IL-12 enhances the natural killer cell cytokine response to Ab-coated tumor cells

An Open-Label Study of Subcutaneous CpG Oligodeoxynucleotide (PF03512676) in Combination with Trastuzumab in Patients with Metastatic HER2+ Breast Cancer

OBJECTIVES

CpG ODN is a Toll-like receptor 9 agonist with immunotherapeutic potential for many cancer types, including aggressive breast cancers. There is strong interest in utilizing CpG ODN as an adjuvant to improve clinical efficacy of current treatments and immunogenicity of breast cancers not traditionally responsive to active immunotherapy, such as those that are human epidermal growth factor receptor 2 (HER2)-positive. This study aimed to study the efficacy and safety of combination CpG ODN plus anti-HER2 antibody trastuzumab treatment in patients with advanced/metastatic breast cancer.

METHODS

This single-arm, open-label phase II clinical trial treated patients (n = 6) with advanced/metastatic HER2-positive breast cancer with weekly subcutaneous CpG ODN and trastuzumab. Patients may have received any number of prior therapies to be enrolled (most enrolled at median 1 prior line of chemotherapy). Peripheral blood was collected at baseline and weeks 2, 6, 12, and 18 for immune analyses. Six patients were enrolled and 50% achieved stable disease (SD) response.

RESULTS

Median PFS was 8.3 months. Three of the six patients enrolled opted to stop treatment due to tolerability issues. Multiplex assay for cytokine measurements revealed significantly higher VEGF-D levels at week 2 compared to baseline. Peripheral blood mononuclear cells analyzed by flow cytometry showed a significant increase in monocytic MDSC between weeks 6 and 12. Patients with progressive disease tended to have higher levels of week 6 monocytic MDSC and PD-1+ T cells than patients with SD. NK cell populations did not significantly change throughout treatment.

CONCLUSIONS

CpG ODN and trastuzumab treatment of metastatic HER2 + breast cancer was safe but was not tolerable for all patients. This combination did induce potentially predictive immune profile changes in treated patients with metastatic HER2 + breast cancer, the significance of which needs to be further explored.

Reprogramming of IL-12 secretion in the PDCD1 locus improves the anti-tumor activity of NY-ESO-1 TCR-T cells

Introduction

Although the engineering of T cells to co-express immunostimulatory cytokines has been shown to enhance the therapeutic efficacy of adoptive T cell therapy, the uncontrolled systemic release of potent cytokines can lead to severe adverse effects. To address this, we site-specifically inserted the interleukin-12 (IL-12) gene into the PDCD1 locus in T cells using clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9)-based genome editing to achieve T-cell activation-dependent expression of IL-12 while ablating the expression of inhibitory PD-1.

Methods

New York esophageal squamous cell carcinoma 1(NY-ESO-1)-specific TCR-T cells was investigated as a model system. We generated ΔPD-1-IL-12 -edited NY-ESO-1 TCR-T cells by sequential lentiviral transduction and CRISPR knock-in into activated human primary T cells.

Results

We showed that the endogenous PDCD1 regulatory elements can tightly control the secretion of recombinant IL-12 in a target cell-dependent manner, at an expression level that is more moderate than that obtained using a synthetic NFAT-responsive promoter. The inducible expression of IL-12 from the PDCD1 locus was sufficient to enhance the effector function of NY-ESO-1 TCR-T cells, as determined by upregulation of effector molecules, increased cytotoxic activity, and enhanced expansion upon repeated antigen stimulation in vitro. Mouse xenograft studies also revealed that PD-1-edited IL-12-secreting NY-ESO-1 TCR-T cells could eliminate established tumors and showed significantly greater in vivo expansion capacity than control TCR-T cells.

Discussion

Our approach may provide a way to safely harness the therapeutic potential of potent immunostimulatory cytokines for the development of effective adoptive T cell therapies against solid tumors.

Antitumor Activities of Interleukin-12 in Melanoma

Melanoma is the most common and serious malignant tumor among skin cancers. Although more and more studies have revolutionized the systematic treatment of advanced melanoma in recent years, access to innovative drugs for melanoma is still greatly restricted in many countries. IL-12 produced mainly by antigen-presenting cells regulates the immune response and affects the differentiation of T cells in the process of antigen presentation. However, the dose-limited toxicity of IL-12 limits its clinical application. The present review summarizes the basic biological functions and toxicity of IL-12 in the treatment of melanoma and discusses the clinical application of IL-12, especially the combination of IL-12 with immune checkpoint inhibitors, cytokines and other therapeutic drugs. We also summarize several promising technological approaches such as carriers that have been developed to improve the pharmacokinetics, efficacy and safety of IL-12 or IL-12 encoding plasmid application.

Cytokine Based Immunotherapy for Cancer and Lymphoma: Biology, Challenges and Future Perspectives

Cytokines regulate both the innate and adaptive immune responses to cancer. Although antitumor activity has been seen for several cytokines in preclinical models, they have had limited success as single therapeutic agents in clinical trials of cancer immunotherapy. However, the possible combinations of cytokines with other immune therapeutics and the advancement in genetic engineering, synthetic biology and cellular and immune therapy has led to the revival of interest in cytokines as anticancer agents. This article will review several immunostimulatory cytokines with anticancer activity, focusing on the those that have been studied in treatment of lymphoma and highlighting recent advances of potential clinical relevance.

A novel fusion protein scaffold 18/12/TxM activates the IL-12, IL-15, and IL-18 receptors to induce human memory-like natural killer cells

Natural killer (NK) cells are cytotoxic innate lymphoid cells that are emerging as a cellular immunotherapy for various malignancies. NK cells are particularly dependent on interleukin (IL)-15 for their survival, proliferation, and cytotoxic function. NK cells differentiate into memory-like cells with enhanced effector function after a brief activation with IL-12, IL-15, and IL-18. N-803 is an IL-15 superagonist composed of an IL-15 mutant (IL-15N72D) bound to the sushi domain of IL-15Rα fused to the Fc region of IgG1, which results in physiological trans-presentation of IL-15. Here, we describe the creation of a novel triple-cytokine fusion molecule, 18/12/TxM, using the N-803 scaffold fused to IL-18 via the IL-15N72D domain and linked to a heteromeric single-chain IL-12 p70 by the sushi domain of the IL-15Rα. This molecule displays trispecific cytokine activity through its binding and signaling through the individual cytokine receptors. Compared with activation with the individual cytokines, 18/12/TxM induces similar short-term activation and memory-like differentiation of NK cells on both the transcriptional and protein level and identical in vitro and in vivo anti-tumor activity. Thus, N-803 can be modified as a functional scaffold for the creation of cytokine immunotherapies with multiple receptor specificities to activate NK cells for adoptive cellular therapy.

Role of microRNAs in COVID-19 with implications for therapeutics

COVID-19 is a pneumonia-like disease with highly transmittable and pathogenic properties caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which infects both animals and humans. Although many efforts are currently underway to test possible therapies, there is no specific FDA approved drug against SARS-CoV-2 yet. miRNA-directed gene regulation controls the majority of biological processes. In addition, the development and progression of several human diseases are associated with dysregulation of miRNAs. In this regard, it has been shown that changes in miRNAs are linked to severity of COVID-19 especially in patients with respiratory diseases, diabetes, heart failure or kidney problems. Therefore, targeting these small noncoding-RNAs could potentially alleviate complications from COVID-19. Here, we will review the roles and importance of host and RNA virus encoded miRNAs in COVID-19 pathogenicity and immune response. Then, we focus on potential miRNA therapeutics in the patients who are at increased risk for severe disease.

Nanotechnology-enhanced immunotherapy for metastatic cancer

A vast majority of cancer deaths occur as a result of metastasis. Unfortunately, effective treatments for metastases are currently lacking due to the difficulty of selectively targeting these small, delocalized tumors distributed across a variety of organs. However, nanotechnology holds tremendous promise for improving immunotherapeutic outcomes in patients with metastatic cancer. In contrast to conventional cancer immunotherapies, rationally designed nanomaterials can trigger specific tumoricidal effects, thereby improving immune cell access to major sites of metastasis such as bone, lungs, and lymph nodes, optimizing antigen presentation, and inducing a persistent immune response. This paper reviews the cutting-edge trends in nano-immunoengineering for metastatic cancers with an emphasis on different nano-immunotherapeutic strategies. Specifically, it discusses directly reversing the immunological status of the primary tumor, harnessing the potential of peripheral immune cells, preventing the formation of a pre-metastatic niche, and inhibiting the tumor recurrence through postoperative immunotherapy. Finally, we describe the challenges facing the integration of nanoscale immunomodulators and provide a forward-looking perspective on the innovative nanotechnology-based tools that may ultimately prove effective at eradicating metastatic diseases.

