antibody combination for unresectable or metastatic melanoma. This novel immunotherapy combination more than doubled median progression-free survival (PFS) when compared to nivolumab monotherapy (10.1 months versus 4.6 months). Here, we analyze the large clinical trial responsible for this historical approval (RELATIVITY-047), and discuss the preclinical and clinical developments that led to its jump into clinical practice. We will also summarize results achieved by other LAG-3 targeting molecules with promising anti-tumor activities currently under clinical development in phases I, I/II, II, and III. Opdualag will boost the entry of more LAG-3 targeting molecules into clinical practice, supporting the accumulating evidence highlighting the pivotal role of LAG-3 in cancer.

Clinical landscape of LAG-3-targeted therapy

Lymphocyte-activated gene 3 (LAG-3) is a cell surface inhibitory receptor and a key regulator of immune homeostasis with multiple biological activities related to T-cell functions. LAG-3 is considered a next-generation immune checkpoint of clinical importance, right next to programmed cell death protein 1 (PD-1) and cytotoxic T-cell lymphocyte antigen-4 (CTLA-4). Indeed, it is the third inhibitory receptor to be exploited in human anticancer immunotherapies. Several LAG-3-antagonistic immunotherapies are being evaluated at various stages of preclinical and clinical development. In addition, combination therapies blocking LAG-3 together with other immune checkpoints are also being evaluated at preclinical and clinical levels. Indeed, the co-blockade of LAG-3 with PD-1 is demonstrating encouraging results. A new generation of bispecific PD-1/LAG-3-blocking agents have also shown strong capacities to specifically target PD-1+ LAG-3+ highly dysfunctional T cells and enhance their proliferation and effector activities. Here we identify and classify preclinical and clinical trials conducted involving LAG-3 as a target through an extensive bibliographic research. The current understanding of LAG-3 clinical applications is summarized, and most of the publically available data up to date regarding LAG-3-targeted therapy preclinical and clinical research and development are reviewed and discussed.

ImmunoPET: harnessing antibodies for imaging immune cells

Dramatic, but uneven, progress in the development of immunotherapies for cancer has created a need for better diagnostic technologies including innovative non-invasive imaging approaches. This review discusses challenges and opportunities for molecular imaging in immuno-oncology and focuses on the unique role that antibodies can fill. ImmunoPET has been implemented for detection of immune cell subsets, activation and inhibitory biomarkers, tracking adoptively transferred cellular therapeutics, and many additional applications in preclinical models. Parallel progress in radionuclide availability and infrastructure supporting biopharmaceutical manufacturing has accelerated clinical translation. ImmunoPET is poised to provide key information on prognosis, patient selection, and monitoring immune responses to therapy in cancer and beyond.

Lymphocyte activation gene-3 (LAG-3) regulatory T cells: An evolving biomarker for treatment response in autoimmune diseases

Regulatory T cells (Tregs) comprise a CD4⁺CD25⁺Foxp3⁺ T cell subset for maintaining immune tolerance, and their deficits and/or dysfunction are observed in autoimmune diseases. The lymphocyte activation gene 3 (LAG-3, also known as CD223), which is an immunoglobulin superfamily member expressed on peripheral immune cells, is recognized as an inhibitory regulator of Tregs. LAG-3⁺ T cells represent a novel protective Tregs subset that produces interleukin-10. Alterations in LAG-3⁺ Tregs have been reported in several autoimmune diseases, suggesting their potential pathogenic role. Recent studies have indicated that LAG-3⁺ Tregs may be associated not only with immunopathology but also with response to therapy in several autoimmune and autoinflammatory diseases, such as rheumatoid arthritis, psoriasis, psoriatic arthritis and others. We present a review of Tregs phenotypes and functions, with a focus on LAG-3⁺ Tregs, and discuss their potential role as biomarkers for treatment response in autoimmune diseases.

Update on lymphocyte-activation gene 3 (LAG-3) in cancers: from biological properties to clinical applications

Immunotherapy that targets checkpoints, especially programmed cell death protein 1 and programmed cell death ligand 1, has revolutionized cancer therapy regimens. The overall response rate to mono-immunotherapy, however, is limited, emphasizing the need to potentiate the efficacy of these regimens. The functions of immune cells are modulated by multiple stimulatory and inhibitory molecules, including lymphocyte activation gene 3 (LAG-3). LAG-3 is co-expressed together with other inhibitory checkpoints and plays key roles in immune suppression. Increasing evidence, particularly in the last 5 years, has shown the potential of LAG-3 blockade in anti-tumor immunity. This review provides an update on the biological properties and clinical applications of LAG-3 in cancers.

