TIGIT immune checkpoint blockade restores CD8+ T-cell immunity against multiple myeloma

PVR/TIGIT and PD-L1/PD-1 expression predicts survival and enlightens combined immunotherapy in lung squamous cell carcinoma

PVR/TIGIT and PD-L1/PD-1 axes play essential roles in tumor immune evasion and could be potential targets for combined immunotherapy. We aimed to evaluate the expression status of the above-mentioned immune markers in lung squamous cell carcinoma (LUSC), and investigate their survival impact and relevance with the immune microenvironment and clinicopathological features. We retrospectively collected specimens from 190 LUSC patients, who underwent pulmonary surgeries, and we performed immunohistochemistry assays of PVR, TIGIT, PD-L1, PD-1 and CD8. In our cohort, the positive rate of PVR was 85.8%, which was much higher than the positive rate of PD-L1 at 26.8%. A total of 32 (16.8%) patients demonstrated co-expression of PVR/PD-L1. High TIGIT density was correlated with positive PD-L1 expression, high PD-1 density, and high CD8 density (PD-L1, P=0.033; PD-1, P<0.001; CD8, P<0.001), and positive PVR expression was correlated with positive PD-L1 expression (P=0.046). High TIGIT density and high PVR/TIGIT expression were correlated with advanced TNM stage (TIGIT density, P=0.020; PVR/TIGIT expression, P=0.041). Patients with positive PVR expression, high TIGIT density, high PVR/TIGIT expression and PVR/PD-L1 co-expression exhibited a significantly worse prognosis (PVR, P=0.038; TIGIT, P=0.027; PVR/TIGIT, P=0.014; PVR/PD-L1, P=0.018). Multivariate analysis demonstrated that PVR/PD-L1 co-expression (Hazard ratio [HR], 1.756, 95% CI, 1.152-2.676, P=0.009) was an independent prognostic factor in LUSC patients. In conclusion, we demonstrated the expression status of PVR/TIGIT and PD-L1/PD-1 in LUSC. PVR/PD-L1 co-expression was an independent prognostic factor in LUSC patients and may serve as a potential predictive biomarker for dual-targeting immunotherapy.

Positron Emission Tomography Probes for Imaging Cytotoxic Immune Cells

Non-invasive positron emission tomography (PET) imaging of immune cells is a powerful approach for monitoring the dynamics of immune cells in response to immunotherapy. Despite the clinical success of many immunotherapeutic agents, their clinical efficacy is limited to a subgroup of patients. Conventional imaging, as well as analysis of tissue biopsies and blood samples do not reflect the complex interaction between tumour and immune cells. Consequently, PET probes are being developed to capture the dynamics of such interactions, which may improve patient stratification and treatment evaluation. The clinical efficacy of cancer immunotherapy relies on both the infiltration and function of cytotoxic immune cells at the tumour site. Thus, various immune biomarkers have been investigated as potential targets for PET imaging of immune response. Herein, we provide an overview of the most recent developments in PET imaging of immune response, including the radiosynthesis approaches employed in their development.

V-Set and immunoglobulin domain containing (VSIG) proteins as emerging immune checkpoint targets for cancer immunotherapy

The development of immune checkpoint inhibitors is becoming a promising approach to fight cancers. Antibodies targeting immune checkpoint proteins such as CTLA-4 and PD-1 can reinvigorate endogenous antitumor T-cell responses and bring durable advantages to several malignancies. However, only a small subset of patients benefit from these checkpoint inhibitors. Identification of new immune checkpoints with the aim of combination blockade of multiple immune inhibitory pathways is becoming necessary to improve efficiency. Recently, several B7 family-related proteins, TIGIT, VSIG4, and VSIG3, which belong to the VSIG family, have attracted substantial attention as coinhibitory receptors during T-cell activation. By interacting with their corresponding ligands, these VSIG proteins inhibit T-cell responses and maintain an immune suppressive microenvironment in tumors. These results indicated that VSIG family members are becoming putative immune checkpoints in cancer immunotherapy. In this review, we summarized the function of each VSIG protein in regulating immune responses and in tumor progression, thus providing an overview of our current understanding of VSIG family members.

T-Cell-Based Cellular Immunotherapy of Multiple Myeloma: Current Developments

Simple Summary

Over the past two decades, there has been significant progress in the treatment of multiple myeloma. Starting with the approval of bortezomib and lenalidomide, followed by newer agents in the same classes, monoclonal antibodies, and most recently idecabtagene vicleucel and ciltacabtagene autoleucel, which are genetically engineered autologous T-cell-based therapies, our view of this disease has changed from incurable to controllable and potentially curable. In addition to multiple myeloma and B-cell lymphomas, T-cell-based therapies are also actively investigated in various types of hematological and non-hematological malignancies and are considered one of the most impactful evolutions in cancer therapeutics. This review aims to summarize existing data regarding the efficacy, toxicity, and management of unique adverse events in T-cell-based therapies that are both clinically available and under investigation. We will also address undergoing efforts to improve the survival outcomes of multiple myeloma patients through this treatment modality.

Abstract

T-cell-based cellular therapy was first approved in lymphoid malignancies (B-cell acute lymphoblastic leukemia and large B-cell lymphoma) and expanding its investigation and application both in hematological and non-hematological malignancies. Two anti-BCMA (B cell maturation antigen) CAR (Chimeric Antigen Receptor) T-cell therapies have been recently approved for relapsed and refractory multiple myeloma with excellent efficacy even in the heavily pre-treated patient population. This new therapeutic approach significantly changes our practice; however, there is still room for further investigation to optimize antigen receptor engineering, cell harvest/selection, treatment sequence, etc. They are also associated with unique adverse events, especially CRS (cytokine release syndrome) and ICANS (immune effector cell-associated neurotoxicity syndrome), which are not seen with other anti-myeloma therapies and require expertise for management and prevention. Other T-cell based therapies such as TCR (T Cell Receptor) engineered T-cells and non-genetically engineered adoptive T-cell transfers (Vγ9 Vδ2 T-cells and Marrow infiltrating lymphocytes) are also actively studied and worth attention. They can potentially overcome therapeutic challenges after the failure of CAR T-cell therapy through different mechanisms of action. This review aims to provide readers clinical data of T-cell-based therapies for multiple myeloma, management of unique toxicities and ongoing investigation in both clinical and pre-clinical settings.

Characterization of the Tumor Microenvironment in Osteosarcoma Identifies Prognostic- and Immunotherapy-Relevant Gene Signatures

The osteosarcoma (OS) microenvironment is composed of tumor cells, immune cells, and stromal tissue and is emerging as a pivotal player in OS development and progression. Thus, microenvironment-targeted strategies are urgently needed to improve OS treatment outcomes. Using principal component analysis (PCA), we systematically examined the tumor microenvironment (TME) and immune cell infiltration of 88 OS cases and constructed a TME scoring system based on the TMEscore high and TMEscore low phenotypes. Our analysis revealed that TMEscore high correlates with longer survival in OS patients, elevated immune cell infiltration, increased immune checkpoints, and increased sensitivity to chemotherapy. TMEscore low strongly correlated with immune exclusion. These observations were externally validated using a GEO dataset (GSE21257) from 53 OS patients. Our laboratory data also proved our findings. This finding enhances our understanding of the immunological landscape in OS and may uncover novel targeted therapeutic strategies.

Multiple Myeloma Therapy: Emerging Trends and Challenges

Multiple myeloma (MM) is a complex hematologic malignancy characterized by the uncontrolled proliferation of clonal plasma cells in the bone marrow that secrete large amounts of immunoglobulins and other non-functional proteins. Despite decades of progress and several landmark therapeutic advancements, MM remains incurable in most cases. Standard of care frontline therapies have limited durable efficacy, with the majority of patients eventually relapsing, either early or later. Induced drug resistance via up-modulations of signaling cascades that circumvent the effect of drugs and the emergence of genetically heterogeneous sub-clones are the major causes of the relapsed-refractory state of MM. Cytopenias from cumulative treatment toxicity and disease refractoriness limit therapeutic options, hence creating an urgent need for innovative approaches effective against highly heterogeneous myeloma cell populations. Here, we present a comprehensive overview of the current and future treatment paradigm of MM, and highlight the gaps in therapeutic translations of recent advances in targeted therapy and immunotherapy. We also discuss the therapeutic potential of emerging preclinical research in multiple myeloma.