Intranasal Administration of Codium fragile Polysaccharide Elicits Anti-Cancer Immunity against Lewis Lung Carcinoma

Natural polysaccharides have shown promising effects on the regulation of immunity in animals. In this study, we examined the immune stimulatory effect of intranasally administered Codium fragile polysaccharides (CFPs) in mice. Intranasal administration of CFPs in C57BL/6 mice induced the upregulation of surface activation marker expression in macrophages and dendritic cells (DCs) in the mediastinal lymph node (mLN) and the production of interleukin-6 (IL-6), IL-12p70, and tumor necrosis factor-α in bronchoalveolar lavage fluid. Moreover, the number of conventional DCs (cDCs) was increased in the mLNs by the upregulation of C-C motif chemokine receptor 7 expression, and subsets of cDCs were also activated following the intranasal administration of CFP. In addition, the intranasal administration of CFPs promoted the activation of natural killer (NK) and T cells in the mLNs, which produce pro-inflammatory cytokines and cytotoxic mediators. Finally, daily administration of CFPs inhibited the infiltration of Lewis lung carcinoma cells into the lungs, and the preventive effect of CFPs on tumor growth required NK and CD8 T cells. Furthermore, CFPs combined with anti-programmed cell death-ligand 1 (PD-L1) antibody (Ab) improved the therapeutic effect of anti-PD-L1 Ab against lung cancer. Therefore, these data demonstrated that the intranasal administration of CFP induced mucosal immunity against lung cancer.

Comparative Metabolomics Reveals the Microenvironment of Common T-Helper Cells and Differential Immune Cells Linked to Unique Periapical Lesions

Periapical abscesses, radicular cysts, and periapical granulomas are the most frequently identified pathological lesions in the alveolar bone. While little is known about the initiation and progression of these conditions, the metabolic environment and the related immunological behaviors were examined for the first time to model the development of each pathological condition. Metabolites were extracted from each lesion and profiled using gas chromatography-mass spectrometry in comparison with healthy pulp tissue. The metabolites were clustered and linked to their related immune cell fractions. Clusters I and J in the periapical abscess upregulated the expression of MMP-9, IL-8, CYP4F3, and VEGF, while clusters L and M were related to lipophagy and apoptosis in radicular cyst, and cluster P in periapical granuloma, which contains L-(+)-lactic acid and ethylene glycol, was related to granuloma formation. Oleic acid, 17-octadecynoic acid, 1-nonadecene, and L-(+)-lactic acid were significantly the highest unique metabolites in healthy pulp tissue, periapical abscess, radicular cyst, and periapical granuloma, respectively. The correlated enriched metabolic pathways were identified, and the related active genes were predicted. Glutamatergic synapse (16–20),-hydroxyeicosatetraenoic acids, lipophagy, and retinoid X receptor coupled with vitamin D receptor were the most significantly enriched pathways in healthy control, abscess, cyst, and granuloma, respectively. Compared with the healthy control, significant upregulation in the gene expression of CYP4F3, VEGF, IL-8, TLR2 (P < 0.0001), and MMP-9 (P < 0.001) was found in the abscesses. While IL-12A was significantly upregulated in cysts (P < 0.01), IL-17A represents the highest significantly upregulated gene in granulomas (P < 0.0001). From the predicted active genes, CIBERSORT suggested the presence of natural killer cells, dendritic cells, pro-inflammatory M1 macrophages, and anti-inflammatory M2 macrophages in different proportions. In addition, the single nucleotide polymorphisms related to IL-10, IL-12A, and IL-17D genes were shown to be associated with periapical lesions and other oral lesions. Collectively, the unique metabolism and related immune response shape up an environment that initiates and maintains the existence and progression of these oral lesions, suggesting an important role in diagnosis and effective targeted therapy.

Implications of a 'Third Signal' in NK Cells

Innate and adaptive immune systems are evolutionarily divergent. Primary signaling in T and B cells depends on somatically rearranged clonotypic receptors. In contrast, NK cells use germline-encoded non-clonotypic receptors such as NCRs, NKG2D, and Ly49H. Proliferation and effector functions of T and B cells are dictated by unique peptide epitopes presented on MHC or soluble humoral antigens. However, in NK cells, the primary signals are mediated by self or viral proteins. Secondary signaling mediated by various cytokines is involved in metabolic reprogramming, proliferation, terminal maturation, or memory formation in both innate and adaptive lymphocytes. The family of common gamma (γc) cytokine receptors, including IL-2Rα/β/γ, IL-7Rα/γ, IL-15Rα/β/γ, and IL-21Rα/γ are the prime examples of these secondary signals. A distinct set of cytokine receptors mediate a ‘third’ set of signaling. These include IL-12Rβ1/β2, IL-18Rα/β, IL-23R, IL-27R (WSX-1/gp130), IL-35R (IL-12Rβ2/gp130), and IL-39R (IL-23Rα/gp130) that can prime, activate, and mediate effector functions in lymphocytes. The existence of the ‘third’ signal is known in both innate and adaptive lymphocytes. However, the necessity, context, and functional relevance of this ‘third signal’ in NK cells are elusive. Here, we define the current paradigm of the ‘third’ signal in NK cells and enumerate its clinical implications.

The Role of Gut Microbiota in Overcoming Resistance to Checkpoint Inhibitors in Cancer Patients: Mechanisms and Challenges

The introduction of immune checkpoint inhibitors has constituted a major revolution in the treatment of patients with cancer. In contrast with the traditional cytotoxic therapies that directly kill tumor cells, this treatment modality enhances the ability of the host’s immune system to recognize and target cancerous cells. While immune checkpoint inhibitors have been effective across multiple cancer types, overcoming resistance remains a key area of ongoing research. The gut microbiota and its role in cancer immunosurveillance have recently become a major field of study. Gut microbiota has been shown to have direct and systemic effects on cancer pathogenesis and hosts anti-tumor immune response. Many studies have also shown that the host microbiota profile plays an essential role in the response to immunotherapy, especially immune checkpoint inhibitors. As such, modulating this microbial environment has offered a potential path to overcome the resistance to immune checkpoint inhibitors. In this review, we will talk about the role of microbiota in cancer pathogenesis and immune-system activity. We will also discuss preclinical and clinical studies that have increased our understanding about the roles and the mechanisms through which microbiota influences the response to treatment with immune checkpoint inhibitors.

Tumor-Associated Macrophages in Pancreatic Ductal Adenocarcinoma: Therapeutic Opportunities and Clinical Challenges

Simple Summary

Macrophages are a major component of the pancreatic tumor microenvironment, and their increased abundance is associated with poor patient survival. Given the multi-faceted role of macrophages in promoting pancreatic tumor development and progression, these cells represent promising targets for anti-cancer therapy.

Abstract

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive malignant disease with a 5-year survival rate of less than 10%. Macrophages are one of the earliest infiltrating cells in the pancreatic tumor microenvironment, and are associated with an increased risk of disease progression, recurrence, metastasis, and shorter overall survival. Pre-clinical studies have demonstrated an unequivocal role of macrophages in PDAC by contributing to chronic inflammation, cancer cell stemness, desmoplasia, immune suppression, angiogenesis, invasion, metastasis, and drug resistance. Several macrophage-targeting therapies have also been investigated in pre-clinical models, and include macrophage depletion, inhibiting macrophage recruitment, and macrophage reprogramming. However, the effectiveness of these drugs in pre-clinical models has not always translated into clinical trials. In this review, we discuss the molecular mechanisms that underpin macrophage heterogeneity within the pancreatic tumor microenvironment, and examine the contribution of macrophages at various stages of PDAC progression. We also provide a comprehensive update of macrophage-targeting therapies that are currently undergoing clinical evaluation, and discuss clinical challenges associated with these treatment modalities in human PDAC patients.

Ebola virus triggers receptor tyrosine kinase-dependent signaling to promote the delivery of viral particles to entry-conducive intracellular compartments

Filoviruses, such as the Ebola virus (EBOV) and Marburg virus (MARV), are causative agents of sporadic outbreaks of hemorrhagic fevers in humans. To infect cells, filoviruses are internalized via macropinocytosis and traffic through the endosomal pathway where host cathepsin-dependent cleavage of the viral glycoproteins occurs. Subsequently, the cleaved viral glycoprotein interacts with the late endosome/lysosome resident host protein, Niemann-Pick C1 (NPC1). This interaction is hypothesized to trigger viral and host membrane fusion, which results in the delivery of the viral genome into the cytoplasm and subsequent initiation of replication. Some studies suggest that EBOV viral particles activate signaling cascades and host-trafficking factors to promote their localization with host factors that are essential for entry. However, the mechanism through which these activating signals are initiated remains unknown. By screening a kinase inhibitor library, we found that receptor tyrosine kinase inhibitors potently block EBOV and MARV GP-dependent viral entry. Inhibitors of epidermal growth factor receptor (EGFR), tyrosine protein kinase Met (c-Met), and the insulin receptor (InsR)/insulin like growth factor 1 receptor (IGF1R) blocked filoviral GP-mediated entry and prevented growth of replicative EBOV in Vero cells. Furthermore, inhibitors of c-Met and InsR/IGF1R also blocked viral entry in macrophages, the primary targets of EBOV infection. Interestingly, while the c-Met and InsR/IGF1R inhibitors interfered with EBOV trafficking to NPC1, virus delivery to the receptor was not impaired in the presence of the EGFR inhibitor. Instead, we observed that the NPC1 positive compartments were phenotypically altered and rendered incompetent to permit viral entry. Despite their different mechanisms of action, all three RTK inhibitors tested inhibited virus-induced Akt activation, providing a possible explanation for how EBOV may activate signaling pathways during entry. In sum, these studies strongly suggest that receptor tyrosine kinases initiate signaling cascades essential for efficient post-internalization entry steps.

