Role of antibody-dependent cell-mediated cytotoxicity in the efficacy of therapeutic anti-cancer monoclonal antibodies

A comprehensive overview of recent advances in generative models for antibodies

Therapeutic antibodies are an important class of biopharmaceuticals. With the rapid development of deep learning methods and the increasing amount of antibody data, antibody generative models have made great progress recently. They aim to solve the antibody space searching problems and are widely incorporated into the antibody development process. Therefore, a comprehensive introduction to the development methods in this field is imperative. Here, we collected 34 representative antibody generative models published recently and all generative models can be divided into three categories: sequence-generating models, structure-generating models, and hybrid models, based on their principles and algorithms. We further studied their performance and contributions to antibody sequence prediction, structure optimization, and affinity enhancement. Our manuscript will provide a comprehensive overview of the status of antibody generative models and also offer guidance for selecting different approaches.

Cancer immunotherapy and its facilitation by nanomedicine

Cancer immunotherapy has sparked a wave of cancer research, driven by recent successful proof-of-concept clinical trials. However, barriers are emerging during its rapid development, including broad adverse effects, a lack of reliable biomarkers, tumor relapses, and drug resistance. Integration of nanomedicine may ameliorate current cancer immunotherapy. Ultra-large surface-to-volume ratio, extremely small size, and easy modification surface of nanoparticles enable them to selectively detect cells and kill cancer cells in vivo. Exciting synergistic applications of the two approaches have emerged in treating various cancers at the intersection of cancer immunotherapy and cancer nanomedicine, indicating the potential that the combination of these two therapeutic modalities can lead to new paradigms in the treatment of cancer. This review discusses the status of current immunotherapy and explores the possible opportunities that the nanomedicine platform can make cancer immunotherapy more powerful and precise by synergizing the two approaches.

Neuroblastoma-A Review of Combination Immunotherapy

Neuroblastoma is the most common extracranial solid tumor found in childhood and is responsible for 15% of deaths among children with cancer. Although multimodal therapies focused on surgery, chemotherapy, radiotherapy, and stem cell transplants have favorable results in many cases, the use of conventional therapies has probably reached the limit their possibility. Almost half of the patients with neuroblastoma belong to the high-risk group. Patients in this group require a combination of several therapeutic approaches. It has been shown that various immunotherapies combined with conventional methods can work synergistically. Due to the development of such therapeutic methods, we present combinations and forms of combining immunotherapy, focusing on their mechanisms and benefits but also their limitations and potential side effects.

TLR9 agonism differentially impacts human NK cell-mediated direct killing and antibody-dependent cell-mediated cytotoxicity

There are two known mechanisms by which natural killer (NK) cells recognize and kill diseased targets: (i) direct killing and (ii) antibody-dependent cell-mediated cytotoxicity (ADCC). We investigated an indirect NK cell activation strategy for the enhancement of human NK cell killing function. We did this by leveraging the fact that toll-like receptor 9 (TLR9) agonism within pools of human peripheral blood mononuclear cells (PBMCs) results in a robust interferon signaling cascade that leads to NK cell activation. After TLR9 agonist stimulation, NK cells were enriched and incorporated into assays to assess their ability to kill tumor cell line targets. Notably, differential impacts of TLR9 agonism were observed-direct killing was enhanced while ADCC was not increased. To ensure that the observed differential effects were not attributable to differences between human donors, we recapitulated the observation using our Natural Killer-Simultaneous ADCC and Direct Killing Assay (NK-SADKA) that controls for human-to-human differences. Next, we observed a treatment-induced decrease in NK cell surface CD16-known to be shed by NK cells post-activation. Given the essential role of CD16 in ADCC, such shedding could account for the observed differential impact of TLR9 agonism on NK cell-mediated killing capacity.

A single bout of vigorous intensity exercise enhances the efficacy of rituximab against human chronic lymphocytic leukaemia B-cells ex vivo

Chronic lymphocytic leukaemia (CLL) is characterised by the clonal proliferation and accumulation of mature B-cells and is often treated with rituximab, an anti-CD20 monoclonal antibody immunotherapy. Rituximab often fails to induce stringent disease eradication, due in part to failure of antibody-dependent cellular cytotoxicity (ADCC) which relies on natural killer (NK)-cells binding to rituximab-bound CD20 on B-cells. CLL cells are diffusely spread across lymphoid and other bodily tissues, and ADCC resistance in survival niches may be due to several factors including low NK-cell frequency and a suppressive stromal environment that promotes CLL cell survival. It is well established that exercise bouts induce a transient relocation of NK-cells and B-cells into peripheral blood, which could be harnessed to enhance the efficacy of rituximab in CLL by relocating both target and effector cells together with rituximab in blood. In this pilot study, n = 20 patients with treatment-naïve CLL completed a bout of cycling 15 % above anaerobic threshold for ∼ 30-minutes, with blood samples collected pre-, immediately post-, and 1-hour post-exercise. Flow cytometry revealed that exercise evoked a 254 % increase in effector (CD3-CD56+CD16+) NK-cells in blood, and a 67 % increase in CD5+CD19+CD20+ CLL cells in blood (all p < 0.005). NK-cells were isolated from blood samples pre-, and immediately post-exercise and incubated with primary isolated CLL cells with or without the presence of rituximab to determine specific lysis using a calcein-release assay. Rituximab-mediated cell lysis increased by 129 % following exercise (p < 0.001). Direct NK-cell lysis of CLL cells - independent of rituximab - was unchanged following exercise (p = 0.25). We conclude that exercise improved the efficacy of rituximab-mediated ADCC against autologous CLL cells ex vivo and propose that exercise should be explored as a means of enhancing clinical responses in patients receiving anti-CD20 immunotherapy.

Current and Future States of Natural Killer Cell-Based Immunotherapy in Hepatocellular Carcinoma

Natural killer (NK) cells are innate lymphoid cells that exhibit high levels of cytotoxicity against NK-specific targets. NK cells also produce various cytokines, and interact with T cells, B cells, and dendritic cells to effectively serve as frontliners of the innate immune system. Produce various cytokines, and interact with T cells, B cells, and dendritic cells to effectively serve as frontliners of the innate immune system. Moreover, NK cells constitute the second most common immune cell in the liver. These properties have drawn significant attention towards leveraging NK cells in treating liver cancer, especially hepatocellular carcinoma (HCC), which accounts for 75% of all primary liver cancer and is the fourth leading cause of cancer-related death worldwide. Notable anti-cancer functions of NK cells against HCC include activating antibody-dependent cell cytotoxicity (ADCC), facilitating Gasdermin E-mediated pyroptosis of HCC cells, and initiating an antitumor response via the cGAS-STING signaling pathway. In this review, we describe how these mechanisms work in the context of HCC. We will then discuss the existing preclinical and clinical studies that leverage NK cell activity to create single and combined immunotherapies.

Unlocking the potential of allogeneic Vδ2 T cells for ovarian cancer therapy through CD16 biomarker selection and CAR/IL-15 engineering

Allogeneic Vγ9Vδ2 (Vδ2) T cells have emerged as attractive candidates for developing cancer therapy due to their established safety in allogeneic contexts and inherent tumor-fighting capabilities. Nonetheless, the limited clinical success of Vδ2 T cell-based treatments may be attributed to donor variability, short-lived persistence, and tumor immune evasion. To address these constraints, we engineer Vδ2 T cells with enhanced attributes. By employing CD16 as a donor selection biomarker, we harness Vδ2 T cells characterized by heightened cytotoxicity and potent antibody-dependent cell-mediated cytotoxicity (ADCC) functionality. RNA sequencing analysis supports the augmented effector potential of Vδ2 T cells derived from CD16 high (CD16Hi) donors. Substantial enhancements are further achieved through CAR and IL-15 engineering methodologies. Preclinical investigations in two ovarian cancer models substantiate the effectiveness and safety of engineered CD16Hi Vδ2 T cells. These cells target tumors through multiple mechanisms, exhibit sustained in vivo persistence, and do not elicit graft-versus-host disease. These findings underscore the promise of engineered CD16Hi Vδ2 T cells as a viable therapeutic option for cancer treatment.

