KIR Genes and Their Ligands Predict the Response to Anti-EGFR Monoclonal Antibodies in Solid Tumors

Immunological and biological dissection of normal and tumoral salivary glands

Salivary glands naturally play central roles in oral immunity. The salivary glands microenvironment inevitable may be exposed to exogenous factors consequently triggering the initiation and formation of various malignant and benign tumors. Mesenchymal stem cells are recruited into salivary gland microenvironment, interact with tumor cells, and induce inhibitory cytokines as well as cells with immunosuppressive phenotypes such as myeloid-derived suppressor cells (MDSCs) and regulatory T cells (Tregs). The immune components and tumor immune responses in malignant and benign SGTs are still under investigation. Immune responses may directly play a limiting role in tumor growth and expansion, or may participate in formation of a rich milieu for tumor growth in cooperation with other cellular and regulatory molecules. Immune checkpoint molecules (e.g. PDLs, HLA-G and LAG3) are frequently expressed on tumor cells and/or tumor-infiltrating lymphocytes (TILs) in salivary gland microenvironment, and an increase in their expression is associated with T cell exhaustion, immune tolerance and tumor immune escape. Chemokines and chemokine receptors have influential roles on aggressive behaviors of SGTs, and thereby they could be candidate targets for cancer immunotherapy. To present a broad knowledge on salivary glands, this review first provides a brief description on immunological functions of normal salivary glands, and then describe the SGT's tumor microenvironment, by focusing on mesenchymal stem cells, immune cell subsets, immune checkpoint molecules, chemokines and chemokine receptors, and finally introduces immune checkpoint inhibitors as well as potential targets for cancer therapy.

KIR- Ligand Interactions in Hypertensive Disorders in Pregnancy

Hypothesis

The activity of natural killer (NK) cells is considered an important factor for the tolerance of the fetus during pregnancy. The complications of pregnancy, such as hypertensive disorders (HDP), may be therefore associated with this immune compartment.

Methods

The current study included 41 pregnant women diagnosed with HDPs (Gestational Hypertension; GH or Preeclampsia; PE) and 21 healthy women. All the patients were under continuous obstetric care during the pregnancy and labour. The number of mother-child mismatches within killer immunoglobulin-like receptors (KIRs), their ligands [MM], and missing KIR ligands [MSLs] was assessed. KIRs and their ligands were assessed with Next Generation Sequencing (NGS) and Polymerase Chain Reaction Sequence-Specific Oligonucleotide (PCR-SSO) typing. The subsets of NK cells were assessed with multicolor flow cytometry and correlated to the number of MSLs.

Results

The number of MSLs was significantly higher in HDP patients when compared to healthy non-complicated pregnancy patients. Some MSLs, such as those with 2DS2 activating KIR, were present only in HDP patients. The percentage of CD56+CD16-CD94+ NK cells and CD56+CD16-CD279+ NK cells correlated with the number of MSLs with inhibiting KIRs only in healthy patients. In HDP patients, there was a correlation between the percentage of CD56-CD16+CD69+ NK cells and the number of MSLs with inhibiting and activating KIRs. As compared to the healthy group, the percentage of CD56+CD16-CD279+ NK cells and CD56-CD16+CD279+ NK cells were lower in HDP patients. HDP patients were also characterized by a higher percentage of CD56+CD16+perforin+ NK cells than their healthy counterparts.

Conclusions

Patients with HDP were characterized by a higher number of MSLs within the KIRs receptors. It seemed that the number of MSLs in the healthy group was balanced by various receptors, such as CD94 or inhibitory CD279, expressed on NK cells. Conversely, in HDP patients the number of MSLs was associated with the activation detected as the increased level of CD69+ NK cells.

