Natural killer cells and cancer: regulation by the killer cell Ig-like receptors (KIR)

Increased donor inhibitory KIR are associated with reduced GVHD and improved survival following HLA-matched unrelated donor HCT in paediatric acute leukaemia

Killer immunoglobulin-like receptor (KIR) and KIR-ligand (KIRL) interactions play an important role in natural killer cell-mediated effects after haematopoietic stem cell transplantation (HCT). Previous work has shown that accounting for known KIR-KIRL interactions may identify donors with optimal NK cell-mediated alloreactivity in the adult transplant setting. Paediatric acute leukaemia patients were retrospectively analysed, and KIR-KIRL combinations and maximal inhibitory KIR ligand (IM-KIR) scores were determined. Clinical outcomes were examined using a series of graphs depicting clinical events and endpoints. The graph methodology demonstrated that prognostic variables significant in the occurrence of specific clinical endpoints remained significant for relevant downstream events. KIR-KIRL combinations were significantly predictive for reduced grade 3-4 aGVHD likelihood, in patients transplanted with increased inhibitory KIR gene content and IM-KIR = 5 scores. Improvements were also observed in associated outcomes for both ALL and AML patients, including relapse-free survival, GRFS and overall survival. This study demonstrates that NK cell KIR HLA interactions may be relevant to the paediatric acute leukaemia transplant setting. Reduction in aGVHD suggests KIR effects may extend beyond NK cells. Moving forward clinical trials utilizing donors with a higher iKIR should be considered for URD HCT in paediatric recipients with acute leukaemia to optimize clinical outcomes.

Identification of Novel Cuproptosis-Related Genes Mediating the Prognosis and Immune Microenvironment in Cholangiocarcinoma

BACKGROUND

Cuproptosis is a novel type of mediated cell death strongly associated with the progression of several cancers and has been implicated as a potential therapeutic target. However, the role of cuproptosis in cholangiocarcinoma for prognostic prediction, subgroup classification, and therapeutic strategies remains largely unknown.

METHODS

A systematic analysis was conducted among 146 cuproptosis-related genes and clinical information based on independent mRNA and protein datasets to elucidate the potential mechanisms and prognostic prediction value of cuproptosis-related genes. A 10-cuproptosis-related gene prediction model was constructed, and its effects on cholangiocarcinoma prognosis were significantly connected to poor patient survival. Additionally, the expression patterns of our model included genes that were validated with several cholangiocarcinoma cancer cell lines and a normal biliary epithelial cell line.

RESULTS

First, a 10-cuproptosis-related gene signature (ADAM9, ADAM17, ALB, AQP1, CDK1, MT2A, PAM, SOD3, STEAP3, and TMPRSS6) displayed excellent predictive performance for the overall survival of cholangiocarcinoma. The low-cuproptosis group had a significantly better prognosis than the high-cuproptosis group with transcriptome and protein cohorts. Second, compared with the high-risk and low-risk groups, the 2 groups displayed distinct tumor microenvironments, reduced proportions of endothelial cells, and increased levels of cancer-associated fibroblasts based on CIBERSORTx and EPIC analyses. Third, patients' sensitivities to chemotherapeutic drugs and immune checkpoints revealed distinctive differences between the 2 groups. Finally, in replicating the expression patterns of the 10 genes, these results were validated with quantitative real-time polymerase chain reaction results validating the abnormal expression pattern of the target genes in cholangiocarcinoma.

CONCLUSIONS

Collectively, we established and verified an effective prognostic model that could separate cholangiocarcinoma patients into 2 heterogeneous cuproptosis subtypes based on the molecular or protein characteristics of 10 cuproptosis-related genes. These findings may provide potential benefits for unveiling molecular characteristics and defining subgroups could improve the early diagnosis and individualized treatment of cholangiocarcinoma patients.

The KIR2DL1 intermediate upstream element participates in gene activation

The human KIR genes encode a family of class I MHC receptors that are expressed on subsets of NK cells. The expression of KIR proteins is controlled by a stochastic process, and competition between sense and antisense promoter elements has been suggested to program the variegated expression of these genes. Previous studies have demonstrated distinct roles of distal, intermediate, and proximal sense promoter/enhancer elements in gene activation and expression. Conversely, proximal and intronic antisense promoter transcripts have been associated with gene silencing at different stages of NK cell development. In the current study, we examine the effect of intermediate promoter deletion on KIR2DL1 expression in the YTS cell line. Homozygous deletion of the KIR2DL1 intermediate element did not affect proximal promoter activity but resulted in increased detection of upstream transcripts. No significant changes in alternative mRNA splicing or expression levels of KIR2DL1 protein were observed. However, intermediate element deletion was associated with a reduced frequency of gene activation by 5-azacytidine. Taken together, these results indicate that the intermediate element is not an enhancer required for KIR expression; however, it is required for the efficient activation of the gene.

KIR genotype and haplotype repertoire in Kuwaiti healthy donors, hematopoietic cell transplant recipients and healthy family members

The gene complex located on chromosome 19q13.4 encodes the Killer-cell Immunoglobulin-like Receptors (KIRs), which exhibit remarkable polymorphism in both gene content and sequences. Further, the repertoire of KIR genes varies within and between populations, creating a diverse pool of KIR genotypes. This study was carried out to characterize KIR genotypes and haplotypes among 379 Arab Kuwaiti individuals including 60 subjects from 20 trio families, 49 hematopoietic cell transplantation (HCT) recipients and 270 healthy Kuwaiti volunteer HCT donors. KIR Genotyping was performed by a combination of reverse sequence specific oligonucleotide probes (rSSO) and/or Real Time PCR. The frequencies of KIR genes in 270 healthy Kuwaiti volunteer donors were compared to previously reported frequencies in other populations. In addition, we compared the differences in KIR repertoire of patients and healthy donors to investigate the reproducibility of previously reported significant differences between patients with hematological malignancies and healthy donors. The observed frequencies in our cohort volunteer HCT donors was comparable to those reported in neighboring Arab populations. The activating genes KIR2DS1, KIR2DS5 and KIR3DS1 and the inhibitory gene KIR2DL5 were significantly more frequent in patients compared to healthy donors, however, none of the previously reported differences were reproducible in our Kuwaiti cohort. This report is the first description of KIR gene carrier frequency and haplotype characterization in a fairly large cohort of the Kuwaiti population, which may have implications in KIR based HCT donor selection strategies.

Efficient and accurate KIR and HLA genotyping with massively parallel sequencing data

Killer cell immunoglobulin like receptor (KIR) genes and human leukocyte antigen (HLA) genes play important roles in innate and adaptive immunity. They are highly polymorphic and cannot be genotyped with standard variant calling pipelines. Compared with HLA genes, many KIR genes are similar to each other in sequences and may be absent in the chromosomes. Therefore, although many tools have been developed to genotype HLA genes using common sequencing data, none of them work for KIR genes. Even specialized KIR genotypers could not resolve all the KIR genes. Here we describe T1K, a novel computational method for the efficient and accurate inference of KIR or HLA alleles from RNA-seq, whole-genome sequencing, or whole-exome sequencing data. T1K jointly considers alleles across all genotyped genes, so it can reliably identify present genes and distinguish homologous genes, including the challenging KIR2DL5A/KIR2DL5B genes. This model also benefits HLA genotyping, where T1K achieves high accuracy in benchmarks. Moreover, T1K can call novel single-nucleotide variants and process single-cell data. Applying T1K to tumor single-cell RNA-seq data, we found that KIR2DL4 expression was enriched in tumor-specific CD8+ T cells. T1K may open the opportunity for HLA and KIR genotyping across various sequencing applications.

Association of KIR genes polymorphism and its HLA ligands in Diffuse Large B-cell Lymphoma

INTRODUCTION

Non-Hodgkin lymphoma (NHL) is a heterogeneous disease, with each subtype associated with different risk factors. Within this group, diffuse large B-cell lymphoma (DLBCL) can be highlighted, the most common type of NHL.NK cells are key components of the innate immune response and may play an important antitumor role.

OBJECTIVE

The objective of the present work was to determine the polymorphism of KIR genes in Brazilian patients with DLBCL.