B cell depletion therapies in autoimmune diseases: Monoclonal antibodies or chimeric antigen receptor-based therapy?

Immune system detects foreign pathogens, distinguishes them from self-antigens and responds to defend human body. When this self-tolerance is disrupted, the overactive immune system attacks healthy tissues or organs and the autoimmune diseases develop. B cells and plasma cells contribute a lot to pathogenesis and persistence of autoimmune diseases in both autoantibody-dependent and autoantibody-independent ways. Accumulating data indicates that treatments aiming to eliminate antibody-secreting cells (B cells or plasma cells) are effective in a wide spectrum of autoimmune diseases. Monoclonal antibodies (mAbs) deplete B cell lineage or plasma cells by signaling disruption, complement-dependent cytotoxicity (CDC) and antibody-dependent cellular cytotoxicity (ADCC). Engineered-T cells armed with chimeric antigen receptors (CARs) have been adopted from field of hematological malignancies as a method to eliminate B cells or plasma cells. In this review, we update our understanding of B cell depletion therapies in autoimmune diseases, review the mechanism, efficacy, safety and application of monoclonal antibodies and CAR-based immunotherapies, and discuss the strengths and weaknesses of these treatment options for patients.

Antimicrobial Resistance and Recent Alternatives to Antibiotics for the Control of Bacterial Pathogens with an Emphasis on Foodborne Pathogens

Antimicrobial resistance (AMR) is one of the most important global public health problems. The imprudent use of antibiotics in humans and animals has resulted in the emergence of antibiotic-resistant bacteria. The dissemination of these strains and their resistant determinants could endanger antibiotic efficacy. Therefore, there is an urgent need to identify and develop novel strategies to combat antibiotic resistance. This review provides insights into the evolution and the mechanisms of AMR. Additionally, it discusses alternative approaches that might be used to control AMR, including probiotics, prebiotics, antimicrobial peptides, small molecules, organic acids, essential oils, bacteriophage, fecal transplants, and nanoparticles.

Syngeneic mouse model of human HER2+ metastatic breast cancer for the evaluation of trastuzumab emtansine combined with oncolytic rhabdovirus

Background

Established mouse models of HER2+ cancer are based on the over-expression of rodent Neu/Erbb2 homologues, which are incompatible with human HER2 (huHER2) targeted therapeutics. Additionally, the use of immune-deficient xenograft or transgenic models precludes assessment of native anti-tumour immune responses. These hurdles have been a challenge for our understanding of the immune mechanisms behind huHER2-targeting immunotherapies.

Methods

To assess the immune impacts of our huHER2-targeted combination strategy, we generated a syngeneic mouse model of huHER2+ breast cancer, using a truncated form of huHER2, HER2T. Following validation of this model, we next treated tumour-bearing with our immunotherapy strategy: oncolytic vesicular stomatitis virus (VSVΔ51) with clinically approved antibody-drug conjugate targeting huHER2, trastuzumab emtansine (T-DM1). We assessed efficacy through tumour control, survival, and immune analyses.

Results

The generated truncated HER2T construct was non-immunogenic in wildtype BALB/c mice upon expression in murine mammary carcinoma 4T1.2 cells. Treatment of 4T1.2-HER2T tumours with VSVΔ51+T-DM1 yielded robust curative efficacy compared to controls, and broad immunologic memory. Interrogation of anti-tumour immunity revealed tumour infiltration by CD4+ T cells, and activation of B, NK, and dendritic cell responses, as well as tumour-reactive serum IgG.

Conclusions

The 4T1.2-HER2T model was used to evaluate the anti-tumour immune responses following our complex pharmacoviral treatment strategy. These data demonstrate utility of the syngeneic HER2T model for assessment of huHER2-targeted therapies in an immune-competent in vivo setting. We further demonstrated that HER2T can be implemented in multiple other syngeneic tumour models, including but not limited to colorectal and ovarian models. These data also suggest that the HER2T platform may be used to assess a range of surface-HER2T targeting approaches, such as CAR-T, T-cell engagers, antibodies, or even retargeted oncolytic viruses.

Therapeutic landscape of advanced HER2-positive breast cancer in 2022

HER2-positive breast cancer is an aggressive subtype of breast cancer with five-year survival rates of 30% for the advanced stage. The development of anti-HER2 treatments has led to a paradigm shift in the management and clinical outcomes of advanced HER2-positive breast cancer patients. The standard first-line treatment consists of taxane-based chemotherapy plus dual anti-HER2 therapies with trastuzumab and pertuzumab. The antibody-drug conjugate (ADC) ado-trastuzumab emtansine (T-DM1) has been a second-line therapeutic standard, but the second-line treatment approach is rapidly evolving. Given a substantial advantage of another ADC, Fam-trastuzumab deruxtecan (T-DXd), compared to T-DM1 in a recent randomized trial in the second-line setting, T-DXd is currently the preferred second-line option. Optimal third-line treatment strategies are still not established, and multiple approaches have been used including combinations based on capecitabine, trastuzumab, or both with oral anti-HER2 tyrosine kinase inhibitors. Tucatinib plus capecitabine and trastuzumab, lapatinib plus trastuzumab, neratinib or lapatinib plus capecitabine are some of the FDA approved combinations. Another newer agent approved for third- or later-line therapy in the metastatic setting is margetuximab, an Fc-engineered anti-HER2 monoclonal antibody, in combination with chemotherapy. Other novel agents currently under clinical trials are the drugs that indirectly target HER2, including immune cell cycle inhibitors, PI3K/mTOR inhibitors, and immunotherapy agents.

Recent Progress in the Discovery and Development of Monoclonal Antibodies against Viral Infections

Monoclonal antibodies (mAbs), the new revolutionary class of medications, are fast becoming tools against various diseases thanks to a unique structure and function that allow them to bind highly specific targets or receptors. These specialized proteins can be produced in large quantities via the hybridoma technique introduced in 1975 or by means of modern technologies. Additional methods have been developed to generate mAbs with new biological properties such as humanized, chimeric, or murine. The inclusion of mAbs in therapeutic regimens is a major medical advance and will hopefully lead to significant improvements in infectious disease management. Since the first therapeutic mAb, muromonab-CD3, was approved by the U.S. Food and Drug Administration (FDA) in 1986, the list of approved mAbs and their clinical indications and applications have been proliferating. New technologies have been developed to modify the structure of mAbs, thereby increasing efficacy and improving delivery routes. Gene delivery technologies, such as non-viral synthetic plasmid DNA and messenger RNA vectors (DMabs or mRNA-encoded mAbs), built to express tailored mAb genes, might help overcome some of the challenges of mAb therapy, including production restrictions, cold-chain storage, transportation requirements, and expensive manufacturing and distribution processes. This paper reviews some of the recent developments in mAb discovery against viral infections and illustrates how mAbs can help to combat viral diseases and outbreaks.