A comprehensive review about the utilization of immune checkpoint inhibitors and combination therapy in hepatocellular carcinoma: an updated review

A pharmacological class known as immune checkpoint inhibitors (ICIs) has been developed as a potential treatment option for various malignancies, including HCC. In HCC, ICIs have demonstrated clinically significant advantages as monotherapy or combination therapy. ICIs that target programmed cell death protein 1 (PD-1) and programmed cell death protein ligand 1 (PD-L1), as well as cytotoxic T lymphocyte antigen 4 (CTLA-4), have made significant advances in cancer treatment. In hepatocellular carcinoma (HCC), several ICIs are being tested in clinical trials, and the area is quickly developing. As immunotherapy-related adverse events (irAEs) linked with ICI therapy expands and gain worldwide access, up-to-date management guidelines become crucial to the safety profile of ICIs. This review aims to describe the evidence for ICIs in treating HCC, emphasizing the use of combination ICIs.

High Expression of the Costimulatory Checkpoint Factor DNAM-1 by CD4+ T-Cells from Multiple Myeloma Patients Refractory to Daratumumab-Containing Regimens

Multiple myeloma is an incurable disease characterized by unregulated growth of malignant plasma cells in the bone marrow (BM). Tumor-induced dysfunction of T-cells may be responsible for immune evasion and failure of immunotherapy. Therefore, a better understanding of the phenotype of T-cells at the tumor site is needed. We assessed the expression of immune regulatory receptors on T-cell subsets from peripheral blood (PB) and BM using multicolor flow cytometry. Paired PB and BM samples were collected from newly diagnosed, treatment-naïve myeloma patients (n = 19) and patients progressing during treatment with the CD38 monoclonal antibody daratumumab alone or in combination with other anti-myeloma drugs (n = 39). We observed that CD4+ T-cells from both PB and BM of patients relapsing on daratumumab have a higher expression of the costimulatory checkpoint receptor DNAM-1. The potential role of DNAM-1+CD4+ T-cells in the development of resistance to daratumumab needs further exploration. We also observed that the inhibitory checkpoint receptor TIGIT is more frequently expressed by BM CD8+ T-cells from myeloma patients than PD-1 and CTLA-4, which supports the hypothesis that TIGIT may play a central role in the immune escape of the malignant plasma cells.

A Journey through the Inter-Cellular Interactions in the Bone Marrow in Multiple Myeloma: Implications for the Next Generation of Treatments

Tumors are composed of a plethora of extracellular matrix, tumor and non-tumor cells that form a tumor microenvironment (TME) that nurtures the tumor cells and creates a favorable environment where tumor cells grow and proliferate. In multiple myeloma (MM), the TME is the bone marrow (BM). Non-tumor cells can belong either to the non-hematological compartment that secretes soluble mediators to create a favorable environment for MM cells to grow, or to the immune cell compartment that perform an anti-MM activity in healthy conditions. Indeed, marrow-infiltrating lymphocytes (MILs) are associated with a good prognosis in MM patients and have served as the basis for developing different immunotherapy strategies. However, MM cells and other cells in the BM can polarize their phenotype and activity, creating an immunosuppressive environment where immune cells do not perform their cytotoxic activity properly, promoting tumor progression. Understanding cell-cell interactions in the BM and their impact on MM proliferation and the performance of tumor surveillance will help in designing efficient anti-MM therapies. Here, we take a journey through the BM, describing the interactions of MM cells with cells of the non-hematological and hematological compartment to highlight their impact on MM progression and the development of novel MM treatments.

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.

Invariant NKT cells dictate antitumor immunity elicited by a bispecific antibody cotargeting CD3 and BCMA

CD3-engaging bispecific antibodies (BsAbs) have emerged as powerful therapeutic approaches by their ability to redirect T cells to eliminate tumor cells in an MHC-independent manner. However, it remains largely unknown how we can potentiate the efficacy of BsAbs. To address this, we investigated immunological mechanisms of action of a BsAb co-targeting CD3 and B-cell maturation antigen (BCMA) in syngeneic preclinical myeloma models. Treatment with the CD3/BCMA BsAb stimulated multiple CD3-expressing T cell subsets, as well as natural killer (NK) cells in the myeloma bone marrow (BM), highlighting its broad immunostimulatory effect. Notably, the BsAb-mediated immunostimulatory and anti-tumor effects were abrogated in mice lacking invariant NKT (iNKT) cells. Mechanistically, activation of iNKT cells and IL-12 production from dendritic cells (DCs) were crucial upstream events for triggering effective anti-tumor immunity by the BsAb. Myeloma progression was associated with reduced numbers of BM iNKT cells. Importantly, the therapeutic efficacy of a single dose of the CD3/BCMA BsAb was remarkably augmented by restoring iNKT cell activity using adoptive transfer of α-galactosylceramide-loaded DCs. Together, these results reveal iNKT cells as a critical player for the anti-tumor activity of CD3-engaging BsAbs, providing important translational implications.

Targeting the Microenvironment for Treating Multiple Myeloma

Multiple myeloma (MM) is a malignant, incurable disease characterized by the expansion of monoclonal terminally differentiated plasma cells in the bone marrow. MM is consistently preceded by an asymptomatic monoclonal gammopathy of undetermined significance, and in the absence of myeloma defining events followed by a stage termed smoldering multiple myeloma (SMM), which finally progresses to active myeloma if signs of organ damage are present. The reciprocal interaction between tumor cells and the tumor microenvironment plays a crucial role in the development of MM and the establishment of a tumor-promoting stroma facilitates tumor growth and myeloma progression. Since myeloma cells depend on signals from the bone marrow microenvironment (BMME) for their survival, therapeutic interventions targeting the BMME are a novel and successful strategy for myeloma care. Here, we describe the complex interplay between myeloma cells and the cellular components of the BMME that is essential for MM development and progression. Finally, we present BMME modifying treatment options such as anti-CD38 based therapies, immunomodulatory drugs (IMiDs), CAR T-cell therapies, bispecific antibodies, and antibody-drug conjugates which have significantly improved the long-term outcome of myeloma patients, and thus represent novel therapeutic standards.

Emergence of the CD226 Axis in Cancer Immunotherapy

In recent years, a set of immune receptors that interact with members of the nectin/nectin-like (necl) family has garnered significant attention as possible points of manipulation in cancer. Central to this axis, CD226, TIGIT, and CD96 represent ligand (CD155)-competitive co-stimulatory/inhibitory receptors, analogous to the CTLA-4/B7/CD28 tripartite. The identification of PVRIG (CD112R) and CD112 has introduced complexity and enabled additional nodes of therapeutic intervention. By virtue of the clinical progression of TIGIT antagonists and emergence of novel CD96- and PVRIG-based approaches, our overall understanding of the ‘CD226 axis’ in cancer immunotherapy is starting to take shape. However, several questions remain regarding the unique characteristics of, and mechanistic interplay between, each receptor-ligand pair. This review provides an overview of the CD226 axis in the context of cancer, with a focus on the status of immunotherapeutic strategies (TIGIT, CD96, and PVRIG) and their underlying biology (i.e., cis/trans interactions). We also integrate our emerging knowledge of the immune populations involved, key considerations for Fc gamma (γ) receptor biology in therapeutic activity, and a snapshot of the rapidly evolving clinical landscape.

