Lipoplex mediated silencing of membrane regulators (CD46, CD55 and CD59) enhances complement-dependent anti-tumor activity of trastuzumab and pertuzumab

Lipoplexes' Structure, Preparation, and Role in Managing Different Diseases

Lipid-based vectors are becoming promising alternatives to traditional therapies over the last 2 decades specially for managing life-threatening diseases like cancer. Cationic lipids are the most prevalent non-viral vectors utilized in gene delivery. The increasing number of clinical trials about lipoplex-based gene therapy demonstrates their potential as well-established technology that can provide robust gene transfection. In this regard, this review will summarize this important point. These vectors however have a modest transfection efficiency. This limitation can be partly addressed by using functional lipids that provide a plethora of options for investigating nucleic acid-lipid interactions as well as in vitro and in vivo nucleic acid delivery for biomedical applications. Despite their lower gene transfer efficiency, lipid-based vectors such as lipoplexes have several advantages over viral ones: they are less toxic and immunogenic, can be targeted, and are simple to produce on a large scale. Researchers are actively investigating the parameters that are essential for an effective lipoplex delivery method. These include factors that influence the structure, stability, internalization, and transfection of the lipoplex. Thorough understanding of the design principles will enable synthesis of customized lipoplex formulations for life-saving therapy.

Informed by Cancer Stem Cells of Solid Tumors: Advances in Treatments Targeting Tumor-Promoting Factors and Pathways

Cancer stem cells (CSCs) represent a subpopulation within tumors that promote cancer progression, metastasis, and recurrence due to their self-renewal capacity and resistance to conventional therapies. CSC-specific markers and signaling pathways highly active in CSCs have emerged as a promising strategy for improving patient outcomes. This review provides a comprehensive overview of the therapeutic targets associated with CSCs of solid tumors across various cancer types, including key molecular markers aldehyde dehydrogenases, CD44, epithelial cellular adhesion molecule, and CD133 and signaling pathways such as Wnt/β-catenin, Notch, and Sonic Hedgehog. We discuss a wide array of therapeutic modalities ranging from targeted antibodies, small molecule inhibitors, and near-infrared photoimmunotherapy to advanced genetic approaches like RNA interference, CRISPR/Cas9 technology, aptamers, antisense oligonucleotides, chimeric antigen receptor (CAR) T cells, CAR natural killer cells, bispecific T cell engagers, immunotoxins, drug-antibody conjugates, therapeutic peptides, and dendritic cell vaccines. This review spans developments from preclinical investigations to ongoing clinical trials, highlighting the innovative targeting strategies that have been informed by CSC-associated pathways and molecules to overcome therapeutic resistance. We aim to provide insights into the potential of these therapies to revolutionize cancer treatment, underscoring the critical need for a multi-faceted approach in the battle against cancer. This comprehensive analysis demonstrates how advances made in the CSC field have informed significant developments in novel targeted therapeutic approaches, with the ultimate goal of achieving more effective and durable responses in cancer patients.

Molecular Targeting of the Human Epidermal Growth Factor Receptor-2 (HER2) Genes across Various Cancers

Human epidermal growth factor receptor 2 (HER2) belongs to the ErbB family, a group of four transmembrane glycoproteins with tyrosine kinase activity, all structurally related to epidermal growth factor receptor (EGFR). These tyrosine kinases are involved in the transmission of cellular signals controlling normal cell growth and differentiation. If this transmission goes awry, it can lead to dysregulated growth of the cell. HER2 specifically can be implicated in the pathogenesis of at least eight malignancies. HER2 positivity quickly became a well-characterized indicator of aggressiveness and poor prognosis, with high rates of disease progression and mortality. After realizing the implication of HER2, it first became investigated as a target for treatment in breast cancer, and later expanded to areas of research in other cancer types. To this day, the most therapeutic advancements of anti-HER2 therapy have been in breast cancer; however, there have been strong advancements made in the incorporation of anti-HER2 therapy in other cancer types as well. This comprehensive review dissects HER2 to its core, incorporating the most up to date information. The topics touched upon are discussed in detail and up to 200 published sources from the most highly recognized journals have been integrated. The importance of knowing about HER2 is exemplified by the groundbreaking advancements that have been made, and the change in treatment plans it has brought to the oncological world in the last twenty years. Since its groundbreaking discovery there have been significant breakthroughs in knowledge regarding the actual receptor, the receptors biology, its mechanism of action, and advancements in tests to detect HER2 and significant strides on how to best incorporate targeted treatment. Due to the success of this field thus far, the review concludes by discussing the future of novel anti-HER2 therapy currently in development that everyone should be aware of.

Revolutionizing cancer immunotherapy: unleashing the potential of bispecific antibodies for targeted treatment

Recent progressions in immunotherapy have transformed cancer treatment, providing a promising strategy that activates the immune system of the patient to find and eliminate cancerous cells. Bispecific antibodies, which engage two separate antigens or one antigen with two distinct epitopes, are of tremendous concern in immunotherapy. The bi-targeting idea enabled by bispecific antibodies (BsAbs) is especially attractive from a medical standpoint since most diseases are complex, involving several receptors, ligands, and signaling pathways. Several research look into the processes in which BsAbs identify different cancer targets such angiogenesis, reproduction, metastasis, and immune regulation. By rerouting cells or altering other pathways, the bispecific proteins perform effector activities in addition to those of natural antibodies. This opens up a wide range of clinical applications and helps patients with resistant tumors respond better to medication. Yet, further study is necessary to identify the best conditions where to use these medications for treating tumor, their appropriate combination partners, and methods to reduce toxicity. In this review, we provide insights into the BsAb format classification based on their composition and symmetry, as well as the delivery mode, focus on the action mechanism of the molecule, and discuss the challenges and future perspectives in BsAb development.

Unlocking the Power of Complement-Dependent Cytotoxicity: Engineering Strategies for the Development of Potent Therapeutic Antibodies for Cancer Treatments

The complement system is a crucial part of the innate immune response, providing defense against invading pathogens and cancer cells. Recently, it has become evident that the complement system plays a significant role in anticancer activities, particularly through complement-dependent cytotoxicity (CDC), alongside antibody-dependent cell-mediated cytotoxicity (ADCC) and antibody-dependent cell-mediated phagocytosis (ADCP). With the discovery of new roles for serum complement molecules in the human immune system, various approaches are being pursued to develop CDC-enhanced antibody therapeutics. In this review, we focus on successful antibody engineering strategies for enhancing CDC, analyzing the lessons learned and the limitations of each approach. Furthermore, we outline potential pathways for the development of antibody therapeutics specifically aimed at enhancing CDC for superior therapeutic efficacy in the future.

High FOXA1 levels induce ER transcriptional reprogramming, a pro-metastatic secretome, and metastasis in endocrine-resistant breast cancer

Aberrant activation of the forkhead protein FOXA1 is observed in advanced hormone-related cancers. However, the key mediators of high FOXA1 signaling remain elusive. We demonstrate that ectopic high FOXA1 (H-FOXA1) expression promotes estrogen receptor-positive (ER+) breast cancer (BC) metastasis in a xenograft mouse model. Mechanistically, H-FOXA1 reprograms ER-chromatin binding to elicit a core gene signature (CGS) enriched in ER+ endocrine-resistant (EndoR) cells. We identify Secretome14, a CGS subset encoding ER-dependent cancer secretory proteins, as a strong predictor for poor outcomes of ER+ BC. It is elevated in ER+ metastases vs. primary tumors, irrespective of ESR1 mutations. Genomic ER binding near Secretome14 genes is also increased in mutant ER-expressing or mitogen-treated ER+ BC cells and in ER+ metastatic vs. primary tumors, suggesting a convergent pathway including high growth factor receptor signaling in activating pro-metastatic secretome genes. Our findings uncover H-FOXA1-induced ER reprogramming that drives EndoR and metastasis partly via an H-FOXA1/ER-dependent secretome.