Natural killer cells: Innate immune system as a part of adaptive immunotherapy in hematological malignancies

Natural killer (NK) cells are part of a phylogenetically old defense system, which is characterized by its strong cytolytic function against physiologically stressed cells such as tumor cells and virus-infected cells. Their use in the treatment of hematological malignancies may be more advantageous in several ways when compared with the already established T lymphocyte-based immunotherapy. Given the different mechanisms of action, allogeneic NK cell products can be produced in a non-personal based manner without the risk of the formidable graft-versus-host disease. Advanced manufacturing processes are capable of producing NK cells relatively easily in large and clinically sufficient numbers, useable without subsequent manipulations or after genetic modifications, which can solve the lack of specificity and improve clinical efficacy of NK cell products. This review summarizes the basic characteristics of NK cells and provides a quick overview of their sources. Results of clinical trials in hematological malignancies are presented, and strategies on how to improve the clinical outcome of NK cell therapy are discussed.

Natural products modulating interleukins and other inflammatory mediators in tumor-bearing animals: A systematic review

BACKGROUND

Cancer is a group of diseases characterized by abnormal cell growth and proliferation. Natural products are a potentially important source for bioactive phytochemicals in the management of cancer, which regulate a broad range of biological events via the modulation of interleukins (ILs), pro- and anti-inflammatory modulators, and other cancer hallmark-mediated signaling pathways.

PURPOSE

To systematically review the literature to identify in vivo studies investigating the anticancer properties of medicinal plants and natural molecules as modulators of ILs and their related pro- and anti-inflammatory signaling markers in tumor-bearing animals.

METHODS

Articles published in English were searched, without any constraint in respect of countries. The electronic databases PubMed, Embase, Scopus, and Web of Science were used for the literature search for studies published between January 2010 and January 2022. The search terms used included medicinal plants, anticancer, antineoplasic agent, ILs, cytokine, and their combinations. A manual search to detect any articles not found in the databases was also made. The identified studies were then critically reviewed and relevant data were extracted and summarized.

RESULTS

Natural products were found to modulate ILs, including IL-1β, IL-2, IL-4, IL-6, IL-8, IL-18, IL-23, and IL-12, and interferon gamma; increase tissue inhibitor metalloprotease; decrease vascular endothelial growth factor, tumor necrosis factor alpha, granulocyte macrophage colony-stimulating factor, and nuclear factor kappa B; augment immunity by increasing the major histocompatibility complexes II and CD4+, cluster of differentiation 8 + T cell and class II trans-activator expression; and heighten the action of antioxidant enzymes, which are involved in the detoxification of free radicals and reactive oxygen species.

CONCLUSION

Natural products discussed in this review show great potential to regulate ILs and weaken associated pro- and anti-inflammatory signaling markers in tumor-bearing animals. Flavonoids, polyphenols, polysaccharides, alkaloids and tannins are important phytochemicals in the modulation of ILs, especially pro-inflammatory ones. However, in terms of future research, the importance of clinical trials to investigate their beneficial properties should be warranted.

Role of Toll-like receptors in natural killer cell function in acute lymphoblastic leukemia

Natural killer (NK) cells are specialized lymphocytes primarily involved in the response to infection and tumors. NK cells are characterized by the presence of specific surface molecules, as well as a wide repertoire of receptors that impart microenvironment-dependent effector functions. Among these receptors, Toll-like receptors (TLRs) can be activated to condition the NK response to either a cytotoxic or immunoregulatory phenotype. However, cellular function is frequently impaired during disorders such as cancer. In the last decade, it has become increasingly evident that the stimulation of NK cells is a requirement for their increased cytotoxic activity. TLR activation has been suggested as an alternative route for reestablishing the antitumor activity of NK cells. The present review summarizes the characteristics of NK cells, their receptors, the expression and function of NK cell TLRs, and their functional status in cancer, primarily acute lymphoblastic leukemia.

Targeting TIGIT for Immunotherapy of Cancer: Update on Clinical Development

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

Wnt/β-catenin signaling in cancers and targeted therapies

Wnt/β-catenin signaling has been broadly implicated in human cancers and experimental cancer models of animals. Aberrant activation of Wnt/β-catenin signaling is tightly linked with the increment of prevalence, advancement of malignant progression, development of poor prognostics, and even ascendence of the cancer-associated mortality. Early experimental investigations have proposed the theoretical potential that efficient repression of this signaling might provide promising therapeutic choices in managing various types of cancers. Up to date, many therapies targeting Wnt/β-catenin signaling in cancers have been developed, which is assumed to endow clinicians with new opportunities of developing more satisfactory and precise remedies for cancer patients with aberrant Wnt/β-catenin signaling. However, current facts indicate that the clinical translations of Wnt/β-catenin signaling-dependent targeted therapies have faced un-neglectable crises and challenges. Therefore, in this study, we systematically reviewed the most updated knowledge of Wnt/β-catenin signaling in cancers and relatively targeted therapies to generate a clearer and more accurate awareness of both the developmental stage and underlying limitations of Wnt/β-catenin-targeted therapies in cancers. Insights of this study will help readers better understand the roles of Wnt/β-catenin signaling in cancers and provide insights to acknowledge the current opportunities and challenges of targeting this signaling in cancers.

The Role of Fc Receptors on the Effectiveness of Therapeutic Monoclonal Antibodies

Since the approval of the first monoclonal antibody (mAb) in 1986, a huge effort has been made to guarantee safety and efficacy of therapeutic mAbs. As of July 2021, 118 mAbs are approved for the European market for a broad range of clinical indications. In order to ensure clinical efficacy and safety aspects, (pre-)clinical experimental approaches evaluate the respective modes of action (MoA). In addition to antigen-specificity including binding affinity and -avidity, MoA comprise Fc-mediated effector functions such as antibody dependent cellular cytotoxicity (ADCC) and the closely related antibody dependent cellular phagocytosis (ADCP). For this reason, a variety of cell-based assays have been established investigating effector functions of therapeutic mAbs with different effector/target-cell combinations and several readouts including Fcγ receptor (FcγR)-mediated lysis, fluorescence, or luminescence. Optimized FcγR-mediated effector functions regarding clinical safety and efficacy are addressed with modification strategies such as point mutations, altered glycosylation patterns, combination of different Fc subclasses (cross isotypes), and Fc-truncation of the mAb. These strategies opened the field for a next generation of therapeutic mAbs. In conclusion, it is of major importance to consider FcγR-mediated effector functions for the efficacy of therapeutic mAbs.

Double-edged effects of interferons on the regulation of cancer-immunity cycle

Interferons (IFNs) are a large family of pleiotropic cytokines that regulate both innate and adaptive immunity and show anti-cancer effects in various cancer types. Moreover, it was revealed that IFN signaling plays critical roles in the success of cancer therapy strategies, thereby enhancing their therapeutic effects. However, IFNs have minimal or even adverse effects on cancer eradication, and mediate cancer immune escape in some instances. Thus, IFNs have a double-edged effect on the cancer immune response. Recent studies suggest that IFNs regulate each step of the cancer immunity-cycle, consisting of cancer antigen release, presentation of antigens and activation of T cells, trafficking and infiltration of effector T cells into the tumor microenvironment, and recognition and killing of cancer cells, which contributes to our understanding of the mechanisms of IFNs in regulating cancer immunity. In this review, we focus on IFNs and cancer immunity and elaborate on the roles of IFNs in regulating the cancer-immunity cycle.

