Analysis of in vitro ADCC and clinical response to trastuzumab: possible relevance of FcγRIIIA/FcγRIIA gene polymorphisms and HER-2 expression levels on breast cancer cell lines

Immune microenvironment dynamics of HER2 overexpressing breast cancer under dual anti-HER2 blockade

Introduction

The clinical prognosis of the HER2-overexpressing (HER2-OE) subtype of breast cancer (BC) is influenced by the immune infiltrate of the tumor. Specifically, monocytic cells, which are promoters of pro-tumoral immunosuppression, and NK cells, whose basal cytotoxic function may be enhanced with therapeutic antibodies. One of the standards of care for HER2+ BC patients includes the combination of the anti-HER2 antibodies trastuzumab and pertuzumab. This dual combination was a breakthrough against trastuzumab resistance; however, this regimen does not yield complete clinical benefit for a large fraction of patients. Further therapy refinement is still hampered by the lack of knowledge on the immune mechanism of action of this antibody-based dual HER2 blockade.

Methods

To explore how the dual antibody challenge influences the phenotype and function of immune cells infiltrating the HER2-OE BC microenvironment, we developed in vitro 3D heterotypic cell models of this subtype. The models comprised aggregates of HER2+ BC cell lines and human peripheral blood mononuclear cells. Cells were co-encapsulated in a chemically inert alginate hydrogel and maintained in agitation-based culture system for up to 7 days.

Results

The 3D models of the HER2-OE immune microenvironment retained original BC molecular features; the preservation of the NK cell compartment was achieved upon optimization of culture time and cytokine supplementation. Challenging the models with the standard-of-care combination of trastuzumab and pertuzumab resulted in enhanced immune cytotoxicity compared with trastuzumab alone. Features of the response to therapy within the immune tumor microenvironment were recapitulated, including induction of an immune effector state with NK cell activation, enhanced cell apoptosis and decline of immunosuppressive PD-L1+ immune cells.

Conclusions

This work presents a unique human 3D model for the study of immune effects of anti-HER2 biologicals, which can be used to test novel therapy regimens and improve anti-tumor immune function.

Trastuzumab Mechanism of Action; 20 Years of Research to Unravel a Dilemma

Trastuzumab as a first HER2-targeted therapy for the treatment of HER2-positive breast cancer patients was introduced in 1998. Although trastuzumab has opened a new avenue to treat patients with HER2-positive breast cancer and other types of cancer, some patients are not responsive or become resistant to this treatment. So far, several mechanisms have been suggested for the mode of action of trastuzumab; however, the findings regarding these mechanisms are controversial. In this review, we aimed to provide a detailed insight into the various mechanisms of action of trastuzumab.

ADCC-Inducing Antibody Trastuzumab and Selection of KIR-HLA Ligand Mismatched Donors Enhance the NK Cell Anti-Breast Cancer Response

Simple Summary

Natural killer (NK) cells are potent killers of tumor cells. Many tumors, including breast cancers, develop mechanisms to suppress anti-tumor immune responses, requiring the development of strategies to overcome suppression. Here, we tested a combination therapy that aims to (1) enhance NK cell activation and (2) reduce NK cell inhibition mediated by suppressive factors in tumors or in the tumor microenvironment. We cultured cell lines under hypoxia to mimic the tumor microenvironment or used patient-derived breast cancer cells that were primed by the patient’s tumor environment. Our results demonstrated that cytokine-activated NK cells remained active under hypoxia and that tumor-targeting antibodies enhanced the NK cell anti-breast cancer response. Moreover, we observed that NK cell suppression by inhibitory ligands on the tumor cells can be reduced by the selection of NK cell donors with NK receptors that are incompatible with these ligands. Collectively, we present two powerful strategies to enhance the NK cell responses against breast cancer.

Abstract

Natural killer (NK)-cell-based immunotherapies are an attractive treatment option for cancer. We previously showed that alloreactive mouse NK cells cured mice of 4T1 breast cancer. However, the tumor microenvironment can inhibit immune responses, and these suppressive factors must be overcome to unfold the NK cells’ full anti-tumor potential. Here, we investigated the combination of antibody-dependent cellular cytotoxicity (ADDC) and the selection of KIR-HLA-ligand mismatched NK cells to enhance NK cell anti-breast cancer responses in clinically relevant settings. Donor-derived and IL-2-activated NK cells were co-cultured with patient-derived breast cancer cells or cell lines MCF7 or SKBR3 together with the anti-HER2 antibody trastuzumab. NK cells mediated anti-breast cancer cytotoxicity under normoxic and hypoxic conditions. Under both conditions, trastuzumab vigorously enhanced NK cell degranulation (CD107a) against HER2-overexpressing SKBR3 cells, but we observed a discrepancy between highly degranulating NK cells and a rather modest increase in cytotoxicity of SKBR3. Against patient-derived breast cancer cells, the anti-tumor efficacy was rather limited, and HLA class I expression seemed to contribute to inhibited NK cell functionality. KIR-ligand-mismatched NK cells degranulated stronger compared to the matched NK cells, further highlighting the role of HLA. In summary, trastuzumab and KIR-ligand-mismatched NK cells could be two strategies to potently enhance NK cell responses to breast cancer.

Site-Selective Chemoenzymatic Modification on the Core Fucose of an Antibody Enhances Its Fcγ Receptor Affinity and ADCC Activity

Fc glycosylation profoundly impacts the effector functions of antibodies and often dictates an antibody's pro- or anti-inflammatory activities. It is well established that core fucosylation of the Fc domain N-glycans of an antibody significantly reduces its affinity for FcγRIIIa receptors and antibody-dependent cellular cytotoxicity (ADCC). Previous structural studies have suggested that the presence of a core fucose remarkably decreases the unique and favorable carbohydrate-carbohydrate interactions between the Fc and the receptor N-glycans, leading to reduced affinity. We report here that in contrast to natural core fucose, special site-specific modification on the core fucose could dramatically enhance the affinity of an antibody for FcγRIIIa. The site-selective modification was achieved through an enzymatic transfucosylation with a novel fucosidase mutant, which was shown to be able to use modified α-fucosyl fluoride as the donor substrate. We found that replacement of the core l-fucose with 6-azide- or 6-hydroxy-l-fucose (l-galactose) significantly enhanced the antibody's affinity for FcγRIIIa receptors and substantially increased the ADCC activity. To understand the mechanism of the modified fucose-mediated affinity enhancement, we performed molecular dynamics simulations. Our data revealed that the number of glycan contacts between the Fc and the Fc receptor was increased by the selective core-fucose modifications, showing the importance of unique carbohydrate-carbohydrate interactions in achieving high FcγRIIIa affinity and ADCC activity of antibodies. Thus, the direct site-selective modification turns the adverse effect of the core fucose into a favorable force to promote the carbohydrate-carbohydrate interactions.