Update in TIGIT Immune-Checkpoint Role in Cancer

The in-depth characterization of cross-talk between tumor cells and T cells in solid and hematological malignancies will have to be considered to develop new therapeutical strategies concerning the reactivation and maintenance of patient-specific antitumor responses within the patient tumor microenvironment. Activation of immune cells depends on a delicate balance between activating and inhibitory signals mediated by different receptors. T cell immunoreceptor with immunoglobulin and ITIM domain (TIGIT) is an inhibitory receptor expressed by regulatory T cells (Tregs), activated T cells, and natural killer (NK) cells. TIGIT pathway regulates T cell-mediated tumor recognition in vivo and in vitro and represents an exciting target for checkpoint blockade immunotherapy. TIGIT blockade as monotherapy or in combination with other inhibitor receptors or drugs is emerging in clinical trials in patients with cancer. The purpose of this review is to update the role of TIGIT in cancer progression, looking at TIGIT pathways that are often upregulated in immune cells and at possible therapeutic strategies to avoid tumor aggressiveness, drug resistance, and treatment side effects. However, in the first part, we overviewed the role of immune checkpoints in immunoediting, the TIGIT structure and ligands, and summarized the key immune cells that express TIGIT.

Preclinical platforms to study therapeutic efficacy of human γδ T cells

BACKGROUND

Gamma delta (γδ) T lymphocytes are promising candidate for adoptive T cell therapy, however, their treatment efficacy is not satisfactory. Vδ2 T cells are unique to primates and few suitable models are available to assay their anti-tumour function.

METHODS

We tested human γδ T cell activation, tumour infiltration, and tumour-killing in four three-dimensional (3D) models, including unicellular, bicellular and multicellular melanoma spheroids, and patient-derived melanoma organoids. We studied the effects of checkpoint inhibitors on γδ T cells and performed a small molecule screen using these platforms.

RESULTS

γδ T cells rapidly responded to melanoma cells and infiltrated melanoma spheroids better than αβ T cells in PBMCs. Cancer-associated fibroblasts (CAFs) in bicellular spheroids, stroma cells in multicellular melanoma spheroids and inhibitory immune cells in organoids significantly inhibited immune cell infiltrates including γδ T cells and lessened their cytotoxicity to tumour cells. Tumour-infiltrating γδ T cells showed exhausted immunophenotypes with high checkpoints expression (CTLA-4, PD-1 and PD-L1). Immune checkpoint inhibitors increased γδ T cell infiltration of 3D models and killing of melanoma cells in all four 3D models. Our small molecule screen assay and subsequent mechanistic studies demonstrated that epigenetic modifiers enhanced the chemotaxis and cytotoxicity of γδ T cells through upregulating MICA/B, inhibiting HDAC6/7 pathway and downregulating the levels of PD-L1 and PD-L2 in CAFs and tumour cells. These compounds increased CXCR4 and CD107a expression, IFN-γ production and decreased PD-1 expression of γδ T cells.

CONCLUSIONS

Tumour-infiltrating γδ T cells show exhausted immunophenotypes and limited anti-tumour capacity in melanoma 3D models. Checkpoint inhibitors and epigenetic modifiers enhance anti-tumour functions of γδ T cells. These four 3D models provided valuable preclinical platforms to test γδ T cell functions for immunotherapy.

TIGIT/CD47 dual high expression predicts prognosis and is associated with immunotherapy response in lung squamous cell carcinoma

Background

Recent studies indicated that T cell immunoreceptor with immunoglobulin and ITIM domains (TIGIT) and cluster of differentiation 47 (CD47) have emerged as new potential immunotherapy targets. However, the roles of TIGIT and CD47 in lung squamous cell carcinoma (LUSC) have not been fully illustrated.

Methods

The specimens and clinicopathological information from 190 LUSC patients who underwent surgeries in our center were retrospectively collected. Immunohistochemical staining for TIGIT and CD47 was conducted. Transcriptional and clinical data of 479 LUSC were downloaded from The Cancer Genome Atlas (TCGA).

Results

In the TCGA LUSC cohort, 142 (29.6%) cases were TIGIT/CD47 dual high expression at RNA level. The expression levels of TIGIT and CD47 were significantly correlated (p < 0.001). The proportions of patients with high TIGIT expression (p = 0.001) and high TIGIT/CD47 dual high expression (p = 0.049) were both higher in female cases. Advanced TNM stage (p = 0.006) and TIGIT/CD47 dual high expression (p = 0.047) were independent prognostic factors for LUSC. In the 190 LUSC cohort of our center, 75 (39.5%) cases were TIGIT/CD47 dual high expression at protein level. Cross‐table analysis showed a correlation between TIGIT and CD47 expression. Older age (p = 0.001), advanced TNM stage (p < 0.001) and TIGIT/CD47 dual high expression (p = 0.046) were independent prognostic factors in our cohort.

Conclusion

We found that TIGIT and CD47 dual high expression was associated with poor prognosis in LUSC. We speculated that patients with dual high expression of CD47/TIGIT might be suitable for new target immunotherapy in the future.

Co-Expression of TIGIT and Helios Marks Immunosenescent CD8+ T Cells During Aging

Aging leads to alterations in the immune system that result in ineffective responsiveness against pathogens. Features of this process, collectively known as immunosenescence, accumulate in CD8⁺ T cells with age and have been ascribed to differentiation of these cells during the course of life. Here we aimed to identify novel markers in CD8⁺ T cells associated with immunosenescence. Furthermore, we assessed how these markers relate to the aging-related accumulation of highly differentiated CD27^-CD28^- cells. We found that co-expression of the transcription factor Helios and the aging-related marker TIGIT identifies CD8⁺ T cells that fail to proliferate and show impaired induction of activation markers CD69 and CD25 in response to stimulation in vitro. Despite this, in blood of older adults we found TIGIT⁺Helios⁺ T cells to become highly activated during an influenza-A virus infection, but these higher frequencies of activated TIGIT⁺Helios⁺ T cells associate with longer duration of coughing. Moreover, in healthy individuals, we found that TIGIT⁺Helios⁺ CD8⁺ T cells accumulate with age in the highly differentiated CD27^-CD28^- population. Interestingly, TIGIT⁺Helios⁺ CD8⁺ T cells also accumulate with age among the less differentiated CD27⁺CD28^- T cells before their transit into the highly differentiated CD27^-CD28^- stage. This finding suggests that T cells with immunosenescent features become prominent at old age also within the earlier differentiation states of these cells. Our findings show that co-expression of TIGIT and Helios refines the definition of immunosenescent CD8⁺ T cells and challenge the current dogma of late differentiation stage as proxy for T-cell immunosenescence.

PVR (CD155) Expression as a Potential Prognostic Marker in Multiple Myeloma

Poliovirus receptor (PVR, CD155) is upregulated during tumor progression, and PVR expression is associated with poor prognosis in cancer patients; however, prognostic implications for PVR in multiple myeloma (MM) have not been investigated. PVR plays an immunomodulatory role by interacting with CD226, CD96, and TIGIT. TIGIT is a checkpoint inhibitory receptor that can limit adaptive and innate immunity, and it binds to PVR with the highest affinity. We used immunohistochemistry, ELISA, qPCR, and flow cytometry to investigate the role of PVR in MM. PVR was highly expressed in patients with MM, and membrane PVR expression showed a significant correlation with soluble PVR levels. PVR expression was significantly associated with the Revised-International Staging System stage, presence of extramedullary plasmacytoma and bone lesion, percentage of bone marrow plasma cells (BMPCs), and β2-microglobulin levels, suggesting a possible role in advanced stages and metastasis. Furthermore, TIGIT expression was significantly correlated with the percentage of BMPCs. Patients with high PVR expression had significantly shorter overall and progression-free survival, and PVR expression was identified as an independent prognostic factor for poor MM survival. These findings indicate that PVR expression is associated with MM stage and poor prognosis, and is a potential prognostic marker for MM.