Immune Checkpoint LAG3 and Its Ligand FGL1 in Cancer

LAG3 is the most promising immune checkpoint next to PD-1 and CTLA-4. High LAG3 and FGL1 expression boosts tumor growth by inhibiting the immune microenvironment. This review comprises four sections presenting the structure/expression, interaction, biological effects, and clinical application of LAG3/FGL1. D1 and D2 of LAG3 and FD of FGL1 are the LAG3-FGL1 interaction domains. LAG3 accumulates on the surface of lymphocytes in various tumors, but is also found in the cytoplasm in non-small cell lung cancer (NSCLC) cells. FGL1 is found in the cytoplasm in NSCLC cells and on the surface of breast cancer cells. The LAG3-FGL1 interaction mechanism remains unclear, and the intracellular signals require elucidation. LAG3/FGL1 activity is associated with immune cell infiltration, proliferation, and secretion. Cytokine production is enhanced when LAG3/FGL1 are co-expressed with PD-1. IMP321 and relatlimab are promising monoclonal antibodies targeting LAG3 in melanoma. The clinical use of anti-FGL1 antibodies has not been reported. Finally, high FGL1 and LAG3 expression induces EGFR-TKI and gefitinib resistance, and anti-PD-1 therapy resistance, respectively. We present a comprehensive overview of the role of LAG3/FGL1 in cancer, suggesting novel anti-tumor therapy strategies.

Perspectives on the role of breast cancer susceptibility gene in breast cancer

PURPOSE

Breast cancer susceptibility gene 1/2 can repair damaged DNA through homologous recombination. Besides, the local immune microenvironment of breast cancer is closely linked to the prognosis of patients. But the relationship of breast cancer susceptibility gene 1/2 expression and local immunosuppressive microenvironment in breast cancer is not clear. The aim of this study was to discuss the correlation between them.

METHODS

The fresh primary breast tumors and paired normal tissues of 156 cases of breast cancer patients as well as peripheral blood of 156 cases among them in Tianjin Medical University Cancer Institute and Hospital from January 2014 to October 2018 were collected. The association between breast cancer susceptibility gene 1/2 germline mutation and immune status of microenvironment in situ was analyzed.

RESULTS

The results indicated that the germline mutation of breast cancer susceptibility gene 1/2 was inconsistent with the breast cancer susceptibility gene 1/2 protein expression, and the proportion of immune cells in patients with negative expression of breast cancer susceptibility gene 1/2 protein was higher than patients with positive expression of breast cancer susceptibility gene 1/2 protein (p < 0.05). And the expression of programmed cell death protein 1, cytotoxic T-Lymphocyte Antigen 4, programmed death ligand-1 of CD3⁺ T cells in patients with negative expression of breast cancer susceptibility gene 1/2 protein was higher than patients with positive expression of breast cancer susceptibility gene 1/2 protein (p < 0.05). The breast cancer susceptibility gene 1 protein expression was significantly correlated with family history of breast cancer patients (p = 0.006), local lymph node metastases (p = 0.001), and TNM staging (p ≤ 0.001). The breast cancer susceptibility gene 2 protein expression was significantly related to local lymph node metastases (p ≤ 0.001), III stage rate(p = 0.003) and molecular subtyping (p ≤ 0.001). Besides, the 5 years disease free survival was worse for G1 group and pathological III stage patients than other groups and other TNM stage patients.

CONCLUSION

In short, the immune therapy may be a potential therapy method for breast cancer patients with negative expression of breast cancer susceptibility gene 1/2 protein.

Seven mysteries of LAG-3: a multi-faceted immune receptor of increasing complexity

Despite three decades of research to its name and increasing interest in immunotherapies that target it, LAG-3 remains an elusive co-inhibitory receptor in comparison to the well-established PD-1 and CTLA-4. As such, LAG-3 targeting therapies have yet to achieve the clinical success of therapies targeting other checkpoints. This could, in part, be attributed to the many unanswered questions that remain regarding LAG-3 biology. Of these, we address: (i) the function of the many LAG-3-ligand interactions, (ii) the hurdles that remain to acquire a high-resolution structure of LAG-3, (iii) the under-studied LAG-3 signal transduction mechanism, (iv) the elusive soluble form of LAG-3, (v) the implications of the lack of (significant) phenotype of LAG-3 knockout mice, (vi) the reports of LAG-3 expression on the epithelium, and (vii) the conflicting reports of LAG-3 expression (and potential contributions to pathology) in the brain. These mysteries which surround LAG-3 highlight how the ever-evolving study of its biology continues to reveal ever-increasing complexity in its role as an immune receptor. Importantly, answering the questions which shroud LAG-3 in mystery will allow the maximum therapeutic benefit of LAG-3 targeting immunotherapies in cancer, autoimmunity and beyond.