The Peripheral Immune Landscape of Breast Cancer: Clinical Findings and In Vitro Models for Biomarker Discovery

Breast cancer is the deadliest female malignancy worldwide and, while much is known about phenotype and function of infiltrating immune cells, the same attention has not been paid to the peripheral immune compartment of breast cancer patients. To obtain faster, cheaper, and more precise monitoring of patients' status, it is crucial to define and analyze circulating immune profiles. This review compiles and summarizes the disperse knowledge on the peripheral immune profile of breast cancer patients, how it departs from healthy individuals and how it changes with disease progression. We propose this data to be used as a starting point for validation of clinically relevant biomarkers of disease progression and therapy response, which warrants more thorough investigation in patient cohorts of specific breast cancer subtypes. Relevant clinical findings may also be explored experimentally using advanced 3D cellular models of human cancer-immune system interactions, which are under intensive development. We review the latest findings and discuss the strengths and limitations of such models, as well as the future perspectives. Together, the scientific advancement of peripheral biomarker discovery and cancer-immune crosstalk in breast cancer will be instrumental to uncover molecular mechanisms and putative biomarkers and drug targets in an all-human setting.

Clinical Potential of Kinase Inhibitors in Combination with Immune Checkpoint Inhibitors for the Treatment of Solid Tumors

Oncogenic kinases contribute to immunosuppression and modulate the tumor microenvironment in solid tumors. Increasing evidence supports the fundamental role of oncogenic kinase signaling networks in coordinating immunosuppressive tumor microenvironments. This has led to numerous studies examining the efficacy of kinase inhibitors in inducing anti-tumor immune responses by increasing tumor immunogenicity. Kinase inhibitors are the second most common FDA-approved group of drugs that are deployed for cancer treatment. With few exceptions, they inevitably lead to intrinsic and/or acquired resistance, particularly in patients with metastatic disease when used as a monotherapy. On the other hand, cancer immunotherapies, including immune checkpoint inhibitors, have revolutionized cancer treatment for malignancies such as melanoma and lung cancer. However, key hurdles remain to successfully incorporate such therapies in the treatment of other solid cancers. Here, we review the recent literature on oncogenic kinases that regulate tumor immunogenicity, immune suppression, and anti-tumor immunity. Furthermore, we discuss current efforts in clinical trials that combine kinase inhibitors and immune checkpoint inhibitors to treat breast cancer and other solid tumors.

Novel TLR 7/8 agonists for improving NK cell mediated antibody-dependent cellular cytotoxicity (ADCC)

There is a significant interest in designing therapeutic agents that can enhance ADCC and thereby improve clinical responses with approved antibodies. We recently reported the combination of an imidazoquinoline-based TLR7/8 agonist (522) with a monoclonal antibody improved ADCC in vitro and in vivo. In the present study, we tested several new small molecule TLR7/8 agonists that induce significantly higher cytokines compared to both the FDA-approved TLR7 agonist, imiquimod, and 522. We evaluated these agonists in combination with monoclonal antibody therapy, with the main goal of enhancing ADCC. Our studies show these TLR7/8 agonists induce robust pro-inflammatory cytokine secretion and activate NK cells. Specifically, we found the agonists 574 and 558 significantly enhanced NK cell-mediated ADCC in vitro as well as enhanced the anti-cancer efficacy of monoclonal antibodies in two different in vivo mouse models. Additionally, we found the agonists were able to stimulate CD8 T cells, likely indicative of an early adaptive immune response.

Exosomal long noncoding RNA AGAP2-AS1 regulates trastuzumab resistance via inducing autophagy in breast cancer

Trastuzumab has been widely used for treatment of HER-2-positive breast cancer patients, however, the clinical response has been restricted due to emergence of resistance. Recent studies indicate that long noncoding RNA AGAP2-AS1 (lncRNA AGAP2-AS1) plays an important role in cancer resistance. However, the precise regulatory function and therapeutic potential of AGAP2-AS1 in trastuzumab resistance is still not defined. In this study, we sought to reveal the essential role of AGAP2-AS1 in trastuzumab resistance. Our results suggest that AGAP2-AS1 disseminates trastuzumab resistance via packaging into exosomes. Exosomal AGAP2-AS1 induces trastuzumab resistance via modulating ATG10 expression and autophagy activity. Mechanically, AGAP2-AS1 is associated with ELAVL1 protein, and the AGAP2-AS1-ELAVL1 complex could directly bind to the promoter region of ATG10, inducing H3K27ac and H3K4me3 enrichment, which finally activates ATG10 transcription. AGAP2-AS1-targeting antisense oligonucleotides (ASO) substantially increased trastuzumab-induced cytotoxicity. Clinically, increased expression of serum exosomal AGAP2-AS1 was associate with poor response to trastuzumab treatment. In conclusion, exosomal AGAP2-AS1 increased trastuzumab resistance via promoting ATG10 expression and inducing autophagy. Therefore, AGAP2-AS1 may serve as predictive biomarker and therapeutic target for HER-2+ breast cancer patients.