An anti-HER2 biparatopic antibody that induces unique HER2 clustering and complement-dependent cytotoxicity

Human epidermal growth factor receptor 2 (HER2) is a receptor tyrosine kinase that plays an oncogenic role in breast, gastric and other solid tumors. However, anti-HER2 therapies are only currently approved for the treatment of breast and gastric/gastric esophageal junction cancers and treatment resistance remains a problem. Here, we engineer an anti-HER2 IgG1 bispecific, biparatopic antibody (Ab), zanidatamab, with unique and enhanced functionalities compared to both trastuzumab and the combination of trastuzumab plus pertuzumab (tras + pert). Zanidatamab binds adjacent HER2 molecules in trans and initiates distinct HER2 reorganization, as shown by polarized cell surface HER2 caps and large HER2 clusters, not observed with trastuzumab or tras + pert. Moreover, zanidatamab, but not trastuzumab nor tras + pert, elicit potent complement-dependent cytotoxicity (CDC) against high HER2-expressing tumor cells in vitro. Zanidatamab also mediates HER2 internalization and downregulation, inhibition of both cell signaling and tumor growth, antibody-dependent cellular cytotoxicity (ADCC) and phagocytosis (ADCP), and also shows superior in vivo antitumor activity compared to tras + pert in a HER2-expressing xenograft model. Collectively, we show that zanidatamab has multiple and distinct mechanisms of action derived from the structural effects of biparatopic HER2 engagement.

miR-132-3p regulates antibody-mediated complement-dependent cytotoxicity in colon cancer cells by directly targeting CD55

The overexpression of membrane-bound complement regulatory proteins (mCRPs) on tumour cells helps them survive complement attacks by suppressing antibody-mediated complement-dependent cytotoxicity (CDC). Consequently, mCRP overexpression limits monoclonal antibody drug immune efficacy. CD55, an mCRP, plays an important role in inhibiting antibody-mediated CDC. However, the mechanisms regulating CD55 expression in tumour cells remain unclear. Here, the aim was to explore CD55-targeting miRNAs. We previously constructed an in vitro model comprising cancer cell lines expressing α-gal and serum containing natural antibodies against α-gal and complement. This was used to simulate antibody-mediated CDC in colon cancer cells. We screened microRNAs that directly target CD55 using LoVo and Ls-174T colon cell lines, which express CD55 at low and high levels, respectively. miR-132-3p expression was dramatically lower in Ls-174T cells than in LoVo cells. miR-132-3p overexpression or inhibition transcriptionally regulated CD55 expression by specifically targeting its mRNA 3'-untranslated regions. Further, miR-132-3p modulation regulated colon cancer cell sensitivity to antibody-mediated CDC through C5a release and C5b-9 deposition. Moreover, miR-132-3p expression was significantly reduced, whereas CD55 expression was increased, in colon cancer tissues compared to levels in adjacent normal tissues. CD55 protein levels were negatively correlated with miR-132-3p expression in colon cancer tissues. Our results indicate that miR-132-3p regulates colon cancer cell sensitivity to antibody-mediated CDC by directly targeting CD55. In addition, incubating the LoVo human tumour cell line, stably transfected with the xenoantigen α-gal, with human serum containing natural antibodies comprises a stable and cheap in vitro model to explore the mechanisms underlying antibody-mediated CDC.

Targeting HER2-positive breast cancer: advances and future directions

The long-sought discovery of HER2 as an actionable and highly sensitive therapeutic target was a major breakthrough for the treatment of highly aggressive HER2-positive breast cancer, leading to approval of the first HER2-targeted drug - the monoclonal antibody trastuzumab - almost 25 years ago. Since then, progress has been swift and the impressive clinical activity across multiple trials with monoclonal antibodies, tyrosine kinase inhibitors and antibody-drug conjugates that target HER2 has spawned extensive efforts to develop newer platforms and more targeted therapies. This Review discusses the current standards of care for HER2-positive breast cancer, mechanisms of resistance to HER2-targeted therapy and new therapeutic approaches and agents, including strategies to harness the immune system.

Knockdown of membrane-bound complement regulatory proteins suppresses colon cancer growth in mice through inducing tumor cell apoptosis

CD46, CD55 and CD59 are membrane-bound complement regulatory proteins (mCRPs) and highly expressed in many tumor tissues. Our analysis by RNA sequencing and qRT-PCR revealed that the expression of mCRPs was significantly elevated in cancer tissues of 15 patients with colon cancer. To further investigate the role of mCRPs in the development of colon cancer, we suppressed the expression of mCRPs by CD46-shRNA, CD55-shRNA and CD59-shRNA in colon cancer cell lines, SW620 and HT-29 cells. The results indicated that CD46-shRNA, CD55-shRNA and CD59-shRNA effectively reduced the expression of mCRPs, accompanied with the increased LDH release and the percentage of Annexin V + 7-AAD- early phase of apoptotic cells. The similar cytotoxic effects were also observed in the cells treated with CD46 neutralizing antibody (aCD46), associated with the increased C5b-9 deposition, cleaved caspase-3 and Bax expression in the treated cells. The cytotoxic effects by mCRPs knock-down were potentiated in the cells co-treated with doxorubicin (Dox). In addition, STAT3, STAT6, and p38 MAPK inhibitors, including C188-9, AS1517499 and SB203580 effectively reduced the expression of CD46 in the treated colon cells, associated with increased cell apoptosis and LDH release. Further study with mouse model revealed that mCRPs knockdown by mCRPs-shRNA significantly reduced colon cancer growth, associated with increased expression of Bax, cleaved caspase-3 and C5b-9 deposition, but reduced expression of Bcl-2, IL-6 and IL-1beta in tumor tissues of nude mice transplanted with SW620 cells. Thereby, mCRPs expression in human colon cancer cells were upregulated by STAT3/STAT6/p38 MAPK signaling and mCRPs knockdown reduced colon cancer growth in mice through inducing tumor cell apoptosis.

CD46 protects the bladder cancer cells from cetuximab-mediated cytotoxicity

Epidermal growth factor receptor (EGFR) is an effective target for those patients with metastatic colorectal cancers that retain the wild-type RAS gene. However, its efficacy in many cancers, including bladder cancer, is unclear. Here, we studied the in vitro effects of cetuximab monoclonal antibodies (mAbs) targeting EGFR on the bladder cancer cells and role of CD46. Cetuximab was found to inhibit the growth of both colon and bladder cancer cell lines. Furthermore, cetuximab treatment inhibited AKT and ERK phosphorylation in the bladder cancer cells and reduced the expression of CD46 membrane-bound proteins. Restoration of CD46 expression protected the bladder cancer cells from cetuximab-mediated inhibition of AKT and ERK phosphorylation. We hypothesized that CD46 provides protection to the bladder cancer cells against mAb therapies. Bladder cancer cells were also susceptible to cetuximab-mediated immunologic anti-tumor effects. Further, cetuximab enhanced the cell killing by activating both antibody-dependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC) in bladder cancer cells. Restoration of CD46 expression protected the cells from both CDC and ADCC induced by cetuximab. Together, CD46 exhibited a cancer-protective effect against both direct (by involvement of PBMC or complement) and indirect cytotoxic activity by cetuximab in bladder cancer cells. Considering its clinical importance, CD46 could be an important link in the action mechanism of ADCC and CDC intercommunication and may be used for the development of novel therapeutic strategies.

Resistance to Trastuzumab

Simple Summary

Trastuzumab is a humanized antibody that has significantly improved the management and treatment outcomes of patients with cancers that overexpress HER2. Many research groups, both in academia and industry, have contributed towards understanding the various mechanisms engaged by trastuzumab to mediate its anti-tumor effects. Nevertheless, data from several clinical studies have indicated that a significant proportion of patients exhibit primary or acquired resistance to trastuzumab therapy. In this article, we discuss underlying mechanisms that contribute towards to resistance. Furthermore, we discuss the potential strategies to overcome some of the mechanisms of resistance to enhance the therapeutic efficacy of trastuzumab and other therapies based on it.

Abstract

One of the most impactful biologics for the treatment of breast cancer is the humanized monoclonal antibody, trastuzumab, which specifically recognizes the HER2/neu (HER2) protein encoded by the ERBB2 gene. Useful for both advanced and early breast cancers, trastuzumab has multiple mechanisms of action. Classical mechanisms attributed to trastuzumab action include cell cycle arrest, induction of apoptosis, and antibody-dependent cell-mediated cytotoxicity (ADCC). Recent studies have identified the role of the adaptive immune system in the clinical actions of trastuzumab. Despite the multiple mechanisms of action, many patients demonstrate resistance, primary or adaptive. Newly identified molecular and cellular mechanisms of trastuzumab resistance include induction of immune suppression, vascular mimicry, generation of breast cancer stem cells, deregulation of long non-coding RNAs, and metabolic escape. These newly identified mechanisms of resistance are discussed in detail in this review, particularly considering how they may lead to the development of well-rationalized, patient-tailored combinations that improve patient survival.

Immunological Landscape of HER-2 Positive Breast Cancer

Understanding the biological aspects of immune response in HER2+ breast cancer is crucial to implementing new treatment strategies in these patients. It is well known that anti-HER2 therapy has improved survival in this population, yet a substantial percentage may relapse, creating a need within the scientific community to uncover resistance mechanisms and determine how to overcome them. This systematic review indicates the immunological mechanisms through which trastuzumab and other agents target cancer cells, also outlining the main trials studying immune checkpoint blockade. Finally, we report on anti-HER2 vaccines and include a figure exemplifying their mechanisms of action.