Molecular and Clinical Characterization of LAG3 in Breast Cancer Through 2994 Samples

Despite the promising impact of cancer immunotherapy targeting CTLA4 and PD1/PDL1, numerous cancer patients fail to respond. LAG3 (Lymphocyte Activating 3), also named CD233, serves as an alternative inhibitory receptor to be targeted in the clinic. The impacts of LAG3 on immune cell populations and coregulation of immune responses in breast cancer remain largely unknown. To characterize the role of LAG3 in breast cancer, we investigated transcriptome data and associated clinical information derived from 2,994 breast cancer patients. We estimated the landscape of the relationship between LAG3 and 10 types of cell populations of breast cancer. We investigated the correlation pattern between LAG3 and immune modulators in pancancer, particularly the synergistic role of LAG3 with other immune checkpoint members in breast cancer. LAG3 expression was closely related to the malignancy of breast cancer and may serve as a potential biomarker. LAG3 may play an important role in regulating the tumor immune microenvironment of T cells and other immune cells. More important, LAG3 may synergize with CTLA4, PD1/PDL1, and other immune checkpoints, thereby contributing more evidence to improve combination cancer immunotherapy by simultaneously targeting LAG3, PD1/PDL1, and CTLA4.

PD-L1/LAG-3 bispecific antibody enhances tumor-specific immunity

Anti-programmed cell death-1 (PD-1)/PD-ligand-1 (PD-L1) treatments are effective in a fraction of patients with advanced malignancies. However, the majority of patients do not respond to it. Resistance to cancer immunotherapy can be mediated by additional immune checkpoints. We hypothesized that co-targeting of PD-L1 and lymphocyte-activation gene 3 (LAG-3) could provide an alternative therapeutic approach. Here, we developed IBI323, a dual blockade bispecific antibody targeting PD-L1 and LAG-3.

We assessed the binding affinity, blocking activity, cell bridging effect, and immunomodulation function of IBI323 using in vitro assays. We also evaluated, in two humanized mouse models, anti-tumor effects and antitumor T cell immunity induced by IBI323.

IBI323 bound to PD-L1 and LAG-3 with similar potency as its parental antibodies and blocked the interaction of PD-1/PD-L1, CD80/PD-L1, and LAG-3/MHC-II. Moreover, IBI323 mediated the bridging of PD-L1+ cells and LAG-3+ cells and demonstrated superior immune stimulatory activity compared to each parent antibody in mixed leukocyte reaction. In PD-L1/LAG-3 double knock-in mice bearing human PD-L1 knock-in MC38 tumors, IBI323 showed stronger anti-tumor activity compared to each parental antibody. The better antitumor response correlated with increased tumor-specific CD8+ and CD4+ T cells. IBI323 also induced stronger anti-tumor effect against established A375 tumors compared with combination in mice reconstituted with human immune cells.

Collectively, these data demonstrated that IBI323 preserved the blockade activities of parental antibodies while processing a novel cell bridging function. Based on the encouraging preclinical results, IBI323 has significant value in further clinical development.

Immunotherapy in endometrial cancer: rationale, practice and perspectives

Tumor immunotherapy has attracted more and more attention nowadays, and multiple clinical trials have confirmed its effect in a variety of solid tumors. Immune checkpoint inhibitors (ICIs), cancer vaccines, adoptive cell transfer (ACT), and lymphocyte-promoting cytokines are the main immunotherapy methods. Endometrial cancer (EC) is one of the most frequent tumors in women and the prognosis of recurrent or metastatic EC is poor. Since molecular classification has been applied to EC, immunotherapy for different EC subtypes (especially POLE and MSI-H) has gradually attracted attention. In this review, we focus on the expression and molecular basis of the main biomarkers in the immunotherapy of EC firstly, as well as their clinical application significance and limitations. Blocking tumor immune checkpoints is one of the most effective strategies for cancer treatment in recent years, and has now become the focus in the field of tumor research and treatment. We summarized clinical date of planned and ongoing clinical trials and introduced other common immunotherapy methods in EC, such as cancer vaccine and ACT. Hormone aberrations, metabolic syndrome (MetS) and p53 mutant and that affect the immunotherapy of endometrial cancer will also be discussed in this review.

Understanding LAG-3 Signaling

Lymphocyte activation gene 3 (LAG-3) is a cell surface inhibitory receptor with multiple biological activities over T cell activation and effector functions. LAG-3 plays a regulatory role in immunity and emerged some time ago as an inhibitory immune checkpoint molecule comparable to PD-1 and CTLA-4 and a potential target for enhancing anti-cancer immune responses. LAG-3 is the third inhibitory receptor to be exploited in human anti-cancer immunotherapies, and it is considered a potential next-generation cancer immunotherapy target in human therapy, right next to PD-1 and CTLA-4. Unlike PD-1 and CTLA-4, the exact mechanisms of action of LAG-3 and its relationship with other immune checkpoint molecules remain poorly understood. This is partly caused by the presence of non-conventional signaling motifs in its intracellular domain that are different from other conventional immunoregulatory signaling motifs but with similar inhibitory activities. Here we summarize the current understanding of LAG-3 signaling and its role in LAG-3 functions, from its mechanisms of action to clinical applications.