MSC-induced lncRNA AGAP2-AS1 promotes stemness and trastuzumab resistance through regulating CPT1 expression and fatty acid oxidation in breast cancer

Trastuzumab resistance has been becoming a major obstacle for treatment of HER-2-positive breast cancer patients. Increasing evidence suggests that mesenchymal stem cells (MSCs) play critical roles during the formation of drug resistance, however, the underlying mechanism is not well known. In this study, mass spectrometry, RNA pulldown and RNA immunoprecipitation assays were performed to verify the direct interactions among AGAP2-AS1 and other associated targets, such as human antigen R (HuR), miR-15a-5p, and carnitine palmitoyl transferase 1 (CPT1). In vitro and in vivo experimental assays were done to clarify the functional role of AGAP2-AS1 in trastuzumab resistance, stemness, and fatty acid oxidation (FAO). The results showed that MSC co-culture induced trastuzumab resistance. AGAP2-AS1 was upregulated in MSC-cultured cells, and knockdown of AGAP2-AS1 reversed the MSC-mediated trastuzumab resistance. Furthermore, MSC culture-induced AGAP2-AS1 regulates stemness and trastuzumab resistance via activating FAO. Mechanistically, AGAP2-AS1 is associated with HuR, and the AGAP2-AS1-HuR complex could directly bind to the CPT1, increasing its expression via improving RNA stability. In addition, AGAP2-AS1 could serve as ceRNA via sponging miR-15a-5p and releasing CPT1 mRNA. Clinically, increased expression of serum AGAP2-AS1 predicts poor response to trastuzumab treatment in breast cancer patients. In conclusion, MSC culture-induced AGAP2-AS1 caused stemness and trastuzumab resistance via promoting CPT1 expression and inducing FAO. Our results provide new insight of the role of MSCs in trastuzumab resistance and AGAP2-AS1 could be promising predictive biomarker and therapeutic target for HER-2+ breast cancer patients.

A novel co-culture assay to assess anti-tumor CD8+ T cell cytotoxicity via luminescence and multicolor flow cytometry

T cell immunotherapies have shown great promise in patients with advanced cancer disease, revolutionizing treatment. T cell cytotoxicity is crucial in its efficacy, therefore developing ex vivo methods testing tumor and T cell interactions is pivotal. Increasing efforts have been made in developing co-culture assays with sophisticated materials and platforms aiming to mimic the tumor microenvironment (TME), but its complexity makes it difficult to develop the ideal model. In this study, we developed a simple co-culture assay, reproducible in any lab, but respecting the multicellular nature of the TME. Our goal is to combine in a single assay well-established techniques such as a luciferase assay for target cell viability analysis, a CD107a degranulation assay, and multicolor flow cytometry for the detection of cytokines and cytotoxicity markers. Cell suspensions of whole spleens and tumors containing splenic or tumor-infiltrating effector T cells of mice bearing Lewis lung carcinoma (LLC) or CT26 colon carcinoma tumors treated with radiation alone or in combination with immunotherapies were used for co-culture. LLC and CT26 cell lines transduced with the firefly luciferase gene were used as target cells. We demonstrated that splenocytes and tumor-infiltrating T cells derived from mice treated with combination therapy were able to kill approximately 50% of target cells after 48 h of co-culture. This effect was tumor cell-specific and dependent on CD8+ T cells evidenced by in vitro CD8+ T cell depletion. Flow cytometry demonstrated increased expression of CD107a and production of granzyme B, IFNγ, and TNFα by CD8+ T cells. Our co-culture assay is therefore suitable as proof of principle for in vivo therapeutic studies testing immunotherapies, and specifically to assess the involvement of cytotoxic CD8+ T cells in treatment response in LLC and CT26 tumor models. We also propose this assay as an ex vivo platform for high-throughput screening of immunomodulating agents to be tested in these two murine tumor models. This assay can be adapted to other tumor models after optimizations.

Toward a Better Understanding of Bioassays for the Development of Biopharmaceuticals by Exploring the Structure-Antibody-Dependent Cellular Cytotoxicity Relationship in Human Primary Cells

Pharmaceutical manufacturing relies on rigorous methods of quality control of drugs and in particular of the physico-chemical and functional characterizations of monoclonal antibodies. To that end, robust bioassays are very often limited to reporter gene assays and the use of immortalized cell lines that are supposed to mimic immune cells such as natural killer (NK) cells to the detriment of primary materials, which are appreciated for their biological validity but are also difficult to exploit due to the great diversity between individuals. Here, we characterized the phenotype of the peripheral blood circulating cytotoxic cells of 30 healthy donors, in particular the repertoire of cytotoxic markers, using flow cytometry. In parallel, we characterized the antibody-dependent cellular cytotoxicity (ADCC) effector functions of these primary cells by measuring their cytolytic activity against a cancer cell-line expressing HER2 in the presence of trastuzumab and with regards to FCGR3A genotype. We could not establish a correlation or grouping of individuals using the data generated from whole peripheral blood mononuclear cells, however the isolation of the CD56-positive population, which is composed not only of NK cells but also of natural killer T (NKT) and γδ-T cells, as well as subsets of activated cytotoxic T cells, monocytes and dendritic cells, made it possible to standardize the parameters of the ADCC and enhance the overall functional avidity without however eliminating the inter-individual diversity. Finally, the use of primary CD56+ cells in ADCC experiments comparing glycoengineered variants of trastuzumab was conclusive to test the limits of this type of ex vivo system. Although the effector functions of CD56+ cells reflected to some extent the in vitro receptor binding properties and cytolytic activity data using NK92 cells, as previously published, reaching a functional avidity plateau could limit their use in a quality control framework.

Generation and testing of engineered multimeric Fabs of trastuzumab

Recombinant antibodies fragments in several new formats are routinely investigated and used in diagnostic and therapeutic applications as anti-cancers molecules. New antibody formats are generated to compensate the need for multispecificity and site-specific introduction of fluorescent dyes, cytotoxic payloads or for generating semisynthetic multimeric molecules. Fabs of trastuzumab bearing transglutaminase (MTG) reactive sites were generated by periplasmic expression in E. coli and purified. Multimeric Fabs were generated by either disulfide bridge formation or by using MTG-sensitive peptide linkers. Binding to receptor was assessed by ELISA and SPR methods. Internalization and growth inhibition assays were performed on BT-474 and SKBR3 Her2+ cells. Fabs were successfully produced and dimerized or trimerized using MTG and suitably designed peptide linkers. Site-specific derivatizations with fluorophores were similarly achieved. The monomeric, dimeric and trimeric variants bind the receptor with affinities similar or superior to the full antibody. Fab and Fab2 are rapidly internalized in Her2+ cells and exhibit growth inhibition abilities similar to the full antibody. Altogether, the data show that the recombinant Fabs can be produced in E. coli and converted into multimeric variants by MTG-based bioconjugation. Similar approaches are extendable to the introduction of cytotoxic payloads for the generation of novel Antibody Drug Conjugates.