Development and Characterization of an Anti-Cancer Monoclonal Antibody for Treatment of Human Carcinomas

NEO-201 is an IgG1 humanized monoclonal antibody (mAb) that binds to tumor-associated variants of carcinoembryonic antigen-related cell adhesion molecule (CEACAM)-5 and CEACAM-6. NEO-201 reacts to colon, ovarian, pancreatic, non-small cell lung, head and neck, cervical, uterine and breast cancers, but is not reactive against most normal tissues. NEO-201 can kill tumor cells via antibody-dependent cell-mediated cytotoxicity (ADCC) and complement dependent cytotoxicity (CDC) to directly kill tumor cells expressing its target. We explored indirect mechanisms of its action that may enhance immune tumor killing. NEO-201 can block the interaction between CEACAM-5 expressed on tumor cells and CEACAM-1 expressed on natural killer (NK) cells to reverse CEACAM-1-dependent inhibition of NK cytotoxicity. Previous studies have demonstrated safety/tolerability in non-human primates, and in a first in human phase 1 clinical trial at the National Cancer Institute (NCI). In addition, preclinical studies have demonstrated that NEO-201 can bind to human regulatory T (Treg) cells. The specificity of NEO-201 in recognizing suppressive Treg cells provides the basis for combination cancer immunotherapy with checkpoint inhibitors targeting the PD-1/PD-L1 pathway.

NEAT1: Culprit lncRNA linking PIG-C, MSLN, and CD80 in triple-negative breast cancer

BACKGROUND

Breast cancer (BC) is the most common cancer in women. Despite the effectiveness of conventional therapies, they cause detrimental side effects. Glycosyl-Phosphatidyl-Inositol (GPI) pathway is a conserved pathway that culminates in the generation of GPI anchored proteins (GPI-AP). Phosphatidyl-Inositol-Glycan Biosynthesis Class C (PIG-C) is the first step in GPI pathway and upon its overexpression, Mesothelin (MSLN); an oncogenic GPI-AP, expression is induced. Therefore, blocking GPI pathway is a potential therapy through which multiple pathways can be rectified. Recombinant GPI-CD80 proved to be a potent immunostimulatory protein and currently being evaluated as tumor vaccine. In fact, CD80 is a unique immunomodulator that binds to CD28, CTLA-4 and PD-L1. Furthermore, research advancement showed that non-coding RNAs (ncRNAs) are key epigenetic modulators. Therefore, epigenetic tuning of GPI-APs remains an unexplored area. This study aims at investigating the potential role of ncRNAs in regulating MSLN, PIG-C and CD80 in BC.

METHODS

Potential ncRNAs were filtered by bioinformatics algorithms. MDA-MB-231 cells were transfected with RNA oligonucleotides. Surface CD80 and MSLN were assessed by FACS and immunofluorescence. Gene expression was tested by q-PCR.

RESULTS

PIG-C gene was overexpressed in TNBC and its manipulation altered MSLN surface level. Aligning with bioinformatics analysis, miR-2355 manipulated PIG-C and MSLN expression, while miR-455 manipulated CD80 expression. NEAT1 sponged both miRNAs. Paradoxically, NEAT1 lowered PIG-C gene expression while increased MSLN gene expression.

CONCLUSION

This study unravels novel immunotherapeutic targets for TNBC. NEAT1 is potential immunomodulator by sponging several miRNAs. Finally, this study highlights GPI pathway applications, therefore integrating epigenetics, post-translational modifications and immunomodulation.

Trastuzumab/Pertuzumab combination therapy stimulates anti-tumor responses through complement-dependent cytotoxicity and phagocytosis

Standard-of-care treatment for advanced HER2+ breast cancers (BC) is comprised of two HER2-specific monoclonal antibodies (mAb), Trastuzumab (T) and Pertuzumab (P) with chemotherapy. While this combination (T+P) is highly effective, its synergistic mechanism of action (MOA) is not completely known. Initial studies had demonstrated that Pertuzumab suppressed HER2 hetero-dimerization as the potential therapeutic MOA, thus the improved outcome associated with the T+P combination MOA compared to Trastuzumab alone has been widely reported as being due to Pertuzumab-mediated suppression of HER2 signaling in combination with Trastuzumab-mediated induction of anti-tumor immunity. Unraveling this MOA may be critical to extend this combination strategy to other antigens or other cancers, as well as improving this current treatment modality. Using novel murine and human versions of Pertuzumab, we found it induced both Antibody-Dependent-Cellular-Phagocytosis (ADCP) by tumor-associated macrophages and suppression of HER2 oncogenic signaling. Most significantly, we identified that only T+P combination therapy, but not when either antibody used in isolation, allows for the activation of the classical complement pathway, resulting in both direct complement-dependent cytotoxicity (CDC) as well as complement-dependent cellular phagocytosis (CDCP) of HER2+ BC cells. Notably, we show that tumor expression of C1q was positively associated with survival outcome in HER2+ BC patients, whereas expression of complement regulators CD55 and CD59 were inversely correlated, suggesting the importance of complement activity in clinical outcomes. Accordingly, inhibition of C1 activity in mice abolished the synergistic therapeutic activity of T+P therapy, whereas knockdown of CD55 and CD59 expression enhanced T+P efficacy. In summary, our study identifies classical complement activation as a significant anti-tumor MOA for T+P therapy that may be functionally enhanced to augment therapeutic efficacy in the clinic.

Current and Future Therapies for Immunogenic Cell Death and Related Molecules to Potentially Cure Primary Breast Cancer

Simple Summary

How a cure for primary breast cancer after (neo)adjuvant therapy can be achieved at the molecular level remains unclear. Immune activation by anticancer drugs may contribute to the eradication of residual tumor cells by postoperative (neo)adjuvant chemotherapy. In addition, chemotherapy-induced immunogenic cell death (ICD) may result in long-term immune activation by memory effector T cells, leading to the curing of primary breast cancer. In this review, we discuss the molecular mechanisms by which anticancer drugs induce ICD and immunogenic modifications for antitumor immunity and targeted therapy against damage-associated molecular patterns. Our aim was to gain a better understanding of how to eradicate residual tumor cells treated with anticancer drugs and cure primary breast cancer by enhancing antitumor immunity with immune checkpoint inhibitors and vaccines.

Abstract

How primary breast cancer can be cured after (neo)adjuvant therapy remains unclear at the molecular level. Immune activation by anticancer agents may contribute to residual tumor cell eradication with postsurgical (neo)adjuvant chemotherapy. Chemotherapy-induced immunogenic cell death (ICD) may result in long-term immune activation with memory effector T cells, leading to a primary breast cancer cure. Anthracycline and taxane treatments cause ICD and immunogenic modulations, resulting in the activation of antitumor immunity through damage-associated molecular patterns (DAMPs), such as adenosine triphosphate, calreticulin, high mobility group box 1, heat shock proteins 70/90, and annexin A1. This response may eradicate residual tumor cells after surgical treatment. Although DAMP release is also implicated in tumor progression, metastasis, and drug resistance, thereby representing a double-edged sword, robust immune activation by anticancer agents and the subsequent acquisition of long-term antitumor immune memory can be essential components of the primary breast cancer cure. This review discusses the molecular mechanisms by which anticancer drugs induce ICD and immunogenic modifications for antitumor immunity and targeted anti-DAMP therapy. Our aim was to improve the understanding of how to eradicate residual tumor cells treated with anticancer drugs and cure primary breast cancer by enhancing antitumor immunity with immune checkpoint inhibitors and vaccines.

Mechanisms of Therapeutic Antitumor Monoclonal Antibodies

Monoclonal antibodies (mAb) are a major component of cancer therapy. In this review, we summarize the different therapeutic mAbs that have been successfully developed against various tumor-expressed antigens and examine our current understanding of their different mechanisms of antitumor action. These mechanisms of action (MOA) largely center on the stimulation of different innate immune effector processes, which appear to be principally responsible for the efficacy of most unconjugated mAb therapies against cancer. This is evident in studies of mAbs targeting antigens for hematologic cancers, with emerging data also demonstrating the critical nature of innate immune-mediated mechanisms in the efficacy of anti-HER2 mAbs against solid HER2+ cancers. Although HER2-targeted mAbs were originally described as inhibitors of HER2-mediated signaling, multiple studies have since demonstrated these mAbs function largely through their engagement with Fc receptors to activate innate immune effector functions as well as complement activity. Next-generation mAbs are capitalizing on these MOAs through improvements to enhance Fc-activity, although regulation of these mechanisms may vary in different tumor microenvironments. In addition, novel antibody-drug conjugates have emerged as an important means to activate different MOAs. Although many unknowns remain, an improved understanding of these immunologic MOAs will be essential for the future of mAb therapy and cancer immunotherapy.