Adult immuno-oncology: using past failures to inform the future

In oncology, "immunotherapy" is a broad term encompassing multiple means of utilizing the patient's immune system to combat malignancy. Prominent among these are immune checkpoint inhibitors, cellular therapies including chimeric antigen receptor T-cell therapy, vaccines, and oncolytic viruses. Immunotherapy for glioblastoma (GBM) has had mixed results in early trials. In this context, the past, present, and future of immune oncology for the treatment of GBM was discussed by clinical, research, and thought leaders as well as patient advocates at the first annual Remission Summit in 2019. The goal was to use current knowledge (published and unpublished) to identify possible causes of treatment failures and the best strategies to advance immunotherapy as a treatment modality for patients with GBM. The discussion focuses on past failures, current limitations, failure analyses, and proposed best practices moving forward.

Targeting Lymphocyte Activation Gene 3 to Reverse T-Lymphocyte Dysfunction and Improve Survival in Murine Polymicrobial Sepsis

BACKGROUND

Lymphocyte activation gene 3 (LAG-3) is one of the immune checkpoint molecules, negatively regulating the T-cell reactions. The present study investigated the role of LAG-3 in sepsis-induced T-lymphocyte disability.

METHODS

Mice sepsis was induced by cecal ligation and puncture (CLP). LAG-3 expression on some immune cells were detected 24 hours after CLP. LAG-3 knockout and anti-LAG-3 antibody were applied to investigate the effects on the survival, bacterial clearance. Cytokine levels, T-cell counts, and the presence of apoptosis (in blood, spleen, and thymus) were also determined. In vitro T-cell apoptosis, interferon γ secretion, and proliferation were measured. The expression of interleukin 2 receptor on T cells was also determined after CLP.

RESULTS

LAG-3 was up-regulated on CD4+/CD8+ T, CD19+ B, natural killer, CD4+CD25+ regulatory T cells and dendritic cells. Both LAG-3 knockout and anti-LAG-3 antibody had a positive effect on survival and on blood or peritoneal bacterial clearance in mice undergoing CLP. Cytokine levels and T-cell apoptosis decreased in anti-LAG-3 antibody-treated mice. Induced T-cell apoptosis decreased, whereas interferon γ secretion and proliferation were improved by anti-LAG-3 antibody in vitro. Interleukin 2 receptor was up-regulated on T cells in both wild-type and LAG-3-knockout mice undergoing CLP.

CONCLUSIONS

LAG-3 knockout or anti-LAG-3 antibody blockade protected mice undergoing CLP from sepsis-associated immunodysfunction and may be a new target for the treatment.

Emerging Immunotherapy for Acute Myeloid Leukemia

Several immune checkpoint molecules and immune targets in leukemic cells have been investigated. Recent studies have suggested the potential clinical benefits of immuno-oncology (IO) therapy against acute myeloid leukemia (AML), especially targeting CD33, CD123, and CLL-1, as well as immune checkpoint inhibitors (e.g., anti-PD (programmed cell death)-1 and anti-CTLA4 (cytotoxic T-lymphocyte-associated protein 4) antibodies) with or without conventional chemotherapy. Early-phase clinical trials of chimeric antigen receptor (CAR)-T or natural killer (NK) cells for relapsed/refractory AML showed complete remission (CR) or marked reduction of marrow blasts in a few enrolled patients. Bi-/tri-specific antibodies (e.g., bispecific T-cell engager (BiTE) and dual-affinity retargeting (DART)) exhibited 11-67% CR rates with 13-78% risk of cytokine-releasing syndrome (CRS). Conventional chemotherapy in combination with anti-PD-1/anti-CTLA4 antibody for relapsed/refractory AML showed 10-36% CR rates with 7-24 month-long median survival. The current advantages of IO therapy in the field of AML are summarized herein. However, although cancer vaccination should be included in the concept of IO therapy, it is not mentioned in this review because of the paucity of relevant evidence.

Molecular characterization of HLA class II binding to the LAG-3 T cell co-inhibitory receptor

Immune checkpoint inhibitors (antibodies that block the T cell co-inhibitory receptors PD-1/PD-L1 or CTLA-4) have revolutionized the treatment of some forms of cancer. Importantly, combination approaches using drugs that target both pathways have been shown to boost the efficacy of such treatments. Subsequently, several other T cell inhibitory receptors have been identified for the development of novel immune checkpoint inhibitors. Included in this list is the co-inhibitory receptor lymphocyte activation gene-3 (LAG-3), which is upregulated on T cells extracted from tumor sites that have suppressive or exhausted phenotypes. However, the molecular rules that govern the function of LAG-3 are still not understood. Using surface plasmon resonance combined with a novel bead-based assay (AlphaScreenTM ), we demonstrate that LAG-3 can directly and specifically interact with intact human leukocyte antigen class II (HLA-II) heterodimers. Unlike the homologue CD4, which has an immeasurably weak affinity using these biophysical approaches, LAG-3 binds with low micromolar affinity. We further validated the interaction at the cell surface by staining LAG-3+ cells with pHLA-II-multimers. These data provide new insights into the mechanism by which LAG-3 initiates T cell inhibition.