MATERIALS AND METHODS

Furthermore, we evaluated the association between the polymorphism of these genes and their ligands with the clinical course of the disease. For the study, 112 patients with DLBCL and 222 voluntary blood and bone marrow donors. The genetic material of these samples were extracted for KIR and HLA typing, determination of HLA ligands, determination of the KIR haplotype and search for the deletion of 22 bp in the KIR2DS4 gene. KIR genotype distributions were made by direct counting using 2 × 2 contingency tables using Fisher's exact test. The magnitude of the association was measured by odds ratio (OR) and 95% confidence interval. P values <.05 were considered significant. Overall survival and progression-free survival were assessed with a Kaplan-Meier estimator.

RESULTS

In the present study, an association of HLA-Bw4 and HLA-Bw480I ligand was found with more advanced stages of the disease. Also, an association of the KIR2DL3 gene with a better response to treatment was found.

CONCLUSION

With this, we can conclude that the polymorphism of KIR genes and the association with HLA ligands can influence the prognosis of DLBCL, as well as the response to treatment was found. With this, we can conclude that the polymorphism of KIR genes and the association with HLA ligands can influence the prognosis of DLBCL, as well as the response to treatment.Non-Hodgkin lymphoma (NHL) is a heterogeneous disease, with each subtype associated with different risk factors. Within this group, diffuse large B-cell lymphoma (DLBCL) can be highlighted, the most common type of NHL.NK cells are key components of the innate immune response and may play an important antitumor role. The objective of the present work was to determine the polymorphism of KIR genes in Brazilian patients with DLBCL. Furthermore, we evaluated the association between the polymorphism of these genes and their ligands with the clinical course of the disease. For the study, 112 patients with DLBCL and 222 voluntary blood and bone marrow donors. The genetic material of these samples were extracted for KIR and HLA typing, determination of HLA ligands, determination of the KIR haplotype and search for the deletion of 22 bp in the KIR2DS4 gene. KIR genotype distributions were made by direct counting using 2 × 2 contingency tables using Fisher's exact test. The magnitude of the association was measured by odds ratio (OR) and 95% confidence interval. P values <.05 were considered significant. Overall survival and progression-free survival were assessed with a Kaplan-Meier estimator. In the present study, an association of HLA-Bw4 and HLA-Bw480I ligand was found with more advanced stages of the disease. Also, an association of the KIR2DL3 gene with a better response to treatment was found. With this, we can conclude that the polymorphism of KIR genes and the association with HLA ligands can influence the prognosis of DLBCL, as well as the response to treatment was found. With this, we can conclude that the polymorphism of KIR genes and the association with HLA ligands can influence the prognosis of DLBCL, as well as the response to treatment.

Biological therapy in elderly patients with acute myeloid leukemia

INTRODUCTION

The introduction of target molecules and immunological therapies is changing the treatment landscape of acute myeloid leukemia (AML).

AREAS COVERED

We recapitulate the biological therapies that can be employed in the treatment of elderly patients with AML. Alongside small molecules inhibitors that target specific gene mutations, antibodies, tumor microenvironment modulators, and cellular therapies are being developed for the cure of the disease. Here, we report the biological activities, the efficacy and toxicities of humanized antibodies and antibody-drug conjugates that targets surface antigens as CD33 (gemtuzumab ozogamicine) or CD123 (pivekimab sunirine). We further explore mechanisms and effectiveness of medications that modify the microenvironment, such as glasdegib, or that harness the immune system against leukemia, such as CD47 antibody magrolimab, PD1/PDL1 inhibitors pembrolizumab and nivolumab, TIM3 inhibitor sabatolimab, T-cell and NK-cell engagers. Cellular therapies are considered, even if a large trial is still pending for the feasibility of the approach. In this scenario, a brief overview of the mechanism of action of target agents is provided, particularly with respect to their biological mechanisms.

EXPERT OPINION

Overall, this therapeutic armamentarium will constitute the basis for multimodal and personalized combinations that, in the idea of precision medicine, will enormously benefit elderly AML patients.

Safety and Efficacy of Allogeneic Natural Killer Cells in Combination with Pembrolizumab in Patients with Chemotherapy-Refractory Biliary Tract Cancer: A Multicenter Open-Label Phase 1/2a Trial

Background and Aim: This study investigated the administration of combination therapy, allogeneic natural killer (NK) cells and pembrolizumab in the treatment of advanced biliary tract cancer to determine the safety and tolerability (phase 1) and the efficacy and safety (phase 2a). Methods: Forty patients (phase 1, n = 6; phase 2a, n = 34) were enrolled between December 2019 and June 2021. The patients received highly activated allogeneic NK cells (“SMT-NK”) on weeks 1 and 2 and pembrolizumab on week 1. This 3-week schedule (one cycle) was repeated until confirmed disease progression, intolerable adverse events (AEs), patient withdrawal, or finishing the maximum treatment schedule. The tumor response was evaluated after every three cycles. Results: In phase 1, four patients (66.7%) experienced seven AEs, but no severe AE was observed. In phase 2a, 126 AEs occurred in 29 patients (85.3%). Severe AEs (≥grade 3) were reported in 16 patients (47.1%). The overall response rate (ORR) was 17.4% in the full analysis set and 50.0% in the per-protocol set. Conclusions: SMT-NKs plus pembrolizumab resulted in no severe AEs directly related to the drug combination. The combination therapy also exerted antitumor activity with improved efficacy compared to the recent monotherapy with pembrolizumab in patients with advanced biliary tract cancer.

Harnessing natural killer cells for cancer immunotherapy: dispatching the first responders

Natural killer (NK) cells have crucial roles in the innate immunosurveillance of cancer and viral infections. They are 'first responders' that can spontaneously recognize abnormal cells in the body, rapidly eliminate them through focused cytotoxicity mechanisms and potently produce pro-inflammatory cytokines and chemokines that recruit and activate other immune cells to initiate an adaptive response. From the initial discovery of the diverse cell surface receptors on NK cells to the characterization of regulatory events that control their function, our understanding of the basic biology of NK cells has improved dramatically in the past three decades. This advanced knowledge has revealed increased mechanistic complexity, which has opened the doors to the development of a plethora of exciting new therapeutics that can effectively manipulate and target NK cell functional responses, particularly in cancer patients. Here, we summarize the basic mechanisms that regulate NK cell biology, review a wide variety of drugs, cytokines and antibodies currently being developed and used to stimulate NK cell responses, and outline evolving NK cell adoptive transfer approaches to treat cancer.

The Evolution Of Immune Dysfunction In Multiple Myeloma

OBJECTIVES

This review discusses the role of immune dysfunction at the different stages of MM.

METHODS

Narrative review RESULTS: Multiple myeloma (MM) is a complex disease and immune dysfunction has been known to play an important role in disease pathogenesis, progression, and drug resistance. MM is known to be preceded by asymptomatic precursor states and progression from the precursor states to MM is likely related to a progressive impairment of the immune system.

CONCLUSIONS

An understanding of the role of the immune system in the progression of MM is important to guide the development of immunotherapeutic strategies for this disease.

Cross-Talk Between Tumor Cells Undergoing Epithelial to Mesenchymal Transition and Natural Killer Cells in Tumor Microenvironment in Colorectal Cancer

Tumor cells undergoing epithelial to mesenchymal transition (EMT) and immune cells in tumor microenvironment (TME) reciprocally influence each other. Immune cells, by supplying TME with bioactive molecules including cytokines, chemokines, enzymes, metabolites, and by physical interactions with tumor cells via their receptors, represent an important factor that affects EMT. Chronical inflammation in TME favorizes tumor growth and invasiveness and stimulates synthesis of EMT promoting transcription factors. Natural killer (NK) cells, owing to their unique ability to exert cytotoxic function independent of major histocompatibility (MHC)-mediated antigen presentation, play a significant role in the control of metastasis in colorectal cancer (CRC). Although, the cross-talk between immune cells and tumor cells in general favors the induction of EMT and inhibition of antitumor immune responses, there are some changes in the immunogenicity of tumor cells during EMT of CRC cells that increase their susceptibility to NK cell cytotoxic lysis. However, suppressive TME downmodulates the expression of activating NK cell receptors, decreases the expression of activating and increases the expression of inhibitory NK cell ligands on tumor cells, and impairs NK cell metabolism that altogether negatively affects the overall NK cell function. Furthermore, process of EMT is often associated with increased expression of programmed cell death ligand (PD-L) and expression of immune checkpoint molecules PD-1, TIGIT, and TIM3 on functionally exhausted NK cells in TME in CRC. In this review we discuss modalities of cross-talk between tumor cells and NK cells, with regard of EMT-driven changes.