Preparation and biological activities of anti-HER2 monoclonal antibodies with multi-branched complex-type N-glycans

Immunoglobulin G (IgG) has a conserved N-glycosylation site at Asn297 in the fragment crystallizable (Fc) region. Previous studies have shown that N-glycosylation of this site is a critical mediator of the antibody's effector functions, such as antibody-dependent cellular cytotoxicity. While the N-glycan structures attached to the IgG-Fc region are generally heterogenous, IgGs engineered to be homogenously glycosylated with functional N-glycans may improve the efficacy of antibodies. The major glycoforms of the N-glycans on the IgG-Fc region are bi-antennary complex-type N-glycans, while multi-branched complex-type N-glycans are not typically found. However, IgGs with tri-antennary complex-type N-glycans have been generated using the N-glycan remodeling technique, suggesting that more branched N-glycans might be artificially attached. At present, little is known about the properties of these IgGs. In this study, IgGs with multi-branched N-glycans on the Fc region were prepared by using a combination of the glycosynthase/oxazoline substrate-based N-glycan remodeling technique and successive reactions with glycosyltransferases. Among the IgGs produced by these methods, the largest N-glycan attached was a bisecting N-acetylglucosamine (GlcNAc) containing a sialylated penta-antennary structure. Concerning the Fc-mediated effector functions, the majority of IgGs with tri- and tetra-antennary N-glycans on their Fc region showed properties similar to IgGs with ordinary bi-antennary N-glycans.

FUT8 and Protein Core Fucosylation in Tumours: From Diagnosis to Treatment

Glycosylation changes are key molecular events in tumorigenesis, progression and glycosyltransferases play a vital role in the this process. FUT8 belongs to the fucosyltransferase family and is the key enzyme involved in N-glycan core fucosylation. FUT8 and/or core fucosylated proteins are frequently upregulated in liver, lung, colorectal, pancreas, prostate,breast, oral cavity, oesophagus, and thyroid tumours, diffuse large B-cell lymphoma, ependymoma, medulloblastoma and glioblastoma multiforme and downregulated in gastric cancer. They can be used as markers of cancer diagnosis, occurrence, progression and prognosis. Core fucosylated EGFR, TGFBR, E-cadherin, PD1/PD-L1 and α3β1 integrin are potential targets for tumour therapy. In addition, IGg1 antibody defucosylation can improve antibody affinity, which is another aspect of FUT8 that could be applied to tumour therapy.

The Advances and Challenges of NK Cell-Based Cancer Immunotherapy

Natural killer (NK) cells can be widely applied for cancer immunotherapy due to their ability to lyse tumor targets without prior sensitization or human leukocyte antigens-matching. Several NK-based therapeutic approaches have been attempted in clinical practice, but their efficacy is not sufficient to suppress tumor development mainly because of lacking specificity. To this end, the engineering of NK cells with T cell receptor along with CD3 subunits (TCR-NK) has been developed to increase the reactivity and recognition specificity of NK cells toward tumor cells. Here, we review recent advances in redirecting NK cells for cancer immunotherapy and discuss the major challenges and future explorations for their clinical applications.

New Therapeutics in HER2-Positive Advanced Breast Cancer: Towards a Change in Clinical Practices?pi

Over the last few decades, improved knowledge of oncogenic activation mechanisms of HER2 protein has led to the development of HER2 targeted therapies that are currently commonly used in HER2-positive advanced breast cancer, such as trastuzumab, lapatinib, pertuzumab, and ado-trastuzumab emtansine. The management of this breast cancer subgroup has thus been revolutionized and its prognosis has changed dramatically. Nevertheless, HER2-positive advanced breast cancer remains an incurable disease and resistance to conventional anti-HER2 drugs is almost unavoidable. Nowadays, biochemical and pharmaceutical advances are meeting the challenge of developing increasingly sophisticated therapies directed against HER2, including novel anti HER2 antibodies with increased affinity. New antibody-drug conjugates (ADC) with more advanced pharmacological properties, and dual targeting of epitopes via bispecific monoclonal antibodies are also emerging. In addition, more potent and more specific HER2 tyrosine kinase inhibitors have shown interesting outcomes and are under development. Finally, researchers' interest in tumor microenvironment, particularly tumor-infiltrating lymphocytes, and the major role that signaling pathways, such as the PI3K/AKT/mTOR pathway, play in the development of resistance to anti-HER2 therapies have spurred the development of clinical trials evaluating innovative combinations of anti-HER2 with PD-1/PDL-1, CDK4/6 and PI3K inhibitors. However, several questions remain unresolved, like the optimal management of HER2-positive/HR-positive advanced breast cancer and the identification of predictive biomarkers to better define populations that can benefit most from these new therapies and approaches.

Lignin-graft-PLGA drug-delivery system improves efficacy of MEK1/2 inhibitors in triple-negative breast cancer cell line

Aim: Few targeted therapies are available for triple-negative breast cancer (TNBC) patients. Here, we propose a novel alkaline-lignin-conjugated-poly(lactic- co-glycolic acid) (L-PLGA) nanoparticle drug delivery system to improve the efficacy of targeted therapies. Materials & methods: L-PLGA nanoparticles (NPs) loaded with the MEK1/2 inhibitor GDC-0623 were characterized, tested in vitro on MDA-MB-231 TNBC cell line and compared with loaded PLGA NPs. Results: Loaded L-PLGA NPs were less than half the size of PLGA NPs, had slower drug release and improved the efficacy of GDC-0623 when tested in vitro. We demonstrated that GDC-0623 reversed epithelial-to-mesenchymal transition in TNBC. Conclusion: Our findings indicate that L-PLGA NPs are superior to PLGA NPs in delivering GDC-0623 to cancer cells for improved efficacy in vitro.

Pharmacotherapeutics of capecitabine and trastuzumab in the treatment of metastatic breast cancer

Metastatic HER2-positive breast cancer is an incurable disease with a poor prognosis. This article presents a critical appraisal of two treatments commonly used in the treatment of metastatic HER2-positive breast cancer: the oral chemotherapy drug, capecitabine, and the monoclonal antibody, trastuzumab. What follows is a critical discussion of the pharmacotherapeutics of capecitabine and trastuzumab, which considers their use both as single agents and as a combination regimen in the treatment of metastatic breast cancer. The implications of side effects of these drugs are discussed, both individually and in combination, as are the challenges these bring to the prescriber. The article evaluates the use of these agents and concludes that the combination of capecitabine and trastuzumab is an attractive treatment option for patients and for the prescriber.

Ex vivo tissue slice culture system to measure drug-response rates of hepatic metastatic colorectal cancer

Background

The lack of predictive biomarkers or test systems contributes to high failure rates of systemic therapy in metastasized colorectal carcinoma, accounting for a still unfavorable prognosis. Here, we present an ex vivo functional assay to measure drug-response based on a tissue slice culture approach.

Methods

Tumor tissue slices of hepatic metastases of nine patients suffering from colorectal carcinoma were cultivated for 72 h and treated with different concentrations of the clinically relevant drugs Oxaliplatin, Cetuximab and Pembrolizumab. Easy to use, objective and automated analysis routines based on the Halo platform were developed to measure changes in proliferative activity and the morphometric make-up of the tumor. Apoptotic indices were assessed semiquantitatively.

Results

Untreated tumor tissue slices showed high morphological comparability with the original “in vivo”-tumor, preserving proliferation and stromal-tumor interactions. All but one patients showed a dosage dependent susceptibility to treatment with Oxaliplatin, whereas only two patients showed responses to Cetuximab and Pembrolizumab, respectively. Furthermore, we identified possible non-responders to Cetuximab therapy in absence of RAS-mutations.