Immune checkpoint: The novel target for antitumor therapy

Inhibitory checkpoint molecules include programmed cell death-1 (PD-1), programmed cell death ligand-1 (PD-L1), cytotoxic T lymphocyte antigen-4 (CTLA-4), human endogenous retrovirus-H Long terminal repeat-associating 2 (HHLA2), B7 homolog 4 protein (B7-H4), T cell membrane protein-3 (TIM-3) and Lymphocyte-activation gene 3 (LAG-3), which are up-regulated during tumorigenesis. These pathways are essential to down-regulate the immune system by blocking the activation of T cells. In recent years, immune checkpoint blockers (ICBs) against PD-1, PD-L1, CTLA-4 or TIM-3 has made remarkable progress in the clinical application, revolutionizing the treatment of malignant tumors and improving patients' overall survival. However, the efficacy of ICBs in some patients does not seem to be good enough, and more immune-related adverse events (irAEs) will inevitably occur. Therefore, biomarkers research provides practical guidance for clinicians to identify patients who are most likely to benefit from or exhibit resistance to particular types of immune checkpoint therapy. There are two points in general. On the one hand, given the spatial and temporal differential expression of immune checkpoint molecules during immunosuppression process, it is essential to understand their mechanisms to design the most effective individualized therapy. On the other hand, due to the lack of potent immune checkpoints, it is necessary to combine them with novel biomarkers (such as exosomes and ctDNA) and other anticancer modalities (such as chemotherapy and radiotherapy).

Lymphocyte-activation gene 3 expression associates with poor prognosis and immunoevasive contexture in Epstein-Barr virus-positive and MLH1-defective gastric cancer patients

Lymphocyte activation gene 3 (LAG-3) is a transmembrane immune checkpoint that facilitates immune escape via suppressing T-cell-mediated anti-tumor immunity. The role of LAG-3 in gastric cancer is little known. Consequently, we assessed the clinical significance of LAG-3 in gastric cancer. In our study, patients with gastric cancer from Zhongshan Hospital (n = 464) and data from the Asian Cancer Research Group (n = 300) were analyzed. LAG-3⁺ cell infiltration and other immune contexture in gastric cancer were detected by immunohistochemistry. Kaplan-Meier curves and log-rank test were used for survival analyses. Intratumoral LAG-3⁺ cells mainly accumulated in Epstein-Barr virus (EBV)-positive (EBV subtype) and MLH1-defective (dMLH1 subtype) gastric cancer. Furthermore, LAG-3⁺ cell infiltration was strongly associated with inferior clinical outcomes in patients with these two subtypes of gastric cancer. Moreover, we found intratumoral LAG-3⁺ cell high infiltration was associated with an immunoevasive contexture featured by decreased IFN-γ⁺ cells and perforin-1⁺ cells, but increased regulatory T cells and M2-like macrophages in EBV/dMLH1 subtype of gastric cancer. LAG-3 was a poor prognostic factor and might be a potential immunotherapeutic target in EBV-positive and MLH1-defective gastric cancer.

Immune-Directed Molecular Imaging Biomarkers

Imaging has played a critical role in the management of patients with cancer. Novel therapies are emerging rapidly; however, they are effective only in some patients. With the advent of new targeted therapeutics and immunotherapy, the limitations of conventional imaging methods are becoming more evident. FDG-PET imaging is restricted to the optimal assessment of immune therapies. There is a critical unmet need for pharmacodynamic and prognostic imaging biomarkers. Radiolabeled antibodies or small molecules can allow for specific assessment of targets in expression and concentration. Several such imaging agents have been under preclinical development. Early human studies with radiolabeled monoclonal antibodies or small molecules targeted to the epidermal growth factor receptor pathway have shown potential; targeted imaging of CA19.9 and CA-IX and are being further explored. Immune-directed imaging agents are highly desirable as biomarkers and preliminary studies with radiolabeled antibodies targeting immune mechanisms appear promising. While novel agents are being developed, larger well-designed studies are needed to validate the role of these agents as biomarkers in the clinical management of patients.