Annexin A1 as a Regulator of Immune Response in Cancer

Annexin A1 is a 37 kDa phospholipid-binding protein that is expressed in many tissues and cell types, including leukocytes, lymphocytes and epithelial cells. Although Annexin A1 has been extensively studied for its anti-inflammatory activity, it has been shown that, in the cancer context, its activity switches from anti-inflammatory to pro-inflammatory. Remarkably, Annexin A1 shows pro-invasive and pro-tumoral properties in several cancers either by eliciting autocrine signaling in cancer cells or by inducing a favorable tumor microenvironment. Indeed, the signaling of the N-terminal peptide of AnxA1 has been described to promote the switching of macrophages to the pro-tumoral M2 phenotype. Moreover, AnxA1 has been described to prevent the induction of antigen-specific cytotoxic T cell response and to play an essential role in the induction of regulatory T lymphocytes. In this way, Annexin A1 inhibits the anti-tumor immunity and supports the formation of an immunosuppressed tumor microenvironment that promotes tumor growth and metastasis. For these reasons, in this review we aim to describe the role of Annexin A1 in the establishment of the tumor microenvironment, focusing on the immunosuppressive and immunomodulatory activities of Annexin A1 and on its interaction with the epidermal growth factor receptor.

Mechanosensation and Mechanotransduction in Natural Killer Cells

Natural killer (NK) cells are a main subset of innate lymphocytes that contribute to host immune protection against viruses and tumors by mediating target cell killing and secreting a wide array of cytokines. Their functions are finely regulated by a balance between activating and inhibitory receptors and involve also adhesive interactions. Mechanotransduction is the process in which physical forces sensed by mechanosensors are translated into chemical signaling. Herein, we report findings on the involvement of this mechanism that is mainly mediated by actin cytoskeleton, in the regulation of NK cell adhesion, migration, tissue infiltration and functions. Actin represents the structural basis for NK cell immunological synapse (NKIS) and polarization of secretory apparatus. NK-target cell interaction involves the formation of both uropods and membrane nanotubes that allow target cell interaction over long distances. Actin retrograde flow (ARF) regulates NK cell signaling and controls the equilibrium between activation versus inhibition. Activating NKIS is associated with rapid lamellipodial ARF, whereas lower centripetal actin flow is present during inhibitory NKIS where β actin can associate with the tyrosine phosphatase SHP-1. Overall, a better knowledge of mechanotransduction might represent a future challenge: Realization of nanomaterials tailored for NK cells, would be important to translate in vitro studies in in vivo new immunotherapeutic approaches.

Molecular-scale spatio-chemical control of the activating-inhibitory signal integration in NK cells

The role of juxtaposition of activating and inhibitory receptors in signal inhibition of cytotoxic lymphocytes remains strongly debated. The challenge lies in the lack of tools that allow simultaneous spatial manipulation of signaling molecules. To circumvent this, we produced a nanoengineered multifunctional platform with molecular-scale spatial control of ligands, which was applied to elucidate KIR2DL1-mediated inhibition of NKG2D signaling-receptors of natural killer cells. This platform was conceived by bimetallic nanodot patterning with molecular-scale registry, followed by a ternary functionalization with distinct moieties. We found that a 40-nm gap between activating and inhibitory ligands provided optimal inhibitory conditions. Supported by theoretical modeling, we interpret these findings as a consequence of the size mismatch and conformational flexibility of ligands in their spatial interaction. This highly versatile approach provides an important insight into the spatial mechanism of inhibitory immune checkpoints, which is essential for the rational design of future immunotherapies.

TREM2 promotes natural killer cell development in CD3-CD122+NK1.1+ pNK cells

Background

Triggering receptor expressed on myeloid cells 2 (TREM2) signaling is considered to regulate anti-inflammatory responses in macrophages, dendritic cell maturation, osteoclast development, induction of obesity, and Alzheimer’s disease pathogenesis. However, little is known regarding the effect of TREM2 on natural killer (NK) cells.

Results

Here, we demonstrated for the first time that CD3⁻CD122⁺NK1.1⁺ precursor NK (pNK) cells expressed TREM2 and their population increased in TREM2-overexpressing transgenic (TREM2-TG) mice compared with that in female C57BL/6 J wild type (WT) mice. Both NK cell-activating receptors and NK cell-associated genes were expressed at higher levels in various tissues of TREM2-TG mice than in WT mice. In addition, bone marrow-derived hematopoietic stem cells (HSCs) of TREM2-TG mice (TG-HSCs) successfully differentiated into NK cells in vitro, with a higher yield from TG-HSCs than from WT-HSCs. In contrast, TREM2 signaling inhibition by TREM2-Ig or a phosphatidylinositol 3-kinase (PI3K) inhibitor affected the expression of the NK cell receptor repertoire and decreased the expression levels of NK cell-associated genes, resulting in significant impairment of NK cell differentiation. Moreover, in melanoma-bearing WT mice, injection of bone marrow cells from TREM2-TG mice exerted greater antitumor effects than that with cells from WT control mice.

Conclusions

Collectively, our data clearly showed that TREM2 promoted NK cell development and tumor regression, suggesting TREM2 as a new candidate for cancer immunotherapy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12865-021-00420-0.

Immunomodulation of Chinese Herbal Medicines on NK cell populations for cancer therapy: A systematic review

ETHNOPHARMACOLOGICAL RELEVANCE

Immunomodulation has become a crucial modality for cancer treatment. Chinese Herbal Medicines (CHMs) are expected as adjuvant therapy for immunomodulation against cancer, but face the key challenge of poor scientific evidence. Changes of natural killer (NK) cells on numbers and/or cytotoxicity are a novel respect to evaluate the immunomodulation of CHMs.

AIM OF THE STUDY

The purpose of this review is to investigate the immunomodulation of Chinese Herbal Medicines (CHMs) on NK cell populations for cancer therapy.

MATERIALS AND METHODS

A systematic review was conducted and outside mainstream electronic databases were screened for potential reference articles. This review tried to report and critically analyzed all the correlative studies, especially these clinical trials (3 CHM extracts and 11 CHM formulas).

RESULTS

Evidence-based functions of CHMs against cancer could be summarized as: (1) enhancement of NK cells activity or relative percentage; (2) prevention of tumor growth and metastasis; (3) relief on side-effects or complications of therapeutic strategies (i.e. chemotherapy, radiotherapy and resection). Briefly, most of cellular studies and two thirds animal studies were based on the extract or components of single herbs, whilst most of clinical trials were keen on formula or prescription of CHMs. The main components of CHMs were demonstrated active on promoting the cytotoxicity of NK cells, including Angelica sinensis, Ganoderma lucidum, Panax ginseng, Radix Astragali, Lentinus edodes, etc. CONCLUSIONS: This comprehensive review demonstrated NK cells activity was positively associated with quality of life but not survival benefit of cancer patients. Thus exploring the roles of NK cells in adjuvant therapy against cancer is confirmed to be beneficial to explore the underlying relationship between immunomodulation and quality of life.

Engaging the Innate and Adaptive Antitumor Immune Response in Lymphoma

Immunotherapy has emerged as a powerful therapeutic strategy for many malignancies, including lymphoma. As in solid tumors, early clinical trials have revealed that immunotherapy is not equally efficacious across all lymphoma subtypes. For example, immune checkpoint inhibition has a higher overall response rate and leads to more durable outcomes in Hodgkin lymphomas compared to non-Hodgkin lymphomas. These observations, combined with a growing understanding of tumor biology, have implicated the tumor microenvironment as a major determinant of treatment response and prognosis. Interactions between lymphoma cells and their microenvironment facilitate several mechanisms that impair the antitumor immune response, including loss of major histocompatibility complexes, expression of immunosuppressive ligands, secretion of immunosuppressive cytokines, and the recruitment, expansion, and skewing of suppressive cell populations. Accordingly, treatments to overcome these barriers are being rapidly developed and translated into clinical trials. This review will discuss the mechanisms of immune evasion, current avenues for optimizing the antitumor immune response, clinical successes and failures of lymphoma immunotherapy, and outstanding hurdles that remain to be addressed.