Role of Complement in Regulating Inflammation Processes in Renal and Prostate Cancers

For decades, the complement system, the central pillar of innate immune response, was recognized as a protective mechanism against cancer cells and the manipulation of complement effector functions in cancer setting offered a great opportunity to improve monoclonal antibody-based cancer immunotherapies. Similarly, cellular senescence, the process of cell cycle arrest that allow DNA and tissue repair has been traditionally thought to be able to suppress tumor progression. However, in recent years, extensive research has identified the complement system and cellular senescence as two main inducers of tumour growth in the context of chronic, persistent inflammation named inflammaging. Here, we discuss the data describing the ambivalent role of senescence in cancer with a particular focus on tumors that are strongly dependent on complement activation and can be understood by a new, senescence-related point of view: prostate cancer and renal cell carcinoma.

On-target IgG hexamerisation driven by a C-terminal IgM tail-piece fusion variant confers augmented complement activation

The majority of depleting monoclonal antibody (mAb) drugs elicit responses via Fc-FcγR and Fc-C1q interactions. Optimal C1q interaction is achieved through hexameric Fc:Fc interactions at the target cell surface. Herein is described an approach to exploit the tailpiece of the naturally multimeric IgM to augment hexamerisation of IgG. Fusion of the C-terminal tailpiece of IgM promoted spontaneous hIgG hexamer formation, resulting in enhanced C1q recruitment and complement-dependent cytotoxicity (CDC) but with off-target complement activation and reduced in-vivo efficacy. Mutation of the penultimate tailpiece cysteine to serine (C575S) ablated spontaneous hexamer formation, but facilitated reversible hexamer formation after concentration in solution. C575S mutant tailpiece antibodies displayed increased complement activity only after target binding, in-line with the concept of 'on-target hexamerisation', whilst retaining efficient in-vivo efficacy and augmented target cell killing in the lymph node. Hence, C575S-tailpiece technology represents an alternative format for promoting on-target hexamerisation and enhanced CDC.

Eupatorin Suppressed Tumor Progression and Enhanced Immunity in a 4T1 Murine Breast Cancer Model

Eupatorin is a polymethoxy flavone extracted from Orthosiphon stamineus and was reported to exhibit cytotoxic effects on several cancer cell lines. However, its effect as an anti-breast cancer agent in vivo has yet to be determined. This study aims to elucidate the potential of eupatorin as an anti-breast cancer agent in vivo using 4T1 challenged BALB/c mice model. In this article, BALB/c mice (20-22 g) challenged with 4T1 cells were treated with 5 mg/kg or 20 mg/kg eupatorin, while the untreated and healthy mice were fed with olive oil (vehicle) via oral gavage. After 28 days of experiment, the mice were sacrificed and blood was collected for serum cytokine assay, while tumors were harvested to extract RNA and protein for gene expression assay and hematoxylin-eosin staining. Organs such as spleen and lung were harvested for immune suppression and clonogenic assay, respectively. Eupatorin (20 mg/kg) was effective in delaying the tumor development and reducing metastasis to the lung compared with the untreated mice. Eupatorin (20 mg/kg) also enhanced the immunity as the population of NK1.1+ and CD8+ in the splenocytes and the serum interferon-γ were increased. Concurrently, eupatorin treatment also has downregulated the expression of pro-inflammatory and metastatic related genes (IL-1β. MMP9, TNF-α, and NF-κB). Thus, this study demonstrated that eupatorin at the highest dosage of 20 mg/kg body weight was effective in delaying the 4T1-induced breast tumor growth in the animal model.

Roles of fragment crystallizable-mediated effector functions in broadly neutralizing antibody activity against HIV

PURPOSE OF REVIEW

'Broadly neutralizing antibodies' (bNAbs), are rare HIV-specific antibodies which exhibit the atypical ability to potently neutralize diverse viral isolates. While efforts to elicit bNAbs through vaccination have yet to succeed, recent years have seen remarkable preclinical and clinical advancements of passive immunization approaches targeting both HIV prevention and cure. We focus here on the potential to build upon this success by moving beyond neutralization to additionally harness the diverse effector functionalities available to antibodies via fragment crystallizable-effector (Fc) functions.

RECENT FINDINGS

Recent studies have leveraged the ability to engineer bNAb Fc domains to either enhance or abrogate particular effector functions to demonstrate that activities such as antibody-dependent cell-mediated cytotoxicity contribute substantially to in-vivo antiviral activity. Intriguingly, recent studies in both nonhuman primates and in humans have suggested that passive bNAb infusion can lead to durable immunity by enhancing virus-specific T-cell responses through a 'vaccinal effect'.

SUMMARY

The combination of antibody engineering strategies designed to enhance effector functions, with the broad and potent antigen recognition profile of bNAbs, has the potential to give rise to powerful new therapeutics for HIV. We aim to provide a timely review of recent advances to catalyze this development.

The Complement System in Ovarian Cancer: An Underexplored Old Path

Ovarian cancer is one of the most lethal gynecological cancers. Current therapeutic strategies allow temporary control of the disease, but most patients develop resistance to treatment. Moreover, although successful in a range of solid tumors, immunotherapy has yielded only modest results in ovarian cancer. Emerging evidence underscores the relevance of the components of innate and adaptive immunity in ovarian cancer progression and response to treatment. Particularly, over the last decade, the complement system, a pillar of innate immunity, has emerged as a major regulator of the tumor microenvironment in cancer immunity. Tumor-associated complement activation may support chronic inflammation, promote an immunosuppressive microenvironment, induce angiogenesis, and activate cancer-related signaling pathways. Recent insights suggest an important role of complement effectors, such as C1q or anaphylatoxins C3a and C5a, and their receptors C3aR and C5aR1 in ovarian cancer progression. Nevertheless, the implication of these factors in different clinical contexts is still poorly understood. Detailed knowledge of the interplay between ovarian cancer cells and complement is required to develop new immunotherapy combinations and biomarkers. In this context, we discuss the possibility of targeting complement to overcome some of the hurdles encountered in the treatment of ovarian cancer.

Regulation of antibody-mediated complement-dependent cytotoxicity by modulating the intrinsic affinity and binding valency of IgG for target antigen

Complement-dependent cytotoxicity (CDC) is a potent effector mechanism, engaging both innate and adaptive immunity. Although strategies to improve the CDC activity of antibody therapeutics have primarily focused on enhancing the interaction between the antibody crystallizable fragment (Fc) and the first subcomponent of the C1 complement complex (C1q), the relative importance of intrinsic affinity and binding valency of an antibody to the target antigen is poorly understood. Here we show that antibody binding affinity to a cell surface target antigen evidently affects the extent and efficacy of antibody-mediated complement activation. We further report the fundamental role of antibody binding valency in the capacity to recruit C1q and regulate CDC. More specifically, an array of affinity-modulated variants and functionally monovalent bispecific derivatives of high-affinity anti-epidermal growth factor receptor (EGFR) and anti-human epidermal growth factor receptor 2 (HER2) therapeutic immunoglobulin Gs (IgGs), previously reported to be deficient in mediating complement activation, were tested for their ability to bind C1q by biolayer interferometry using antigen-loaded biosensors and to exert CDC against a panel of EGFR and HER2 tumor cells of various histological origins. Significantly, affinity-reduced variants or monovalent derivatives, but not their high-affinity bivalent IgG counterparts, induced near-complete cell cytotoxicity in tumor cell lines that had formerly been shown to be resistant to complement-mediated attack. Our findings suggest that monovalent target engagement may contribute to an optimal geometrical positioning of the antibody Fc to engage C1q and deploy the complement pathway.