Natural Killer Cells: the Missing Link in Effective Treatment for High-Grade Serous Ovarian Carcinoma

OPINION STATEMENT

Ovarian cancer (OC), especially high-grade serous cancer (HGSC), is a highly heterogeneous malignancy with limited options for curative treatment and a high frequency of relapse. Interactions between OC and the immune system may permit immunoediting and immune escape, and current standard of care therapies can influence immune cell infiltration and function within the tumor microenvironment. Natural killer (NK) cells are involved in cancer immunosurveillance and immunoediting and can be activated by therapy, but deliberate approaches to maximize NK cell reactivity for treatment of HGSC are in their infancy. NK cells may be the ideal target for immunotherapy of HGSC. The diverse functions of NK cells, and their established roles in immunosurveillance, make them attractive candidates for more precise and effective HGSC treatment. NK cells' functional capabilities differ because of variation in receptor expression and genetics, with meaningful impacts on their anticancer activity. Studying HGSC:NK cell interactions will define the features that predict the best outcomes for patients with the disease, but the highly diverse nature of HGSC will likely require combination therapies or approaches to simultaneously target multiple, co-existing features of the tumor to avoid tumor escape and relapse. We expect that the ideal therapy will enable NK cell infiltration and activity, reverse immunosuppression within the tumor microenvironment, and enable effector functions against the diverse subpopulations that comprise HGSC.

KIR-HLA Functional Repertoire Influences Trastuzumab Efficiency in Patients With HER2-Positive Breast Cancer

Trastuzumab induced a high rate of pathological Complete Response (pCR) in patients affected by locally advanced HER2-positive Breast Cancer (HER2-BC), by exploiting immune-mediated mechanisms as Antibody-Dependent Cell Cytotoxicity (ADCC) involving Natural Killer (NK) cells. Host's immune genetics could influence the response to therapy, through the expression of variants that characterize NK receptors involved in ADCC effectiveness. Killer cell immunoglobin-like receptors (KIRs) modulate NK cell activity through their binding to class-I Human Leukocyte Antigens (HLA). The impact of the KIR/HLA repertoire in HER2-BC is under study. We characterized KIR genotypes of 36 patients with locally advanced HER2-BC treated with neoadjuvant chemotherapy including trastuzumab. We monitored pCR achievement before surgery and Disease-Free Survival (DFS) and Overall Survival (OS) after adjuvant therapy. HLA, and Fc gamma receptor IIIa (FcγR3A) and IIa (FcγR2A) were genotyped through targeted PCR and Sanger sequencing in 35/36 patients. The KIR-HLA combinations were then described as functional haplotypes and divided in two main categories as inhibitory tel A and stimulatory tel B. Trastuzumab-dependent ADCC activity was monitored with an in vitro assay using a HER2-BC model and patients' NK cells.We observed a higher frequency of KIR activators in patients who achieved a pCR compared to partial responders. During the study of functional haplotypes, individuals carrying a tel B haplotype showed greater ADCC efficiency than tel A cases. In subjects with the tel A haplotype the presence of the favorite V allele in FcγR3A receptor improved their low ADCC levels. Regardless of the haplotypes detected, the presence of KIR3DL2/HLA-A03 or A11 was always associated with the FcγR3A V allele, and therefore correlated with greater ADCC efficiency. However, this particular KIR receptor appeared to harm DFS and OS. Indeed, patients with tel B haplotype without KIR3DL2/HLA-A03 or A11 showed a better outcome. Our data, although preliminary, suggested a potential predictive role for KIR haplotype tel B, in identifying patients who achieve a pCR after neoadjuvant treatment with trastuzumab, and supported a negative prognostic impact of KIR3DL2/HLA-A03 or A11 in the adjuvant setting.