Ebola virus (EBOV) and Marburg virus (MARV) are zoonotic pathogens that can cause severe hemorrhagic fevers in humans and non-human primates. They are members of the growing Filoviridae family that also includes three other species of Ebolaviruses known to be highly pathogenic in humans. While vaccines for EBOV are being deployed and showed high efficacy, pan-filoviral treatment is still lacking. To infect cells, EBOV requires the endosomal/lysosomal resident protein Niemann-Pick C1 (NPC1). Accordingly, viral particles require extensive trafficking within endosomal pathways for entry and delivery of the viral genome into the host cell cytoplasm. Here, we used chemical biology to reveal that EBOV triggers receptor tyrosine kinase (RTK)-dependent signaling to traffic to intracellular vesicles that contain the receptor and are conducive to entry. The characterization of host trafficking factors and signaling pathways that are potentially triggered by the virus are important as these could be targeted for antiviral therapies. In our study, we identified several RTK inhibitors, some of which are FDA-approved drugs, that potently block EBOV infection. Since all filoviruses known to date, even Měnglà virus that was recently discovered in bats in China, use NPC1 as their entry receptor, these inhibitors have the potential to be effective pan-filovirus antivirals.

Exploring the Emerging Role of the Gut Microbiota and Tumor Microenvironment in Cancer Immunotherapy

The tumor microenvironment (TME) is a complex ecosystem, which includes many different types of cells, abnormal vascular systems, and immunosuppressive cytokines. TME serves an important function in tumor tolerance and escapes from immune surveillance leading to tumor progression. Indeed, there is increasing evidence that gut microbiome is associated with cancer in a variety of ways, as specific microbial signatures are known to promote cancer development and influence safety, tolerability, and efficacy of therapies. Studies over the past five years have shown that the composition of the intestinal microbiota has a significant impact on the efficacy of anticancer immunosurveillance, which contribute to the therapeutic activity of cancer immunotherapies based on targeting cytotoxic T lymphocyte protein 4 (CTLA-4) or programmed cell death protein 1 (PD-1)-programmed cell death 1 ligand 1 (PD-L1) axis. In this review, we mainly discuss the impact of TME on cancer and immunotherapy through immune-related mechanisms. We subsequently discuss the influence of gut microbiota and its metabolites on the host immune system and the formation of TME. In addition, this review also summarizes the latest research on the role of gut microbiota in cancer immunotherapy.

Oncolytic effects of the recombinant Newcastle disease virus, rAF-IL12, against colon cancer cells in vitro and in tumor-challenged NCr-Foxn1nu nude mice

Colon cancer remains one of the main cancers causing death in men and women worldwide as certain colon cancer subtypes are resistant to conventional treatments and the development of new cancer therapies remains elusive. Alternative modalities such as the use of viral-based therapeutic cancer vaccine is still limited, with only the herpes simplex virus (HSV) expressing granulocyte-macrophage colony- stimulating factor (GM-CSF) or talimogene laherparepvec (T-Vec) being approved in the USA and Europe so far. Therefore, it is imperative to continue the search for a new treatment modality. This current study evaluates a combinatorial therapy between the oncolytic Newcastle disease virus (NDV) and interleukin-12 (IL-12) cytokine as a potential therapeutic vaccine to the current anti-cancer drugs. Several in vitro analyses such as MTT assay, Annexin V/FITC flow cytometry, and cell cycle assay were performed to evaluate the cytotoxicity effect of recombinant NDV, rAF-IL12. Meanwhile, serum cytokine, serum biochemical, histopathology of organs and TUNEL assay were carried out to assess the anti-tumoral effects of rAF-IL12 in HT29 tumor-challenged nude mice. The apoptosis mechanism underlying the effect of rAF-IL12 treatment was also investigated using NanoString Gene expression analysis. The recombinant NDV, rAF-IL12 replicated in HT29 colon cancer cells as did its parental virus, AF2240-i. The rAF-IL12 treatment had slightly better cytotoxicity effects towards HT29 cancer cells when compared to the AF2240-i as revealed by the MTT, Annexin V FITC and cell cycle assay. Meanwhile, the 28-day treatment with rAF-IL12 had significantly (p < 0.05) perturbed the growth and progression of HT29 tumor in NCr-Foxn1nu nude mice when compared to the untreated and parental wild-type NDV strain AF2240-i. The rAF-IL12 also modulated the immune system in nude mice by significantly (p < 0.05) increased the level of IL-2, IL-12, and IFN-γ cytokines. Treatment with rAF-IL12 had also significantly (p < 0.05) increased the expression level of apoptosis-related genes such as Fas, caspase-8, BID, BAX, Smad3 and granzyme B in vitro and in vivo. Besides, rAF-IL12 intra-tumoral delivery was considered safe and was not hazardous to the host as evidenced in pathophysiology of the normal tissues and organs of the mice as well as from the serum biochemistry profile of liver and kidney. Therefore, this study proves that rAF-IL12 had better cytotoxicity effects than its parental AF2240-i and could potentially be an ideal treatment for colon cancer in the near future.

Immunogenicity and antitumor efficacy of a novel human PD-1 B-cell vaccine (PD1-Vaxx) and combination immunotherapy with dual trastuzumab/pertuzumab-like HER-2 B-cell epitope vaccines (B-Vaxx) in a syngeneic mouse model

Therapeutic blockade of PD-1/PD-L1 signaling with monoclonal antibodies (mAbs) has shown clinical success and activity across a broad set of cancer subtypes. However, monotherapy with PD-1/PD-L1 inhibitors are only effective in a subset of patients and ongoing studies show efficacy of treatment depends on a combinatorial approach. Contrary to mAbs chimeric B-cell cancer vaccines incorporating a “promiscuous” T-cell epitope have the advantage of producing a polyclonal B-cell antibody that can potentially induce memory B- and T-cell responses, while reducing immune evasion and suppression. Here, we describe a novel PD-1 B-cell peptide epitope vaccine (amino acid 92–110; PD1-Vaxx) linked to a measles virus fusion peptide (MVF) amino acid 288–302 via a four amino acid residue (GPSL) emulsified in Montanide ISA 720VG that aims to induce the production of polyclonal antibodies that block PD-1 signaling and thus trigger anticancer effects similar to nivolumab. In preclinical studies, the PD1-Vaxx outperformed the standard anti-mouse PD-1 antibody (mAb 29F.1A12) in a mouse model of human HER-2 expressing colon carcinoma. Furthermore, the combination of PD1-Vaxx with combo HER-2 peptide vaccine (B-Vaxx) showed enhanced inhibition of tumor growth in colon carcinoma BALB/c model challenged with CT26/HER-2 cells. The PD-1 or combined vaccines were safe with no evidence of toxicity or autoimmunity.

Increased IL-2 and Reduced TGF-β Upon T-Cell Stimulation are Associated with GM-CSF Upregulation in Multiple Immune Cell Types in Multiple Sclerosis

Granulocyte macrophage colony stimulating factor (GM-CSF) is a pro-inflammatory cytokine produced by immune cells. Recent evidence suggests that GM-CSF plays an important role in multiple sclerosis (MS) pathogenesis. We investigated the expression and regulation of GM-CSF in different immune cells in MS. We also investigated the differentiation and frequency of GM-CSF-producing Th cells that do not co-express interferon (IFN)-γ or interleukin-17 (IL-17) (Th-GM cells) in MS. We found a significant increase in the percentage of GM-CSF-expressing Th cells, Th1 cells, Th-GM cells, cytotoxic T (Tc) cells, monocytes, natural killer (NK) cells, and B cells in PBMC from MS patients stimulated with T cell stimuli. Stimulated PBMC culture supernatants from MS patients contained significantly higher levels of IL-2, IL-12, IL-1β, and GM-CSF and significantly lower levels of transforming growth factor (TGF-)β. Blocking IL-2 reduced the frequency of Th-GM cells in PBMC from MS patients. The frequency of Th-GM cells differentiated in vitro from naïve CD4⁺ T cells was significantly higher in MS patients and was further increased in MS with IL-2 stimulation. These findings suggest that all main immune cell subsets produce more GM-CSF in MS after in vitro stimulation, which is associated with defective TGF-β and increased IL-2 and IL-12 production. Th-GM cells are increased in MS. GM-CSF may be a potential therapeutic target in MS.

Effect of interleukins (IL-2, IL-15, IL-18) on receptors activation and cytotoxic activity of natural killer cells in breast cancer cell

INTRODUCTION

Breast cancer is one of the leading cause of cancer deaths in women. Metastasis in BC is caused by immunosurveillance deficiency, such NK cell maturation, low NK activity and decreasing cytotoxicity. This study was performed to improve activating receptors and cytotoxicity of NK cells using interleukins (ILs).

METHODS

Human recombinant IL-2, -15, and -18 were used to induce NK cells. We measured the activating and inhibiting receptors, proliferation activity of NK cells, and the cytotoxicity of NK cells on BC cells (MCF7). The effects of ILs were tested on the NK cell receptors CD314, CD158a and CD107a with flowcytometry, proliferation at various incubation times with 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxy methoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay and concentrations of TNF-α and IFN-γ by NK cells with ELISA.

RESULTS

ILs increased NK cell receptor levels (CD314, CD158a, and CD107a) at 24 hours of incubation. ILs increased NK cell viability, which increased with longer incubation. Moreover, ILs-induced NK cells inhibited proliferation in MCF7 cells, as well as increased TNF-α, IFN-γ, PRF1 and GzmB secretion.