The Role of Complement in the Mechanism of Action of Therapeutic Anti-Cancer mAbs

Unconjugated anti-cancer IgG1 monoclonal antibodies (mAbs) activate antibody-dependent cellular cytotoxicity (ADCC) by natural killer (NK) cells and antibody-dependent cellular phagocytosis (ADCP) by macrophages, and these activities are thought to be important mechanisms of action for many of these mAbs in vivo. Several mAbs also activate the classical complement pathway and promote complement-dependent cytotoxicity (CDC), although with very different levels of efficacy, depending on the mAb, the target antigen, and the tumor type. Recent studies have unraveled the various structural factors that define why some IgG1 mAbs are strong mediators of CDC, whereas others are not. The role of complement activation and membrane inhibitors expressed by tumor cells, most notably CD55 and CD59, has also been quite extensively studied, but how much these affect the resistance of tumors in vivo to IgG1 therapeutic mAbs still remains incompletely understood. Recent studies have demonstrated that complement activation has multiple effects beyond target cell lysis, affecting both innate and adaptive immunity mediated by soluble complement fragments, such as C3a and C5a, and by stimulating complement receptors expressed by immune cells, including NK cells, neutrophils, macrophages, T cells, and dendritic cells. Complement activation can enhance ADCC and ADCP and may contribute to the vaccine effect of mAbs. These different aspects of complement are also briefly reviewed in the specific context of FDA-approved therapeutic anti-cancer IgG1 mAbs.

Inflammatory Breast Cancer: Clinical Implications of Genomic Alterations and Mutational Profiling

Simple Summary

Inflammatory breast cancer (IBC) is an aggressive disease with high mortality rates. Nowadays, there is no targeted treatment for this tumor type. Based on this context, we investigated the molecular profile of this disease by using well-established methodologies (high-resolution microarray platform, targeted next-generation sequencing, and immunohistochemistry) that have proven potential to unveil cancer biomarkers. We found alterations related to IBC aggressiveness and metastasis (gains of MDM4, losses of CHL1, and high homologous recombination deficiency scores), and worse overall survival (variants in HR and mismatch repair genes). We also compared the mutational profiling of our cases with literature data, which includes both non-IBC and IBC cases, validating our findings. Overall, we describe genetic alterations with the potential to be used as prognostic or predictive biomarkers and ultimately improve IBC patients’ care.

Abstract

Inflammatory breast cancer (IBC) is a rare and aggressive type of breast cancer whose molecular basis is poorly understood. We performed a comprehensive molecular analysis of 24 IBC biopsies naïve of treatment, using a high-resolution microarray platform and targeted next-generation sequencing (105 cancer-related genes). The genes more frequently affected by gains were MYC (75%) and MDM4 (71%), while frequent losses encompassed TP53 (71%) and RB1 (58%). Increased MYC and MDM4 protein expression levels were detected in 18 cases. These genes have been related to IBC aggressiveness, and MDM4 is a potential therapeutic target in IBC. Functional enrichment analysis revealed genes associated with inflammatory regulation and immune response. High homologous recombination (HR) deficiency scores were detected in triple-negative and metastatic IBC cases. A high telomeric allelic imbalance score was found in patients having worse overall survival (OS). The mutational profiling was compared with non-IBC (TCGA, n = 250) and IBC (n = 118) from four datasets, validating our findings. Higher frequency of TP53 and BRCA2 variants were detected compared to non-IBC, while PIKC3A showed similar frequency. Variants in mismatch repair and HR genes were associated with worse OS. Our study provided a framework for improved diagnosis and therapeutic alternatives for this aggressive tumor type.

How Do mAbs Make Use of Complement to Kill Cancer Cells? The Role of Ca2

We examined the kinetics and mechanisms by which monoclonal antibodies (mAbs) utilize complement to rapidly kill targeted cancer cells. Based on results from flow cytometry, confocal microscopy and high-resolution digital imaging experiments, the general patterns which have emerged reveal cytotoxic activities mediated by substantial and lethal Ca2+ fluxes. The Ca2+ fluxes are common to the reported pathways that have been utilized by other toxins in killing nucleated cells. These reactions terminate in very high levels of cell killing, and based on these considerations, we suggest additional strategies to further enhance mAb-based targeting of cancer with complement.

Marker Identification of the Grade of Dysplasia of Intraductal Papillary Mucinous Neoplasm in Pancreatic Cyst Fluid by Quantitative Proteomic Profiling

The incidence of patients with pancreatic cystic lesions, particularly intraductal papillary mucinous neoplasm (IPMN), is increasing. Current guidelines, which primarily consider radiological features and laboratory data, have had limited success in predicting malignant IPMN. The lack of a definitive diagnostic method has led to low-risk IPMN patients undergoing unnecessary surgeries. To address this issue, we discovered IPMN marker candidates by analyzing pancreatic cystic fluid by mass spectrometry. A total of 30 cyst fluid samples, comprising IPMN dysplasia and other cystic lesions, were evaluated. Mucus was removed by brief sonication, and the resulting supernatant was subjected to filter-aided sample preparation and high-pH peptide fractionation. Subsequently, the samples were analyzed by LC-MS/MS. Using several bioinformatics tools, such as gene ontology and ingenuity pathway analysis, we detailed IPMNs at the molecular level. Among the 5834 proteins identified in our dataset, 364 proteins were differentially expressed between IPMN dysplasia. The 19 final candidates consistently increased or decreased with greater IPMN malignancy. CD55 was validated in an independent cohort by ELISA, Western blot, and IHC, and the results were consistent with the MS data. In summary, we have determined the characteristics of pancreatic cyst fluid proteins and discovered potential biomarkers for IPMN dysplasia.

Targeted Antitumor Mechanism of C-PC/CMC-CD55sp Nanospheres in HeLa Cervical Cancer Cells

In vitro studies had shown that C-Phycocyanin (C-PC) inhibited cervical cancer HeLa cells growth. We constructed C-PC/CMC-CD55sp nanospheres using C-PC, Carboxymethyl Chitosan (CMC), and CD55 ligand peptide (CD55sp) to allow for targeted antitumor effects against HeLa cells in vitro and in vivo. The characteristics of the nanospheres were determined using FTIR, electron microscopy, and laser particle size analysis. Flow cytometry, laser confocal microscopy and small animal imaging system showed the targeting of C-PC/CMC-CD55sp nanospheres on HeLa cells. Subsequently, the proliferation and apoptosis were analyzed by Cell Counting Kit-8 (CCK-8), flow cytometry, TUNEL assay and electron microscopy. The expression of the apoptosis-related protein was determined using western blot. The stainings of Hematoxylin and Eosin (HE) were employed to evaluate the cell condition of tumor tissue sections. The cytokines in the blood in tumor-bearing nude mice was determined using ELISA. These results showed that C-PC/CMC-CD55sp nanospheres were successfully constructed and targeted HeLa cells. The constructed nanospheres were more effective than C-PC alone in inhibiting the proliferation and inducing apoptosis in HeLa cells. We also found that C-PC/CMC-CD55sp nanospheres had a significant inhibitory effect on the expression of antiapoptotic protein Bcl-2 and a promotion on the transformation of caspase 3 to cleaved caspase 3. C-PC/CMC-CD55sp nanospheres played an important role in tumor suppression, reduced the expression TGF-β, and increased IL-6 and TNF-α. This study demonstrates that the constructed new C-PC/CMC-CD55sp nanospheres exerted targeted antitumor effects in vivo and in vitro which provided a novel idea for application of C-PC, and provided experimental basis for comprehensive targeted treatment of tumors.

Deciphering the Intricate Roles of Radiation Therapy and Complement Activation in Cancer

The complement system consists of a collection of serum proteins that act as the main frontline effector arm of the innate immune system. Activation of complement can occur through 3 individual induction pathways: the classical, mannose-binding lectin, and alternative pathways. Activation results in opsonization, recruitment of effector cells through potent immune mediators known as anaphylatoxins, and cell lysis via the formation of the membrane attack complex. Stringent regulation of complement is required to protect against inappropriate activation of the complement cascade. Complement activation within the tumor microenvironment does not increase antitumoral action; instead, it enhances tumor growth and disease progression. Radiation therapy (RT) is a staple in the treatment of malignancies and controls tumor growth through direct DNA damage and the influx of immune cells, reshaping the makeup of the tumor microenvironment. The relationship between RT and complement activity in the tumor microenvironment is uncertain at best. The following review will focus on the complex interaction of complement activation and the immune-modulating effects of RT and the overall effect on tumor progression. The clinical implications of complement activation in cancer and the use of therapeutics and potential biomarkers will also be covered.

Drivers and regulators of humoral innate immune responses to infection and cancer

The complement cascade consists of cell bound and serum proteins acting together to protect the host from pathogens, remove cancerous cells and effectively links innate and adaptive immune responses. Despite its usefulness in microbial neutralization and clearance of cancerous cells, excessive complement activation causes an immune imbalance and tissue damage in the host. Hence, a series of complement regulatory proteins present at a higher concentration in blood plasma and on cell surfaces tightly regulate the cascade. The complement cascade can be initiated by B-1 B cell production of natural antibodies. Natural antibodies arise spontaneously without any known exogenous antigenic or microbial stimulus and protect against invading pathogens, clear apoptotic cells, provide tissue homeostasis, and modulate adaptive immune functions. Natural IgM antibodies recognize microbial and cancer antigens and serve as an activator of complement mediated lysis. This review will discuss advances in complement activation and regulation in bacterial and viral infections, and cancer. We will also explore the crosstalk of natural antibodies with bacterial populations and cancer.