The Role of T Cell Immunity in Monoclonal Gammopathy and Multiple Myeloma: From Immunopathogenesis to Novel Therapeutic Approaches

Multiple Myeloma (MM) is a malignant growth of clonal plasma cells, typically arising from asymptomatic precursor conditions, namely monoclonal gammopathy of undetermined significance (MGUS) and smoldering MM (SMM). Profound immunological dysfunctions and cytokine deregulation are known to characterize the evolution of the disease, allowing immune escape and proliferation of neoplastic plasma cells. In the past decades, several studies have shown that the immune system can recognize MGUS and MM clonal cells, suggesting that anti-myeloma T cell immunity could be harnessed for therapeutic purposes. In line with this notion, chimeric antigen receptor T cell (CAR-T) therapy is emerging as a novel treatment in MM, especially in the relapsed/refractory disease setting. In this review, we focus on the pivotal contribution of T cell impairment in the immunopathogenesis of plasma cell dyscrasias and, in particular, in the disease progression from MGUS to SMM and MM, highlighting the potentials of T cell-based immunotherapeutic approaches in these settings.

Candida albicans evades NK cell elimination via binding of Agglutinin-Like Sequence proteins to the checkpoint receptor TIGIT

Candida albicans is the most common fungal pathogen and a prevalent cause of deadly bloodstream infections. Better understanding of the immune response against it, and the ways by which it evades immunity, are crucial for developing new therapeutics against it. Natural Killer (NK) cells are innate lymphocytes best known for their role against viruses and tumors. In recent years it became clear that NK cells also play an important role in anti-fungal immunity. Here we show that while NK cells recognize and eliminate C. albicans, the fungal cells inhibit NK cells by manipulating the immune checkpoint receptor TIGIT (T cell immunoreceptor with Ig and ITIM domains) in both humans and mice. We identify the responsible fungal ligands as members of the Als (Agglutinin-Like Sequences) protein family. Furthermore, we show that blocking this interaction using immunotherapy with a TIGIT-blocking antibody can re-establish anti-Candida immunity and serve as a potential therapeutic tool.

Natural killer cells have emerged as critical immune cells in the response to fungal infection. Here the authors identify how Candida albicans evades the natural killer cell response via expression of ligands that directly modify the natural killer cell response and can be therapeutically targeted to restore the anti-Candida immunity.

The Leading Role of the Immune Microenvironment in Multiple Myeloma: A New Target with a Great Prognostic and Clinical Value

Multiple myeloma (MM) is a plasma cell (PC) malignancy whose development flourishes in the bone marrow microenvironment (BMME). The BMME components’ immunoediting may foster MM progression by favoring initial immunotolerance and subsequent tumor cell escape from immune surveillance. In this dynamic process, immune effector cells are silenced and become progressively anergic, thus contributing to explaining the mechanisms of drug resistance in unresponsive and relapsed MM patients. Besides traditional treatments, several new strategies seek to re-establish the immunological balance in the BMME, especially in already-treated MM patients, by targeting key components of the immunoediting process. Immune checkpoints, such as CXCR4, T cell immunoreceptor with immunoglobulin and ITIM domains (TIGIT), PD-1, and CTLA-4, have been identified as common immunotolerance steps for immunotherapy. B-cell maturation antigen (BCMA), expressed on MMPCs, is a target for CAR-T cell therapy, antibody-(Ab) drug conjugates (ADCs), and bispecific mAbs. Approved anti-CD38 (daratumumab, isatuximab), anti-VLA4 (natalizumab), and anti-SLAMF7 (elotuzumab) mAbs interfere with immunoediting pathways. New experimental drugs currently being evaluated (CD137 blockers, MSC-derived microvesicle blockers, CSF-1/CSF-1R system blockers, and Th17/IL-17/IL-17R blockers) or already approved (denosumab and bisphosphonates) may help slow down immune escape and disease progression. Thus, the identification of deregulated mechanisms may identify novel immunotherapeutic approaches to improve MM patients’ outcomes.

TIGIT axis: novel immune checkpoints in anti-leukemia immunity

Hematologic malignancy evades immune-mediated recognition through upregulating various checkpoint inhibitory receptors (IRs) on several types of lymphocytes. Immunotherapies targeting IRs have provided ample evidence supporting regulating innate and adaptive immunity and obtaining clinical benefits. Newly described IRs have received considerable attention and are under investigation in cancer immunotherapy. Specifically, T cell immunoglobulin and ITIM domain is a novel inhibitory checkpoint receptor, and its immune checkpoint axis includes additional receptors such as CD96 and CD226, which are very promising targets. However, how the dynamics and functions of these receptor networks remain unknown, this review addresses the recent findings of the relevance of this complex receptor-ligand system and discusses their potential approaches in translating these preclinical findings into novel clinical agents in anti-leukemia immunotherapy.

TIGIT-CD226-PVR axis: advancing immune checkpoint blockade for cancer immunotherapy

Recent advances in understanding the roles of immune checkpoints in allowing tumors to circumvent the immune system have led to successful therapeutic strategies that have fundamentally changed oncology practice. Thus far, immunotherapies against only two checkpoint targets have been approved, CTLA-4 and PD-L1/PD-1. Antibody blockade of these targets enhances the function of antitumor T cells at least in part by relieving inhibition of the T cell costimulatory receptor CD28. These successes have stimulated considerable interest in identifying other pathways that may bte targeted alone or together with existing immunotherapies. One such immune checkpoint axis is comprised of members of the PVR/nectin family that includes the inhibitory receptor T cell immunoreceptor with Ig and immunoreceptor tyrosine-based inhibitory domains (TIGIT). Interestingly, TIGIT acts to regulate the activity of a second costimulatory receptor CD226 that works in parallel to CD28. There are currently over two dozen TIGIT-directed blocking antibodies in various phases of clinical development, testament to the promise of modulating this pathway to enhance antitumor immune responses. In this review, we discuss the role of TIGIT as a checkpoint inhibitor, its interplay with the activating counter-receptor CD226, and its status as the next advance in cancer immunotherapy.

Key Players of the Immunosuppressive Tumor Microenvironment and Emerging Therapeutic Strategies

The tumor microenvironment (TME) is a complex, dynamic battlefield for both immune cells and tumor cells. The advent of the immune checkpoint inhibitors (ICI) since 2011, such as the anti-cytotoxic T-lymphocyte associated protein (CTLA)-4 and anti-programmed cell death receptor (PD)-(L)1 antibodies, provided powerful weapons in the arsenal of cancer treatments, demonstrating unprecedented durable responses for patients with many types of advanced cancers. However, the response rate is generally low across tumor types and a substantial number of patients develop acquired resistance. These primary or acquired resistance are attributed to various immunosuppressive elements (soluble and cellular factors) and alternative immune checkpoints in the TME. Therefore, a better understanding of the TME is absolutely essential to develop therapeutic strategies to overcome resistance. Numerous clinical studies are underway using ICIs and additional agents that are tailored to the characteristics of the tumor or the TME. Some of the combination treatments are already approved by the Food and Drug Administration (FDA), such as platinum-doublet chemotherapy, tyrosine kinase inhibitor (TKI) -targeting vascular endothelial growth factor (VEGF) combined with anti-PD-(L)1 antibodies or immuno-immuno combinations (anti-CTLA-4 and anti-PD-1). In this review, we will discuss the key immunosuppressive cells, metabolites, cytokines or chemokines, and hypoxic conditions in the TME that contribute to tumor immune escape and the prospect of relevant clinical trials by targeting these elements in combination with ICIs.

Targeting PD-L1 and TIGIT could restore intratumoral CD8 T cell function in human colorectal cancer

Microsatellite stable colorectal cancers (MSS-CRC) are resistant to anti-PD-1/PD-L1 therapy but the combination of immune checkpoints inhibitors (ICI) could be a clue to reverse resistance. Our aim was to evaluate ex vivo the capacity of the combination of atezolizumab (anti-PD-L1) and tiragolumab (anti-TIGIT) to reactivate the immune response of tumor infiltrating lymphocytes (TILs) in MSS-CRC. We analysed CRC tumor tissue and the associated blood sample in parallel. For each patient sample, extensive immunomonitoring and cytokine production were tested. We generated an ex vivo assay to study immune reactivity following immune stimulation with checkpoint inhibitors of tumor cell suspensions. Three microsatellite instable (MSI) and 13 MSS-CRC tumors were analysed. To generalize our observations, bioinformatics analyses were performed on public data of single cell RNA sequencing of CRC TILs and RNA sequencing data of TCGA. Atezolizumab alone could only reactivate T cells from MSI tumors. Atezolizumab and tiragolumab reactivated T cells in 46% of MSS-CRC samples. Reactivation by ICK was observed in patients with higher baseline frequency of Th1 and Tc1 cells, and was also associated with higher baseline T cell polyfunctionality and higher CD96 expression. We showed that a high frequency of CD96 expression on T cells could be a surrogate marker of atezolizumab and tiragolumab efficacy. Together these data suggest that the association of atezolizumab and tiragolumab could restore function of CD4 and CD8 TILs in MSS-CRC and could be tested in a clinical trial in colorectal cancer patients with MSS status.