Monoclonal Antibodies in Cancer Therapy

Monoclonal antibody-based immunotherapy is now considered to be a main component of cancer therapy, alongside surgery, radiation, and chemotherapy. Monoclonal antibodies possess a diverse set of clinically relevant mechanisms of action. In addition, antibodies can directly target tumor cells while simultaneously promoting the induction of long-lasting anti-tumor immune responses. The multifaceted properties of antibodies as a therapeutic platform have led to the development of new cancer treatment strategies that will have major impacts on cancer care. This review focuses on the known mechanisms of action, current clinical applications for the treatment of cancer, and mechanisms of resistance of monoclonal antibody therapy. We further discuss how monoclonal antibody-based strategies have moved towards enhancing anti-tumor immune responses by targeting immune cells instead of tumor antigens as well as some of the current combination therapies.

Anti-CD20 rituximab IgG1, IgG3, and IgG4 but not IgG2 subclass trigger Ca2+ mobilization and cytotoxicity in human NK cells

NK cell-mediated Ab-dependent cellular cytotoxicity (ADCC) is increasingly recognized to play an important role in cancer immunotherapy, transplant rejection, and autoimmunity. However, several aspects of the molecular interactions of IgG subclasses with the Fc-gamma receptor IIIA (FcγRIIIA)/CD16a expressed on NK cells remain unknown. The aim of the current study was to further analyze the role of IgG subclasses and FCGR3A V158F single nucleotide polymorphism (SNP) on Ca²⁺ signaling and NK cell-mediated ADCC against Daudi target cells in vitro. NK cells were isolated from donors with different FCGR3A SNP. The affinity of rituximab IgG subclasses to CD20 expressed on Daudi cells showed similar dissociation constant as tested by flow cytometry. Induction of Ca²⁺ signaling, degranulation, intracellular cytokine production, and ADCC was demonstrated for IgG1 and IgG3, to a lesser degree also for IgG4, but not for IgG2. Compared to NK cells carrying the low-affinity (FF) variant for the FCGR3A V158F SNP, binding of IgG1 and IgG3 to NK cells carrying the high-affinity (VV) and VF SNP variants was two- to threefold higher. Variations of FCGR3A SNP among the eight tested donors (1 VV, 3FF, and 4VF) revealed no significant differences of Ca²⁺ signaling and degranulation; however, ADCC was somewhat weaker in donors with the low-affinity FF variation. In conclusion, this is the first study correlating Ca²⁺ signaling and NK cell-mediated ADCC triggered by the four IgG subclasses with the FCGR3A V158F SNP. Our findings indicate important differences in the interactions of IgG subclasses with FcγRIIIA/CD16a but no major impact of FCGR3A SNP and may therefore help to better correlate the functional properties of particular engineered therapeutic antibodies in vitro with individual differences of their clinical efficacy.

Evolution of the EU Biosimilar Framework: Past and Future

The approval of biosimilars in the EU follows a comprehensive scientific assessment based on stringent regulatory standards. While the initial approach to biosimilars was understandably cautious and conservative in that uncharted territory to protect patients’ safety, the analytical and scientific progress and accumulated experience with biosimilars continues to reshape regulatory requirements, generally leading to a reduced burden of clinical trials. This trend is expected to continue, for example, by increasingly employing pharmacodynamic endpoints and biomarkers, but much work remains to make this happen, especially for complex molecules with several or unknown mechanisms of action. We reviewed the available guidance and European Public Assessment Reports (EPARs) of biosimilars approved in the EU via the centralised procedure. This review focuses on the nature and extent of clinical confirmation of biosimilarity considered necessary in addition to analytical and functional data. Cases with conflicting results from different parts of the comparability exercise are discussed, with the aim of identifying whether certain elements of the comparability exercise are more important than others in determining biosimilarity. Taken together, analytical and functional comparison is the foundation of any biosimilar development. In addition, pharmacokinetic similarity is an indispensable prerequisite for any biosimilar approval, so careful planning on behalf of the applicant is mandated to avoid potential failure of such studies, for example, because of large interindividual variability, underpowered trial designs or other methodological causes. Comparative pharmacokinetic studies are a basic requirement for biosimilar development and are usually more sensitive than clinical efficacy trials when detecting potential product-related differences. This may explain why a demonstration of equivalent efficacy could not overrule a finding of dissimilar pharmacokinetic profiles in two cases of biosimilar pegfilgrastim. However, the outcome of efficacy trials depends not only on drug exposure but also on proper pharmacological action of the biological substance in vivo. Therefore, the objectives of both types of studies differ. Efficacy trials should usually be designed as equivalence trials to ensure that the efficacy of the biosimilar is neither decreased nor increased compared with the reference product. However, some remaining uncertainty regarding potentially increased efficacy of the biosimilar may be acceptable in exceptional cases, provided that the data from other parts of the comparability exercise clearly support a conclusion of biosimilarity and safety is assured. In contrast, uncertainties regarding potentially inferior efficacy of the biosimilar may not be acceptable at all. We conclude that the EU biosimilar regulatory framework is robust and able to adapt to advancing knowledge and experience and to strike a balance between regulatory standards, patient safety and feasibility of biosimilar development.

Roles of neutrophil/lymphocyte ratio in prognosis and in differentiation of potential beneficiaries in HER2-positive breast cancer with trastuzumab therapy

Background

The relationship of neutrophil/lymphocyte ratio (NLR) to prognosis of HER2-positive breast cancer (BC) is not well studied. We aimed to assess the prognostic role of NLR in HER2-positive BC patients treated with or without trastuzumab.