Pertuzumab in the treatment of HER2-positive breast cancer: an evidence-based review of its safety, efficacy, and place in therapy

Human epidermal growth factor receptor 2 (HER2)-positive breast cancer is a distinct subset of breast cancer that results from overexpression of HER2 protein. Pertuzumab-a recombinant humanized monoclonal antibody that binds to the extracellular dimerization domain II of HER2-was recently approved for adjuvant therapy and neoadjuvant therapy of HER2-positive early breast cancer. As pertuzumab and trastuzumab bind to different domains of the extracellular dimerization domain of HER2, a combination therapy of pertuzumab and trastuzumab is beneficial for the treatment of metastatic cancer, advanced local cancer, or early cancer by dual HER2 blockage. Many clinical trials have been performed using pertuzumab for breast cancer patients; these include the CLEOPATRA trial for palliative therapy, the APHINITY trial for adjuvant therapy, and the NeoSphere and the TRYPHAENA trials for neoadjuvant therapy. These trials revealed pertuzumab to be a safe and effective drug regardless of the patient age and hormone receptor status. Notably, pertuzumab use was associated with severe cardiac toxicity in some cases; however, the risk of pertuzumab-induced cardiac dysfunction was low. The most common adverse effect associated with pertuzumab-use was diarrhea, but most cases were not severe. Several different chemotherapeutic agents have been investigated to determine optimal chemotherapeutic combinations for dual HER2 blockage. Some exploratory analyses indicate that pertuzumab treatment offered little benefit to patients with node-negative and small primary tumors; pertuzumab treatment was also found not be cost-effective. Further research will reveal the appropriate usage of pertuzumab for treating a subset of eligible patients.

FHR4-based immunoconjugates direct complement-dependent cytotoxicity and phagocytosis towards HER2-positive cancer cells

Directing selective complement activation towards tumour cells is an attractive strategy to promote their elimination. In the present work, we have generated heteromultimeric immunoconjugates that selectively activate the complement alternative pathway (AP) on tumour cells. We used the C4b‐binding protein C‐terminal‐α‐/β‐chain scaffold for multimerisation to generate heteromultimeric immunoconjugates displaying (a) a multivalent‐positive regulator of the AP, the human factor H‐related protein 4 (FHR4) with; (b) a multivalent targeting function directed against erbB2 (HER2); and (c) a monovalent enhanced GFP tracking function. Two distinct V_HH targeting two different epitopes against HER2 and competing either with trastuzumab or with pertuzumab‐recognising epitopes [V_HH(T) or V_HH(P)], respectively, were used as HER2 anchoring moieties. Optimised high‐FHR4 valence heteromultimeric immunoconjugates [FHR4/V_HH(T) or FHR4/V_HH(P)] were selected by sequential cell cloning and a selective multistep His‐Trap purification. Optimised FHR4‐heteromultimeric immunoconjugates successfully overcame FH‐mediated complement inhibition threshold, causing increased C3b deposition on SK‐OV‐3, BT474 and SK‐BR3 tumour cells, and increased formation of lytic membrane attack complex densities and complement‐dependent cytotoxicity (CDC). CDC varies according to the pattern expression and densities of membrane‐anchored complement regulatory proteins on tumour cell surfaces. In addition, opsonised BT474 tumour cells were efficiently phagocytosed by macrophages through complement‐dependent cell‐mediated cytotoxicity. We showed that the degree of FHR4‐multivalency within the multimeric immunoconjugates was the key element to efficiently compete and deregulate FH and FH‐mediated convertase decay locally on tumour cell surface. FHR4 can thus represent a novel therapeutic molecule, when expressed as a multimeric entity and associated with an anchoring system, to locally shift the complement steady‐state towards activation on tumour cell surface.

Monoclonal antibody therapy of solid tumors: clinical limitations and novel strategies to enhance treatment efficacy

Monoclonal antibodies (mAbs) have become a cornerstone in the therapeutic guidelines of a wide range of solid tumors. The targeted nature of these biotherapeutics has improved treatment outcomes by offering enhanced specificity to reduce severe side effects experienced with conventional chemotherapy. Notwithstanding, poor tumor tissue penetration and the heterogeneous distribution achieved therein are prominent drawbacks that hamper the clinical efficacy of therapeutic antibodies. Failure to deliver efficacious doses throughout the tumor can lead to treatment failure and the development of acquired resistance mechanisms. Comprehending the morphological and physiological characteristics of solid tumors and their microenvironment that affect tumor penetration and distribution is a key requirement to improve clinical outcomes and realize the full potential of monoclonal antibodies in oncology. This review summarizes the essential architectural characteristics of solid tumors that obstruct macromolecule penetration into the targeted tissue following systemic delivery. It further describes mechanisms of resistance elucidated for blockbuster antibodies for which extensive clinical data exists, as a way to illustrate various modes in which cancer cells can overcome the anticancer activity of therapeutic antibodies. Thereafter, it describes novel strategies designed to improve clinical outcomes of mAbs by increasing potency and/or improving tumor delivery; focusing on the recent clinical success and growing clinical pipeline of antibody-drug conjugates, immune checkpoint inhibitors and nanoparticle-based delivery systems.

Complement C5b-9 and Cancer: Mechanisms of Cell Damage, Cancer Counteractions, and Approaches for Intervention

The interactions of cancer cells with components of the complement system are highly complex, leading to an outcome that is either favorable or detrimental to cancer cells. Currently, we perceive only the "tip of the iceberg" of these interactions. In this review, we focus on the complement terminal C5b-9 complex, known also as the complement membrane attack complex (MAC) and discuss the complexity of its interaction with cancer cells, starting with a discussion of its proposed mode of action in mediating cell death, and continuing with a portrayal of the strategies of evasion exhibited by cancer cells, and closing with a proposal of treatment approaches targeted at evasion strategies. Upon intense complement activation and membrane insertion of sufficient C5b-9 complexes, the afflicted cells undergo regulated necrotic cell death with characteristic damage to intracellular organelles, including mitochondria, and perforation of the plasma membrane. Several pro-lytic factors have been proposed, including elevated intracellular calcium ion concentrations and activated JNK, Bid, RIPK1, RIPK3, and MLKL; however, further research is required to fully characterize the effective cell death signals activated by the C5b-9 complexes. Cancer cells over-express a multitude of protective measures which either block complement activation, thus reducing the number of membrane-inserted C5b-9 complexes, or facilitate the elimination of C5b-9 from the cell surface. Concomitantly, cancer cells activate several protective pathways that counteract the death signals. Blockage of complement activation is mediated by the complement membrane regulatory proteins CD46, CD55, and CD59 and by soluble complement regulators, by proteases that cleave complement proteins and by protein kinases, like CK2, which phosphorylate complement proteins. C5b-9 elimination and inhibition of cell death signals are mediated by caveolin and dynamin, by Hsp70 and Hsp90, by the mitochondrial stress protein mortalin, and by the protein kinases PKC and ERK. It is conceivable that various cancers and cancers at different stages of development will utilize distinct patterns of these and other MAC resistance strategies. In order to enhance the impact of antibody-based therapy on cancer, novel precise reagents that block the most effective protective strategies will have to be designed and applied as adjuvants to the therapeutic antibodies.

Interaction of host immunity with HER2-targeted treatment and tumor heterogeneity in HER2-positive breast cancer

Growing evidence suggests a clear role of the host immune system in HER2+ breast cancer. In addition, HER2+ breast cancer is generally considered more immunogenic than hormone receptor-positive (HR+)/HER2-, and specific molecular HER2+ subgroups (e.g. HER2-enriched disease) are more immunogenic than others (e.g. Luminal A or B). From a clinical perspective, the immune system plays a relevant prognostic role in HER2+ breast cancer and contributes to the therapeutic effects of trastuzumab. However, as more HER2-targeted agents become available, a better understanding of the role played by the immune system in modulating therapy response to different agents will be needed. Furthermore, the recent introduction in oncology of immune checkpoint inhibitors capable of unleashing anti-tumor immune response opens new possibilities for therapeutic combinations in HER2+ breast cancer. Here, we review the current pre-clinical and clinical data on the interplay between the immune system and HER2+ breast cancer, focusing on different HER2-targeted treatments and the biological heterogeneity that exists within HER2+ disease. Finally, we discuss new therapeutic approaches exploiting the immune system to increase activity or revert resistance to HER2-targeted agents.