KIR Receptors as Key Regulators of NK Cells Activity in Health and Disease

Natural killer (NK) cells are part of the cellular immune response. They target mainly cancer and virally infected cells. To a high extent cytotoxic activity of NK cells is regulated inter alia by signals from killer immunoglobulin-like receptors (KIR). The major histocompatibility complex (MHC) class I molecules are important ligands for KIR receptors. Binding of ligands (such as MHC I) to the KIR receptors has the important role in solid organ or hematopoietic cell transplantation. Of note, the understanding of the relationship between KIR and MHC receptors may contribute to the improvement of transplant results. Donor-recipient matching, which also includes the KIR typing, may improve monitoring, individualize the treatment and allow for predicting possible effects after transplantation, such as the graft-versus-leukemia effect (GvL) or viral re-infection. There are also less evident implications of KIR/MHC matching, such as with pregnancy and cancer. In this review, we present the most relevant literature reports on the importance of the KIR/MHC relationship on NK cell activity and hematopoietic stem cell transplantation (HSCT)/solid organ transplantation (SOT) effects, the risk of allograft rejection, protection against post-transplant cytomegalovirus (CMV) infection, pregnancy complications, cancer and adoptive therapy with NK cells.

Improving selection of patients with metastatic colorectal cancer to benefit from cetuximab based on KIR genotypes

AIM

Cetuximab is a standard-of-care treatment for KRAS wild-type metastatic colorectal cancer (mCRC), but it may also be effective in a subgroup of KRAS mutant patients by its immunomodulatory activity. Here, we explore if KIR (killer cell immunoglobulin-like receptor) genotyping can provide a significant added value in the clinical outcome of patients with KRAS mutant mCRC based on cetuximab treatment.

METHODS

We included 69 patients with histologically confirmed mCRC and KRAS mutation, positive EGFR expression, and Eastern Cooperative Oncology Group performance status ≤2. Based on KIR gene content, haplotype (A or B) was defined and genotypes (AA or Bx) were grouped for each patient.

RESULTS

We demonstrated with new evidence the immunomodulatory activity of cetuximab in patients with KRAS mutant mCRC. Patients with homozygous genotypes (AA or BB) showed shorter 12-month progression-free survival (PFS12) and poorer overall survival (OS) than those with heterozygotes (AB). Moreover, multivariate analysis confirmed stratification of patients based on genotype was an independent marker of PFS12 (HR 2.16) and the centromeric and telomeric distribution of KIRs was an independent predictor of both PFS12 (HR 2.26) and OS (HR 1.93) in patients with mCRC with KRAS mutation treated with cetuximab.

CONCLUSIONS

Selection of patients with mCRC based on their KIR genotypes opens a therapeutic opportunity for patients with KRAS mutation, and it should be tested in clinical trials in comparison with other alternatives with scarce benefit.

TRIAL REGISTRATION NUMBER

NCT01450319, EudraCT 2010-023580-18.

Activating killer cell immunoglobulin-like receptors: Detection, function and therapeutic use

Killer cell immunoglobulin-like receptors (KIRs) have a central role in the control of natural killer (NK) cell function. The functions of the activating KIRs, as compared to those of the inhibitory KIR, have been more difficult to define due to difficulties in antibody-mediated identification and their apparent low affinities for HLA class I. Immunogenetic studies have shown associations of activating KIRs with the outcome of autoimmune diseases, pregnancy-associated disorders, infectious diseases and cancers. Activating KIR are thus thought to have important roles in the control of natural killer cell functions and their role in disease. In this review, we discuss current knowledge on activating KIR, their ligands and, their roles in the pathogenesis and potential therapy of human diseases.

Activating and inhibitory killer cell immunoglobulin like receptors (KIR) genes are involved in an increased susceptibility to colorectal adenocarcinoma and protection against invasion and metastasis

BACKGROUND

A set of activating and inhibitory KIRs (aKIR, iKIR) are involved in NK cell mediated immunity. This study was carried out in order to investigate the KIRs pattern and its association with colorectal carcinoma (CRC) development and clinical outcomes.

METHODS

Sequence-specific primers-polymerase chain reaction (SSP-PCR) for typing of 16 KIR genes was utilized in 165 patients with colorectal adenocarcinoma with 165 age and gender matched healthy controls (CNs).