Roles for the FCRL6 Immunoreceptor in Tumor Immunology

Members of the Fc receptor-like (FCRL1-6) gene family encode transmembrane glycoproteins that are preferentially expressed by B cells and generally repress responses via cytoplasmic tyrosine-based regulation. Given their distribution and function, there is a growing appreciation for their roles in lymphoproliferative disorders and as immunotherapeutic targets. In contrast to FCRL1-5, FCRL6 is distinctly expressed outside the B lineage by cytotoxic T and NK lymphocytes. Its restricted expression by these orchestrators of cell-mediated immunity, along with its inhibitory properties and extracellular interactions with MHCII/HLA-DR, represent a newly appreciated axis with relevance in tolerance and cancer defense. The significance of FCRL6 in this arena has been recently demonstrated by its upregulation in HLA-DR⁺ tumor samples from melanoma, breast, and lung cancer patients who relapsed following PD-1 blockade. These findings imply a potential mechanistic role for FCRL6 in adaptive evasion to immune checkpoint therapy. Here we review these new developments in the FCRL field and identify new evidence for the prognostic significance of FCRL6 in malignancies that collectively indicate its potential as a biomarker and therapeutic target.

Lymphocyte Activation Gene-3 Maintains Mitochondrial and Metabolic Quiescence in Naive CD4+ T Cells

Lymphocyte activation gene-3 (LAG-3) is an inhibitory receptor expressed by CD4⁺ T cells and tempers their homeostatic expansion. Because CD4⁺ T cell proliferation is tightly coupled to bioenergetics, we investigate the role of LAG-3 in modulating naive CD4⁺ T cell metabolism. LAG-3 deficiency enhances the metabolic profile of naive CD4⁺ T cells by elevating levels of mitochondrial biogenesis. In vivo, LAG-3 blockade partially restores expansion and the metabolic phenotype of wild-type CD4⁺ T cells to levels of Lag3^-/- CD4⁺ T cells, solidifying that LAG-3 controls these processes. Lag3^-/- CD4⁺ T cells also demonstrate greater signal transducer and activator of transcription 5 (STAT5) activation, enabling resistance to interleukin-7 (IL-7) deprivation. These results implicate this pathway as a target of LAG-3-mediated inhibition. Additionally, enhancement of STAT5 activation, as a result of LAG-3 deficiency, contributes to greater activation potential in these cells. These results identify an additional mode of regulation elicited by LAG-3 in controlling CD4⁺ T cell responses.

Serafino Zappacosta: An Enlightened Mentor and Educator

With this article, the authors aim to honor the memory of Serafino Zappacosta, who had been their mentor during the early years of their career in science. The authors discuss how the combination of Serafino Zappacosta's extraordinary commitment to teaching and passion for science created a fostering educational environment that led to the creation of the “Ruggero Ceppellini Advanced School of Immunology.” The review also illustrates how the research on the MHC and the inspirational scientific context in the Zappacosta's laboratory influenced the authors' early scientific interests, and subsequent professional work as immunologists.

Single-Cell Transcriptome Analysis Reveals Disease-Defining T-cell Subsets in the Tumor Microenvironment of Classic Hodgkin Lymphoma

Hodgkin lymphoma is characterized by an extensively dominant tumor microenvironment (TME) composed of different types of noncancerous immune cells with rare malignant cells. Characterization of the cellular components and their spatial relationship is crucial to understanding cross-talk and therapeutic targeting in the TME. We performed single-cell RNA sequencing of more than 127,000 cells from 22 Hodgkin lymphoma tissue specimens and 5 reactive lymph nodes, profiling for the first time the phenotype of the Hodgkin lymphoma-specific immune microenvironment at single-cell resolution. Single-cell expression profiling identified a novel Hodgkin lymphoma-associated subset of T cells with prominent expression of the inhibitory receptor LAG3, and functional analyses established this LAG3⁺ T-cell population as a mediator of immunosuppression. Multiplexed spatial assessment of immune cells in the microenvironment also revealed increased LAG3⁺ T cells in the direct vicinity of MHC class II-deficient tumor cells. Our findings provide novel insights into TME biology and suggest new approaches to immune-checkpoint targeting in Hodgkin lymphoma. SIGNIFICANCE: We provide detailed functional and spatial characteristics of immune cells in classic Hodgkin lymphoma at single-cell resolution. Specifically, we identified a regulatory T-cell-like immunosuppressive subset of LAG3⁺ T cells contributing to the immune-escape phenotype. Our insights aid in the development of novel biomarkers and combination treatment strategies targeting immune checkpoints.See related commentary by Fisher and Oh, p. 342.This article is highlighted in the In This Issue feature, p. 327.

Characterization of LAG-3, CTLA-4, and CD8+ TIL density and their joint influence on the prognosis of patients with esophageal squamous cell carcinoma

Background

We aimed to characterize the relationships of lymphocyte activation gene-3 (LAG-3) expression, cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4) expression, and CD8⁺ tumor-infiltrating lymphocyte (TIL) density, and to investigate the joint prognostic impact of these three markers in patients with surgically resected esophageal squamous cell carcinoma (ESCC).