CONCLUSION

IL-2, IL-15, and IL-18 improved activating receptors and proliferation of NK cells. IL-induced NK cells increased TNF-α, IFN-γ, PRF1 and GzmB secretion and cytotoxic activity on BC cells. High NK cell numbers increased BC cell growth inhibition.

Mechanisms of Resistance to NK Cell Immunotherapy

Immunotherapy has recently been a major breakthrough in cancer treatment. Natural killer (NK) cells are suitable targets for immunotherapy owing to their potent cytotoxic activity that may target cancer cells in a major histocompatibility complex (MHC) and antigen-unrestricted manner. Current therapies targeting NK cells include monoclonal antibodies that promote NK cell antibody-dependent cell-mediated cytotoxicity (ADCC), hematopoietic stem cell transplantation (HSCT), the adoptive transfer of NK cells, the redirection of NK cells using chimeric antigen receptor (CAR)-NK cells and the use of cytokines and immunostimulatory drugs to boost the anti-tumor activity of NK cells. Despite some encouraging clinical results, patients receiving these therapies frequently develop resistance, and a myriad of mechanisms of resistance affecting both the immune system and cancer cells have been reported. A first contributing factor that modulates the efficacy of the NK cell therapy is the genetic profile of the individual, which regulates all aspects of NK cell biology. Additionally, the resistance of cancer cells to apoptosis and the immunoediting of cancer cells, a process that decreases their immunogenicity and promotes immunosuppression, are major determinants of the resistance to NK cell therapy. Consequently, the efficacy of NK cell anti-tumor therapy is specific to each patient and disease. The elucidation of such immunosubversive mechanisms is crucial to developing new procedures and therapeutic strategies to fully harness the anti-tumor potential of NK cells.

Clinical development of immunotherapies for HER2+ breast cancer: a review of HER2-directed monoclonal antibodies and beyond

Human epidermal growth factor receptor 2-positive (HER2⁺) breast cancer accounts for ~25% of breast cancer cases. Monoclonal antibodies (mAbs) against HER2 have led to unparalleled clinical benefit for a subset of patients with HER2⁺ breast cancer. In this narrative review, we summarize advances in the understanding of immune system interactions, examine clinical developments, and suggest rationales for future investigation of immunotherapies for HER2⁺ breast cancer. Complex interactions have been found between different branches of the immune system, HER2⁺ breast cancer, and targeted treatments (approved and under investigation). A new wave of immunotherapies, such as novel HER2-directed mAbs, antibody drug conjugates, vaccines, and adoptive T-cell therapies, are being studied in a broad population of patients with HER2-expressing tumors. The development of immunotherapies for HER2⁺ breast cancer represents an evolving field that should take into account interactions between different components of the immune system.

Influence of the Tumor Microenvironment on NK Cell Function in Solid Tumors

Natural killer (NK) cells are a population of innate lymphoid cells playing a pivotal role in host immune responses against infection and tumor growth. These cells have a powerful cytotoxic activity orchestrated by an intricate network of inhibitory and activating signals. The importance of NK cells in controlling tumor growth and in mediating a robust anti-metastatic effect has been demonstrated in different experimental mouse cancer models. Consistently, high density of tumor-infiltrating NK cells has been linked with a good prognosis in multiple human solid tumors. However, there are also tumors that appear to be refractory to NK cell-mediated killing for the presence of an immunosuppressive microenvironment affecting NK cell function. Immunotherapeutic strategies aimed at restoring and increasing the cytotoxic activity of NK cells in solid tumors, including the adoptive transfer of NK and CAR-NK cells, are currently employed in preclinical and clinical studies. In this review, we outline recent advances supporting the direct role of NK cells in controlling expansion of solid tumors and their prognostic value in human cancers. We summarize the mechanisms adopted by cancer cells and the tumor microenvironment to affect NK cell function, and finally we evaluate current strategies to augment the antitumor function of NK cells for the treatment of solid tumors.

High-dose ascorbic acid synergizes with anti-PD1 in a lymphoma mouse model

Major efforts are underway to identify agents that can potentiate effects of immune checkpoint inhibition. Here, we show that ascorbic acid (AA) treatment caused genomewide demethylation and enhanced expression of endogenous retroviral elements in lymphoma cells. AA also increased 5-hydroxymethylcytosine (5hmC) levels of CD8+ T cells and enhanced their cytotoxic activity in a lymphoma coculture system. High-dose AA treatment synergized with anti-PD1 therapy in a syngeneic lymphoma mouse model, resulting in marked inhibition of tumor growth compared with either agent alone. Analysis of the intratumoral epigenome revealed increased 5hmC with AA treatment, consistent with in vitro findings. Analysis of the tumor immune microenvironment revealed that AA strikingly increased intratumoral infiltration of CD8+ T cells and macrophages, suggesting enhanced tumor immune recognition. The combination treatment markedly enhanced intratumoral infiltration of macrophages and CD8+ T lymphocytes, granzyme B production by cytotoxic cells (cytotoxic T cells and natural killer cells), and interleukin 12 production by antigen-presenting cells compared with single-agent anti-PD1. These data indicate that AA potentiates anti-PD1 checkpoint inhibition through synergistic mechanisms. The study provides compelling rationale for testing combinations of high-dose AA and anti-PD1 agents in patients with aggressive B cell lymphoma as well as in preclinical models of other malignancies.

Gut Microbiome as a Potential Factor for Modulating Resistance to Cancer Immunotherapy

Gut microbiota refers to the diverse community of more than 100 trillion microorganisms residing in our intestines. It is now known that any shift in the composition of gut microbiota from that present during the healthy state in an individual is associated with predisposition to multiple pathological conditions, such as diabetes, autoimmunity, and even cancer. Currently, therapies targeting programmed cell death protein 1/programmed cell death 1 ligand 1 or cytotoxic T-lymphocyte antigen-4 are the focus of cancer immunotherapy and are widely applied in clinical treatment of various tumors. Owing to relatively low overall response rate, however, it has been an ongoing research endeavor to identify the mechanisms or factors for improving the therapeutic efficacy of these immunotherapies. Other than causing mutations that affect gene expression, some gut bacteria may also activate or repress the host's response to immune checkpoint inhibitors. In this review, we have described recent advancements made in understanding the regulatory relationship between gut microbiome and cancer immunotherapy. We have also summarized the potential molecular mechanisms behind this interaction, which can serve as a basis for utilizing different kinds of gut bacteria as promising tools for reversing immunotherapy resistance in cancer.

CD16 pre-ligation by defucosylated tumor-targeting mAb sensitizes human NK cells to γc cytokine stimulation via PI3K/mTOR axis

Obinutuzumab is a glycoengineered tumor-targeting anti-CD20 mAb with a modified crystallizable fragment (Fc) domain designed to increase the affinity for the FcγRIIIA/CD16 receptor, which was recently approved for clinical use in CLL and follicular lymphoma. Here we extend our previous observation that, in human NK cells, the sustained CD16 ligation by obinutuzumab-opsonized targets leads to a markedly enhanced IFN-γ production upon a subsequent cytokine re-stimulation. The increased IFN-γ competence in response to IL-2 or IL-15 is attributable to post-transcriptional regulation, as it does not correlate with the upregulation of IFN-γ mRNA levels. Different from the reference molecule rituximab, we observe that the stimulation with obinutuzumab promotes the upregulation of microRNA (miR)-155 expression. A similar trend was also observed in NK cells from untreated CLL patients stimulated with obinutuzumab-opsonized autologous leukemia. miR-155 upregulation associates with reduced levels of SHIP-1 inositol phosphatase, which acts in constraining PI3K-dependent signals, by virtue of its ability to mediate phosphatidylinositol 3,4,5-trisphosphate (PIP3) de-phosphorylation. Downstream of PI3K, the phosphorylation status of mammalian target of rapamycin (mTOR) effector molecule, S6, results in amplified response to IL-2 or IL-15 stimulation in obinutuzumab-experienced cells. Importantly, NK cell treatment with the PI3K or mTOR inhibitors, idelalisib and rapamycin, respectively, prevents the enhanced cytokine responsiveness, thus, highlighting the relevance of the PI3K/mTOR axis in CD16-dependent priming. The enhanced IFN-γ competence may be envisaged to potentiate the immunoregulatory role of NK cells in a therapeutic setting.

Synergistic cancer immunotherapy combines MVA-CD40L induced innate and adaptive immunity with tumor targeting antibodies

Virus-based vaccines and appropriate costimulation potently enhance antigen-specific T cell immunity against cancer. Here we report the use of recombinant modified vaccinia virus Ankara (rMVA) encoding costimulatory CD40L against solid tumors. Therapeutic treatment with rMVA-CD40L-expressing tumor-associated antigens results in the control of established tumors. The expansion of tumor-specific cytotoxic CD8⁺ T cells is essential for the therapeutic antitumor effects. Strikingly, rMVA-CD40L also induces strong natural killer (NK) cell activation and expansion. Moreover, the combination of rMVA-CD40L and tumor-targeting antibodies results in increased therapeutic antitumor efficacy relying on the presence of Fc receptor and NK cells. We describe a translationally relevant therapeutic synergy between systemic viral vaccination and CD40L costimulation. We show strengthened antitumor immune responses when both rMVA-CD40L-induced innate and adaptive immune mechanisms are exploited by combination with tumor-targeting antibodies. This immunotherapeutic approach could translate into clinical cancer therapies where tumor-targeting antibodies are employed.