Recent Advances of Immune Checkpoint Inhibition and Potential for (Combined) TIGIT Blockade as a New Strategy for Malignant Pleural Mesothelioma

Malignant pleural mesothelioma (MPM) is a fatal cancer type that affects the membranes lining the lungs, and is causally associated with asbestos exposure. Until recently, the first-line treatment consisted of a combination of chemotherapeutics that only had a limited impact on survival, and had not been improved in decades. With the recent approval of combined immune checkpoint inhibition for MPM, promising new immunotherapeutic strategies are now emerging for this disease. In this review, we describe the current preclinical and clinical evidence of various immune checkpoint inhibitors in MPM. We will consider the advantages of combined immune checkpoint blockade in comparison with single agent checkpoint inhibitor drugs. Furthermore, recent evidence suggests a role for T cell immunoglobulin and ITIM domain (TIGIT), an inhibitory immunoreceptor, as a novel target for immunotherapy. As this novel immune checkpoint remains largely unexplored in mesothelioma, we will discuss the potential of TIGIT blockade as an alternative therapeutic approach for MPM. This review will emphasize the necessity for new and improved treatments for MPM, while highlighting the recent advances and future perspectives of combined immune checkpoint blockade, particularly aimed at PD-L1 and TIGIT.

Natural Killer Cells in the Malignant Niche of Multiple Myeloma

Natural killer (NK) cells represent a subset of CD3- CD7+ CD56+/dim lymphocytes with cytotoxic and suppressor activity against virus-infected cells and cancer cells. The overall potential of NK cells has brought them to the spotlight of targeted immunotherapy in solid and hematological malignancies, including multiple myeloma (MM). Nonetheless, NK cells are subjected to a variety of cancer defense mechanisms, leading to impaired maturation, chemotaxis, target recognition, and killing. This review aims to summarize the available and most current knowledge about cancer-related impairment of NK cell function occurring in MM.

Allogeneic Anti-BCMA CAR T Cells Are Superior to Multiple Myeloma-derived CAR T Cells in Preclinical Studies and May Be Combined with Gamma Secretase Inhibitors

Multiple myeloma remains an incurable plasma cell malignancy despite the rapidly evolving treatment landscape. Chimeric antigen receptor T cells targeted against BCMA have recently shown great promise in relapsed refractory multiple myeloma; however, all patients ultimately still progress from their disease. Lack of CAR T-cell persistence, impaired T-cell fitness in autologous CAR T-cell products and the presence of an immunosuppressive bone marrow (BM) microenvironment are contributory factors to treatment failure. We generated anti-BCMA CAR T cells from healthy donors (HD) and patients with multiple myeloma at different stages of disease to compare their T-cell profile, fitness, and cytotoxic activity in preclinical studies. We also used an ex vivo assay with multiple myeloma BM biopsies from distinct genomic subgroups to test the efficacy of HD-derived CAR T cells in a clinically relevant model. HD volunteers showed increased T-cell counts, higher CD4/CD8 ratio, and expanded naïve T-cell population compared with patients with multiple myeloma. After anti-BCMA CAR T-cell production, patients with relapsed multiple myeloma had lower frequencies of CAR⁺ T cells, decreased central memory phenotype, and increased checkpoint inhibitory markers compared with HD-derived products, which compromised their expansion and cytotoxicity against multiple myeloma cells in vitro. Importantly, HD-derived CAR T cells efficiently killed primary multiple myeloma cells within the BM microenvironment of different multiple myeloma genomic subgroups and their cytotoxic activity could be boosted with gamma secretase inhibitors. In conclusion, allogeneic anti-BCMA CAR T cells are a potential therapeutic strategy for patients with relapsed multiple myeloma and should be further developed in the clinic.

Significance

Multiple myeloma is an incurable cancer of the plasma cells. A new therapy with anti-BCMA CAR T cells - the patient's own T cells genetically engineered to find and kill myeloma cancer cells - has shown encouraging results. Unfortunately, patients still relapse. In this study, we propose to use T cells from HD volunteers, which have a stronger T-cell fitness, higher cancer killing capacity, and are ready to be administered when needed.

Structural and functional characterization of a monoclonal antibody blocking TIGIT

TIGIT is an immune checkpoint receptor that is expressed on subsets of activated T cells and natural killer (NK) cells. Several ligands for TIGIT, including poliovirus receptor (PVR), are expressed on cancer cells and mediate inhibitory signaling to suppress antitumor activities of the immune cells. Many studies support that the TIGIT signaling is a potential target for cancer immunotherapy. We developed an IgG4-type monoclonal antibody against human TIGIT, designated as MG1131, using a phage display library of single-chain variable fragments (scFvs). MG1131 interacts with TIGIT much more tightly than PVR does. The crystal structure of a scFv version of MG1131 bound to TIGIT was determined, showing that MG1131 could block the PVR-TIGIT interaction and thus the immunosuppressive signaling of TIGIT. Consistently, MG1131 is bound to TIGIT-expressing cells and interferes with PVR binding to these cells. Moreover, MG1131 increased NK cell-mediated tumor killing activities, inhibited immunosuppressive activity of regulatory T (Treg) cells from healthy donors, and restored interferon-γ secretion from peripheral blood mononuclear cells derived from multiple myeloma patients. MG1131 also increased T cell infiltration to the tumor site and inhibited tumor growth in mice. Collectively, these data indicate that MG1131 modulates the effector functions of T cells and NK cells positively and Treg cells negatively.

Gene of the month: T-cell immunoreceptor with immunoglobulin and ITIM domains (TIGIT)

Immune modulators play a crucial role in carcinogenesis and cancer progression by impairing cancer cell-targeted immune responses. T-cell immunoreceptor with immunoglobulin and immunoreceptor tyrosine-based inhibitory motif domains (TIGIT) regulates T-cell function and cancer cell recognition and was therefore identified as a promising target for cancer immunotherapy. TIGIT is expressed in T cells and natural killer (NK) cells and has three ligands: CD155, CD112 and CD113. CD155 binds TIGIT with the highest affinity and promotes direct and indirect downregulation of T-cell response. TIGIT signalling further inhibits NK function and secretion of proinflammatory cytokines. An association between TIGIT expression and poor survival was identified in multiple cancer entities. Blocking TIGIT with monoclonal antibodies, and a combination of TIGIT and programmed cell death protein 1 blockade in particular, prevented tumour progression, distant metastasis and tumour recurrence in in vivo models. Inhibition of TIGIT is currently evaluated in first clinical trials.

The importance of immune checkpoints in immune monitoring: A future paradigm shift in the treatment of cancer

The growth and development of cancer are directly correlated to the suppression of the immune system. A major breakthrough in cancer immunotherapy depends on various mechanisms to detect immunosuppressive factors that inhibit anti-tumor immune responses. Immune checkpoints are expressed on many immune cells such as T-cells, regulatory B cells (Bregs), dendritic cells (DCs), natural killer cells (NKs), regulatory T (Tregs), M2-type macrophages, and myeloid-derived suppressor cells (MDSCs). Immune inhibitory molecules, including CTLA-4, TIM-3, TIGIT, PD-1, and LAG-3, normally inhibit immune responses via negatively regulating immune cell signaling pathways to prevent immune injury. However, the up-regulation of inhibitory immune checkpoints during tumor progression on immune cells suppresses anti-tumor immune responses and promotes immune escape in cancer. It has recently been indicated that cancer cells can up-regulate various pathways of the immune checkpoints. Therefore, targeting immune inhibitory molecules through antibodies or miRNAs is a promising therapeutic strategy and shows favorable results. Immune checkpoint inhibitors (ICIs) are introduced as a new immunotherapy strategy that enhance immune cell-induced antitumor responses in many patients. In this review, we highlighted the function of each immune checkpoint on different immune cells and therapeutic strategies aimed at using monoclonal antibodies and miRNAs against inhibitory receptors. We also discussed current challenges and future strategies for maximizing these FDA-approved immunosuppressants' effectiveness and clinical success in cancer treatment.