KIR2DL4 genetic diversity in a Brazilian population sample: implications for transcription regulation and protein diversity in samples with different ancestry backgrounds

KIR2DL4 is an important immune modulator expressed in natural killer cells; HLA-G is its main ligand. We have characterized the KIR2DL4 genetic diversity by considering the promoter, all exons, and all introns in a highly admixed Brazilian population sample and by using massively parallel sequencing. We introduce a molecular method to amplify and to sequence the complete KIR2DL4 gene. To avoid the mapping bias and genotype errors commonly observed in gene families, we have developed and validated a bioinformatic pipeline designed to minimize these errors and applied it to survey the variability of 220 individuals from the State of São Paulo, southeastern Brazil. We have also compared the KIR2DL4 genetic diversity in the Brazilian cohort with the diversity previously reported by the 1000Genomes consortium. KIR2DL4 presents high linkage disequilibrium throughout the gene, with coding sequences associated with specific promoters. There are few but divergent promoter haplotypes. We have also detected many new KIR2DL4 sequences, all bearing nucleotide exchanges in introns and encoding previously described proteins. Exons 3 and 4, which encode the external domains, are the most variable. The ancestry background influences the KIR2DL4 allele frequencies and must be considered for association studies regarding KIR2DL4.

The Immune Microenvironment in Multiple Myeloma: Friend or Foe?

Simple Summary

The crosstalk between multiple myeloma and immune cells within the bone marrow niche has been identified as an emerging hallmark of this hematological disease. As our knowledge on this interplay increases, it becomes more evident that successful treatment approaches need to boost the body’s natural defenses through immunotherapy. The present review will focus on the mechanisms by which myeloma cancer cells turn immune populations into their “partners in crime”. Additionally, we will provide an overview of currently ongoing pre-clinical studies targeting the bone marrow immune microenvironment.

Abstract

Multiple myeloma (MM) is one of the most prevalent hematological cancers worldwide, characterized by the clonal expansion of neoplastic plasma cells in the bone marrow (BM). A combination of factors is implicated in disease progression, including BM immune microenvironment changes. Increasing evidence suggests that the disruption of immunological processes responsible for myeloma control ultimately leads to the escape from immune surveillance and resistance to immune effector function, resulting in an active form of myeloma. In fact, one of the hallmarks of MM is the development of a permissive BM milieu that provides a growth advantage to the malignant cells. Consequently, a better understanding of how myeloma cells interact with the BM niche compartments and disrupt the immune homeostasis is of utmost importance to develop more effective treatments. This review focuses on the most up-to-date knowledge regarding microenvironment-related mechanisms behind MM immune evasion and suppression, as well as promising molecules that are currently under pre-clinical tests targeting immune populations.

Identification of Immune Cell Infiltration and Immune-Related Genes in the Tumor Microenvironment of Glioblastomas

Glioblastoma (GBM) is one of the most prevalent malignant brain tumors with poor prognosis. Increasing evidence has revealed that infiltrating immune cells and other stromal components in the tumor microenvironment (TME) are associated with prognosis of GBM. The aim of the present study was to identify immune cells and immune-related genes extracted from TME in GBM. RNA-sequencing and clinical data of GBM were downloaded from The Cancer Genome Atlas (TCGA). Four survival-related immune cells were identified via Kaplan-Meier survival analysis and immune-related differentially expressed genes (DEGs) screened. Functional enrichment and protein-protein interaction (PPI) networks for the genes were constructed. In addition, we identified 24 hub genes and the expressions of 6 of the genes were significantly associated with prognosis of GBM. Finally, the genes were validated in single-cell sequencing studies of GBM, and the immune cells validated in an independent GBM cohort from the Chinese Glioma Genome Atlas (CGGA). Overall, 24 immune-related genes infiltrating the tumor microenvironment were identified in the present study, which could serve as novel biomarkers and immune therapeutic targets.

Harnessing NK Cell Checkpoint-Modulating Immunotherapies

During the host immune response, the precise balance of the immune system, regulated by immune checkpoint, is required to avoid infection and cancer. These immune checkpoints are the mainstream regulator of the immune response and are crucial for self-tolerance. During the last decade, various new immune checkpoint molecules have been studied, providing an attractive path to evaluate their potential role as targets for effective therapeutic interventions. Checkpoint inhibitors have mainly been explored in T cells until now, but natural killer (NK) cells are a newly emerging target for the determination of checkpoint molecules. Simultaneously, an increasing number of therapeutic dimensions have been explored, including modulatory and inhibitory checkpoint molecules, either causing dysfunction or promoting effector functions. Furthermore, the combination of the immune checkpoint with other NK cell-based therapeutic strategies could also strengthen its efficacy as an antitumor therapy. In this review, we have undertaken a comprehensive review of the literature to date regarding underlying mechanisms of modulatory and inhibitory checkpoint molecules.

A phase 1b study of dual PD-1 and CTLA-4 or KIR blockade in patients with relapsed/refractory lymphoid malignancies

Simultaneously targeting other pathways could increase the activity of PD-1 blockade in lymphoid malignancies not sensitive to single-agent blockade. We explored the safety and efficacy of combined PD-1 and CTLA-4 or KIR blockade in patients with relapsed/refractory (R/R) lymphoid malignancies. This phase 1b trial enrolled adult patients with R/R classical Hodgkin lymphoma (cHL), non-Hodgkin lymphoma (NHL), or multiple myeloma (MM). Patients received nivolumab plus ipilimumab (nivo/ipi) or lirilumab (nivo/liri) until complete response (CR), progression, or unacceptable toxicity. The primary endpoint was safety and tolerability, while secondary endpoints included overall (ORR) and CR rates (CRR), progression-free and overall survival. Sixty-five patients were treated with nivo/ipi, and 72 with nivo/liri. Twenty-nine percent of patients experienced grade 3–4 treatment-related adverse events with nivo/ipi, and 15% with nivo/liri. In cHL, ORR was 74% for nivo/ipi and 76% for nivo/liri, CRRs were 23% and 24%, respectively. In B-NHL and T-NHL, ORR range was 9–22% and CRR was 0–6%. No patient with MM had an objective response. While both combinations were active in cHL, the toxicity of nivo/ipi was higher than expected from nivolumab alone. These data suggest no meaningful improvement in the efficacy of the combinations over single-agent nivolumab in the diseases studied.

NK Cell-Based Immune Checkpoint Inhibition

Immunotherapy, with an increasing number of therapeutic dimensions, is becoming an important mode of treatment for cancer patients. The inhibition of immune checkpoints, which are the source of immune escape for various cancers, is one such immunotherapeutic dimension. It has mainly been aimed at T cells in the past, but NK cells are a newly emerging target. Simultaneously, the number of checkpoints identified has been increasing in recent times. In addition to the classical NK cell receptors KIRs, LIRs, and NKG2A, several other immune checkpoints have also been shown to cause dysfunction of NK cells in various cancers and chronic infections. These checkpoints include the revolutionized CTLA-4, PD-1, and recently identified B7-H3, as well as LAG-3, TIGIT & CD96, TIM-3, and the most recently acknowledged checkpoint-members of the Siglecs family (Siglec-7/9), CD200 and CD47. An interesting dimension of immune checkpoints is their candidacy for dual-checkpoint inhibition, resulting in therapeutic synergism. Furthermore, the combination of immune checkpoint inhibition with other NK cell cytotoxicity restoration strategies could also strengthen its efficacy as an antitumor therapy. Here, we have undertaken a comprehensive review of the literature to date regarding NK cell-based immune checkpoints.