A study on screening and antitumor effect of CD55-specific ligand peptide in cervical cancer cells

Background

To improve the targeting ability of antitumor drugs, we identified the antigens with high expression on the surface of tumor cells associated with tumor escape, such as the complement regulatory protein CD55 molecule, which is also known as the decay accelerating factor. In this study, phage display technology was used to screen and identify CD55-specific ligand peptide (CD55sp) bound to CD55 molecule on the surface of cervical cancer HeLa cells. We then explored the role of this peptide in inhibiting the growth of cervical cancer cells in vitro. Our characterization of CD55sp will provide implication for tumor target therapy.

Methods

The phage bound to the surface of HeLa cells were isolated by phage display technology. Positive phage clones were identified by ELISA. Phage was then amplified and determined by agarose gel electrophoresis after monoclonal DNA extraction. DNA sequencing and bioinformatical analysis were conducted to obtain specific ligand peptides. Flow cytometry and immunofluorescence were used to measure the expression of CD55 molecule on the surface of tumor and normal cells. Subsequently, the effects of CD55sp on the proliferation and apoptosis of HeLa and SiHa cells were determined by Cell Counting Kit-8 (CCK-8), flow cytometry, and TUNEL assay, respectively. The morphology of apoptotic cells was examined by electron microscope. The distribution of Cleaved caspase-3 was detected by immunofluorescence. The expression of bcl-2 and Cleaved caspase-3 were determined by Western blot.

Results

The results showed that the peptide (QVNGLGERSQQM) can bind to the CD55 molecule on the surface of cervical cancer HeLa and SiHa cells as a ligand peptide. It can also effectively inhibit the proliferation of cervical cancer cells and induce cell apoptosis.

Conclusion

This study demonstrates that CD55sp screened by phage display technology plays a strong antitumor role.

Expression of the CD59 Glycoprotein Precursor is Upregulated in an Estrogen Receptor-alpha (ER-α)-Negative and a Tamoxifen-Resistant Breast Cancer Cell Line In Vitro

Background

Breast cancer is the most prevalent cancer and the leading cause of cancer death among women. Tamoxifen (TAM) therapy is one of the most widely and successfully used endocrine treatments for estrogen receptor α (ERα)-positive breast cancer. However, resistance to TAM has been a major challenge. In addition, the mechanisms underlying endocrine resistance remain unclear. Here, we report that CD59, a phosphatidylinositol-anchored glycoprotein, is a candidate resistant gene for TAM therapies.

Material/Methods

The breast cancer cell line MCF-7, the MCF-10A cell line, and the TAM-resistant breast cancer cell line TAMR-MCF-7 were cultured. The TAMR-MCF-7 cells were transfected with CD59 siRNA and control siRNA. Then, the CD59 glycoprotein precursor expression was detected by reverse transcription-quantitative polymerase chain reaction and western blot analysis. Cell counting kit-8 and flow cytometry assay were performed to examine cell proliferation, cell apoptosis, and cell cycle. In addition, the expressions of Bax, Bcl2, cleaved-caspase-8, cleaved-caspase-6, cleaved-caspase-3, and cleaved-PARP were analyzed by western blot analysis in the TAMR-MCF-7 cells treated with CD59 siRNA.

Results

In the present study, we found that the CD59 glycoprotein precursor was aberrantly upregulated in the ERα-negative breast cancer MCF-10A cells but not the MCF-7 cells. Furthermore, the CD59 glycoprotein precursor expression was elevated in the TAM-resistant breast cancer cells. Importantly, RNAi-mediated attenuation of CD59 was sufficient to rescue the resistance to TAM in the TAMR-MCF-7 cells.

Conclusions

In summary, our results proposed a candidate biomarker for predicting TAM resistance in ERα-positive breast cancer via targeting CD59, therefore it could be a novel therapeutic option.

Complement as a Biological Tool to Control Tumor Growth

Deposits of complement components have been documented in several human tumors suggesting a potential involvement of the complement system in tumor immune surveillance. In vitro and in vivo studies have revealed a double role played by this system in tumor progression. Complement activation in the cancer microenvironment has been shown to promote cancer growth through the release of the chemotactic peptide C5a recruiting myeloid suppressor cells. There is also evidence that tumor progression can be controlled by complement activated on the surface of cancer cells through one of the three pathways of complement activation. The aim of this review is to discuss the protective role of complement in cancer with special focus on the beneficial effect of complement-fixing antibodies that are efficient activators of the classical pathway and contribute to inhibit tumor expansion as a result of MAC-mediated cancer cell killing and complement-mediated inflammatory process. Cancer cells are heterogeneous in their susceptibility to complement-induced killing that generally depends on stable and relatively high expression of the antigen and the ability of therapeutic antibodies to activate complement. A new generation of monoclonal antibodies are being developed with structural modification leading to hexamer formation and enhanced complement activation. An important progress in cancer immunotherapy has been made with the generation of bispecific antibodies targeting tumor antigens and able to neutralize complement regulators overexpressed on cancer cells. A great effort is being devoted to implementing combined therapy of traditional approaches based on surgery, chemotherapy and radiotherapy and complement-fixing therapeutic antibodies. An effective control of tumor growth by complement is likely to be obtained on residual cancer cells following conventional therapy to reduce the tumor mass, prevent recurrences and avoid disabilities.

Hypoxia restrains the expression of complement component 9 in tumor-associated macrophages promoting non-small cell lung cancer progression

The tumor microenvironment, including stroma cells, signaling molecules, and the extracellular matrix, critically regulates the growth and survival of cancer cells. Dissecting the active molecules in tumor microenvironment may uncover the key factors that can impact cancer progression. Human NSCLC tumor tissue-conditioned medium (TCM) and adjacent nontumor tissue-conditioned medium (NCM) were used to treat two NSCLC cells LSC1 and LAC1, respectively. Cell growth and foci formation assays were applied to assess the effects of TCM and NCM on cancer cells. The active factors were identified by protein mass spectrometry. Cell growth and foci formation assays showed that 8 of 26 NCM and none of TCM could effectively lead to tumor cell lysis, which was known as tumoricidal activity. And then protein mass spectrometry analysis and functional verifications confirmed that complement component 9 (C9) played a crucial role in the complement-dependent cytotoxicity (CDC)-mediated tumoricidal activity in vitro. Furthermore, immunofluorescent staining revealed that C9 specifically expressed in most alveolar macrophages (AMs) in adjacent lung tissues and a small fraction of tumor-associated macrophages (TAMs) in NSCLC tissues. Most importantly, the percentage of C9-positive cells in AMs or TAMs was responsible for the tumoricidal activity of NCM and TCM. Herein, we found that high expression of C9 in TAMs was a significant independent prognostic factor (P = 0.029), and associated with beneficial overall survival (P = 0.012) and disease-free survival (P = 0.016) for patients with NSCLC. Finally, we unveiled that hypoxic tumor microenvironment could switch the phenotype of macrophages from M1 to M2 forms, accompanying with the downregulation of C9 in TAMs. Collectively, our findings elucidated a novel role of TAMs expressing C9 in the prognosis of NSCLC patients, which provided a promising strategy in the development of anticancer treatments based on the CDC-mediated tumoricidal activity.

Effect of membrane-bound complement regulatory proteins on tumor cell sensitivity to complement-dependent cytolysis triggered by heterologous expression of the α-gal xenoantigen

Engineering malignant cells to express a heterologous α-gal antigen can induce heterograft hyperacute rejection, resulting in complement-dependent cytolysis (CDC) of tumor cells, which has been considered as a novel strategy for antitumor therapy. A549 cells engineered to express Galα1-3Galβ1-4GlcNAc-R (α-gal) epitope exhibited strong resistance to CDC treated by normal human serum (NHS) in a previous study. We hypothesized that the expression of membrane-bound complement regulatory proteins (mCRPs) decay accelerating factor (CD55) and protectin (CD59) influenced the efficacy of the α-gal/NHS-mediated antitumor effect to tumor cells in vitro. The present study confirmed that A549 cells expressed high levels of CD55 and CD59, whereas Lovo cells expressed relatively low levels of these proteins. A549 and Lovo cells transfected with plasmids containing or lacking the α-gal epitope were evaluated for their susceptibility to CDC by NHS and detected using a trypan blue exclusion assay. α-gal-expressing Lovo (Lovo-GT) cells were almost completely killed by α-gal-mediated CDC following incubation with 50% NHS, whereas no cytolysis was observed in α-gal expressing A549 (A549-GT) cells. Abrogating CD55 and CD59 function from A549-GT cells by various concentrations of phosphatidylinositol-specific phospholipase C (PI-PLC) or blocking antibodies increased the susceptibility of cells to CDC, and the survival rate decreased significantly comparing to the controls (P<0.05). The findings of the present study indicated that using the α-gal/NHS system to eliminate tumor cells via inducing the complement cascade reaction might represent a feasible approach for the treatment of cancer. However, high levels of mCRP expression may limit the efficacy of this approach. Therefore, an improved efficacy of cancer cell killing may be achieved by combining strategies of heterologous α-gal expression and mCRP downregulation.