Conclusions

This is the first time to demonstrate feasibility of the tissue slice culture approach for metastatic tissue of colorectal carcinoma. An automated readout of proliferation and tumor-morphometry allows for quantification of drug susceptibility. This strongly indicates a potential value of this technique as a patient-specific test-system of targeted therapy in metastatic colorectal cancer. Co-clinical trials are needed to customize for clinical application and to define adequate read-out cut-off values.

DuoMab: a novel CrossMab-based IgG-derived antibody format for enhanced antibody-dependent cell-mediated cytotoxicity

High specificity accompanied with the ability to recruit immune cells has made recombinant therapeutic antibodies an integral part of drug development. Here we present a generic approach to generate two novel IgG-derived antibody formats that are based on a modification of the CrossMab technology. MoAbs harbor two heavy chains (HCs) resulting in one binding entity and one fragment crystallizable region (Fc), whereas DuoMabs are composed of four HCs harboring two binding entities and two Fc regions linked at a disulfide-bridged hinge. The latter bivalent format is characterized by avidity-enhanced target cell binding while simultaneously increasing the 'Fc-load' on the surface. DuoMabs were shown to be producible in high yield and purity and bind to surface cells with affinities comparable to IgGs. The increased Fc load directed at the surface of target cells by DuoMabs modulates their antibody-dependent cell-mediated cytotoxicity competency toward target cells, making them attractive for applications that require or are modulated by FcR interactions.

In Vitro Killing of Colorectal Carcinoma Cells by Autologous Activated NK Cells is Boosted by Anti-Epidermal Growth Factor Receptor-induced ADCC Regardless of RAS Mutation Status

Treatment of advanced metastatic colorectal cancer (mCRC) patients is associated with a poor prognosis and significant morbidity. Moreover, targeted therapies such as anti-epidermal growth factor receptor (EGFR) have no effect in metastatic patients with tumors harboring a mutation in the RAS gene. The failure of conventional treatment to improve outcomes in mCRC patients has prompted the development of adoptive immunotherapy approaches including natural killer (NK)-based therapies. In this study, after confirmation that patients' NK cells were not impaired in their cytotoxic activity, evaluated against long-term tumor cell lines, we evaluated their interactions with autologous mCRC cells. Molecular and phenotypical evaluation of mCRC cells, expanded in vitro from liver metastasis, showed that they expressed high levels of polio virus receptor and Nectin-2, whereas UL16-binding proteins were less expressed in all tumor samples evaluated. Two different patterns of MICA/B and HLA class I expression on the membrane of mCRC were documented; approximately half of mCRC patients expressed high levels of these molecules on the membrane surface, whereas, in the remaining, very low levels were documented. Resting NK cells were unable to display sizeable levels of cytotoxic activity against mCRC cells, whereas their cytotoxic activity was enhanced after overnight or 5-day incubation with IL-2 or IL-15. The susceptibility of NK-mediated mCRC lysis was further significantly enhanced after coating with cetuximab, irrespective of their RAS mutation and HLA class I expression. These data open perspectives for combined NK-based immunotherapy with anti-epidermal growth factor receptor antibodies in a cohort of mCRC patients with a poor prognosis refractory to conventional therapies.

Landscape of B cell immunity and related immune evasion in human cancers

Tumor-infiltrating B cells are an important component in the microenvironment with unclear anti-tumor impacts. We enhanced our previous computational algorithm TRUST to extract the B cell immunoglobulin (Ig) hypervariable regions from bulk tumor RNA-seq data. TRUST assembled over 30 million complementarity-determining region 3 (CDR3s) of the B cell heavy chain (IgH) from The Cancer Genome Atlas (TCGA). Widespread B cell clonal expansions and Ig subclass switch events were observed in diverse human cancers. Prevalent somatic copy number alterations in MICA and MICB genes related to antibody-dependent cell mediated cytotoxicity (ADCC) were identified in tumors with elevated B cell activity. IgG3-1 subclass switch interacts with the B cell receptor affinity maturation and defects in the ADCC pathway. Comprehensive pan-cancer analyses of tumor-infiltrating B cell receptor repertoires identified novel tumor immune evasion mechanisms through genetic alterations. The IgH sequences identified here are potentially useful resources for future development of immunotherapies.

This comprehensive pan-cancer analysis of RNA sequencing data from bulk tumors defines the landscape of tumor-infiltrating B cell receptor repertoires and highlights new mechanisms of tumor immune evasion through genetic alterations.

Gene-modified NK-92MI cells expressing a chimeric CD16-BB-ζ or CD64-BB-ζ receptor exhibit enhanced cancer-killing ability in combination with therapeutic antibody

Natural killer (NK) cells play a pivotal role in monoclonal antibody-mediated immunotherapy through the antibody-dependent cell-mediated cytotoxicity (ADCC) mechanism. NK-92MI is an interleukin-2 (IL-2)-independent cell line, which was derived from NK-92 cells with superior cytotoxicity toward a wide range of tumor cells in vitro and in vivo. Nonetheless, the Fc-receptor (CD16) that usually mediates ADCC is absent in NK-92 and NK-92MI cells. To apply NK-92MI cell-based immunotherapy to cancer treatment, we designed and generated two chimeric receptors in NK-92MI cells that can bind the Fc portion of human immunoglobulins. The construct includes the low-affinity Fc receptor CD16 (158F) or the high-affinity Fc receptor CD64, with the addition of the CD8a extracellular domain, CD28 transmembrane domains, two costimulatory domains (CD28 and 4-1BB), and the signaling domain from CD3ζ. The resulting chimeric receptors, termed CD16-BB-ζ and CD64-BB-ζ, were used to generate modified NK-92MI cells expressing the chimeric receptor, which were named NK-92MI^hCD16 and NK-92MI^hCD64 cells, respectively. We found that NK-92MI^hCD16 and NK-92MI^hCD64 cells significantly improved cytotoxicity against CD20-positive non-Hodgkin's lymphoma cells in the presence of rituximab. These results suggest that the chimeric receptor-expressing NK-92MI cells may enhance the clinical responses to currently available anticancer monoclonal antibodies.

Combining expression of GPC3 in tumors and CD16 on NK cells from peripheral blood to identify patients responding to codrituzumab

Background

Codrituzumab, a monoclonal antibody targeting an oncofetal protein glypican-3 (GPC3) expressed on cell surface of hepatocellular carcinoma (HCC) induces antibody-dependent cellular cytotoxicity (ADCC) and inhibits tumor growth in preclinical studies. Based on this mechanism, tumor GPC3 expression and CD16 expression on NK cells, which are the effector cells of ADCC, were investigated to correlate with codrituzumab's clinical efficacy in patients with advanced HCC.

Results

Joint analyses of the two biomarkers revealed that both high levels of GPC3 and CD16 were required for patients to benefit from codrituzumab; lack of either one of them would lead to a loss of the therapeutic effect.

Conclusions

These results suggest the combination of tumor GPC3 expression and CD16 expression on NK cells from peripheral blood at baseline as a composite biomarker to select HCC patients for codrituzumab.

Impact

The conclusion warrants a future study in an HCC population with both high GPC3 expression and high levels of CD16 at baseline to establish codrituzumab's therapeutic benefit in HCC.

Methods

Data from a phase II clinical trial of codrituzumab were used for the analyses. GPC3 expression in baseline tumor biopsies was determined by immunohistochemistry (IHC) analysis, and baseline CD16 expression on NK cells were quantified by peripheral blood lymphocyte immunophenotyping. According to high or low expression of GPC3 and CD16, different patient subgroups were formed; for each subgroup, overall survival of patients having high codrituzumab exposure was compared to that of patients receiving placebo.