Availability of NK cell expansion agent combined with recombinant IL‑2 and IL‑15 stimulation on the expansion and high‑purity of NK cells in patients with immune‑related pancytopenia in vitro

Natural killer (NK) cells are a group of large granular lymphocytes that play an important regulatory role in innate immunity and adaptive immunity. Immune‑related pancytopenia (IRP) is a type of pancytopenia resulting from bone marrow hematopoietic cells that were destroyed or suppressed by auto‑antibodies. The specific mechanism of IRP is not clear. In the present study, it was identified that the percentage of NK cells in peripheral blood lymphocytes was decreased in patients with IRP. Subsequently, high purity NK cells were extracted from 6 untreated patients with IRP using the immunomagnetic beads sorting, magnetic‑activated cell‑sorting method, which were then cultured then in RPMI‑1640 medium containing 20% FBS. NK cell expansion agents, with or without recombinant interleukin (IL)‑15, were used to amplify high‑purity NK cells on the basic of recombinant IL‑2. Expression of the activated receptors NKG2‑D type II integral membrane protein (NKG2D) and natural killer cell p46‑related protein (NKp46), and the inhibitory receptors CD158a and NKG2‑A/NKG2‑B type II integral membrane protein (NKG2A), in CD56+ NK cells were detected by flow cytometry before and after cell culture. It was observed that treatment with an NK cell expansion agent combined with the stimulation of recombinant IL‑2 and recombinant IL‑15 could increase the number whilst maintaining the purity of NK cells. There were no significant changes in the expression of NKG2D, NKp46, NKG2A and CD158a in patients with IRP before and after NK cell culture. This new amplification method lays a foundation for clinical NK cell immunotherapy and anti‑tumor applications.

From genomic variation to protein aberration: Mutational analysis of single nucleotide polymorphism present in ULBP6 gene and implication in immune response

BACKGROUND

Genetic polymorphisms have been identified as one of the underlying factors in disease pathogenesis and drug resistance since they account for protein dysfunctionality, or in some cases, aberrancy. This explains the high degree of inactivity that characterizes the polymorphic variants of ULBP6 binding protein, which in turn disrupts its primary interaction with human Natural Killer Group 2-member D (NKG2D) and accounts for an impediment to immuno-surveillance. The possible identification of deleterious non-synonymous Single Nucleotide Polymorphisms (nsSNPs) present in the ULBP6 gene is essential for the development of novel gene therapies to prevent the translation of dysfunctional protein variants.

METHODS/RESULTS

In this study, for the first time, we employed an SNP-informatics approach (SNPs retrieval, pathogenic/mutational analysis, phenotypic analysis, and structural analysis) and molecular dynamics techniques to identify and characterize undesirable SNPs coupled with their impact on ULBP6 structural activities relative to dysfunctionality. V52F was predictively pathogenic amongst SNPs studied. Conformational and dynamic studies revealed that in comparison to wildtype ULBP6 (ULBP6^wt), pathogenic ULBP6^V52F demonstrated considerable structural inactivity, which could, in turn, impede biological protein-protein interactions. Moreover, ULBP6^V52F showed relatively limited motions in the conformational space as deduced from estimations of structural stability, fluctuations, and principal components.

CONCLUSION

This study provides a workable paradigm for investigating pathological nsSNPS using computational platforms which findings present ULBP6^V52F as a novel and attractive immunotherapeutic target in combatting immune-associated disorders.

Combining immunotherapies to treat non-small cell lung cancer

Introduction: In recent years, immunotherapy has become an integral part of the treatment of many cancers, including non-small cell lung cancer (NSCLC). Precious therapeutic weapons impacting survival are monoclonal antibodies directed against the programmed death protein-1 (PD-1)/programmed death ligand-1 (PD-L1) immune checkpoint. Areas covered: Unfortunately, not all patients treated with checkpoint inhibitors have durable clinical responses. However, a better understanding of the complexity of interactions between the immune system and cancer, the latter capable of adopting evasion mechanisms, indicates different opportunities to enhance anti-tumor immunity. Expert opinion: In this paper, we review multiple strategies of combining immunotherapies that exploit not only additional immune checkpoint receptors and ligands but also other synergistic approaches such as vaccines or indoleamine 2,3-dioxygenase (IDO) inhibitors with the potential to extend the number of NSCLC patients achieving successful outcomes.

T-cells "à la CAR-T(e)" - Genetically engineering T-cell response against cancer

The last decade will be remembered as the dawn of the immunotherapy era during which we have witnessed the approval by regulatory agencies of genetically engineered CAR T-cells and of checkpoint inhibitors for cancer treatment. Understandably, T-lymphocytes represent the essential player in these approaches. These cells can mediate impressive tumor regression in terminally-ill cancer patients. Moreover, they are amenable to genetic engineering to improve their function and specificity. In the present review, we will give an overview of the most recent developments in the field of T-cell genetic engineering including TCR-gene transfer and CAR T-cells strategies. We will also elaborate on the development of other types of genetic modifications to enhance their anti-tumor immune response such as the use of co-stimulatory chimeric receptors (CCRs) and unconventional CARs built on non-antibody molecules. Finally, we will discuss recent advances in genome editing and synthetic biology applied to T-cell engineering and comment on the next challenges ahead.

Mechanisms of NK Cell Activation and Clinical Activity of the Therapeutic SLAMF7 Antibody, Elotuzumab in Multiple Myeloma

Multiple myeloma (MM) is a bone marrow plasma cell neoplasm and is the second most-common hematologic malignancy. Despite advances in therapy, MM remains largely incurable. Elotuzumab is a humanized IgG1 monoclonal antibody targeting SLAMF7, which is highly expressed on myeloma cells, and the antibody is approved for the treatment of relapsed and/or refractory (RR) MM in combination with lenalidomide and dexamethasone. Elotuzumab can stimulate robust antibody-dependent cellular cytotoxicity (ADCC) through engaging with FcγRIIIA (CD16) on NK cells and antibody-dependent cellular phagocytosis (ADCP) by macrophages. Interestingly, SLAMF7 is also expressed on cytolytic NK cells, which also express the requisite adaptor protein, EAT-2, to mediate activation signaling. Accumulating evidence indicates that antibody crosslinking of SLAMF7 on human and mouse NK cells can stimulate EAT-2-dependent activation of PLCγ, ERK, and intracellular calcium mobilization. The binding of SLAMF7 by elotuzumab can directly induce signal transduction in human NK cells, including co-stimulation of the calcium signaling triggered through other surface receptors, such as NKp46 and NKG2D. In RRMM patients, elotuzumab monotherapy did not produce objective responses, but did enhance the activity of approved standard of care therapies, including lenalidomide or bortezomib, which are known to enhance anti-tumor responses by NK cells. Taken together, these preclinical results and accumulating experience in the clinic provide compelling evidence that the mechanism of action of elotuzumab in MM patients involves the activation of NK cells through both CD16-mediated ADCC and direct co-stimulation via engagement with SLAMF7, as well as promoting ADCP by macrophages. We review the current understanding of how elotuzumab utilizes multiple mechanisms to facilitate immune-mediated attack of myeloma cells, as well as outline goals for future research.

The Role of Stroma in Cholangiocarcinoma: The Intriguing Interplay between Fibroblastic Component, Immune Cell Subsets and Tumor Epithelium

Cholangiocarcinoma (CCA) is a severe and mostly intractable adenocarcinoma of biliary epithelial cells. A typical feature of CCA is its highly desmoplastic microenvironment containing fibrogenic connective tissue and an abundance of immune cells (T lymphocytes, Natural Killer (NK) cells, and macrophages) infiltrating tumor epithelium. This strong desmoplasia is orchestrated by various soluble factors and signals, suggesting a critical role in shaping a tumor growth-permissive microenvironment that is responsible for CCA poor clinical outcome. Indeed stroma not only provides an abundance of factors that facilitate CCA initiation, growth and progression, but also a prejudicial impact on therapeutic outcome. This review will give an overview of tumor-stroma signaling in a microenvironment critically regulating CCA development and progression. Identification of CCA secreted factors by both the fibroblast component and immune cell subsets might provide ample opportunities for pharmacological targeting of this type of cancer.

In Vivo Study of Natural Killer (NK) Cell Cytotoxicity Against Cholangiocarcinoma in a Nude Mouse Model

BACKGROUND/AIM

Natural killer (NK) cells are one of the lymphocytes clinically used for various cancer types. Cytotoxicity of NK cells to cholangiocarcinoma (CC), however, has not yet been studied. Nor NK cell therapy against CC has been clinically applied. In this study, relevance of NK cell therapy for anti-tumor efficacy against CC was pre-clinically investigated.