CD40 agonists have been investigated as a strategy to awaken the immune system against cancers. Here, the authors use a virus encoding CD40L and tumour-associated antigens to enhance innate and adaptive immunity that together with tumour targeting antibodies controls the growth of tumours in mice.

A Phase I/II Trial of Cetuximab in Combination with Interleukin-12 Administered to Patients with Unresectable Primary or Recurrent Head and Neck Squamous Cell Carcinoma

PURPOSE

mAbs including cetuximab can induce antibody-dependent cellular cytotoxicity (ADCC) and cytokine production mediated via innate immune cells with the ability to recognize mAb-coated tumors. Preclinical modeling has shown that costimulation of natural killer (NK) cells via the Fc receptor and the IL12 receptor promotes NK-cell-mediated ADCC and production of cytokines.

PATIENTS AND METHODS

This phase I/II trial evaluated the combination of cetuximab with IL12 for the treatment of EGFR-expressing head and neck cancer. Treatment consisted of cetuximab 500 mg/m² i.v. every 2 weeks with either 0.2 mcg/kg or 0.3 mcg/kg IL12 s.c. on days 2 and 5 of the 2-week cycle, beginning with cycle 2. Correlative studies from blood draws obtained prior to treatment and during therapy included measurement of ADCC, serum cytokine, and chemokine analysis, determination of NK cell FcγRIIIa polymorphisms, and an analysis of myeloid-derived suppressor cell (MDSC) frequency in peripheral blood.

RESULTS

The combination of cetuximab and IL12 was well tolerated. No clinical responses were observed, however, 48% of patients exhibited prolonged progression-free survival (PFS; average of 6.5 months). Compared with patients that did not exhibit clinical benefit, patients with PFS >100 days exhibited increased ADCC as therapy continued compared with baseline, greater production of IFNγ, IP-10, and TNFα at the beginning of cycle 8 compared with baseline values and had a predominance of monocytic MDSCs versus granulocytic MDSCs prior to therapy.

CONCLUSIONS

Further investigation of IL12 as an immunomodulatory agent in combination with cetuximab in head and neck squamous cell carcinoma is warranted.

Amino acid residues involved in the heparin-binding activity of murine IL-12 in the context of an antibody-cytokine fusion protein

An antibody-cytokine fusion protein, composed of the murine single-chain cytokine interleukin-12 (IL-12) genetically fused to a human IgG3 specific for the human tumor-associated antigen HER2/neu maintains antigen binding, cytokine bioactivity, and IL-12 heparin-binding activity. This latter property is responsible for the binding of the cytokine to glycosaminoglycans (GAGs) on the cell surface and the extracellular matrix and has been implicated in modulating IL-12 bioactivity. Previous studies indicate that the p40 subunit of human and murine IL-12 is responsible for the heparin-binding activity of this heterodimeric cytokine. In the present study we used bioinformatic analysis and site-directed mutagenesis to develop a version of the antibody-(IL-12) fusion protein without heparin-binding activity. This was accomplished by replacing the basic arginine (R) and lysine (K) residues in the cluster of amino acids 254-260 (RKKEKMK) of the murine IL-12 p40 subunit by the neutral non-polar amino acid alanine (A), generating an AAAEAMA mutant fusion protein. ELISA and flow cytometry demonstrated that the antibody fusion protein lacks heparin-binding activity but retains antigen binding. A T-cell proliferation assay showed IL-12 bioactivity in this construct. However, the IL-12 bioactivity is decreased compared to its non-mutated counterpart, which is consistent with an ancillary role of the heparin-binding site of IL-12 in modulating its activity. Thus, we have defined a cluster of amino acid residues with a crucial role in the heparin-binding activity of murine IL-12 in the context of an antibody-cytokine fusion protein.

Soy isoflavones and their metabolites modulate cytokine-induced natural killer cell function

Soybeans are a rich source of isoflavones that have been linked with anti-inflammatory processes and various health benefits. However, specific mechanisms whereby soy bioactives impact immune cell subsets are unclear. Isoflavones, such as genistein and daidzein, are metabolized by microbes to bioactive metabolites as O-desmethylangolensin (O-DMA) and equol, whose presence has been linked to health benefits. We examined how soy isoflavones and metabolites impact natural killer (NK) cell signaling and function. We observe no impact of isoflavones on viability of healthy donor peripheral blood mononuclear cells (PBMCs) or NK cells, even at high (25 µM) concentrations. However, pre-treatment of PBMCs with physiologically-relevant concentrations of genistein (p = 0.0023) and equol (p = 0.006) decreases interleukin (IL)-12/IL-18-induced interferon-gamma (IFN-γ) production versus controls. Detailed cellular analyses indicate genistein and equol decrease IL-12/IL-18-induced IFN-γ production by human NK cell subsets, but do not consistently alter cytotoxicity. At the level of signal transduction, genistein decreases IL-12/IL-18-induced total phosphorylated tyrosine, and phosphorylation MAPK pathway components. Further, genistein limits IL-12/IL-18-mediated upregulation of IL-18Rα expression on NK cells (p = 0.0109). Finally, in vivo studies revealed that C57BL/6 mice fed a soy-enriched diet produce less plasma IFN-γ following administration of IL-12/IL-18 versus control-fed animals (p < 0.0001). This study provides insight into how dietary soy modulates NK cell functions.

IL-27 promotes NK cell effector functions via Maf-Nrf2 pathway during influenza infection

Influenza virus targets epithelial cells in the upper respiratory tract. Natural Killer (NK) cell-mediated early innate defense responses to influenza infection include the killing of infected epithelial cells and generation of anti-viral cytokines including interferon gamma (IFN-γ). To date, it is unclear how the underlying cytokine milieu during infection regulates NK cell effector functions. Our data show during influenza infection myeloid cell-derived IL-27 regulates the early-phase effector functions of NK cells in the bronchioalveolar and lung tissue. Lack of IL-27R (Il27ra^−/−) or IL-27 (Ebi3^−/−) resulted in impaired NK cell effector functions including the generation of anti-viral IFN-γ responses. We identify CD27⁺CD11b⁺ NK cells as the primary subset that expresses IL-27R, which predominantly produces IFN-γ within the upper respiratory tract of the infected mice. IL-27 alone was incapable of altering the effector functions of NK cells. However, IL-27 sensitizes NK cells to augment both in vitro and in vivo responses mediated via the NKG2D receptor. This ‘priming’ function of IL-27 is mediated partly via transcriptional pathways regulated by Mafs and Nrf2 transcriptionally regulating TFAM and CPT1. Our data for the first time establishes a novel role for IL-27 in regulating early-phase effector functions of NK cells during influenza infection.

Overcoming Resistance to Natural Killer Cell Based Immunotherapies for Solid Tumors

Despite advances in the diagnostic and therapeutic modalities, the prognosis of several solid tumor malignancies remains poor. Different factors associated with solid tumors including a varied genetic signature, complex molecular signaling pathways, defective cross talk between the tumor cells and immune cells, hypoxic and immunosuppressive effects of tumor microenvironment result in a treatment resistant and metastatic phenotype. Over the past several years, immunotherapy has emerged as an attractive therapeutic option against multiple malignancies. The unique ability of natural killer (NK) cells to target cancer cells without antigen specificity makes them an ideal candidate for use against solid tumors. However, the outcomes of adoptive NK cell infusions into patients with solid tumors have been disappointing. Extensive studies have been done to investigate different strategies to improve the NK cell function, trafficking and tumor targeting. Use of cytokines and cytokine analogs has been well described and utilized to enhance the proliferation, stimulation and persistence of NK cells. Other techniques like blocking the human leukocyte antigen-killer cell receptors (KIR) interactions with anti-KIR monoclonal antibodies, preventing CD16 receptor shedding, increasing the expression of activating NK cell receptors like NKG2D, and use of immunocytokines and immune checkpoint inhibitors can enhance NK cell mediated cytotoxicity. Using genetically modified NK cells with chimeric antigen receptors and bispecific and trispecific NK cell engagers, NK cells can be effectively redirected to the tumor cells improving their cytotoxic potential. In this review, we have described these strategies and highlighted the need to further optimize these strategies to improve the clinical outcome of NK cell based immunotherapy against solid tumors.

Genomic and transcriptional Profiling of tumor infiltrated CD8+ T cells revealed functional heterogeneity of antitumor immunity in hepatocellular carcinoma

As key players in HCC antitumor response, the functions of tumor infiltrated CD8⁺ T cells are significantly affected by surrounding microenvironment. A detailed profiling of their genomic and transcriptional changes could provide valuable insights for both future immunotherapy development and prognosis evaluation. We performed whole exome and transcriptome sequencing on tumor infiltrated CD8⁺ T cells and CD8⁺ T cells isolated from other tissue origins (peritumor tissues and corresponding PBMCs) in eight treatment-naive HCC patients. The results demonstrated that transcriptional changes, rather than genomic alterations were the main contributors to the functional alterations of CD8⁺ T cells in the process of tumor progression. The origins of CD8⁺ T cells defined their transcriptional landscape, while the tumor infiltrated CD8⁺ T cells shared more similarity with peritumor-derived CD8⁺ T cells compared with those CD8⁺ T cells in blood. In addition, tumor infiltrated CD8⁺ T cells also showed larger transcriptional heterogeneity among individuals, which was modulated by clinical features such as HBV levels, preoperative anti-viral treatment and the degree of T cell infiltration. We also identified multiple inter-connected pathways involved in the activation and exhaustion of tumor infiltrated CD8⁺ T cells, among which IL-12 mediated pathway could dynamically reflect the functional status of CD8⁺ TILs and activation of this pathway indicated a better prognosis. Our results presented an overview picture of CD8⁺ TILs' genomic and transcriptional landscape and features, as well as how the functional status of CD8⁺ TILs correlated with patients' clinical course.

