HGS-ETR1, a fully human TRAIL-receptor 1 monoclonal antibody, induces cell death in multiple tumour types in vitro and in vivo

Applying Ultrasound to Mechanically and Noninvasively Sensitize Prostate Tumors to TRAIL-Mediated Apoptosis

Non-surgical and safe prostate cancer (PCa) therapies are in demand. Soluble tumor necrosis factor (TNF-α) related apoptosis inducing ligand (TRAIL), a cancer-specific drug, shows preclinical efficacy but has a short circulation half-life. This research has shown that physiological fluid shear stress activates mechanosensitive ion channels (MSCs), such as Piezo1, enhancing TRAIL-mediated apoptosis in cancer cells. Herein, noninvasive, focal ultrasound (FUS) is implemented to augment the pro-apoptotic effects of TRAIL. Using thermally safe FUS parameters, it is observed that TRAIL sensitivity increases with higher FUS pressure in PCa cells, mediated by Piezo1. This is confirmed by examining the effects of calcium chelation, MSC inhibitors, and PIEZO knockdown. In vivo, a multi-dose study with 10 min FUS exposure shows that 0 and 4-h intervals between TRAIL and FUS significantly reduce tumor burden, with an increase in apoptosis evident by enhanced cleaved-caspase 3 expression. This mechanotherapy offers a clinically translatable approach by utilizing widely available FUS technology, applicable to treat additional cancer types.

Mechanisms and Strategies to Overcome Drug Resistance in Colorectal Cancer

Colorectal cancer (CRC) is a major cause of cancer-related mortality worldwide, with a significant impact on public health. Current treatment options include surgery, chemotherapy, radiotherapy, molecular-targeted therapy, and immunotherapy. Despite advancements in these therapeutic modalities, resistance remains a significant challenge, often leading to treatment failure, poor progression-free survival, and cancer recurrence. Mechanisms of resistance in CRC are multifaceted, involving genetic mutations, epigenetic alterations, tumor heterogeneity, and the tumor microenvironment. Understanding these mechanisms at the molecular level is crucial for identifying novel therapeutic targets and developing strategies to overcome resistance. This review provides an overview of the diverse mechanisms driving drug resistance in sporadic CRC and discusses strategies currently under investigation to counteract this resistance. Several promising strategies are being explored, including targeting drug transport, key signaling pathways, DNA damage response, cell death pathways, epigenetic modifications, cancer stem cells, and the tumor microenvironment. The integration of emerging therapeutic approaches that target resistance mechanisms aims to enhance the efficacy of current CRC treatments and improve patient outcomes.

Top 100 most-cited articles on apoptosis of non-small cell lung cancer over the past two decades: a bibliometrics analysis

Background

Recently there has been an increasing number of studies have explored apoptosis mechanisms in lung cancer (LC). However, no researchers have conducted a bibliometric analysis of the most cited articles in this field.

Objective

To examine the top 100 most influential and cited publications on apoptosis in non-small cell lung cancer (NSCLC) from 2004 to 2023, summarizing research trends and key focus areas.

Methods

This study utilized the Web of Science Core Database (WOSCC) to research NSCLC apoptosis from 2004 to 2023, using keyword selection and manual screening for article searches. Bibliometrix package of R software 4.3.1 was used to generate distribution statistics for the top ten institutions, journals and authors. Citespace6.2. R6 was used to create the visualization maps for keyword co-occurrence and clustering. VOSviewer1.6.19 was used to conduct cluster analysis of publishing countries (regions), with data exported to SCImago Graphica for geographic visualization and cooperation analysis. VOSviewer1.6.19 was used to produced co-citation maps of institutions, journals, authors, and references.

Results

From 2004 to 2023, 13316 articles were retrieved, and the top 100 most cited were chosen. These were authored by 934 individuals from 269 institutions across 18 countries and appeared in 45 journals. Citations ranged from 150 to 1,389, with a median of 209.5. The most influential articles appeared in 2005 and 2007 (n=13). The leading countries (regions), institutions, journals and authors were identified as the United States (n=60), Harvard University (n=64), CANCER RESEARCH (n=15), SUN M and YANG JS (n=6). The top five keywords were "expression", "activation", "apoptosis", "pathway" and "gefitinib". This study indicates that enhancing apoptosis through circular RNA regulation and targeting the Nrf2 signaling pathway could become a key research focus in recent years.