MATERIALS AND METHODS

Human HuCCT-1 cells, an intrahepatic CC cell line, were xenografted into nude mice. The HuCCT-1 tumor-bearing nude mice then received multiple infusions of ex vivo-expanded human NK cells (SMT01) and in vivo cytotoxic activity of the NK cells against the CC cells was evaluated.

RESULTS

SMT01 infusion resulted in significant inhibition of the CC tumor growth. Body weight of the mice administrated with chemotherapy was found to be maintained at the lowest level among all treatment groups while all the SMT01 infusion groups well maintained their body weight.

CONCLUSION

The present in vivo study demonstrates that NK cells contain cytolytic activity against cholangiocarcinoma and show beneficial effect of NK cell therapy in relevance to quality of life. Further investigation of the NK cell-based immunotherapy can be useful to determine cancer therapeutics for the specific tumor.

In Vivo Study of Natural Killer (NK) Cell Cytotoxicity Against Cholangiocarcinoma in a Nude Mouse Model

BACKGROUND/AIM

Natural killer (NK) cells are one of the lymphocytes clinically used for various cancer types. Cytotoxicity of NK cells to cholangiocarcinoma (CC), however, has not yet been studied. Nor NK cell therapy against CC has been clinically applied. In this study, relevance of NK cell therapy for anti-tumor efficacy against CC was pre-clinically investigated.

MATERIALS AND METHODS

Human HuCCT-1 cells, an intrahepatic CC cell line, were xenografted into nude mice. The HuCCT-1 tumor-bearing nude mice then received multiple infusions of ex vivo-expanded human NK cells (SMT01) and in vivo cytotoxic activity of the NK cells against the CC cells was evaluated.

RESULTS

SMT01 infusion resulted in significant inhibition of the CC tumor growth. Body weight of the mice administrated with chemotherapy was found to be maintained at the lowest level among all treatment groups while all the SMT01 infusion groups well maintained their body weight.

CONCLUSION

The present in vivo study demonstrates that NK cells contain cytolytic activity against cholangiocarcinoma and show beneficial effect of NK cell therapy in relevance to quality of life. Further investigation of the NK cell-based immunotherapy can be useful to determine cancer therapeutics for the specific tumor.

Fusobacterium nucleatum Infection in Colorectal Cancer: Linking Inflammation, DNA Mismatch Repair and Genetic and Epigenetic Alterations

It has been recently reported that the population of Fusobacterium, particularly Fusobacterium nucleatum (Fn), is overrepresented in colorectal cancers and adenomas. The promoting effects of Fn infection on adenoma and/or carcinoma formation have been shown in ApcMin/+mice. Characteristics of Fn-associated CRC were identified through studies using human CRC cohorts, and include right-sided colon location, CpG island methylation phenotype-high (CIMP-H), high level of microsatellite instability (MSI-H), and poor patient prognosis. A subset of Fn-associated CRC exhibits a low level of microsatellite instability (MSI-L) and elevated microsatellite alterations in selected tetra-nucleotide repeats (EMAST) induced by translocation of MSH3 from the nucleus to the cytoplasm in response to oxidative DNA damage or inflammatory signals. The association between CIMP/MSI-H and Fn-infection can be explained by the role of the mismatch repair (MMR) protein complex formed between MSH2 and MSH6 (MutSα) to repair aberrant bases generated by ROS to form 7,8-dihydro-8-oxo-guanine (8-oxoG). Clustered 8-oxoGs formed at CpG-rich regions including promoters by ROS is refractory to base excision repair (BER). Under these conditions, MutSα initiates repair in cooperation with DNA methyltransferases (DNMTs) and the polycomb repressive complex 4 (PRC4). DNMTs at damaged sites methylate CpG islands to repress transcription of target genes and promote repair reactions. Thus, continuous generation of ROS through chronic Fn infection may initiate 1) CIMP-positive adenoma and carcinoma in an MSH2/MSH6-dependent manner, and/or 2) MSI-L/EMAST CRC in an MSH3-dependent manner. The poor prognosis of Fn-associated CRC can be explained by Fn-induced immune-evasion and/or chemo-resistance.

The combination of anti-KIR monoclonal antibodies with anti-PD-1/PD-L1 monoclonal antibodies could be a critical breakthrough in overcoming tumor immune escape in NSCLC

Background

The anti-programmed death-1 (PD-1)/programmed death ligand-1 (PD-L1) monoclonal antibody has a good effect in the treatment of non-small cell lung cancer (NSCLC), but not all PD-1/PD-L1 positive patients can get benefit from it. Compensatory expression of other immune checkpoints may be correlated with the poor efficacy of anti-PD-1/PD-L1 monoclonal antibodies. The inhibitory human leukocyte antigen (HLA)/killer cell Ig-like receptor (KIR) can effectively block the killing effect of natural killer (NK) cells on tumors. Our previous studies have confirmed that high expression of KIR was correlated with poor prognosis of NSCLC. Inhibitory KIR expression was positively correlated with the expression of PD-1.

Methods

The expressions of KIR 2D (L1, L3, L4, S4) (BC032422/ADQ31987/NP_002246/NP_036446, Abcam) and PD-1 (NAT 105, Cell marque) proteins was assessed by immunohistochemistry.

Results

The expression of inhibitory KIR in tumor cells or tumor infiltrating lymphocytes (TILs) is associated with PD-1 expression. Among PD-1 positive patients, 76.3% were KIR 2D (L1, L3, L4, S4) positive on tumor cells, and 74.6% were KIR 2D (L1, L3, L4, S4) positive on TILs. We compared the expression of inhibitory KIR before and after treatment with nivolumab in 11 patients with NSCLC. We found that five (45.5%) patients had positive expression of inhibitory KIR in tumor tissue after being treated with anti-PD-1 monoclonal antibodies, two of whom exhibited a significant increase in expression of inhibitory KIR, and three showed no change.

Conclusions

PD-1 expression was correlated with KIR 2D (L1, L3, L4, S4) on tumor cells or TILs. The resistance to anti-PD-1 monoclonal antibody treatment might be related to KIR. The inhibitory HLA/KIR could combine with the PD-1/PD-L1 signaling pathway negatively regulating NSCLC tumor immunity.

KIR 2D (L1, L3, L4, S4) and KIR 3DL1 protein expression in non-small cell lung cancer

Background

Nature killer (NK) cells are the immune system's first line of defense against both viral infections and tumors. Killer cell immunoglobulin-like receptors (KIRs) are associated with susceptibility to different types of cancers. We investigated KIR 2D (L1, L3, L4, S4) and KIR 3DL1 protein expression and their association with survival in non-small cell lung cancer (NSCLC).

Methods

The expression of KIR 2D (L1, L3, L4, S4) (BC032422/ ADQ31987/ NP_002246/ NP_036446, ABCAM) and KIR 3DL1 (AA 1-444, ABCAM) protein was assessed by immunohistochemistry (IHC) in 62 NSCLC patients.

Results

KIR 2D (L1, L3, L4, S4) and KIR 3DL1 were expressed both on NSCLC tumor cells and tumor infiltrating lymphocytes (TILs). Fourteen samples (22.6%) stained positive for KIR 2D (L1, L3, L4, S4) on the tumor cells, and 10 (16.1%) had positive expression on the TILs. Thirty-three samples (53.2%) stained positive for KIR 3DL1 on the tumor cells, and 31 (50.0%) had positive expression on the TILs. Patients with negative KIR 2D (L1, L3, L4, S4) expression on tumor cells or TILs had longer overall survival (OS) than patients who are KIR 2D (L1, L3, L4, S4) positive on tumor cells (40.70 weeks, 95% CI 24.76-56.65 vs. 7.10 weeks, 95% CI 0.00-19.38, P = 0.014) or TILs (40.70 weeks, 95% CI 24.05-57.35 vs. 3.90 weeks, 95% CI 0.00-9.17, P < 0.001). Likewise, longer OS was significantly correlated with negative expression of KIR 3DL1 on tumor cells (62.30 weeks, 95% CI 0.00-177.37 vs. 13.10 weeks, 95% CI 3.42-22.78, P < 0.001) or TILs (62.30 weeks, 95% CI 0.00-152.05 vs. 12.10 weeks, 95% CI 2.61-21.59, P < 0.001). Cox regression analysis showed that KIR 2D (L1, L3, L4, S4) on TILs was correlated with OS (P = 0.032, Odds Ratio 2.628 95%CI 1.089-6.340).