Synthetic integrin-binding immune stimulators target cancer cells and prevent tumor formation

Immuno-oncology approaches mainly utilize monoclonal antibodies or protein-based scaffolds that bind with high affinity to cancer cells and can generate an immune response. Peptides can also bind with high affinity to cancer cells and are intermediate in size between antibodies and small molecules. They are also synthetically accessible and therefore easily modified to optimize their stability, binding affinity and selectivity. Here we describe the design of immune system engagers (ISErs), a novel class of synthetic peptide-based compounds that bind specifically to cancer cells and stimulate the immune system. A prototype, Y9, targets integrin α₃, which is overexpressed on several cancer cells, and activates the immune system via a formyl methionine-containing effector peptide. Injection of Y9 leads to immune cell infiltration into tissue and prevents tumor formation in a guinea pig model. The anti-tumor activity and synthetic accessibility of Y9 illustrate that ISErs could be applied to a wide variety of targets and diseases.

Preparation and biological activities of anti-HER2 monoclonal antibodies with fully core-fucosylated homogeneous bi-antennary complex-type glycans

Recently, the absence of a core-fucose residue in the N-glycan has been implicated to be important for enhancing antibody-dependent cellular cytotoxicity (ADCC) activity of immunoglobulin G monoclonal antibodies (mAbs). Here, we first prepared anti-HER2 mAbs having two core-fucosylated N-glycan chains with the single G2F, G1aF, G1bF, or G0F structure, together with those having two N-glycan chains with a single non-core-fucosylated corresponding structure for comparison, and determined their biological activities. Dissociation constants of mAbs with core-fucosylated N-glycans bound to recombinant Fcγ-receptor type IIIa variant were 10 times higher than those with the non-core-fucosylated N-glycans, regardless of core glycan structures. mAbs with the core-fucosylated N-glycans had markedly reduced ADCC activities, while those with the non-core-fucosylated N-glycans had high activities. These results indicate that the presence of a core-fucose residue in the N-glycan suppresses the binding to the Fc-receptor and the induction of ADCC of anti-HER2 mAbs.

Producing defucosylated antibodies with enhanced in vitro antibody-dependent cellular cytotoxicity via FUT8 knockout CHO-S cells

To engineer a host cell line that produces defucosylated mAbs with superior antibody-dependent cellular cytotoxicity, we disrupted α-1, 6 fucosyltransferase (FUT8) gene in CHO-S (CHO is Chinese hamster ovary) cells by clustered regularly interspaced short palindromic repeats-CRISPR associated nuclease 9. The gene knockout cell line was evaluated for growth, stability, and product quality. The growth profile of FUT8 gene knockout CHO-S (FUT8 ^-/-) cells was comparable with wild type CHO-S cells. FUT8 catalyzes the transfer of a fucose residue from GDP-fucose to N-glycans residue. Defucosylated IgG1 antibodies produced by FUT8 ^-/- cells showed increased binding affinities to human FcγRIIIa and higher activities in mediating antibody-dependent cellular cytotoxicity, comparing with conventional fucosylated IgG1. Our results demonstrated the potential of using the clustered regularly interspaced short palindromic repeats-CRISPR associated nuclease 9 technology in cell line engineering for biopharmaceutical industrial applications.

Clinical value of monoclonal antibodies and tyrosine kinase inhibitors in the treatment of head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC) is a heterogeneous group of malignant tumours that affects over 500,000 patients per year. Treatment failure is generally due to the heterogeneity of these tumours and to the serious adverse effects associated with treatment. Immunological system impairment, which is common in HNSCC, further contributes to treatment failure by mediating tumour escape mechanisms. To date, the only clinically approved targeted therapy agent is cetuximab, a monoclonal antibody (mAb) that binds to, and inhibits, epidermal growth factor receptor, which is widely overexpressed in HNSCC. Cetuximab has been proven to induce antibody-dependent cellular cytotoxicity, further magnifying its therapeutic effect. DNA sequencing of HNSCC cells has identified the presence of mutated genes, thus making their protein products potential targets for therapeutic inhibition. Immune mechanisms have been found to have a significant impact on carcinogenesis, thus providing the rationale to support efforts to identify anticancer compounds with immunomodulatory properties. In the context of the rapid development of novel targeted agents, the aim of the present paper is to review our current understanding of HNSCC and to review the novel anticancer agents (mAbs and TKIs) introduced in recent years, including an assessment of their efficacy and mechanisms of action.

Immunosenescence: limitations of natural killer cell-based cancer immunotherapy

Cancer is primarily considered a disease of old age. Immunosenescence refers to the age-associated changes in the immune system, and its contribution to the increased risk of cancer in old individuals has been discussed for many years. Natural killer (NK) cells are cytotoxic innate immune cells specialized in defence against tumour and virus-infected cells. NK cell cytotoxicity is the result of a fine balance between activating and inhibitory receptors. Several activating receptors have been identified that recognize different ligands frequently found over-expressed on tumour cells or virus-infected cells. The most important NK cell inhibitory receptors interact with major histocompatibility complex class I molecules expressed on almost all nucleated cells preventing NK cell-mediated lysis of healthy cells. NK cell immunosenescence is characterized by a redistribution of NK cell subsets, a diminished expression of several activating receptors and lower per-cell cytotoxicity. Altered expression of activating receptors has also been described in young and elderly cancer patients probably due to chronic exposure to ligands on tumour cells. Thus, the effect of both age and cancer may act synergistically to diminish NK cell-mediated tumour immunosurveillance. Different strategies harnessing the power of NK cells to target tumour cells have been designed including adoptive therapy with autologous or allogeneic expanded NK cells. In addition, checkpoint blockade of inhibitory receptors and the use of agonist antibodies to stimulate activating receptors are emerging areas of research. In this context, the effect of immunosenescence should be considered to improve the efficiency of cancer immunotherapy.

Phase II clinical study of valproic acid plus cisplatin and cetuximab in recurrent and/or metastatic squamous cell carcinoma of Head and Neck-V-CHANCE trial

BACKGROUND

Recurrent/metastatic squamous cell carcinoma of the head and neck (SCCHN) has a poor prognosis and the combination of cisplatin and cetuximab, with or without 5-fluorouracil, is the gold standard treatment in this stage. Thus, the concomitant use of novel compounds represents a critical strategy to improve treatment results. Histone deacetylase inhibitors (HDACi) enhance the activity of several anticancer drugs including cisplatin and anti-Epidermal Growth Factor Receptor (anti-EGFR) compounds. Preclinical studies in models have shown that vorinostat is able to down regulate Epidermal Growth Factor Receptor (EGFR) expression and to revert epithelial to mesenchimal transition (EMT). Due to its histone deacetylase (HDAC) inhibiting activity and its safe use as a chronic therapy for epileptic disorders, valproic acid (VPA) has been considered a good candidate for anticancer therapy. A reasonable option may be to employ the combination of cisplatin, cetuximab and VPA in recurrent/metastatic SCCHN taking advantage of the possible positive interaction between histone deacetylase inhibitors, cisplatin and/or anti-EGFR.