IL-15 enhanced antibody-dependent cellular cytotoxicity mediated by NK cells and macrophages

The goal of cancer immunotherapy is to stimulate the host immune system to attack malignant cells. Antibody-dependent cellular cytotoxicity (ADCC) is a pivotal mechanism of antitumor action of clinically employed antitumor antibodies. IL-15 administered to patients with metastatic malignancy by continuous i.v. infusion at 2 μg/kg/d for 10 days was associated with a 38-fold increase in the number and activation status of circulating natural killer (NK) cells and activation of macrophages which together are ADCC effectors. We investigated combination therapy of IL-15 with rituximab in a syngeneic mouse model of lymphoma transfected with human CD20 and with alemtuzumab (Campath-1H) in a xenograft model of human adult T cell leukemia (ATL). IL-15 greatly enhanced the therapeutic efficacy of both rituximab and alemtuzumab in tumor models. The additivity/synergy was shown to be associated with augmented ADCC. Both NK cells and macrophages were critical elements in the chain of interacting effectors involved in optimal therapeutic responses mediated by rituximab with IL-15. We provide evidence supporting the hypothesis that NK cells interact with macrophages to augment the NK-cell activation and expression of FcγRIV and the capacity of these cells to become effectors of ADCC. The present study supports clinical trials of IL-15 combined with tumor-directed monoclonal antibodies.

Avelumab, an IgG1 anti-PD-L1 Immune Checkpoint Inhibitor, Triggers NK Cell-Mediated Cytotoxicity and Cytokine Production Against Triple Negative Breast Cancer Cells

The standard treatment for Triple Negative Breast Cancer (TNBC) patients is cytotoxic chemotherapy, but it is restricted since the duration of response is usually short. Blocking the PD-1/PD-L1 pathway through monoclonal antibodies (mAbs) appears to be a promising therapeutic strategy for TNBC patients. Avelumab is a human IgG1 anti-PD-L1 mAb being tested in clinical trials that may also trigger antibody-dependent cell-mediated cytotoxicity (ADCC) against cancer cells as an additional antitumor activity. In the present work, we studied in vitro Avelumab-mediated ADCC against a panel of TNBC cells with different PD-L1 expression using peripheral blood mononuclear cells (PBMC) or purified NK cells from healthy donors. We determined that Avelumab significantly enhanced NK-cell mediated cytotoxicity against TNBC cells and that tumor cells expressing higher levels of PD-L1 were more sensitive to Avelumab-mediated ADCC. IFN-γ treatment upregulated PD-L1 expression in tumor cells but had a variable impact on Avelumab-mediated ADCC, which could be related to the simultaneous effect of IFN-γ on the expression of NK cell ligands. Moreover, IL-2 and IL-15 stimulation of NK cells enhanced Avelumab-triggered cytokine production and degranulation along with increased lytic activity against tumor cells. Improving the treatment of TNBC remains still a considerable challenge. This in vitro study suggests that Avelumab-mediated ADCC, independently of the blockade of the PD-1/PD-L1 pathway, could be a valuable mechanism for tumor cell elimination in TNBC. Avelumab combination with immunomodulators such as IL-15 or IL-2 could be taken into consideration to increase the therapeutic efficacy of Avelumab in TNBC.

FcγRIIIa-dependent IFN-γ release in whole blood assay is predictive of therapeutic IgG1 antibodies safety

Immunomodulatory monoclonal IgG1 antibodies developed for cancer and autoimmune disease have an inherent risk of systemic release of pro-inflammatory cytokines. In vitro cytokine release assays are currently used to predict cytokine release syndrome (CRS) risk, but the validation of these preclinical tools suffers from the limited number of characterized CRS-inducing IgG1 antibodies and the poor understanding of the mechanisms regulating cytokine release. Here, we incubated human whole blood from naïve healthy volunteers with four monoclonal IgG1 antibodies with different proven or predicted capacity to elicit CRS in clinic and measured cytokine release using a multiplex assay. We found that, in contrast to anti-CD52 antibodies (Campath-1H homolog) that elicited high level of multiple inflammatory cytokines from human blood cells in vitro, other IgG1 antibodies with CRS-inducing potential consistently induced release of a single tested cytokine, interferon (IFN)-γ, with a smaller magnitude than Campath. IFN-γ expression was observed as early as 2-4 h after incubation, mediated by natural killer cells, and dependent upon tumor necrosis factor and FcγRIII. Importantly, the magnitude of the IFN-γ response elicited by IgG1 antibodies with CRS-inducing potential was determined by donor FcγRIIIa-V158F polymorphism. Overall, our results highlight the importance of FcγRIIIa-dependent IFN-γ release in preclinical cytokine release assay for the prediction of CRS risk associated with therapeutic IgG1 antibodies.

Heterodimeric Fc-fused IL12 shows potent antitumor activity by generating memory CD8+ T cells

Interleukin-12 (IL12) (p35/p40 complex) is a heterodimeric cytokine with potent anti-tumor activity. However, its short serum half-life and high dose-related toxicities limit its clinical efficacy. Here, we constructed heterodimeric immunoglobulin Fc-fused mouse IL12 (mIL12) in a monovalent binding format (mono-mIL12-Fc) to generate long-acting mIL12 in the naturally occurring heterodimeric form. Mono-mIL12-Fc exhibited a much longer plasma half-life than recombinant mIL12, enabling twice-weekly systemic injections to remove established tumors in syngeneic mouse models. Mono-mIL12-Fc was more potent than wild-type Fc-based bivalent-binding IL12-Fc (bi-mIL12-Fc) for eradicating large established immunogenic tumors without noticeable toxicities by enhancing interferon-γ production and the proliferation of immune effector cells in tumors. More importantly, mono-mIL12-Fc triggered weaker IL12 signaling than bi-mIL12-Fc, favoring the generation of functional and protective memory CD8⁺ T cells. Our results demonstrate that heterodimeric-Fc-fused IL12 is a suitable format for augmenting adaptive CD8⁺ T cell immune responses, providing a practical alternative to the systemic administration of IL12 for antitumor therapy.

IL-15 Promotes Polyfunctional NK Cell Responses to Influenza by Boosting IL-12 Production

IL-15 is a key regulator of NK cell maintenance and proliferation and synergizes with other myeloid cell–derived cytokines to enhance NK cell effector function. At low concentrations, trans-presentation of IL-15 by dendritic cells can activate NK cells, whereas at higher concentrations it can act directly on NK cells, independently of accessory cells. In this study, we investigate the potential for IL-15 to boost responses to influenza virus by promoting accessory cell function. We find that coculture of human PBMCs with inactivated whole influenza virus (A/Victoria/361/2011) in the presence of very low concentrations of IL-15 results in increased production of myeloid cell–derived cytokines, including IL-12, IFN-α2, GM-CSF, and IL-1β, and an increased frequency of polyfunctional NK cells (defined by the expression of two or more of CD107a, IFN-γ, and CD25). Neutralization experiments demonstrate that IL-15–mediated enhancement of NK cell responses is primarily dependent on IL-12 and partially dependent on IFN-αβR1 signaling. Critically, IL-15 boosted the production of IL-12 in influenza-stimulated blood myeloid dendritic cells. IL-15 costimulation also restored the ability of less-differentiated NK cells from human CMV-seropositive individuals to respond to influenza virus. These data suggest that very low concentrations of IL-15 play an important role in boosting accessory cell function to support NK cell effector functions.

Nitric Oxide Production by Myeloid-Derived Suppressor Cells Plays a Role in Impairing Fc Receptor-Mediated Natural Killer Cell Function

Purpose: mAbs are used to treat solid and hematologic malignancies and work in part through Fc receptors (FcRs) on natural killer cells (NK). However, FcR-mediated functions of NK cells from patients with cancer are significantly impaired. Identifying the mechanisms of this dysfunction and impaired response to mAb therapy could lead to combination therapies and enhance mAb therapy.Experimental Design: Cocultures of autologous NK cells and MDSC from patients with cancer were used to study the effect of myeloid-derived suppressor cells (MDSCs) on NK-cell FcR-mediated functions including antibody-dependent cellular cytotoxicity, cytokine production, and signal transduction in vitro Mouse breast cancer models were utilized to study the effect of MDSCs on antibody therapy in vivo and test the efficacy of combination therapies including a mAb and an MDSC-targeting agent.Results: MDSCs from patients with cancer were found to significantly inhibit NK-cell FcR-mediated functions including antibody-dependent cellular cytotoxicity, cytokine production, and signal transduction in a contact-independent manner. In addition, adoptive transfer of MDSCs abolished the efficacy of mAb therapy in a mouse model of pancreatic cancer. Inhibition of iNOS restored NK-cell functions and signal transduction. Finally, nonspecific elimination of MDSCs or inhibition of iNOS in vivo significantly improved the efficacy of mAb therapy in a mouse model of breast cancer.Conclusions: MDSCs antagonize NK-cell FcR-mediated function and signal transduction leading to impaired response to mAb therapy in part through nitric oxide production. Thus, elimination of MDSCs or inhibition of nitric oxide production offers a strategy to improve mAb therapy. Clin Cancer Res; 24(8); 1891-904. ©2018 AACR.