Pertuzumab and trastuzumab: the rationale way to synergy

It has now been 15 years since the HER2-targeted monoclonal antibody trastuzumab was introduced in clinical and revolutionized the treatment of HER2-positive breast cancer patients. Despite this achievement, most patients with HER2-positive metastatic breast cancer still show progression of their disease, highlighting the need for new therapies. The continuous interest in novel targeted agents led to the development of pertuzumab, the first in a new class of agents, the HER dimerization inhibitors. Pertuzumab is a novel recombinant humanized antibody directed against extracellular domain II of HER2 protein that is required for the heterodimerization of HER2 with other HER receptors, leading to the activation of downstream signalling pathways. Pertuzumab combined with trastuzumab plus docetaxel was approved for the first-line treatment of patients with HER2-positive metastatic breast cancer and is currently used as a standard of care in this indication. In the neoadjuvant setting, the drug was granted FDA-accelerated approval in 2013. Pertuzumab is also being evaluated in the adjuvant setting. The potential of pertuzumab relies in the dual complete blockade of the HER2/3 axis when administered with trastuzumab. This paper synthetises preclinical and clinical data on pertuzumab and highlights the mechanisms underlying the synergistic activity of the combination pertuzumab-trastuzumab which are essentially due to their complementary mode of action.

Beyond the Role of CD55 as a Complement Component

The complement is a part of the immune system that plays several roles in removing pathogens. Despite the importance of the complement system, the exact role of each component has been overlooked because the complement system was thought to be a nonspecific humoral immune mechanism that worked against pathogens. Decay-accelerating factor (DAF or CD55) is a known inhibitor of the complement system and has recently attracted substantial attention due to its role in various diseases, such as cancer, protein-losing enteropathy, and malaria. Some protein-losing enteropathy cases are caused by CD55 deficiency, which leads to complement hyperactivation, malabsorption, and angiopathic thrombosis. In addition, CD55 has been reported to be an essential host receptor for infection by the malaria parasite. Moreover, CD55 is a ligand of the seven-span transmembrane receptor CD97. Since CD55 is present in various cells, the functional role of CD55 has been expanded by showing that CD55 is associated with a variety of diseases, including cancer, malaria, protein-losing enteropathy, paroxysmal nocturnal hemoglobinuria, and autoimmune diseases. This review summarizes the current understanding of CD55 and the role of CD55 in these diseases. It also provides insight into the development of novel drugs for the diagnosis and treatment of diseases associated with CD55.

CRISPR/Cas9 generated human CD46, CD55 and CD59 knockout cell lines as a tool for complement research

BACKGROUND

To prevent unwanted complement activation and subsequent damage, complement activation must be tightly regulated on healthy host cells. Dysregulation of the complement system contributes to the pathology of diseases like Paroxysmal Nocturnal Hemoglobinuria and atypical Hemolytic Uremic Syndrome. To investigate complement regulator deficiencies, primary patient cells may be used, but access to patient cells may be limited and cells are heterogeneous between different patients. To inhibit regulator function on healthy host cells, blocking antibodies can be used, though it may be difficult to exclude antibody-mediated effects. To circumvent these issues, we created single and combined complement regulator human knockout cells to be able to in vitro investigate complement activation and regulation on human cells.

METHODS

CRISPR/Cas9 was used to knockout (KO) complement regulatory proteins CD46, CD55 and/or CD59 in human HAP1 cells. Single cell derived cell lines were profiled by Sanger sequencing and flow cytometry. To confirm the lack of complement regulatory function, the cells were exposed to complement in normal human serum and subsequently C3 and C4 deposition on the cell surface were detected by using flow cytometry.

RESULTS

We created single KO cell lines that completely lacked CD46, CD55 or CD59. We additionally generated double CD46/CD55, CD46/CD59 and CD55/CD59 KOs and triple CD46/CD55/CD59 KOs. Upon classical pathway activation, deletion of CD46 resulted in increased C3 and C4 deposition, while deleting CD55 mainly resulted to increased C3 deposition, confirming their reported function in complement regulation. Upon alternative pathway activation, C3 deposition was only observed on the triple CD46/CD55/CD59 KO cells and not on any of the other cell lines, suggesting that human cells are resistant to spontaneous complement activation and suggesting a role for CD59 in C3 regulation.

CONCLUSIONS

The generation of complement regulator KO cell lines provides a relevant tool for future in vitro investigations of complement activation and regulation on human cells. Furthermore, these cell lines may also be helpful to evaluate therapeutic complement inhibitors and may shed light on novel roles of complement regulatory proteins as we here observed for CD59.

An oligoclonal antibody durably overcomes resistance of lung cancer to third-generation EGFR inhibitors

Epidermal growth factor receptor (EGFR) mutations identify patients with lung cancer who derive benefit from kinase inhibitors. However, most patients eventually develop resistance, primarily due to the T790M second-site mutation. Irreversible inhibitors (e.g., osimertinib/AZD9291) inhibit T790M-EGFR, but several mechanisms, including a third-site mutation, C797S, confer renewed resistance. We previously reported that a triple mixture of monoclonal antibodies, 3×mAbs, simultaneously targeting EGFR, HER2, and HER3, inhibits T790M-expressing tumors. We now report that 3×mAbs, including a triplet containing cetuximab and trastuzumab, inhibits C797S-expressing tumors. Unlike osimertinib, which induces apoptosis, 3×mAbs promotes degradation of the three receptors and induces cellular senescence. Consistent with distinct mechanisms, treatments combining 3×mAbs plus sub-inhibitory doses of osimertinib synergistically and persistently eliminated tumors. Thus, oligoclonal antibodies, either alone or in combination with kinase inhibitors, might preempt repeated cycles of treatment and rapid emergence of resistance.

Complement in cancer: untangling an intricate relationship

In tumour immunology, complement has traditionally been considered as an adjunctive component that enhances the cytolytic effects of antibody-based immunotherapies, such as rituximab. Remarkably, research in the past decade has uncovered novel molecular mechanisms linking imbalanced complement activation in the tumour microenvironment with inflammation and suppression of antitumour immune responses. These findings have prompted new interest in manipulating the complement system for cancer therapy. This Review summarizes our current understanding of complement-mediated effector functions in the tumour microenvironment, focusing on how complement activation can act as a negative or positive regulator of tumorigenesis. It also offers insight into clinical aspects, including the feasibility of using complement biomarkers for cancer diagnosis and the use of complement inhibitors during cancer treatment.

Integrated MicroRNA-mRNA Analysis Reveals miR-204 Inhibits Cell Proliferation in Gastric Cancer by Targeting CKS1B, CXCL1 and GPRC5A

Gastric cancer (GC) is the second most frequent cause of cancer-related deaths worldwide. MicroRNAs are single-stranded RNA molecules of 21–23 nucleotides that regulate target gene expression through specific base-pairing interactions between miRNA and untranslated regions of targeted mRNAs. In this study, we generated a multistep approach for the integrated analysis of miRNA and mRNA expression. First, both miRNA and mRNA expression profiling datasets in gastric cancer from the Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) identified 79 and 1042 differentially expressed miRNAs and mRNAs, respectively, in gastric cancer. Second, inverse correlations between miRNA and mRNA expression levels identified 3206 miRNA–mRNA pairs combined with 79 dysregulated miRNAs and their 774 target mRNAs predicted by three prediction tools, miRanda, PITA, and RNAhybrid. Additionally, miR-204, which was found to be down-regulated in gastric cancer, was ectopically over-expressed in the AGS gastric cancer cell line and all down-regulated targets were identified by RNA sequencing (RNA-seq) analysis. Over-expression of miR-204 reduced the gastric cancer cell proliferation and suppressed the expression of three targets which were validated by qRT-PCR and luciferase assays. For the first time, we identified that CKS1B, CXCL1, and GPRC5A are putative targets of miR-204 and elucidated that miR-204 acted as potential tumor suppressor and, therefore, are useful as a promising therapeutic target for gastric cancer.