Methods

Expression of LAG-3, CTLA-4 and the density of CD8⁺ TILs were evaluated by immunohistochemistry in resected ESCC. The associations between LAG-3 expression and clinicopathologic characteristics, as well as patient prognoses, were analyzed.

Results

A total of 183 patients were included. LAG-3 expression was observed in 69 (37.7%) patients. Positive LAG-3 expression was significantly associated with CTLA-4 expression (P=0.004). LAG-3 positivity, CTLA-4 positivity, and low CD8⁺ TIL densities were significantly associated with worsening recurrence-free survival (RFS) [LAG-3: hazard ratio (HR), 1.72; 95% confidence interval (CI), 1.10-2.89; P=0.019; CTLA-4: HR, 1.69; 95% CI, 1.04-2.73; P=0.033; CD8⁺: HR, 0.60; 95% CI, 0.38-0.94; P=0.025] and overall survival (OS) (LAG-3: HR, 2.09; 95% CI, 1.24-3.53; P=0.006; CTLA-4: HR, 1.47; 95% CI, 0.86-2.53; P=0.161; CD8⁺: HR, 0.56; 95% CI, 0.33-0.95; P=0.032). Subgroup analysis revealed that the LAG-3 CTLA-4 CD8⁺ group had the best RFS (P<0.001) and OS (P<0.001).

Conclusions

LAG-3 expression was correlated with CTLA-4 expression on TILs. Positive LAG-3 expression was associated with poor prognoses in ESCC. A combination of LAG-3, CTLA-4 expression and CD8⁺ TILs density could further stratify patients into different subgroups with distinct prognoses.

Novel immune checkpoint targets: moving beyond PD-1 and CTLA-4

The emergence of immune checkpoint inhibitors (ICIs), mainly including anti-programmed cell death protein 1/programmed cell death ligand 1 (PD-1/PD-L1) and anti-cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) monoclonal antibodies (mAbs), has shaped therapeutic landscape of some type of cancers. Despite some ICIs have manifested compelling clinical effectiveness in certain tumor types, the majority of patients still showed de novo or adaptive resistance. At present, the overall efficiency of immune checkpoint therapy remains unsatisfactory. Exploring additional immune checkpoint molecules is a hot research topic. Recent studies have identified several new immune checkpoint targets, like lymphocyte activation gene-3 (LAG-3), T cell immunoglobulin and mucin-domain containing-3 (TIM-3), T cell immunoglobulin and ITIM domain (TIGIT), V-domain Ig suppressor of T cell activation (VISTA), and so on. The investigations about these molecules have generated promising results in preclinical studies and/or clinical trials. In this review, we discussed the structure and expression of these newly-characterized immune checkpoints molecules, presented the current progress and understanding of them. Moreover, we summarized the clinical data pertinent to these recent immune checkpoint molecules as well as their application prospects.

Immune and Inflammatory Cells of the Tumor Microenvironment Represent Novel Therapeutic Targets in Classical Hodgkin Lymphoma

Classical Hodgkin Lymphoma (cHL) is a B-cell malignancy that, typically, responds well to standard therapies. However, patients who relapse after standard regimens or are refractory to induction therapy have a dismal outcome. The implementation of novel therapies such as the anti-CD30 monoclonal antibody Brentuximab Vedotin and immune checkpoint inhibitors has provided curative options for many of these patients. Nonetheless, responses are rarely durable, emphasizing the need for new agents. cHL is characterized by a unique microenvironment in which cellular and humoral components interact to promote tumor survival and dissemination. Knowledge of the complex composition of cHL microenvironment is constantly evolving; in particular, there is growing interest in certain cell subsets such as tumor-associated macrophages, myeloid-derived suppressor cells and neutrophils, all of which have a relevant role in the pathogenesis of the disease. The unique biology of the cHL microenvironment has provided opportunities to develop new drugs, many of which are currently being tested in preclinical and clinical settings. In this review, we will summarize novel insights in the crosstalk between tumor cells and non-malignant inflammatory cells. In addition, we will discuss the relevance of tumor-microenvironment interactions as potential therapeutic targets.

The role of immune regulatory molecules in multiple sclerosis

Multiple sclerosis (MS) is the most common demyelinating disease which mainly impacts the integrity of central nervous system (CNS). MS etiology is not clearly known but genetic, environmental factors and immune system are the most frequently explored risk factors. Adaptive immune responses have a critical role in MS pathogenesis in which auto-reactive T-cells and autoantibodies are main orchestrators. Immune responses are modulated by inhibitory molecules which regulates adaptive system activation and hemostasis interface. These molecules suppress immune responses through inhibition of cytokine secretion and T cell proliferation and subsequently reducing the inflammation and respective damage. Therefore the critical role of inhibitory molecules in regulating the healthy and safe immune responses make them very attractive target for immunotherapy. In this review paper, the role of inhibitory molecules expressed on the various immune cell types in MS pathogenesis and experimental autoimmune encephalomyelitis (EAE) animal model will be summarized.