Conclusions

KIR 2D (L1, L3, L4, S4) and KIR 3DL1 expression was correlated with poor prognosis in NSCLC patients.

New strategies in immunotherapy for lung cancer: beyond PD-1/PD-L1

Immunotherapy has significantly altered the treatment landscape for many cancers, including non-small cell lung cancer (NSCLC). Currently approved immuno-oncology agents for lung cancer are aimed at the reversal of immune checkpoints, programmed death protein-1 (PD-1) and programmed death ligand-1 (PD-L1). Although responses to checkpoint inhibitors are encouraging, and in some cases durable, these successes are not universal among all treated patients. In order to optimize our treatment approach utilizing immunotherapy, we must better understand the interaction between cancer and the immune system and evasion mechanisms. In this review, we will provide an overview of the immune system and cancer, and review novel therapies that promote tumor antigen release for immune system detection, activate the effector T-cell response, and reverse inhibitory antitumor signals.

Targeting Multiple Tumors Using T-Cells Engineered to Express a Natural Cytotoxicity Receptor 2-Based Chimeric Receptor

Recent developments in cancer treatment are demonstrating the increasing and powerful potential of immunotherapeutic strategies. In this regard, the adoptive transfer of tumor-specific T-lymphocytes approaches can lead to tumor regression in cancer patients. More recently, the use of T-cells genetically engineered to express cancer-specific receptors such as the anti-CD19 chimeric antigen receptor (CAR) continues to show promise for the treatment of hematological malignancies. Still, there is a crucial need to develop efficient CAR-T cell approaches for the treatment of solid tumors. It has been shown that other lymphocytes such as natural killer (NK) cells can demonstrate potent antitumor function—nonetheless, their use in immunotherapy is rather limited due to difficulties in expanding these cells to therapeutically relevant numbers and to suppression by endogenous inhibitory mechanisms. Cancer recognition by NK cells is partly mediated by molecules termed natural cytotoxicity receptors (NCRs). In the present study, we hypothesize that it is possible to endow T-cells with an NK recognition pattern, providing them with a mean to recognize tumor cells, in a non-MHC restricted way. To test this, we genetically modified human T-cells with different chimeric receptors based on the human NCR2 molecule and then assessed their antitumor activity in vitro and in vivo. Our results show that expression in primary lymphocytes of an NCR2-derived CAR, termed s4428z, confers T-cells with the ability to specifically recognize heterogeneous tumors and to mediate tumor cytotoxicity in a mouse model. This study demonstrates the benefit of combining tumor recognition capability of NK cells with T cell effectiveness to improve cancer immunotherapy.

Natural killer cells unleashed: Checkpoint receptor blockade and BiKE/TriKE utilization in NK-mediated anti-tumor immunotherapy

Natural killer (NK) cells have long been known to mediate anti-tumor responses without prior sensitization or recognition of specific tumor antigens. However, the tumor microenvironment can suppress NK cell function resulting in tumor escape and disease progression. Despite recent advances in cytokine therapy and NK cell adoptive transfer, tumor expression of ligands to NK - expressed checkpoint receptors can still suppress NK mediated tumor lysis. This review will explore many of the checkpoint receptors tumors utilize to manipulate the NK cell response as well as some of the current and upcoming pharmacological solutions to limit tumor suppression of NK cell function. Furthermore, we will discuss the potential to use these drugs in combinational therapies with novel antibody reagents such as bi- and tri-specific killer engagers (BiKEs and TriKEs) against tumor-specific antigens to enhance NK cell-mediated tumor rejection.

Understanding the checkpoint blockade in lung cancer immunotherapy

Immunotherapies have changed the treatment strategy of some types of tumor including melanoma and, more recently, non-small-cell lung cancer (NSCLC). Immune checkpoints are crucial for the maintenance of self-tolerance and it is known that some tumors use checkpoint systems to evade antitumor immune response. The treatment of advanced NSCLC by immune-checkpoint blockade targeting the programmed cell death protein-1 (PD1/PDL1) and cytotoxic T-lymphocyte antigen 4 (CTLA4) pathways has led to significant clinical benefit either as monotherapy or in combination therapy. Moreover, checkpoint receptors such as lymphocyte activation gene 3 protein (LAG3), T-cell immunoglobulin mucin domain 3 (TIM3) and killer immunoglobulin-like receptors (KIRs) are also being investigated as potential immunotherapeutic targets. This review focuses on the mechanisms of action of the main checkpoint inhibitors in lung cancer and presents the most relevant results from preclinical and clinical studies on immune-based treatments.

NK cell dysfunction in chronic lymphocytic leukemia is associated with loss of the mature cells expressing inhibitory killer cell Ig-like receptors

A prospective analysis of natural killer (NK) cell phenotype and function was performed on fresh peripheral blood samples from untreated patients with B-cell chronic lymphocytic leukemia (CLL) or small lymphocytic lymphoma (SLL). Compared to healthy controls, CD56^dim NK cells in CLL patients displayed reduced expression of the NKG2D activating receptor and increased CD27 expression, which indicates declines in mature cells. In addition, NK cells from CLL patients showed reduced degranulation responses toward transformed B cells alone or with rituximab and were more sensitive to activation-induced cell death. We further noted a striking reduction in the frequency and viability of NK cells expressing the inhibitory killer cell Ig-like receptors (KIR)2DL1 and/or KIR3DL1, which progressed over time in most patients. Comparisons between a CLL patient and healthy monozygotic twin were consistent with our results in the larger cohorts. Functional and biomarker alterations were less pronounced on NK cells from SLL patients, which have lower tumor burden in peripheral blood than CLL, but significant reduction in degranulation under ADCC conditions and lower frequency and viability of KIR-expressing NK cells were still evident in SLL. We conclude that mature KIR-expressing NK cells respond to the high circulating B cell tumor burden in CLL, but undergo activation-induced apoptosis. Consequently, CLL patients may benefit from therapies that augment NK cell survival and function.

Biological mechanisms of immune escape and implications for immunotherapy in head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC) is an aggressive malignancy with high morbidity and mortality. Despite advances in cytotoxic therapies and surgical techniques, overall survival (OS) has not improved over the past few decades. This emphasises the need for intense investigation into novel therapies with good tumour control and minimal toxicity. Cancer immunotherapy has led this endeavour, attempting to improve tumour recognition and expand immune responses against tumour cells. While various forms of HNSCC immunotherapy are in preclinical trials, the most promising direction thus far has been with monoclonal antibodies (mAbs), targeting growth factor and immune checkpoint receptors. Preclinical and early phase trials have shown unprecedented efficacy with minimal adverse effects. This article will review biological mechanisms of immune escape and implications for immunotherapy in HNSCC.

Expression of NKp46 Splice Variants in Nasal Lavage Following Respiratory Viral Infection: Domain 1-Negative Isoforms Predominate and Manifest Higher Activity

The natural killer (NK) cell activating receptor NKp46/NCR1 plays a critical role in elimination of virus-infected and tumor cells. The NCR1 gene can be transcribed into five different splice variants, but the functional importance and physiological distribution of NKp46 isoforms are not yet fully understood. Here, we shed light on differential expression of NKp46 splice variants in viral respiratory tract infections and their functional difference at the cellular level. NKp46 was the most predominantly expressed natural cytotoxicity receptor in the nasal lavage of patients infected with four respiratory viruses: respiratory syncytia virus, adenovirus, human metapneumovirus, or influenza A. Expression of NKp30 was far lower and NKp44 was absent in all patients. Domain 1-negative NKp46 splice variants (i.e., NKp46 isoform d) were the predominantly expressed isoform in nasal lavage following viral infections. Using our unique anti-NKp46 mAb, D2-9A5, which recognizes the D2 extracellular domain, and a commercial anti-NKp46 mAb, 9E2, which recognizes D1 domain, allowed us to identify a small subset of NKp46 D1-negative splice variant-expressing cells within cultured human primary NK cells. This NKp46 D1-negative subset also showed higher degranulation efficiency in term of CD107a surface expression. NK-92 cell lines expressing NKp46 D1-negative and NKp46 D1-positive splice variants also showed functional differences when interacting with targets. A NKp46 D1-negative isoform-expressing NK-92 cell line showed enhanced degranulation activity. To our knowledge, we provide the first evidence showing the physiological distribution and functional importance of human NKp46 splice variants under pathological conditions.