METHOD/DESIGN

V-CHANCE is a phase 2 clinical trial evaluating, in patients with recurrent/metastatic squamous cell carcinoma of the head and neck never treated with first-line chemotherapy, the concomitant standard administration of cisplatin (on day 1, every 3 weeks) and cetuximab (on day 1, weekly), in combination with oral VPA given daily from day -14 with a titration strategy in each patient (target serum level of 50-100 μg/ml). Primary end point is the objective response rate measured according to Response Evaluation Criteria in Solid Tumors (RECIST). Sample size, calculated according to Simon 2 stage minimax design will include 21 patients in the first stage with upper limit for rejection being 8 responses, and 39 patients in the second stage, with upper limit for rejection being 18 responses. Secondary endpoints are time to progression, duration of response, overall survival, safety. Objectives of the translational study are the evaluation on tumor samples of markers of treatment efficacy/resistance (i.e. γH2AX, p21/WAF, RAD51, XRCC1, EGFR, p-EGFR, Ki-67) and specific markers of VPA HDAC inhibitory activity (histones and proteins acetylation, Histone deacetylase isoforms) as well as valproate test, histones and proteins acetylation of peripheral blood mononuclear cell, tested on blood samples at baseline and at different time points during treatment.

DISCUSSION

Overall, this study could provide a less toxic and more effective first-line chemotherapy regimen in patients with recurrent/metastatic squamous cell carcinoma of the head and neck by demonstrating the feasibility and efficacy of cisplatin/cetuximab plus valproic acid. Moreover, correlative studies could help to identify responder patients, and will add insights in the mechanism of the synergistic interaction between these agents.

EUDRACT NUMBER

2014-001523-69 TRIAL REGISTRATION: ClinicalTrials.gov number, NCT02624128.

Challenges and opportunities for monoclonal antibody therapy in veterinary oncology

Monoclonal antibodies (mAbs) have come to dominate the biologics market in human cancer therapy. Nevertheless, in veterinary medicine, very few clinical trials have been initiated using this form of therapy. Some of the advantages of mAb therapeutics over conventional drugs are high specificity, precise mode of action and long half-life, which favour infrequent dosing of the antibody. Further advancement in the field of biomedical sciences has led to the production of different forms of antibodies, such as single chain antibody fragment, Fab, bi-specific antibodies and drug conjugates for use in diagnostic and therapeutic purposes. This review describes the potential for mAbs in veterinary oncology in supporting both diagnosis and therapy of cancer. The technical and financial hurdles to facilitate clinical acceptance of mAbs are explored and insights into novel technologies and targets that could support more rapid clinical development are offered.

Prognostic and predictive biomarkers in metastatic colorectal cancer anti-EGFR therapy

AIM: To reviewing genetic and epigenetic make-up of metastatic colorectal cancers (mCRCs) addicted to epidermal growth factor receptor (EGFR) signalling.

METHODS: The present study summarizes the potential value of prognostic and predictive biomarkers in selecting mCRC patients treated with anti-EGFR therapy. A meta-analysis was performed using a systematic search of PubMed, Medline and Web of Science to identify eligible papers until March 21^st, 2016 using these following terms: ‘‘colorectal cancer’’, “predictive biomarkers’’, “anti-EGFR therapy”, “KRAS”, “NRAS’’, “PIK3CA”, “TP53”, “PTEN”, ‘‘EGFR”, “MET”, “HER2”, “epiregulin”, “amphiregulin”, “prognostic biomarkers”, “BRAF”, “miRNA” and “antibody-dependent cell-mediated cytotoxicity (ADCC) activity”. Two investigators independently evaluated and extracted data from each identified studies based on selected criteria of inclusion and exclusion.

RESULTS: The introduction of agents targeting EGFR such as cetuximab and panitumumab increased overall survival of mCRCs. Nevertheless, it has firstly became evident that response rates to cetuximab regimens in unselected patient populations were typically lower than 30%. Clinical data confirmed the predictive value of RAS mutations for resistance to cetuximab and panitumumab leading to the license of these monoclonal antibodies exclusively for the management of patients with RAS-wild type colorectal cancers. So far the identification of predictive biomarkers have generated interesting, though preliminary and, at times, conflicting data on the importance of tumour mRNA levels of EGFR ligands, of activating mutations in other genes such as NRAS and PIK3CA. The prognostic value of selected microRNAs level and ADCC activity is under investigation, while the prognostic impact of BRAF status remains controversial.

CONCLUSION: This review focuses on the personalized treatment of mCRC and discusses the potential of new prognostic and predictive biomarkers in selecting patients treated with anti-EGFR therapy.

Targeting pathways mediating resistance to anti-EGFR therapy in squamous cell carcinoma of the head and neck

INTRODUCTION

As epidermal growth factor receptor (EGFR) is overexpressed in approximately 90% of squamous cell carcinomas of the head and neck (SCCHN), several therapeutic agents that target EGFR have been evaluated for the treatment of SCCHN. Although patients with SCCHN derive clinical benefit from anti-EGFR agents, most notably the EGFR monoclonal antibody cetuximab, these patients eventually become resistant to EGFR-based therapies; preclinical studies have shown activation of secondary signaling pathways that lead to resistance to EGFR inhibition and, as such, serve as potential therapeutic targets to overcome resistance to EGFR inhibitors.

AREAS COVERED

This review summarizes the results of recently completed trials of anti-EGFR agents in SCCHN, highlights the various mechanisms that drive resistance to EGFR inhibitors in SCCHN, and focuses on several novel targeted agents that could potentially help overcome resistance to EGFR-based therapies in SCCHN. Expert commentary: Due to the development of resistance to EGFR-targeted therapies, novel treatment approaches to overcome resistance are a key unmet need for SCCHN.

Enhancement of Immune Effector Functions by Modulating IgG's Intrinsic Affinity for Target Antigen

Antibody-mediated immune effector functions play an essential role in the anti-tumor efficacy of many therapeutic mAbs. While much of the effort to improve effector potency has focused on augmenting the interaction between the antibody-Fc and activating Fc-receptors expressed on immune cells, the role of antibody binding interactions with the target antigen remains poorly understood. We show that antibody intrinsic affinity to the target antigen clearly influences the extent and efficiency of Fc-mediated effector mechanisms, and report the pivotal role of antibody binding valence on the ability to regulate effector functions. More particularly, we used an array of affinity modulated variants of three different mAbs, anti-CD4, anti-EGFR and anti-HER2 against a panel of target cell lines expressing disparate levels of the target antigen. We found that at saturating antibody concentrations, IgG variants with moderate intrinsic affinities, similar to those generated by the natural humoral immune response, promoted superior effector functions compared to higher affinity antibodies. We hypothesize that at saturating concentrations, effector function correlates most directly with the amount of Fc bound to the cell surface. Thus, high affinity antibodies exhibiting slow off-rates are more likely to interact bivalently with the target cell, occupying two antigen sites with a single Fc. In contrast, antibodies with faster off-rates are likely to dissociate each binding arm more rapidly, resulting in a higher likelihood of monovalent binding. Monovalent binding may in turn increase target cell opsonization and lead to improved recruitment of effector cells. This unpredicted relationship between target affinity and effector function potency suggests a careful examination of antibody design and engineering for the development of next-generation immunotherapeutics.