Methods

The clinical data of 843 HER2-positive BC patients from July 2013 to July 2018 were collected. The difference among variables was calculated by chi-square test. The associations between clinicopathological factors, NLR and disease-free survival (DFS) were analyzed by univariate and multivariate analyses.

Results

Patients were divided into three groups. In group 1 containing 255 patients without trastuzumab treatment, pretreatment NLR showed no predictive value. Patients with trastuzumab treatment were divided into two groups on equal, according to pretreatment NLR values, low NLR (group 2) and high NLR (group 3). Patients in group 2 showed significantly higher 3-year DFS rate than patients in group 1 and group 3 (95.3% vs. 91.6% vs. 90.5%, respectively, P = 0.011); patients in the group 1 and group 3 had a similar 3-year DFS outcome. Multivariate analysis showed high pretreatment NLR was significantly associated with shorter DFS (HR = 2.917, 95% CI = 1.055–8.062, P = 0.039) in HER2-positive BC patients treated with trastuzumab.

Conclusions

Among HER2-positive trastuzumab-treated BC patients, low pretreatment NLR value was associated with better DFS, and it might help to differentiate potential beneficiaries of trastuzumab treatment.

Baseline Lymphopenia: A Predictor Of Poor Outcomes In HER2 positive Metastatic Breast Cancer Treated With Trastuzumab

Purpose

Despite selection based on human epidermal growth factor receptor 2 (HER2) overexpression, not all HER2-positive patients benefit from trastuzumab therapy. Recent reports indicate that trastuzumab treatment failure may be associated with immune system dysfunction. We examined the prognostic relevance of the absolute lymphocyte count (ALC) in patients with HER2-positive metastatic breast cancer (MBC) who received trastuzumab combined with chemotherapy.

Methods

Baseline ALC and neutrophil-to-lymphocyte ratio (NLR) data from trastuzumab-treated patients with MBC were studied retrospectively, and associations between baseline ALC and clinical characteristics evaluated. Kaplan–Meier analysis and the Cox regression hazard model were applied to assess effects on outcomes.

Results

Of a total of 68 patients, 19.1% (13/68) had baseline ALCs ≤ 1 G/L. Baseline lymphopenia was correlated with increased lactate dehydrogenase (LDH) and higher NLR. In univariate analysis, higher alkaline phosphatase (ALP) was associated with inferior overall survival (OS) (P = 0.001); higher LDH was associated with inferior progression-free survival (PFS) (P = 0.045) and OS (P = 0.010). We did not observe any differences in objective response rate or disease control rate between patients with lymphopenia and those with normal ALC. Importantly, patients with baseline lymphopenia had inferior PFS (0.60 years vs 1.17 years, P = 0.000009) and OS (1.88 years vs 3.80 years, P = 0.0003). In multivariable analysis, significance of ALCs was retained for lymphopenia (PFS: P = 0.0005; OS: P = 0.016).

Conclusion

Our data indicate that baseline ALC value of ≤1 G/L is a predictor of poor outcomes, but not of response, in patients with MBC treated with trastuzumab.

Anti-CD137 monoclonal antibody enhances trastuzumab-induced, natural killer cell-mediated cytotoxicity against pancreatic cancer cell lines with low human epidermal growth factor-like receptor 2 expression

Because human epidermal growth factor-like receptor (HER) 2 is expressed on the surface of human pancreatic carcinoma cells to varying degrees, trastuzumab, an anti-HER2 monoclonal antibody (mAb), is expected to exert antibody-dependent, natural killer (NK) cell-mediated cytotoxicity (ADCC) against the cells. However, some reports found that the effect of trastuzumab against human pancreatic carcinoma cells was limited because most express only limited HER2. We examined whether anti-CD137 stimulating mAb could enhance trastuzumab-mediated ADCC against Panc-1, a human pancreatic cancer cell line with low HER2 expression, in vitro. Supplementation of anti-CD137 mAb could improve trastuzumab-mediated ADCC against Panc-1 which was insufficient without this stimulating antibody. The ADCC differed in individual cells, and this was related to the expression of CD137 on the surface of NK cells after trastuzumab stimulation in association with the Fcγ-RIIIA polymorphism. NK cells with Fcγ-RIIIA-VV/VF showed high levels of ADCC against Panc-1, but those with Fcγ-RIIIA-FF did not show optimal ADCC. In addition, trastuzumab-mediated ADCC against the human pancreatic cancer cell line Capan-1 with high HER2 expression was generally high and not affected by the Fcγ-RIIIA polymorphism. These results demonstrated that in Fcγ-RIIIA-VV/VF-carrying healthy individuals, trastuzumab plus αCD137 mAb could induce effective ADCC against HER2-low-expressing pancreatic cancer cell lines, and that such an approach may result in similar findings in patients with pancreatic cancer.

Enhancing antibody-dependent cell-mediated cytotoxicity: a strategy for improving antibody-based immunotherapy

The targeting of surface antigens expressed on tumor cells by monoclonal antibodies (mAbs) has revolutionized cancer therapeutics. One mechanism of action of antibody-based immunotherapy is the activation of immune effector cells to mediate antibody-dependent cell-mediated cytotoxicity (ADCC). This review will summarize the process of ADCC, its important role in the efficacy of mAb therapy, how to measure it, and finally future strategies for antibody design that can take advantage of it to improve clinical performance.

FcrR3A-158 Polymorphism and Stromal Tumor-Infiltrating Lymphocytes and Survival among Patients with Metastatic HER2-Positive Breast Cancer Receiving Trastuzumab-Based Treatment

Purpose

The prognosis of human epidermal growth factor receptor 2 (HER2)-positive breast cancer has markedly improved since the introduction of trastuzumab. We aimed to evaluate the association between stromal tumor-infiltrating lymphocyte (sTIL) or FcrR polymorphisms and survival among patients with metastatic HER2-positive breast cancer who were treated with trastuzumab.