CD155 on HIV-Infected Cells Is Not Modulated by HIV-1 Vpu and Nef but Synergizes with NKG2D Ligands to Trigger NK Cell Lysis of Autologous Primary HIV-Infected Cells

Activation of primary CD4⁺ T cells induces the CD155, but not the CD112 ligands for the natural killer (NK) cell activation receptor (aNKR) CD226 [DNAX accessory molecule-1 (DNAM-1)]. We hypothesize that HIV productively infects activated CD4⁺ T cells and makes itself vulnerable to NK cell-mediated lysis when CD155 on infected T cells engages DNAM-1. The primary objective of this study is to determine whether CD155 alone or together with NKG2D ligands triggers autologous NK cell lysis of HIV-infected T cells and whether HIV modulates CD155. To determine whether HIV modulates this activation ligand, we infected "activated" CD4⁺ T cells with HIV in the absence or presence of Nef and/or Vpu and determined by flow cytometry whether they modulated CD155. To determine if CD155 alone, or together with NKG2D ligands, triggered NK cell lysis of autologous HIV-infected T cells, we treated purified NK cells with DNAM-1 and/or NKG2D blocking antibodies before the addition of purified autologous HIV-infected cells in cytolytic assays. Finally, we determined whether DNAM-1 works together with NKG2D as an NK cell coactivation receptor (caNKR) or whether they work independently as aNKRs to induce an NK cell lytic response. We demonstrate that HIV and specifically Nef and/or Vpu do not modulate CD155 on infected primary T cells; and both CD155 and NKG2D ligands synergize as aNKRs to trigger NK cell lysis of the infected cell.

KIR genes and HLA class I ligands in a Caucasian Brazilian population with colorectal cancer

Colorectal cancer (CRC) can occur anywhere in the colon or rectum and represents the third most common cancer in the world in both sexes. Natural killer cells (NK) are part of the innate immune system recognizing class I HLA molecules on target cells through their membrane receptors, called killer cell immunoglobulin-like receptors (KIR). The aim of our study was to evaluate the association between the KIR genes and HLA ligands in patients with colorectal cancer and healthy controls. We examined the polymorphism of 16 KIR genes and their HLA ligands in 154 caucasoid CRC patients and 216 controls. When both groups were compared, no significant differences were found for HLA ligands and KIR genes after Bonferroni correction. However, the Bx haplotypes (heterozygous and homozygous for the haplotype B) were more frequent in controls, when compared with patients. These findings suggest that individuals with Bx haplotypes could have some protection to colorectal cancer. The hypothesis is not related with the presence of a special KIR gene and HLA ligand related to the disease, but to the presence of several activating genes in the individuals with no better action of one in relation to other. Further studies to confirm this observation are warranted.

Typing of killer-cell immunoglobulin-like receptors and their cognate human leukocyte antigen class I ligands predicts survival of Chinese Han patients with metastatic non-small-cell lung cancer

Non-small-cell lung cancer (NSCLC) may establish an immunosuppressive tumor microenvironment that is conducive to tumor growth. Natural killer (NK) cells play a pivotal role in immunological surveillance. Activation of NK cells partially depends on the interactions between killer-cell immunoglobulin-like receptors (KIRs) and human leukocyte antigen (HLA) class I ligands. We herein investigated the association of KIRs and HLA ligands with survival in metastatic NSCLC (mNSCLC) patients treated with chemotherapy in a Chinese Han population. Polymerase chain reaction with sequence-specific primers was used to type 15 KIRs at the DNA and mRNA level and 6 HLA ligands in 70 mNSCLC patients. Survival curves were estimated using the Kaplan-Meier method and compared with the log-rank test. Cox proportional hazard regression model was applied for multivariate survival analysis, with the stepwise selection, to determine independent predictors of survival. It was observed that patients with KIR2DS4del gene expression at the mRNA level or HLA-Bw4T80 exhibited poor overall survival (OS). The multivariate analysis revealed that HLA-Bw4T80 and KIR2DS4del expression were independent predictors of OS. This observation indicated that the KIR/HLA ligand is a promising predictor of survival in mNSCLC and may also provide a strategy for treatment stratification and patient management.

Checkpoint inhibition in myeloma

Historically, attempts at cancer immunotherapy have emphasized strategies designed to stimulate or augment the immune system into action. In the past decade, a complementary approach has developed, that of releasing immune cells from inhibitory restraint. Discoveries in the fundamental biology of how immunity is regulated, how the immune system interfaces with malignancy, and how cancer cells may exploit these processes to evade detection have all been translated into the rapidly growing field of therapeutic immune checkpoint inhibition for cancer. Myeloma is a malignancy associated with significant immune dysfunction imparted both by the disease itself as well as by many of the immunosuppressive therapies that have been used in the past. The growing body of preclinical data regarding immunoregulatory mechanisms that appear active in myeloma has begun to be translated to clinical trials targeting these signaling axes. This review will attempt to summarize the current understanding of the basic biology of several immune checkpoint pathways that may be important in myeloma and provide an up-to-date overview of recent and ongoing clinical trials of immune checkpoint inhibitors in myeloma. Finally, several current challenges and possible future directions of immune checkpoint blockade in myeloma will be reviewed.

Lymphatic dysfunction attenuates tumor immunity through impaired antigen presentation

Tumor growth and metastasis of cancer involve autonomous tumor cell growth and host-tumor interactions. While tumor-specific immunity has been intensively studied in vitro, dynamic roles of lymphatic transport on tumor immunity in vivo have not been fully elucidated. In this study, we examined tumor growth and anti-tumor immune responses using kCYC mice, which demonstrate severe lymphatic dysfunction. Primary tumor growth was augmented in kCYC mice (compared to wild-type mice) when B16 melanoma or EL-4 lymphoma cells were subcutaneously injected. Expression of inflammatory cytokines such as IFN-γ, TNF-α, and IL-2 as well as IL-10 expression in draining lymph nodes (LNs) was significantly reduced in kCYC mice after tumor inoculation. Moreover, decreased levels of tumor-associated antigens were detected in draining LNs in kCYC mice, together with impaired antigen presentation. CD8⁺ T cells in draining LNs derived from kCYC mice bearing B16 melanoma also showed significantly decreased cytotoxic activity in vitro. Finally, tumor suppression activity of CD8⁺ T cells derived from kCYC mice bearing B16 melanoma was reduced when adoptively transferred to naive wild-type mice. In summary, these findings suggest that lymphatic transport is essential in generating optimal tumor-specific immune responses mediated by CD8⁺ T cells.

Scorpion venom activates natural killer cells in hepatocellular carcinoma via the NKG2D-MICA pathway

Previous studies have demonstrated that polypeptides extracted from scorpion venom (PESV) inhibited cell proliferation in several tumors, however, the effect on dysfunctional and exhausted natural killer cells which contribute to tumor escape from immune surveillance remain to be elucidated. In this study, we determined the effect of PESV on NK infiltration into H22 cells orthotopic transplantation tumors and on the expression of MHC class I chain-related proteins A (MICA) in HepG2 cells. We found that tumor growth in mice was significantly inhibited by PESV and the survival time of tumor-bearing mice treated with PESV was significantly prolonged. Moreover, levels of tumor-infiltrating NK cells, NKG2D protein, perforin and granzyme B mRNA were significantly increased in the group treated with PESV compared with the tumor-bearing control group. In addition, In addition, up-regulation of MICA by PESV enhances the susceptibility of HepG2 cells to NK lysis in vitro. These results indicate that the inhibitory effects of PESV on hepatic carcinoma are likely mediated by up-regulation of NK cell activity via the MICA-NKG2D pathway.