A reporter gene assay for determining the biological activity of therapeutic antibodies targeting TIGIT

T cell immunoglobulin and ITIM domain (TIGIT) is a novel immune checkpoint that has been considered as a target in cancer immunotherapy. Current available bioassays for measuring the biological activity of therapeutic antibodies targeting TIGIT are restricted to mechanistic investigations because donor primary T cells are highly variable. Here, we designed a reporter gene assay comprising two cell lines, namely, CHO-CD112-CD3 scFv, which stably expresses CD112 (PVRL2, nectin-2) and a membrane-bound anti-CD3 single-chain fragment variable (scFv) as the target cell, and Jurkat-NFAT-TIGIT, which stably expresses TIGIT as well as the nuclear factor of activated T-cells (NFAT) response element-controlled luciferase gene, as the effector cell. The anti-CD3 scFv situated on the target cells activates Jurkat-NFAT-TIGIT cells through binding and crosslinking CD3 molecules of the effector cell, whereas interactions between CD112 and TIGIT prevent activation. The presence of anti-TIGIT mAbs disrupts their interaction, which in turn reverses the inactivation and luciferase expression. Optimization and validation studies have demonstrated that this assay is superior in terms of specificity, accuracy, linearity, and precision. In summary, this reliable and effective reporter gene assay may potentially be utilized in lot release control, stability assays, screening, and development of novel TIGIT-targeted therapeutic antibodies.

Comprehensive Analysis of m6A RNA Methylation Regulators in the Prognosis and Immune Microenvironment of Multiple Myeloma

Background

N6-methyladenosine is the most abundant RNA modification, which plays a prominent role in various biology processes, including tumorigenesis and immune regulation. Multiple myeloma (MM) is the second most frequent hematological malignancy.

Materials and Methods

Twenty-two m6A RNA methylation regulators were analyzed between MM patients and normal samples. Kaplan–Meier survival analysis and least absolute shrinkage and selection operator (LASSO) Cox regression analysis were employed to construct the risk signature model. Receiver operation characteristic (ROC) curves were used to verify the prognostic and diagnostic efficiency. Immune infiltration level was evaluated by ESTIMATE algorithm and immune-related single-sample gene set enrichment analysis (ssGSEA).

Results

High expression of HNRNPC, HNRNPA2B1, and YTHDF2 and low expression of ZC3H13 were associated with poor survival. Based on these four genes, a prognostic risk signature model was established. Multivariate Cox regression analysis demonstrated that the risk score was an independent prognostic factor of MM. Enrichment analysis showed that cell cycle, immune response, MYC, proteasome, and unfold protein reaction were enriched in high-risk MM patients. Furthermore, patients with higher risk score exhibited lower immune scores and lower immune infiltration level.

Conclusion

The m6A-based prognostic risk score accurately and robustly predicts the survival of MM patients and is associated with the immune infiltration level, which complements current prediction models and enhances our cognition of immune infiltration.

The Novel Tumor Microenvironment-Related Prognostic Gene AIF1 May Influence Immune Infiltrates and is Correlated with TIGIT in Esophageal Cancer

BACKGROUND

Esophageal carcinoma (EC) is the sixth most common cause of cancer-related mortality worldwide. Studying the associations of the tumor microenvironment (TME) with pathology and prognosis would illustrate the underlying mechanism of prognostic prediction and provide novel targets for immunotherapy in the treatment of EC.

METHODS

Transcriptomic profiles of 159 EC patients were obtained from The Cancer Genome Atlas (TCGA) database. Stromal and immune scores were calculated using the ESTIMATE algorithm. Differentially expressed genes (DEGs) were identified by the optimal score cutoff. Functional enrichments were analyzed by DAVID, while prognostic genes were explored using the Kaplan-Meier method. Validation analysis was performed using immunohistochemistry in tissue microarrays containing samples from 145 EC patients. Multiplex immunofluorescence staining was performed to detect a panel of 6 immune markers, including T-cell immunoreceptor with Ig and ITIM domains (TIGIT), in 90 EC patients.

RESULTS

Immune scores significantly increased with increasing age, while stromal scores were dramatically elevated with increasing tumor stage. Fifteen TME-related DEGs including allograft inflammatory factor 1 (AIF1) were identified as prognostic factors of EC. Furthermore, the validation cohort indicated that AIF1 was negatively associated with the prognosis of esophageal squamous cell carcinoma patients. Subsequent analyses suggested that AIF1 may affect immune infiltrates, including T cells and natural-killer cells. Moreover, a correlation between AIF1 and TIGIT was identified.

CONCLUSIONS

These results indicate that the TME-related gene AIF1 is a promising predictor of prognosis and is related to immune infiltrates and TIGIT expression in EC. However, further mechanistic studies are needed.

Promise and pitfalls of allogeneic chimeric antigen receptor therapy in plasma cell and lymphoid malignancies

Chimeric antigen receptor (CAR) T-cell therapy is a promising immunotherapy in haematological malignancies. However, the currently approved products are generated from autologous T cells that require orchestration of several logistically complex steps, which include patient eligibility, apheresis capability, complex manufacturing processes and shipping logistics. Use of third-party donor-derived (allogeneic) effector cells that allows the generation of 'off-the-shelf" CAR T cells (allo-CAR) could circumvent many of the problems associated with autologous CAR T-cell therapy. Several allogeneic products are entering clinical trials, and though early, the results look promising. The recognised potential benefits of allo-CAR do not come without significant challenges, that must be overcome for their widespread use. Alloreactivity, i.e. graft-versus-host disease (GVHD), and rejection of donor T cells is one of the major barriers, while other potential barriers include immunogenicity, unknown in vivo persistence, and CAR T-cell yield. In the present review, we provide a comprehensive review of the challenges associated with autologous CAR, the benefits and potential challenges associated with allo-CAR. Finally, we review the available platforms for allo-CAR for B-cell and plasma cell malignancies.

Immunotherapy in multiple myeloma

Despite available therapies, Multiple Myeloma (MM) remains an incurable hematologic malignancy. Over the past three decades, there have been tremendous developments in therapeutic options for MM. In regards to immunotherapy, Daratumumab was the first monoclonal antibody to receive FDA approval for multiple myeloma. Since then, other monoclonal antibodies such as elotuzumab and isatuximab have received FDA approval. Many clinical trials are underway investigating the efficacy of newer immunotherapies. This review summarizes recently presented and/or published data regarding this growing field, specifically regarding monoclonal antibodies, antibody-drug conjugates, bispecific antibodies, and trispecific antibodies.

Novel Cell and Immune Engagers in Optimizing Tumor- Specific Immunity Post-Autologous Transplantation in Multiple Myeloma

Autologous stem cell transplantation (ASCT) is an important component of treatment of multiple myeloma (MM). The post-ASCT setting offers a unique opportunity to increase myeloma specific immunity through enhancement of T and NK cell responses. The vast array of therapeutics being developed for MM, including cell-based therapies, dendritic vaccines, bispecific antibodies, and IL-15 agonists, provide the opportunity to increase tumor-specific immunity. Maintenance therapies, including immunomodulatory drugs, proteasome inhibitors, and daratumumab, exhibit a significant anti-myeloma response by modulating the immune system. Lenalidomide promotes an antitumoral immune microenvironment, whereas daratumumab can potentially cause NK cell fratricide. Thus, understanding the effects of commonly used maintenance drugs on the immune system is important. In this review, we look at current and emerging therapeutics and their integration post-ASCT in the context of immune reconstitution to improve clinical responses in patients with MM. © 2021 American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc.