Methods

A total of 56 women with recurrent or metastatic HER2-positive breast cancer who received the trastuzumab-taxane combination as first-line treatment were included in this retrospective analysis. The single-step multiplex allele-specific real-time polymerase chain reaction technique was employed for FcrR3A genotyping. sTILs were identified via immunohistochemical analysis of surgical (n=34, 60.7%) or biopsy specimens of metastatic lesions (n=22, 39.3%).

Results

We classified patients based on the sTIL level (≤10% [n=44] or >10% [n=12]); high sTIL counts were more commonly observed in patients with hormone receptor-negative tumors than in those with hormone receptor-positive tumors (34.8% vs. 12.1%, p=0.02). There was a significant association between high sTIL levels and longer progression-free survival in comparison to low sTIL levels (median, 28.4 months vs. 16.8 months; p=0.03). With regard to the FcrR3A-158 genotype, patients were classified into the Phenylalanine/Phenylalanine group (23 patients, 41.1%), Phenylalanine/Valine group (23 patients, 41,1%), or Valine/Valine group (10 patients, 17.9%); these classifications were not associated with clinical outcomes.

Conclusion

High sTIL expression may be associated with better efficacy of trastuzumab-containing therapy in patients with metastatic HER2-positive breast cancer. However, this finding warrants further evaluation in the larger population.

IL-15 enhances the anti-tumor activity of trastuzumab against breast cancer cells but causes fatal side effects in humanized tumor mice (HTM)

Cancer immunotherapy has been shown to enhance established treatment regimens. We evaluated the potential reinforcing effect of IL-15 in trastuzumab treated humanized tumor mice (HTM) which were generated by concurrent transplantation of neonatal NOD-scid IL2Rγnull mice with human hematopoietic stem cells (HSC) and HER2 positive breast cancer cells (metastasizing SK-BR-3, solid tumor forming BT474).

We found that trastuzumab treatment efficacy mainly depends on the immediate anti-tumorigenic cellular effect which is significantly enhanced by tumor interacting immune cells upon cotransplantion of HSC. However, trastuzumab treatment caused elevated CD44 expression on tumor cells that metastasized into the lung and liver but did not hinder tumor cell dissemination into the bone marrow. Moreover, in a number of SK-BR-3-transplanted animals disseminated CD44^high/CD24^low tumor cells lost trastuzumab sensitivity. Concerning the FcγRIIIa polymorphism, trastuzumab treatment efficiency in HTM was higher in mice with NK-cells harboring the high affinity FcγRIIIa compared to those with low affinity FcγRIIIa. In contrast, IL-15 caused the strongest NK-cell activation in heterozygous low affinity FcγRIIIa animals. Although IL-15 enhanced the trastuzumab mediated tumor defense, an unspecific immune stimulation resulted in preterm animal death due to systemic inflammation. Overall, treatment studies based on “patient-like” HTM revealed critical and adverse immune-related mechanisms which must be managed prior to clinical testing.

Expression and function of immune ligand-receptor pairs in NK cells and cancer stem cells: therapeutic implications

BACKGROUND

The interplay between the immune system and cancer cells has come to the forefront of cancer therapeutics, with novel immune blockade inhibitors being approved for the treatment of an increasing list of cancers. However, the majority of cancer patients still display or develop resistance to these promising drugs. It is possible that cancer stem cells (CSCs) are contributing to this therapeutic resistance. Although CSCs usually represent a small percentage of the total number of cancer cells, they are endowed with the ability of self-renewal and to produce differentiated progeny. Additionally, they have shown the capacity to establish tumors after transplantation to animals, even in small numbers. CSCs have also been found to be resistant to various anti-cancer therapies, including chemotherapy, radiation therapy and, more recently, immunotherapy. This is true despite the sensitivity of CSCs to lysis in vitro by natural killer (NK) cells, the main effector cells of the innate immune system. In this paper the expression of ligands specific for NK cells on CSCs, the intracellular network responsible for the expression of the NK cytotoxicity receptors, and the status of activation of NK cells in the tumor micro-environment are reviewed. The aim of this review is to highlight potential strategies for overcoming CSC immune resistance, thereby enhancing the efficacy of current and future anti-cancer therapies.

THERAPEUTIC IMPLICATIONS

NK cell activation in the tumor micro-environment through drugs neutralizing inhibitory immune receptors, and combined with other drugs harnessing the potential of the adaptive immune system, could be the most effective approach for attacking both stem cell and non-stem cell cancer populations.

Clinical significance of quantitative HER2 gene amplification as related to its predictive value in breast cancer patients in neoadjuvant setting

Background

The aims of this study were to determine whether the quantitative HER2 gene amplification level is related to the key clinicopathological features that represent the aggressiveness of breast cancer (BC) and to determine whether the quantitative HER2 gene amplification level could predict the treatment response in the subset of HER2-positive patients who received neoadjuvant targeted therapy.

Materials and methods

Patients treated with weekly cisplatin- and paclitaxel-based neoadjuvant chemotherapy, who had undergone both immunohistochemistry and the fluorescence in situ hybridization test for HER2, were included in the study (n=103). For HER2-positive patients, defined as immunohistochemistry score 3+ or fluorescence in situ hybridization ratio ≥2.0, trastuzumab was recommended with neoadjuvant chemotherapy (n=45). Pathological complete response was defined as complete pathological remission of tumor cells both in breast and axillary lymph nodes postoperation.

Results

In all patients enrolled in the study, a higher HER2 amplification level was significantly correlated with larger tumor size and the absence of ER and PR expression. In HER2-positive patients treated with neoadjuvant trastuzumab concurrent with chemotherapy, both univariate and multivariate logistic regression showed that a higher HER2/CEP17 ratio and HER2 gene copy number were associated with a higher pathological complete response rate. When calculated by receiver operating characteristics analysis, an optimal cutoff of 4.5 for the HER2/CEP17 ratio was expected to distinguish the most sensitive candidate for treatment with a combination of trastuzumab and neoadjuvant chemotherapy.