Blockade of PD-1 and LAG-3 Immune Checkpoints Combined with Vaccination Restores the Function of Antiviral Tissue-Resident CD8+ TRM Cells and Reduces Ocular Herpes Simplex Infection and Disease in HLA Transgenic Rabbits

Chronic viruses such as herpes simplex virus 1 (HSV-1) evade the hosts' immune system by inducing the exhaustion of antiviral T cells. In the present study, we found that exhausted HSV-specific CD8⁺ T cells, with elevated expression of programmed death ligand-1 (PD-1) and lymphocyte activation gene-3 (LAG-3) receptors were frequent in symptomatic patients, with a history of numerous episodes of recurrent corneal herpetic disease, compared to asymptomatic patients who never had corneal herpetic disease. Subsequently, using a rabbit model of recurrent ocular herpes, we found that the combined blockade of PD-1 and LAG-3 pathways with antagonist antibodies significantly restored the function of tissue-resident antiviral CD8⁺ T_RM cells in both the cornea and the trigeminal ganglia (TG). An increased number of functional tissue-resident HSV-specific CD8⁺ T_RM cells in latently infected rabbits was associated with protection against recurrent herpes infection and disease. Compared to the PD-1 or LAG-3 blockade alone, the combined blockade of PD-1 and LAG-3 appeared to have a synergistic effect in generating frequent polyfunctional Ki-67⁺, IFN-γ⁺, CD107⁺, and CD8⁺ T cells. Moreover, using the human leukocyte antigen (HLA) transgenic rabbit model, we found that dual blockade of PD-1 and LAG-3 reinforced the effect of a multiepitope vaccine in boosting the frequency of HSV-1-specific CD8⁺ T_RM cells and reducing disease severity. Thus, both the PD-1 and the LAG-3 exhaustion pathways play a fundamental role in ocular herpes T cell immunopathology and provide important immune checkpoint targets to combat ocular herpes.IMPORTANCE HSV-specific tissue-resident memory CD8⁺ T_RM cells play a critical role in preventing virus reactivation from latently infected TG and subsequent virus shedding in tears that trigger the recurrent corneal herpetic disease. In this report, we determined how the dual blockade of PD-1 and LAG-3 immune checkpoints, combined with vaccination, improved the function of CD8⁺ T_RM cells associated with a significant reduction in recurrent ocular herpes in HLA transgenic (Tg) rabbit model. The combined blockade of PD-1 and LAG-3 appeared to have a synergistic effect in generating frequent polyfunctional CD8⁺ T_RM cells that infiltrated both the cornea and the TG. The preclinical findings using the established HLA Tg rabbit model of recurrent herpes highlight that blocking immune checkpoints combined with a T cell-based vaccine would provide an important strategy to combat recurrent ocular herpes in the clinic.

Preclinical Development of the Anti-LAG-3 Antibody REGN3767: Characterization and Activity in Combination with the Anti-PD-1 Antibody Cemiplimab in Human PD-1xLAG-3-Knockin Mice

In the tumor microenvironment, multiple inhibitory checkpoint receptors can suppress T-cell function, thereby enabling tumor immune evasion. Blockade of one of these checkpoint receptors, PD-1, with therapeutic antibodies has produced positive clinical responses in various cancers; however, the efficacy of this approach can be further improved. Simultaneously targeting multiple inhibitory checkpoint receptors has emerged as a promising therapeutic strategy. Here, we report the development and characterization of REGN3767, a fully human IgG4 antibody targeting LAG-3, another inhibitory receptor on T cells. REGN3767 binds human and monkey LAG-3 with high affinity and specificity and blocks the interaction of LAG-3 with its ligand, MHC class II. In an engineered T-cell/antigen-presenting cell bioassay, REGN3767 alone, or in combination with cemiplimab (REGN2810, human anti-PD-1 antibody), blocked inhibitory signaling to T cells mediated by hLAG-3/MHCII in the presence of PD-1/PD-L1. To test the in vivo activity of REGN3767 alone or in combination with cemiplimab, we generated human PD-1xLAG-3 knockin mice, in which the extracellular domains of mouse Pdcd1 and Lag3 were replaced with their human counterparts. In these humanized mice, treatment with cemiplimab and REGN3767 showed increased efficacy in a mouse tumor model and enhanced the secretion of proinflammatory cytokines by tumor-specific T cells. The favorable pharmacokinetics and toxicology of REGN3767 in nonhuman primates, together with enhancement of antitumor efficacy of anti-PD-1 antibody in preclinical tumor models, support its clinical development.