Enhancement of antibody-dependent cell-mediated cytotoxicity by endowing IgG with FcαRI (CD89) binding

Fc effector functions such as antibody-dependent cell-mediated cytotoxicity (ADCC) and antibody-dependent cell-mediated phagocytosis (ADCP) are crucial to the efficacy of many antibody therapeutics. In addition to IgG, antibodies of the IgA isotype can also promote cell killing through engagement of myeloid lineage cells via interactions between the IgA-Fc and FcαRI (CD89). Herein, we describe a unique, tandem IgG1/IgA2 antibody format in the context of a trastuzumab variable domain that exhibits enhanced ADCC and ADCP capabilities. The IgG1/IgA2 tandem Fc format retains IgG1 FcγR binding as well as FcRn-mediated serum persistence, yet is augmented with myeloid cell-mediated effector functions via FcαRI/IgA Fc interactions. In this work, we demonstrate anti-human epidermal growth factor receptor-2 antibodies with the unique tandem IgG1/IgA2 Fc can better recruit and engage cytotoxic polymorphonuclear (PMN) cells than either the parental IgG1 or IgA2. Pharmacokinetics of IgG1/IgA2 in BALB/c mice are similar to the parental IgG, and far surpass the poor serum persistence of IgA2. The IgG1/IgA2 format is expressed at similar levels and with similar thermal stability to IgG1, and can be purified via standard protein A chromatography. The tandem IgG1/IgA2 format could potentially augment IgG-based immunotherapeutics with enhanced PMN-mediated cytotoxicity while avoiding many of the problems associated with developing IgAs.

Prospective Evaluation of Cetuximab-Mediated Antibody-Dependent Cell Cytotoxicity in Metastatic Colorectal Cancer Patients Predicts Treatment Efficacy

Cetuximab is a monoclonal antibody to the EGFR that induces antibody-dependent cell cytotoxicity (ADCC) through Fcγ receptors on immune cells. Although SNPs in genes encoding Fcγ receptors are functionally relevant to cetuximab-mediated ADCC in colorectal cancer, a direct correlation between in vitro ADCC and clinical response to cetuximab is not defined. We therefore enrolled 96 consecutive metastatic colorectal cancer (mCRC) patients at diagnosis in a study that assessed FcγR status and cetuximab-mediated ADCC. Patients carrying the FcγRIIa H alleles 131H/Hand 131H/R had significantly higher ADCC compared with patients with the 131R/R alleles (P= 0.013). Patients carrying FcγRIIIa genotypes with the V alleles 158V/V and 158V/F displayed higher ADCC compared with patients carrying the 158F/F genotype (P= 0.001). Progression-free survival of patients with an FcγRIIIa 158V allele was significantly longer compared with patients carrying 158F/F (P= 0.05), whereas no significant difference was observed for overall survival. Twenty-eight of 50 mCRC patients with wild-type KRAS received cetuximab. The average ADCC-mediated killing was 30% of assay targets for patients who experienced cetuximab complete or partial response, 21% in patients with stable disease and 9% in patients with progressive disease. To characterize basal natural killer (NK) activity, cytotoxicity was evaluated in 39 of 96 mCRC patients. Patients who responded to first-line treatment had higher NK-cell cytotoxicity. Thus, although limited to this cohort of patients, in vitro cetuximab-mediated ADCC correlated with FcγR polymorphisms and predicted cetuximab responsiveness.

Production of monoclonal antibodies in plants for cancer immunotherapy

Plants are considered as an alternative platform for recombinant monoclonal antibody (mAb) production due to the improvement and diversification of transgenic techniques. The diversity of plant species offers a multitude of possibilities for the valorization of genetic resources. Moreover, plants can be propagated indefinitely, providing cheap biomass production on a large scale in controlled conditions. Thus, recent studies have shown the successful development of plant systems for the production of mAbs for cancer immunotherapy. However, their several limitations have to be resolved for efficient antibody production in plants.

Glycoengineered Monoclonal Antibodies with Homogeneous Glycan (M3, G0, G2, and A2) Using a Chemoenzymatic Approach Have Different Affinities for FcγRIIIa and Variable Antibody-Dependent Cellular Cytotoxicity Activities

Many therapeutic antibodies have been developed, and IgG antibodies have been extensively generated in various cell expression systems. IgG antibodies contain N-glycans at the constant region of the heavy chain (Fc domain), and their N-glycosylation patterns differ during various processes or among cell expression systems. The Fc N-glycan can modulate the effector functions of IgG antibodies, such as antibody-dependent cellular cytotoxicity (ADCC) and complement dependent cytotoxicity (CDC). To control Fc N-glycans, we performed a rearrangement of Fc N-glycans from a heterogeneous N-glycosylation pattern to homogeneous N-glycans using chemoenzymatic approaches with two types of endo-β-N-acetyl glucosaminidases (ENG'ases), one that works as a hydrolase to cleave all heterogeneous N-glycans, another that is used as a glycosynthase to generate homogeneous N-glycans. As starting materials, we used an anti-Her2 antibody produced in transgenic silkworm cocoon, which consists of non-fucosylated pauci-mannose type (Man2-3GlcNAc2), high-mannose type (Man4-9GlcNAc2), and complex type (Man3GlcNAc3-4) N-glycans. As a result of the cleavage of several ENG'ases (endoS, endoM, endoD, endoH, and endoLL), the heterogeneous glycans on antibodies were fully transformed into homogeneous-GlcNAc by a combination of endoS, endoD, and endoLL. Next, the desired N-glycans (M3; Man3GlcNAc1, G0; GlcNAc2Man3GlcNAc1, G2; Gal2GlcNAc2Man3GlcNAc1, A2; NeuAc2Gal2GlcNAc2Man3GlcNAc1) were transferred from the corresponding oxazolines to the GlcNAc residue on the intact anti-Her2 antibody with an ENG'ase mutant (endoS-D233Q), and the glycoengineered anti-Her2 antibody was obtained. The binding assay of anti-Her2 antibody with homogenous N-glycans with FcγRIIIa-V158 showed that the glycoform influenced the affinity for FcγRIIIa-V158. In addition, the ADCC assay for the glycoengineered anti-Her2 antibody (mAb-M3, mAb-G0, mAb-G2, and mAb-A2) was performed using SKBR-3 and BT-474 as target cells, and revealed that the glycoform influenced ADCC activity.

Ex vivo antibody-dependent cellular cytotoxicity inducibility predicts efficacy of cetuximab

We conducted in vitro studies and a clinical trial for patients with squamous cell carcinoma of the head and neck (SCCHN) to study the relationship between FcγRIIIa polymorphisms and antibody-dependent cellular cytotoxicity (ADCC). In vitro, FcγRIIIa genotype was correlated with ADCC and innate cytotoxicity using natural killer (NK) cells harvested from healthy donors. In the phase II study, patients with recurrent or metastatic SCCHN were treated with cetuximab (500 mg/m(2) i.v. every 2 weeks) and lenalidomide (25 mg daily). FcγRIIIa genotype and ex vivo ADCC were correlated with clinical response, progression-free survival (PFS), and overall survival (OS). In vitro, healthy donors with a FcγRIIIa 158-V allele demonstrated more effective ADCC against two colon cancer cell lines HT29 and SW480, mean cytotoxicity: FF 16.1%, VF/VV 24.3% (P = 0.015) and FF 11.7%, VF/VV 21.0% (P = 0.008), respectively. We observed a linear relationship between ADCC response and innate cytotoxicity. In the phase II trial, 40 patients received cetuximab and lenalidomide with median PFS of 7.2 weeks and OS of 16.4 weeks. Thirty-six patients had FcγRIIIa genotype: VV (2), VF (20), and FF (14), and 25 patients had sufficient NK-cell yield to perform ex vivo ADCC. FcγRIIIa genotype was not associated with any clinical outcomes. Patients mounting ex vivo ADCC response had a higher likelihood of stable disease (P = 0.01) and showed a trend toward increased PFS: 14 weeks versus 6.8 weeks, respectively (P = 0.13). Enhanced ex vivo ADCC and innate immunity responses were more predictive of clinical response than FcγRIIIa and may offer a functional assay to select patients suitable for cetuximab therapy.