Modulation of Innate Immunity by lignin-Carbohydrate, a Novel TLR4 Ligand, Results in Augmentation of Mucosal IgA and Systemic IgG Production

Previous study revealed that a specific lignin-carbohydrate preparation, named as lignin-rich enzyme lignin (LREL) derived from plant husk, is a novel toll-like receptor 4 ligand and shows a potent immune-stimulatory activity against dendritic cells (DCs) in vitro. In this report, we investigated immune-stimulatory activity of LREL in vivo. Single intraperitoneal (i.p.) or oral treatment of LREL elicited activation of systemic and mucosal DCs, which were accompanied by significant elevation of cell surface activation markers and ratio of IL-12p40 producing cells. In addition, LREL-fed mice showed not only mucosal DCs activation but also significant increase of IFN-γ⁺ CD4⁺ T cells in mesenteric lymph node (MLN), respectively. We further examined the effect of LREL oral immunization in combination with ovalbumin (OVA) on the activation of acquired immune system. In LREL administered group, total mucosal IgA concentration was significantly increased, while antigen-specific immunoglobulin A (IgA) concentration was not changed between groups. On the other hand, both total and antigen-specific IgG concentrations in plasma were significantly increased in the LREL administered group. Taken together, oral treatment of LREL is able to affect mucosal and systemic antibodies induction and might be useful for effective immune-stimulatory functional foods and mucosal vaccine adjuvant.

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.

Co-stimulation of the fc receptor and interleukin-12 receptor on human natural killer cells leads to increased expression of cd25

Natural killer (NK) cells serve a critical role in the immune response against microbes and developing tumors. We have demonstrated that NK cells produce stimulatory cytokines (e.g., IFN-γ) in response to potent stimulation via immobilized IgG (to engage Fc receptors) and interleukin (IL)-12. CD25 is a component of the high-affinity IL-2R, which promotes NK cell activation in response to low doses of IL-2 such as those released by activated T cells. We hypothesized that stimulation of NK cells via IgG and IL-12 would enhance CD25 expression and promote NK cell anti-tumor activity in response to low-dose IL-2. It was confirmed that this dual stimulation strategy significantly enhanced NK cell CD25 expression compared to unstimulated cells or cells treated with IgG or IL-12 alone. Dual stimulated NK cells also were more responsive to low-dose IL-2. Dual stimulated NK cells subsequently treated with low-dose IL-2 (10 pg/mL) displayed enhanced intracellular signaling as indicated by increased pSTAT5 levels. IFN-γ production and cytotoxicity against K562 cells by NK cells stimulated with low-dose IL-2 was comparable to that of cells treated with high-dose IL-2 (10 ng/mL). Importantly, cells isolated from head and neck cancer patients receiving the mAb cetuximab and IL-12 on a clinical trial displayed increased CD25 expression following combination therapy compared to baseline. Altogether, these findings suggest that FcR and IL-12R co-stimulation induces expression of the high-affinity IL-2R and promotes NK cell anti-tumor activity.

Natural Killer Cells - Their Role in Tumour Immunosurveillance

An important component of the innate immune system, the natural killer cells that originate from the lymphoid cell lineage, hold tremendous potential as an effective therapeutic tool to combat a variety of cancers. Their vast capability to kill altered cells such as opsonized cells (antibody coated), tumour cells, genotoxically changed cells without affecting the healthy cells of the body, make them an effective therapeutic agent for various types of cancers. Besides, through interplay and molecular crosstalk via several cytokines, they also augment the adaptive immune response by, promoting the differentiation, activation and recruitment of component cells of the system. With the current advance knowledge of Natural Killer (NK) cells, their receptor-ligand interactions involved in functional regulation, various mechanistic approaches involving the role of cytokines led to desired modulation of NK cell activity in a tailor-made manner, for triggering clinically relevant responces. Several strategies have been adopted by researchers, to augment the efficacy of NK cells. Still many challenges exist for increasing the therapeutic relevance of these cells.

MICA-Expressing Monocytes Enhance Natural Killer Cell Fc Receptor-Mediated Antitumor Functions

Natural killer (NK) cells are large granular lymphocytes that promote the antitumor response via communication with other cell types in the tumor microenvironment. Previously, we have shown that NK cells secrete a profile of immune stimulatory factors (e.g., IFNγ, MIP-1α, and TNFα) in response to dual stimulation with the combination of antibody (Ab)-coated tumor cells and cytokines, such as IL12. We now demonstrate that this response is enhanced in the presence of autologous monocytes. Monocyte enhancement of NK cell activity was dependent on cell-to-cell contact as determined by a Transwell assay. It was hypothesized that NK cell effector functions against Ab-coated tumor cells were enhanced via binding of MICA on monocytes to NK cell NKG2D receptors. Strategies to block MICA-NKG2D interactions resulted in reductions in IFNγ production. Depletion of monocytes in vivo resulted in decreased IFNγ production by murine NK cells upon exposure to Ab-coated tumor cells. In mice receiving trastuzumab and IL12 therapy, monocyte depletion resulted in significantly greater tumor growth in comparison to mock-depleted controls (P < 0.05). These data suggest that NK cell-monocyte interactions enhance NK cell antitumor activity in the setting of monoclonal Ab therapy for cancer. Cancer Immunol Res; 5(9); 778-89. ©2017 AACR.

Patient's Natural Killer Cells in the Era of Targeted Therapies: Role for Tumor Killers

Natural killer (NK) cells are potent antitumor effectors, involved in hematological malignancies and solid tumor immunosurveillance. They infiltrate various solid tumors, and their numbers are correlated with good outcome. The function of NK cells extends their lytic capacities toward tumor cells expressing stress-induced ligands, through secretion of immunoregulatory cytokines, and interactions with other immune cells. Altered NK cell function due to tumor immune escape is frequent in advanced tumors; however, strategies to release the function of NK infiltrating tumors are emerging. Recent therapies targeting specific oncogenic mutations improved the treatment of cancer patients, but patients often relapse. The actual development consists in combined therapeutic strategies including agents targeting the proliferation of tumor cells and others restorating functional antitumor immune effectors for efficient and durable efficacy of anticancer treatment. In that context, we discuss the recent results of the literature to propose hypotheses concerning the potential use of NK cells, potent antitumor cytotoxic effectors, to design novel antitumor strategies.

Activation of the FcgammaReceptorIIIa on human natural killer cells leads to increased expression of functional interleukin-21 receptor

Natural killer (NK) cells are innate immune effector cells that play a crucial role in immune surveillance and the destruction of cancer cells. NK cells express a low-affinity receptor for the Fc or constant region of immunoglobulin G (FcγRIIIa) and multiple cytokine receptors that respond to antibody-coated targets and cytokines in the tumor microenvironment. In the present work, microarray gene expression analysis revealed that the IL-21 receptor (IL-21R) was strongly upregulated following FcR stimulation. The IL-21R was found to be upregulated on FcR-stimulated NK cells at the transcript level as determined by reverse transcription polymerase chain reaction (RT-PCR). Immunoblot analysis revealed that protein expression of the IL-21R peaked at 8 h post-stimulation of the FcR. Inhibition of the mitogen-activated protein kinase (MAPK) pathway downstream of the FcR blocked the induction of IL-21R expression. Increased expression of the IL-21R sensitized NK cells to IL-21 stimulation, as treatment of FcR-stimulated NK cells led to significantly increased phosphorylation of STAT1 and STAT3, as measured by intracellular flow cytometry and immunoblot analysis. Following FcR-stimulation, IL-21-activated NK cells were better able to mediate the lysis of trastuzumab-coated human epidermal growth factor receptor 2 (HER2⁺) SK-BR-3 tumor cells as compared to control-treated cells. Likewise, IL-21-induced NK cell secretion of IFNγ following exposure to antibody-coated tumor cells was enhanced following FcR-stimulation. The analysis of NK cells from patients receiving trastuzumab therapy for HER2⁺ cancer exhibited increased levels of the IL-21R following the administration of antibody suggesting that the presence of monoclonal antibody-coated tumor cells in vivo can stimulate the increased expression of IL-21R on NK cells.

Tocilizumab (Anti-IL-6R) Suppressed TNFα Production by Human Monocytes in an In Vitro Model of Anti-HLA Antibody-Induced Antibody-Dependent Cellular Cytotoxicity

Background

We previously demonstrated that natural killer (NK) cells activated via FcγRIIIa (CD16) interactions with anti-HLA antibodies binding to peripheral blood mononuclear cells (PBMCs) in the in vitro antibody-dependent cellular cytotoxicity (ADCC) assay produced IFNγ. Here we investigate if other CD16 bearing cells are responsive to alloantigen via alloantibody in the in vitro ADCC and if the ADCC-induced cytokine reactions and cytotoxicity can be modified by the anti-interleukin 6 receptor (IL-6R) monoclonal antibody, Tocilizumab (TCZ).