Conclusion

A higher HER2 amplification level was correlated with larger tumor size and reduced ER and PR expression, which may indicate more aggressive tumor behavior. For HER2-positive patients, the HER2/CEP17 ratio and HER2 gene copy number may be good predictive factors for concurrent neoadjuvant trastuzumab and chemotherapy.

FcγRIIA and IIIA polymorphisms predict clinical outcome of trastuzumab-treated metastatic gastric cancer

Trastuzumab has substantial antitumor activity in metastatic gastric cancer. One such mechanism by which it exerts its antitumor activity is antibody-dependent cell-mediated cytotoxicity, which has been reported to be influenced by FcγRIIA and IIIA polymorphisms. This study is the first to assess their impact on trastuzumab efficacy in patients with metastatic gastric cancer. We retrospectively examined 42 Her-2-positive patients receiving fluorouracil and platinum-based chemotherapy and trastuzumab, and 68 Her-2-negative patients receiving fluorouracil and platinum-based chemotherapy only as the first-line treatment. FcγRIIA and IIIA polymorphisms were assessed, and their associations with efficacy in both settings were analyzed. In patients treated with trastuzumab, the FcγRIIA H/H genotype was associated with significantly superior progression-free survival (PFS) (hazard ratio [HR] [95% CI]: 0.36 [0.16–0.82], adjusted HR [95% CI]: 0.18 [0.07–0.48], P=0.001). When combining FcγRIIA and IIIA polymorphisms, the FcγRIIA H/H or FcγRIIIA V/V genotype was associated with a significantly improved disease control rate (P=0.04) and PFS (HR [95% CI]: 0.29 [0.13–0.67], adjusted HR [95% CI]: 0.17 [0.07–0.45], P<0.001). As expected, no association of FcγRIIA and IIIA polymorphisms with efficacy was found in patients receiving chemotherapy only. We concluded that FcγRIIA and IIIA polymorphisms might predict disease control rate and PFS in metastatic gastric cancer patients receiving trastuzumab treatment.

Endophilin A2 promotes HER2 internalization and sensitivity to trastuzumab-based therapy in HER2-positive breast cancers

Background

Human epidermal growth factor receptor-2 (HER2) is amplified and a clinical target in a subset of human breast cancers with high rates of metastasis. Targeted therapies involving the antibody trastuzumab and trastuzumab-emtansine (T-DM1) have greatly improved outcomes for HER2-positive (HER2+) breast cancer patients. However, resistance to these targeted therapies can develop and limit their efficacy. Here, we test the involvement of the endocytic adaptor protein endophilin A2 (Endo II) in HER2+ breast cancer models, and their responses to treatments with trastuzumab and T-DM1.

Methods

Endo II expression in human breast tumors and lymph node metastases were analyzed by immunohistochemistry. Stable silencing of Endo II was achieved in HER2+ cancer cell lines (SK-BR-3 and HCC1954) to test Endo II effects on HER2 levels, localization and signaling, cell motility and tumor metastasis. The effects of Endo II silencing on the responses of HER2+ cancer cells to trastuzumab or T-DM1 treatments were tested using real-time cell motility and cytotoxicity assays.

Results

High Endo II protein expression was detected in HER2-positive tumors, and was linked to worse overall survival in node-positive HER2+ breast cancers at the mRNA level. Stable silencing of Endo II in HER2+ cell lines led to elevated levels of HER2 on the cell surface, impaired epidermal growth factor-induced HER2 internalization, and reduced signaling to downstream effector kinases Akt and Erk. Endo II silencing also led to decreased migration and invasion of HER2+ cancer cells in vitro, and impaired lung seeding following tail vein injection in mice. In addition, Endo II silencing also impaired HER2 internalization in response to Trastuzumab, and led to reduced cytotoxicity response in HER2+ cancer cells treated with T-DM1.

Conclusions

Our study provides novel evidence of Endo II function in HER2+ cancer cell motility and trafficking of HER2 that relates to effective treatments with trastuzumab or T-DM1. Thus, differential expression of Endo II may relate to sensitivity or resistance to trastuzumab-based therapies for HER2+ cancers.

Electronic supplementary material

The online version of this article (doi:10.1186/s13058-017-0900-z) contains supplementary material, which is available to authorized users.

Tyrosine kinase inhibitors as modulators of trastuzumab-mediated antibody-dependent cell-mediated cytotoxicity in breast cancer cell lines

BACKGROUND

Trastuzumab is an anti-HER2 monoclonal antibody (mAb) therapy capable of antibody-dependent cell-mediated cytotoxicity (ADCC) and used in the treatment of HER2+ breast cancer. Through interactions with FcƴR+ immune cell subsets, trastuzumab functions as a passive immunotherapy. The EGFR/HER2-targeting tyrosine kinase inhibitor (TKI) lapatinib and the next generation TKIs afatinib and neratinib, can alter HER2 levels, potentially modulating the ADCC response to trastuzumab. Using LDH-release assays, we investigated the impact of antigen modulation, assay duration and peripheral blood mononuclear cell (PBMC) activity on trastuzumab-mediated ADCC in breast cancer models of maximal (SKBR3) and minimal (MCF-7) target antigen expression to determine if modulating the ADCC response to trastuzumab using TKIs may be a viable approach for enhancing tumor immune reactivity.

METHODS

HER2 levels were determined in lapatinib, afatinib and neratinib-treated SKBR3 and MCF-7 using high content analysis (HCA). Trastuzumab-mediated ADCC was assessed following treatment with TKIs utilising a colorimetric LDH release-based protocol at 4 and 12h timepoints. PBMC activity was assessed against non-MHC-restricted K562 cells. A flow cytometry-based method (CFSE/7-AAD) was also used to measure trastuzumab-mediated ADCC in medium-treated SKBR3 and MCF-7.

RESULTS

HER2 antigen levels were significantly altered by the three TKIs in both cell line models. The TKIs significantly reduced LDH levels directly in SKBR3 cells but not MCF-7. Lapatinib and neratinib augment trastuzumab-related ADCC in SKBR3 but the effect was not consistent with antigen expression levels and was dependent on volunteer PBMC activity (vs. K562). A 12h assay timepoint produced more consistent results. Trastuzumab-mediated ADCC (PBMC:target cell ratio of 10:1) was measured at 7.6±4.7% (T12) by LDH assay and 19±3.2 % (T12) using the flow cytometry-based method in the antigen-low model MCF-7.