Targeting TIGIT for Immunotherapy of Cancer: Update on Clinical Development

Immune checkpoint blockers have dramatically improved the chances of survival in patients with metastatic cancer, but only a subset of the patients respond to treatment. Search for novel targets that can improve the responder rates and overcome the limitations of adverse events commonly seen with combination therapies, like PD-1 plus CTLA-4 blockade and PD-1/PD-L1 plus chemotherapy, led to the development of monoclonal antibodies blocking T-cell immunoglobulin and ITIM domain (TIGIT), a inhibitory checkpoint receptor expressed on activated T cells and NK cells. The strategy showed potential in pre-clinical and early clinical studies, and 5 molecules are now in advanced stages of evaluation (phase II and above). This review aims to provide an overview of clinical development of anti-TIGIT antibodies and describes the factors considered and thought process during early clinical development. Critical aspects that can decide the fate of clinical programs, such as origin of the antibody, Ig isotype, FCγR binding, and the dose as well as dosing schedule, are discussed along with the summary of available efficacy and safety data from clinical studies and the challenges in the development of anti-TIGIT antibodies, such as identifying patients who can benefit from therapy and getting payer coverage.

Intratumoral TIGIT+ CD8+ T-cell infiltration determines poor prognosis and immune evasion in patients with muscle-invasive bladder cancer

Background

T-cell immunoglobulin and ITIM domain (TIGIT) is identified as a novel checkpoint receptor that can facilitate immune escape via mediating T-cell exhaustion in tumors. However, the clinical significance and immune contexture correlation of intratumoral TIGIT⁺ CD8⁺ T-cells remain to be further explored in muscle-invasive bladder cancer (MIBC).

Methods

259 patients with MIBC from two clinical centers (Zhongshan Hospital, n=141; Shanghai Cancer Center, n=118) were analyzed to evaluate the prognostic value and immune contexture association of TIGIT⁺ CD8⁺ T-cells through immunohistochemistry. Fresh tumor tissue samples from 26 patients with MIBC were examined to discover the phenotype of this CD8 subpopulation by flow cytometry.

Results

High infiltration of intratumoral TIGIT⁺ CD8⁺ T-cells predicted poor overall survival (OS) and recurrence-free survival (RFS) in MIBC. For patients with stage II MIBC with low infiltration of TIGIT⁺ CD8⁺ cells, adjuvant chemotherapy (ACT) could significantly prolong their OS and RFS. Intratumoral TIGIT⁺ CD8⁺ T-cell abundance was correlated with impaired CD8⁺ T-cell cytotoxicity and exhibited production of immunosuppressive cytokine IL-10. Further analysis of tumor-infiltrating immune cell landscape revealed TIGIT⁺ CD8⁺ T-cells were associated with suppressive immune contexture, including Th2 cells, regulatory T-cells, mast cells and neutrophils.

Conclusion

Intratumoral TIGIT⁺ CD8⁺ T-cell abundance could serve as an independent prognosticator for clinical outcome and a predictive biomarker for inferior ACT responsiveness. Intratumoral TIGIT⁺ CD8⁺ T-cell abundance correlated with dampened CD8⁺ T-cell antitumor immunity and immunosuppressive contexture abundance, highlighting a tumor-promoting role of TIGIT⁺ CD8⁺ T-cells.

Harnessing the Immune System to Fight Multiple Myeloma

Multiple myeloma (MM) is a heterogeneous plasma cell malignancy differing substantially in clinical behavior, prognosis, and response to treatment. With the advent of novel therapies, many patients achieve long-lasting remissions, but some experience aggressive and treatment refractory relapses. So far, MM is considered incurable. Myeloma pathogenesis can broadly be explained by two interacting mechanisms, intraclonal evolution of cancer cells and development of an immunosuppressive tumor microenvironment. Failures in isotype class switching and somatic hypermutations result in the neoplastic transformation typical of MM and other B cell malignancies. Interestingly, although genetic alterations occur and evolve over time, they are also present in premalignant stages, which never progress to MM, suggesting that genetic mutations are necessary but not sufficient for myeloma transformation. Changes in composition and function of the immune cells are associated with loss of effective immune surveillance, which might represent another mechanism driving malignant transformation. During the last decade, the traditional view on myeloma treatment has changed dramatically. It is increasingly evident that treatment strategies solely based on targeting intrinsic properties of myeloma cells are insufficient. Lately, approaches that redirect the cells of the otherwise suppressed immune system to take control over myeloma have emerged. Evidence of utility of this principle was initially established by the observation of the graft-versus-myeloma effect in allogeneic stem cell-transplanted patients. A variety of new strategies to harness both innate and antigen-specific immunity against MM have recently been developed and intensively tested in clinical trials. This review aims to give readers a basic understanding of how the immune system can be engaged to treat MM, to summarize the main immunotherapeutic modalities, their current role in clinical care, and future prospects.

Immunotherapy of Multiple Myeloma: Promise and Challenges

Whereas the treatment of MM was dependent solely on alkylating agents and corticosteroids during the prior three decades, the landscape of therapeutic measures to treat the disease began to expand enormously early in the current century. The introduction of new classes of small-molecule drugs, such as proteasome blockers (bortezomib and carfilzomib), immunomodulators (lenalidomide and pomalidomide), nuclear export inhibitors (selinexor), and histone deacetylase blockers (panobinostat), as well as the application of autologous stem cell transplantation (ASCT), resulted in a seismic shift in how the disease is treated. The picture changed dramatically once again starting with the 2015 FDA approval of two monoclonal antibodies (mAbs) - the anti-CD38 daratumumab and the anti-SLAMF7 elotuzumab. Daratumumab, in particular, has had a great impact on MM therapy and today is often included in various regimens to treat the disease, both in newly diagnosed cases and in the relapse/refractory setting. Recently, other immunotherapies have been added to the arsenal of drugs available to fight this malignancy. These include isatuximab (also anti-CD38) and, in the past year, the antibody-drug conjugate (ADC) belantamab mafodotin and the chimeric antigen receptor (CAR) T-cell product idecabtagene vicleucel (ide-cel). While the accumulated benefits of these newer agents have resulted in a doubling of the disease's five-year survival rate to more than 5 years and improved quality of life, the disease remains incurable. Almost without exception patients experience relapse and/or become refractory to the drugs used, making the search for innovative therapies all the more essential. This review covers the current scope of anti-myeloma immunotherapeutic agents, both those in clinical use and on the horizon, including naked mAbs, ADCs, bi- and multi-targeted mAbs, and CAR T-cells. Emphasis is placed on the benefits of each along with the challenges that need to be overcome if MM is to be considered curable in the future.

Poliovirus receptor (PVR)-like protein cosignaling network: new opportunities for cancer immunotherapy

Immune checkpoint molecules, also known as cosignaling molecules, are pivotal cell-surface molecules that control immune cell responses by either promoting (costimulatory molecules) or inhibiting (coinhibitory molecules) a signal. These molecules have been studied for many years. The application of immune checkpoint drugs in the clinic provides hope for cancer patients. Recently, the poliovirus receptor (PVR)-like protein cosignaling network, which involves several immune checkpoint receptors, i.e., DNAM-1 (DNAX accessory molecule-1, CD226), TIGIT (T-cell immunoglobulin (Ig) and immunoreceptor tyrosine-based inhibitory motif (ITIM)), CD96 (T cell activation, increased late expression (TACLILE)), and CD112R (PVRIG), which interact with their ligands CD155 (PVR/Necl-5), CD112 (PVRL2/nectin-2), CD111 (PVRL1/nectin-1), CD113 (PVRL3/nectin-3), and Nectin4, was discovered. As important components of the immune system, natural killer (NK) and T cells play a vital role in eliminating and killing foreign pathogens and abnormal cells in the body. Recently, increasing evidence has suggested that this novel cosignaling network axis costimulates and coinhibits NK and T cell activation to eliminate cancer cells after engaging with ligands, and this activity may be effectively targeted for cancer immunotherapy. In this article, we review recent advances in research on this novel cosignaling network. We also briefly outline the structure of this cosignaling network, the signaling cascades and mechanisms involved after receptors engage with ligands, and how this novel cosignaling network costimulates and coinhibits NK cell and T cell activation for cancer immunotherapy. Additionally, this review comprehensively summarizes the application of this new network in preclinical trials and clinical trials. This review provides a new immunotherapeutic strategy for cancer treatment.