RESULTS

Possessing KIR2DS1, 2DS5, 3DS1, 2DS4fl, 2DL5, telomeric half KIR genes, ≥ 4 aKIR and CXT4 genotype were associated with an increased susceptibility to colorectal adenocarcinoma while KIR2DS4del and iKIR >aKIR confer resistance to CRC. On the other hand, clinical associations revealed the defensive role of telomeric KIR3DL1, 3DS1, 2DS1, 2DS4, genotypes with ≥ 4 aKIR and more inhibitory KIRs than activating ones (I > A) against metastasis and CXTX genotype in perineural invasion.

CONCLUSION

According to current results it appears that KIRs system play distinctive roles in development and metastasis of colorectal adenocarcinoma.

Tumor immunotherapy: New aspects of natural killer cells

A group of impressive immunotherapies for cancer treatment, including immune checkpoint-blocking antibodies, gene therapy and immune cell adoptive cellular immunotherapy, have been established, providing new weapons to fight cancer. Natural killer (NK) cells are a component of the first line of defense against tumors and virus infections. Studies have shown dysfunctional NK cells in patients with cancer. Thus, restoring NK cell antitumor functionality could be a promising therapeutic strategy. NK cells that are activated and expanded ex vivo can supplement malfunctional NK cells in tumor patients. Therapeutic antibodies, chimeric antigen receptor (CAR), or bispecific proteins can all retarget NK cells precisely to tumor cells. Therapeutic antibody blockade of the immune checkpoints of NK cells has been suggested to overcome the immunosuppressive signals delivered to NK cells. Oncolytic virotherapy provokes antitumor activity of NK cells by triggering antiviral immune responses. Herein, we review the current immunotherapeutic approaches employed to restore NK cell antitumor functionality for the treatment of cancer.

Interplay between Natural Killer Cells and Anti-HER2 Antibodies: Perspectives for Breast Cancer Immunotherapy

Overexpression of the human epidermal growth factor receptor 2 (HER2) defines a subgroup of breast tumors with aggressive behavior. The addition of HER2-targeted antibodies (i.e., trastuzumab, pertuzumab) to chemotherapy significantly improves relapse-free and overall survival in patients with early-stage and advanced disease. Nonetheless, considerable proportions of patients develop resistance to treatment, highlighting the need for additional and co-adjuvant therapeutic strategies. HER2-specific antibodies can trigger natural killer (NK) cell-mediated antibody-dependent cellular cytotoxicity and indirectly enhance the development of tumor-specific T cell immunity; both mechanisms contributing to their antitumor efficacy in preclinical models. Antibody-dependent NK cell activation results in the release of cytotoxic granules as well as the secretion of pro-inflammatory cytokines (i.e., IFNγ and TNFα) and chemokines. Hence, NK cell tumor suppressive functions include direct cytolytic killing of tumor cells as well as the regulation of subsequent antitumor adaptive immunity. Albeit tumors with gene expression signatures associated to the presence of cytotoxic lymphocyte infiltrates benefit from trastuzumab-based treatment, NK cell-related biomarkers of response/resistance to HER2-specific therapeutic antibodies in breast cancer patients remain elusive. Several variables, including (i) the configuration of the patient NK cell repertoire; (ii) tumor molecular features (i.e., estrogen receptor expression); (iii) concomitant therapeutic regimens (i.e., chemotherapeutic agents, tyrosine kinase inhibitors); and (iv) evasion mechanisms developed by progressive breast tumors, have been shown to quantitatively and qualitatively influence antibody-triggered NK cell responses. In this review, we discuss possible interventions for restoring/enhancing the therapeutic activity of HER2 therapeutic antibodies by harnessing NK cell antitumor potential through combinatorial approaches, including immune checkpoint blocking/stimulatory antibodies, cytokines and toll-like receptor agonists.