CONCLUSIONS

In the presence of effector cells with high cytotoxic capacity, TKIs have the ability to augment the passive immunotherapeutic potential of trastuzumab in SKBR3, a model of HER2+ breast cancer. ADCC levels detected by LDH release assays are extremely low in MCF-7; the flow cytometry-based CFSE/7-AAD method is more sensitive and consistent for the determination of ADCC in HER2-low models.

Elevated basal antibody-dependent cell-mediated cytotoxicity (ADCC) and high epidermal growth factor receptor (EGFR) expression predict favourable outcome in patients with locally advanced head and neck cancer treated with cetuximab and radiotherapy

BACKGROUND

Antibody-dependent cell-mediated cytotoxicity (ADCC) may contribute to the antitumor activity of cetuximab. However, the extent of this contribution is unclear. In this study, we investigated the impact of baseline ADCC on the outcome of patients with locally advanced squamous cell carcinoma treated with cetuximab and radiotherapy.

METHODS

We determined baseline ADCC in 28 patients treated with cetuximab and radiotherapy and in 15 patients treated with chemoradiation. We linked the values observed with complete response and with overall survival. We also considered the role of epidermal growth factor receptor (EGFR) expression and studied the combined effect of EGFR and ADCC.

RESULTS

We observed a wide range of baseline values of ADCC. Complete response did not correlate with either ADCC or EGFR expression. However, when ADCC and EGFR were considered together using a mixed score, they significantly correlated with achieving a complete response (p = 0.04). High baseline ADCC significantly correlated with outcome compared to low (p = 0.03), but not in patients treated without cetuximab. Patients showing high baseline levels of both ADCC and EGFR3+ achieved the best outcome compared to the others (p = 0.02).

CONCLUSIONS

In this study, patients treated with cetuximab and radiotherapy, showing high baseline of both ADCC and EGFR3+, have significant higher probability of achieving a complete response and a long overall survival compared to the others.

Drifts in ADCC-related quality attributes of Herceptin®: Impact on development of a trastuzumab biosimilar

A biosimilar product needs to demonstrate biosimilarity to the originator reference product, and the quality profile of the latter should be monitored throughout the period of the biosimilar's development to match the quality attributes of the 2 products that relate to efficacy and safety. For the development of a biosimilar version of trastuzumab, the reference product, Herceptin®, was extensively characterized for the main physicochemical and biologic properties by standard or state-of-the-art analytical methods, using multiple lots expiring between March 2015 and December 2019. For lots with expiry dates up to July 2018, a high degree of consistency was observed for all the tested properties. However, among the lots expiring in August 2018 or later, a downward drift was observed in %afucose (G0+G1+G2). Furthermore, the upward drift of %high mannose (M5+M6) was observed in the lots with expiry dates from June 2019 to December 2019. As a result, the combination of %afucose and %high mannose showed 2 marked drifts in the lots with expiry dates from August 2018 to December 2019, which was supported by the similar trend of biologic data, such as FcγRIIIa binding and antibody-dependent cell-mediated cytotoxicity (ADCC) activity. Considering that ADCC is one of the clinically relevant mechanisms of action for trastuzumab, the levels of %afucose and %high mannose should be tightly monitored as critical quality attributes for biosimilar development of trastuzumab.

Effect of Fu-Zheng-Xiao-Liu Granules on Expression of Human Epidermal Growth Factor Receptor 2 (HER-2) and Proliferation and Apoptosis of Breast Cancer Cell Line SKBR-3

Background

Previous research showed that granulized Fu-Zheng-Xiao-Liu has a significant effect on breast cancer. However, it remains unclear whether HER-2 plays a role in this anti-cancer effect.

Material/Methods

Serum of male SD rats administered Fu-Zheng-Xiao-Liu granules (SF) was prepared and used to treat HER-2 positive breast cancer cell line SKBR-3. PBS and herceptin were used as negative and positive controls, respectively. MTT was used to detect the proliferation of SKBR-3 cells. Flow cytometry was used to measure the apoptosis of SKBR-3 cells. Western blot and immunofluorescence were used to measure the expression change of HER-2.

Results

Serum of male SD rats administered Fu-Zheng-Xiao-Liu granules had significantly reduced HER-2 expression at both mRNA level and protein level, significantly inhibited proliferation of SKBR-3 cells, and significantly increased apoptosis of SKBR-3 cells, compared to that of the blank control group or serum control group.

Conclusions

Fu-Zheng-Xiao-Liu granules affect proliferation and apoptosis through inhibition of HER-2 transcription and translation, providing an experimental basis for further study of the mechanism by which Fu-Zheng-Xiao-Liu granules affect breast cancer.

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.

Activity of 8F4, a T-cell receptor-like anti-PR1/HLA-A2 antibody, against primary human AML in vivo

The PR1 peptide, derived from the leukemia-associated antigens proteinase 3 and neutrophil elastase, is overexpressed on HLA-A2 in acute myeloid leukemia (AML). We developed a high affinity T cell receptor-like murine monoclonal antibody, 8F4, which binds to the PR1/HLA-A2 complex, mediates lysis of AML, and inhibits leukemia colony formation. Here, we explored whether 8F4 was active in vivo against chemotherapy-resistant AML, including secondary AML. In a screening model, co-incubation of AML with 8F4 ex vivo prevented engraftment of all tested AML subtypes in immunodeficient NSG mice. In a treatment model of established human AML, administration of 8F4 significantly reduced or eliminated AML xenografts and extended survival compared with isotype antibody-treated mice. Moreover, in secondary transfer experiments, mice inoculated with bone marrow from 8F4-treated mice showed no evidence of AML engraftment, supporting possible activity of 8F4 against the subset of AML with self-renewing potential. Our data provide evidence that 8F4 antibody is highly active in AML, including chemotherapy-resistant disease, supporting its potential use as a therapeutic agent in patients with AML.