On the road to eliminating long-lived plasma cells-"are we there yet?"

Central to protective humoral immunity is the activation of B cells and their terminal differentiation into antibody-secreting plasma cells. Long-lived plasma cells (LLPC) may survive for years to decades. Such long-lived plasma cells are also responsible for producing pathogenic antibodies that cause a variety of challenges such as autoimmunity, allograft rejection, and drug neutralization. Up to now, various therapeutic strategies aimed at durably eliminating pathogenic antibodies have failed, in large part due to their inability to efficiently target LLPCs. Several antibody-based therapies have recently gained regulatory approval or are in clinical phases of development for the treatment of multiple myeloma, a malignancy of plasma cells. We discuss the exciting potential of using these emerging cancer immunotherapies to solve the antibody problem.

TIGIT, the Next Step Towards Successful Combination Immune Checkpoint Therapy in Cancer

T cell immunoreceptor with Ig and ITIM domains (TIGIT) is an inhibitory receptor expressed on several types of lymphocytes. Efficacy of antibody blockade of TIGIT in cancer immunotherapy is currently widely being investigated in both pre-clinical and clinical studies. In multiple cancers TIGIT is expressed on tumor-infiltrating cytotoxic T cells, helper T cells, regulatory T cells and NK cells, and its main ligand CD155 is expressed on tumor-infiltrating myeloid cells and upregulated on cancer cells, which contributes to local suppression of immune-surveillance. While single TIGIT blockade has limited anti-tumor efficacy, pre-clinical studies indicate that co-blockade of TIGIT and PD-1/PD-L1 pathway leads to tumor rejection, notably even in anti-PD-1 resistant tumor models. Among inhibitory immune checkpoint molecules, a unique property of TIGIT blockade is that it enhances not only anti-tumor effector T-cell responses, but also NK-cell responses, and reduces the suppressive capacity of regulatory T cells. Numerous clinical trials on TIGIT-blockade in cancer have recently been initiated, predominantly combination treatments. The first interim results show promise for combined TIGIT and PD-L1 co-blockade in solid cancer patients. In this review, we summarize the current knowledge and identify the gaps in our current understanding of TIGIT’s roles in cancer immunity, and provide, based on these insights, recommendations for its positioning in cancer immunotherapy.

Immune checkpoint inhibitors for the treatment of myeloma: novel investigational options

INTRODUCTION

Multiple myeloma (MM) is still considered incurable and the outcome of patients with triple-class refractory remains very poor. Immunotherapy is considered as a standard of care for the treatment of MM. Among immunotherapeutic approaches, the PD-1/PD-L1 axis is an attractive target because PD-L1 is highly expressed in most myeloma plasma cells. While many types of cancer benefit from checkpoint inhibitor treatment, their relevance in multiple myeloma needs to be defined.

AREAS COVERED

The authors evaluate the published data regarding the mechanism of action, safety profile, and clinical efficacy of the immune checkpoint inhibitors (ICI) for the treatment of multiple myeloma.

EXPERT OPINION

The use of ICI monotherapy does not offer any clinical benefit in myeloma patients. In combination with immunomodulatory drugs (IMID), ICI failed to demonstrate clinical benefit and were associated with increased toxicity. Given the toxicities of these treatments, predictive markers would be useful to select patients who would benefit most. Clinical studies are necessary to evaluate the safety and efficacy of checkpoint inhibitors in combination with other standards of care such as proteasome inhibitors and monoclonal antibodies. The combination of anti-PD-1 with T-cell engager (TCE) or CAR-T cells seems theoretically attractive and should be explored in clinical trials.

The Cancer-Immunity Cycle in Multiple Myeloma

Multiple myeloma is a plasma cell malignancy that primarily affects the elderly. The global burden of multiple myeloma is increasing in many countries due to an aging population. Despite recent advances in therapy, myeloma remains an incurable disease, highlighting the pressing need for new therapies. Accumulating evidence supports that triggering the host immune system is a critical therapeutic mechanism of action by various anti-myeloma therapies. These anti-myeloma therapies include proteasome inhibitors, immunomodulatory drugs, monoclonal antibody drugs, and autologous stem cell transplantation. More recently, T cell-based immunotherapeutics (including chimeric antigen receptor T-cell therapies and bispecific T-cell engagers) have shown dramatic clinical benefits in patients with relapsed or refractory multiple myeloma. While immune-based therapeutic approaches are recognized as key modalities for improved clinical outcomes in myeloma patients, understanding the immune system in multiple myeloma patients remains elusive. The cancer-immunity cycle is a conceptual framework illustrating how immune cells recognize and eliminate tumor cells. Based on this framework, this review will provide an overview of the immune system in multiple myeloma patients and discuss potential therapeutic approaches to stimulate anti-tumor immunity.

Towards efficient immunotherapy for bacterial infection

The emergence of multiantibiotic-resistant bacteria, often referred to as superbugs, is leading to infections that are increasingly difficult to treat. Further, bacteria have evolved mechanisms by which they subvert the immune response, meaning that even antibiotic-sensitive bacteria can persist through antibiotic therapy. For these reasons, a broad range of viable therapeutic alternatives or conjunctions to traditional antimicrobial therapy are urgently required to reduce the burden of disease threatened by antibiotic resistance. Immunotherapy has emerged as a leading treatment option in cancer, and researchers are now attempting to apply this to infectious disease. This review summarizes and discusses the recent advances in the field and highlights current and future perspectives of using immunotherapies to treat bacterial infections.

Impact of serum soluble CD155 level at diagnosis on interim response to CHOP with or without rituximab in diffuse large B cell lymphoma

CD155 is frequently overexpressed in human malignant tumors, and it is associated with poor prognosis. The expression of its soluble form (sCD155) as well as its prognostic value were not studied previously in diffuse large B cell lymphoma (DLBCL). Serum sCD155 level was measured in DLBCL patients at diagnosis using enzyme-linked immunosorbent assay. Its impact on response following three cycles of CHOP with or without rituximab (CHOP ± R) was analyzed. Serum sCD155 level was significantly elevated in DLBCL patients at diagnosis than in controls (P < 0.001). Serum sCD155 level at diagnosis correlated significantly with International Prognostic Index risk score (P = 0.005). Elevated serum sCD155 was associated with lack of response following three cycles of CHOP ± R in univariate analysis (P = 0.003). On multivariate analysis, there was a 1.601 probability of lack of response in patients with increased sCD155 level (95% confidence interval = 0.774-3.309, P = 0.204). Serum sCD155 is overexpressed in DLBCL, and it is associated with lack of interim response to CHOP ± R.

Detection of Immune Checkpoint Receptors - A Current Challenge in Clinical Flow Cytometry

Immunological therapy principles are increasingly determining modern medicine. They are used to treat diseases of the immune system, for tumors, but also for infections, neurological diseases, and many others. Most of these therapies base on antibodies, but small molecules, soluble receptors or cells and modified cells are also used. The development of immune checkpoint inhibitors is amazingly fast. T-cell directed antibody therapies against PD-1 or CTLA-4 are already firmly established in the clinic. Further targets are constantly being added and it is becoming increasingly clear that their expression is not only relevant on T cells. Furthermore, we do not yet have any experience with the long-term systemic effects of the treatment. Flow cytometry can be used for diagnosis, monitoring, and detection of side effects. In this review, we focus on checkpoint molecules as target molecules and functional markers of cells of the innate and acquired immune system. However, for most of the interesting and potentially relevant parameters, there are still no test kits suitable for routine use. Here we give an overview of the detection of checkpoint molecules on immune cells in the peripheral blood and show examples of a possible design of antibody panels.