Methods

Whole blood from a normal individual was incubated overnight with irradiated allo-PBMCs pretreated with anti-HLA antibody positive (in vitro ADCC) or negative sera (mixed lymphocyte reaction [MLR]), with or without TCZ or control IgG. IFNγ+, TNFα+ or IL-6+ cell% in NK cells, monocytes and CD8+ T cells were enumerated by cytokine flow cytometry. ADCC using PBMCs (effector) and Farage B cells (FB, target) with anti-HLA antibody positive sera, with or without TCZ, was measured by flow cytometry.

Results

IFNγ+ and/or TNFα+ cell% in NK cells, monocytes and CD8+ T cells were elevated in the ADCC compared to the MLR condition. IL-6+ cells were significantly increased in ADCC versus MLR (10.2 ± 4.8% vs 2.7 ± 1.5%, P = 0.0003), but only in monocytes. TCZ treatment significantly reduced TNFα+ cell% in monocytes in ADCC, but had no effect on other cytokine+ cells. TCZ showed no effect on cytotoxicity in ADCC.

Conclusions

IFNγ, TNFα, and IL-6 production induced by HLA antibody-mediated CD16 bearing cell activation in NK cells, monocytes, and CD8+ T cells suggests a potential role for ADCC and these inflammatory cytokines in mediation of antibody-mediated rejection. TCZ suppressed TNFα production in monocytes in the ADCC condition, suggesting a role of IL-6/IL-6R pathway in monocytes activation. Inhibition of this pathway could reduce the inflammatory cascade induced by alloantibody, although the inhibitory effect on cytotoxicity is minimal.

Fluorescent nanodiamonds engage innate immune effector cells: A potential vehicle for targeted anti-tumor immunotherapy

Fluorescent nanodiamonds (FNDs) are nontoxic, infinitely photostable, and emit fluorescence in the near infrared region. Natural killer (NK) cells and monocytes are part of the innate immune system and are crucial to the control of carcinogenesis. FND-mediated stimulation of these cells may serve as a strategy to enhance anti-tumor activity. FNDs were fabricated with a diameter of 70±28 nm. Innate immune cell FND uptake, viability, surface marker expression, and cytokine production were evaluated in vitro. Evaluation of fluorescence emission from the FNDs was conducted in an animal model. In vitro results demonstrated that treatment of immune cells with FNDs resulted in significant dose-dependent FND uptake, no compromise in cell viability, and immune cell activation. FNDs were visualized in an animal model. Hence, FNDs may serve as novel agents with "track and trace" capabilities to stimulate innate immune cell anti-tumor responses, especially as FNDs are amenable to surface-conjugation with immunomodulatory molecules.

Folate-conjugated immunoglobulin targets melanoma tumor cells for NK cell effector functions

The folate receptor (FR) is overexpressed on the vascular side of cancerous cells including those of the breast, ovaries, testes, and cervix. We hypothesized that a folate-conjugated immunoglobulin (F-IgG) would bind to the FR that is overexpressed on melanoma tumor cells to target these cells for lysis by natural killer (NK) cells. Folate receptor expression was confirmed in the Mel-39 (human melanoma) cell line by flow cytometry and immunoblot analysis using KB (human oral epithelial) and F01 (human melanoma) as a positive and a negative control, respectively. FR-positive and FR-negative cell lines were treated with F-IgG or control immunoglobulin G in the presence or absence of cytokines to determine NK cell ability to lyse FR-positive cell lines. NK cell activation was significantly upregulated and lysis of Mel 39 tumor cells increased following treatment with F-IgG compared with control immunoglobulin G at all effector : target (E : T) ratios (P<0.01). This trend further increased by NK cell stimulation with the activating cytokine interleukin-12. NK cell production of cytokines such as interferon-gamma, macrophage inflammatory protein 1α, and regulated on activation normal T-cell expressed and secreted (RANTES) was also significantly increased in response to costimulation with interleukin-12 stimulation and F-IgG-coated Mel 39 target cells compared with controls (P<0.01). In contrast, F-IgG did not bind to the FR-negative cell line F01 and had no significant effect on NK cell lysis or cytokine production. This research indicates the potential use of F-IgG for its ability to induce an immune response from NK cells against FR-positive melanoma tumor cells, which can be further increased by the addition of cytokines.

A Phase I Trial to Evaluate Antibody-Dependent Cellular Cytotoxicity of Cetuximab and Lenalidomide in Advanced Colorectal and Head and Neck Cancer

mAbs can induce antibody-dependent cellular cytotoxicity (ADCC) via the innate immune system's ability to recognize mAb-coated cancer cells and activate immune effector cells. Lenalidomide is an immunomodulatory agent with the capacity to stimulate immune cell cytokine production and ADCC activity. This phase I trial evaluated the combination of cetuximab with lenalidomide for the treatment of advanced colorectal and head and neck squamous cell cancers (HNSCC). This trial included patients with advanced colorectal cancer or HNSCC. Treatment consisted of cetuximab 500 mg/m(2) i.v. every two weeks with lenalidomide given orally days 1-21 on a 28-day cycle. Three dose levels of lenalidomide were evaluated (15, 20, 25 mg). Correlative studies included measurement of ADCC, FcγRIIIA polymorphism genotyping, measurement of serum cytokine levels, and flow cytometric analysis of immune cell subtypes. Twenty-two patients were enrolled (19 colorectal cancer, 3 HNSCC). Fatigue was the only dose-limiting toxicity. One partial response was observed and 8 patients had stable disease at least 12 weeks. The recommended phase II dose is cetuximab 500 mg/m(2) with lenalidomide 25 mg daily, days 1-21. Correlative studies demonstrated a dose-dependent increase in natural killer cytotoxic activity with increasing doses of lenalidomide. Cetuximab and lenalidomide were well tolerated. There was a lenalidomide dose-dependent increase in ADCC with higher activity in patients enrolled in cohort 3 than those enrolled in cohorts 1/2. Although response was not a primary endpoint, there was evidence of antitumor activity for the combination therapy. Further investigation of lenalidomide as an immunomodulator in solid tumors is warranted. Mol Cancer Ther; 15(9); 2244-50. ©2016 AACR.

IL-21 Enhances Natural Killer Cell Response to Cetuximab-Coated Pancreatic Tumor Cells

PURPOSE

Alternative strategies to EGFR blockage by mAbs is necessary to improve the efficacy of therapy in patients with locally advanced or metastatic pancreatic cancer. One such strategy includes the use of NK cells to clear cetuximab-coated tumor cells, as need for novel therapeutic approaches to enhance the efficacy of cetuximab is evident. We show that IL-21 enhances NK cell-mediated effector functions against cetuximab-coated pancreatic tumor cells irrespective of KRAS mutation status.

EXPERIMENTAL DESIGN

NK cells from normal donors or donors with pancreatic cancer were used to assess ADCC, IFN-γ release, and T-cell chemotaxis toward human pancreatic cancer cell lines. The in vivo efficacy of IL-21 in combination with cetuximab was evaluated in a subcutaneous and intraperitoneal model of pancreatic cancer.

RESULTS

NK cell lysis of cetuximab-coated wild-type and mutant kras pancreatic cancer cell lines were significantly higher following NK cell IL-21 treatment. In response to cetuximab-coated pancreatic tumor cells, IL-21-treated NK cells secreted significantly higher levels of IFN-γ and chemokines, increased chemotaxis of T cells, and enhanced NK cell signal transduction via activation of ERK and STAT1. Treatment of mice bearing subcutaneous or intraperitoneal EGFR-positive pancreatic tumor xenografts with mIL-21 and cetuximab led to significant inhibition of tumor growth, a result further enhanced by the addition of gemcitabine.

CONCLUSIONS

These results suggest that cetuximab treatment in combination with IL-21 adjuvant therapy in patients with EGFR-positive pancreatic cancer results in significant NK cell activation, irrespective of KRAS mutation status, and may be a potential therapeutic strategy. Clin Cancer Res; 23(2); 489-502. ©2016 AACR.

An Fc engineering approach that modulates antibody-dependent cytokine release without altering cell-killing functions

Cytotoxic therapeutic monoclonal antibodies (mAbs) often mediate target cell-killing by eliciting immune effector functions via Fc region interactions with cellular and humoral components of the immune system. Key functions include antibody-dependent cell-mediated cytotoxicity (ADCC), antibody-dependent cellular phagocytosis (ADCP), and complement-dependent cytotoxicity (CDC). However, there has been increased appreciation that along with cell-killing functions, the induction of antibody-dependent cytokine release (ADCR) can also influence disease microenvironments and therapeutic outcomes. Historically, most Fc engineering approaches have been aimed toward modulating ADCC, ADCP, or CDC. In the present study, we describe an Fc engineering approach that, while not resulting in impaired ADCC or ADCP, profoundly affects ADCR. As such, when peripheral blood mononuclear cells are used as effector cells against mAb-opsonized tumor cells, the described mAb variants elicit a similar profile and quantity of cytokines as IgG1. In contrast, although the variants elicit similar levels of tumor cell-killing as IgG1 with macrophage effector cells, the variants do not elicit macrophage-mediated ADCR against mAb-opsonized tumor cells. This study demonstrates that Fc engineering approaches can be employed to uncouple macrophage-mediated phagocytic and subsequent cell-killing functions from cytokine release.