Conclusion

Apoptosis has been the subject of extensive research over many years, particularly in relation to its role in the pathogenesis, diagnosis, and treatment of NSCLC. This study aims to identify highly influential articles and forecast emerging research trends, thereby offering insights into novel therapeutic targets and strategies to overcome drug resistance. The findings are intended to serve as a valuable reference for scholars engaged in this field of study.

Phage display for discovery of anticancer antibodies

Antibodies and antibody-based immunotherapeutics are the mainstays of cancer immunotherapy. Expanding the repertoire of cancer-specific and cancer-associated epitopes targetable with antibodies represents an important area of research. Phage display is a powerful approach allowing the use of diverse antibody libraries to be screened for binding to a wide range of targets. In this review, we summarize the basics of phage display technology and highlight the advances in anticancer antibody identification and modification via phage display platform. Finally, we describe phage display-derived anticancer monoclonal antibodies that have been approved to date or are in clinical development.

Carboxypeptidase A4 negatively regulates HGS-ETR1/2-induced pyroptosis by forming a positive feedback loop with the AKT signalling pathway

Pyroptosis, a mode of inflammatory cell death, has recently gained significant attention. However, the underlying mechanism remains poorly understood. HGS-ETR1/2 is a humanized monoclonal antibody that can bind to DR4/5 on the cell membrane and induce cell apoptosis by activating the death receptor signalling pathway. In this study, by using morphological observation, fluorescence double staining, LDH release and immunoblot detection, we confirmed for the first time that HGS-ETR1/2 can induce GSDME-mediated pyroptosis in hepatocellular carcinoma cells. Our study found that both inhibition of the AKT signalling pathway and silencing of CPA4 promote pyroptosis, while the overexpression of CPA4 inhibits it. Furthermore, we identified a positive regulatory feedback loop is formed between CPA4 and AKT phosphorylation. Specifically, CPA4 modulates AKT phosphorylation by regulating the expression of the AKT phosphatase PP2A, while inhibition of the AKT signalling pathway leads to a decreased transcription and translation levels of CPA4. Our study reveals a novel mechanism of pyroptosis induced by HGS-ETR1/2, which may provide a crucial foundation for future investigations into cancer immunotherapy.

Targeting TRAIL Death Receptors in Triple-Negative Breast Cancers: Challenges and Strategies for Cancer Therapy

The tumor necrosis factor (TNF) superfamily member TNF-related apoptosis-inducing ligand (TRAIL) induces apoptosis in cancer cells via death receptor (DR) activation with little toxicity to normal cells or tissues. The selectivity for activating apoptosis in cancer cells confers an ideal therapeutic characteristic to TRAIL, which has led to the development and clinical testing of many DR agonists. However, TRAIL/DR targeting therapies have been widely ineffective in clinical trials of various malignancies for reasons that remain poorly understood. Triple negative breast cancer (TNBC) has the worst prognosis among breast cancers. Targeting the TRAIL DR pathway has shown notable efficacy in a subset of TNBC in preclinical models but again has not shown appreciable activity in clinical trials. In this review, we will discuss the signaling components and mechanisms governing TRAIL pathway activation and clinical trial findings discussed with a focus on TNBC. Challenges and potential solutions for using DR agonists in the clinic are also discussed, including consideration of the pharmacokinetic and pharmacodynamic properties of DR agonists, patient selection by predictive biomarkers, and potential combination therapies. Moreover, recent findings on the impact of TRAIL treatment on the immune response, as well as novel strategies to address those challenges, are discussed.

Gigavalent Display of Proteins on Monodisperse Polyacrylamide Hydrogels as a Versatile Modular Platform for Functional Assays and Protein Engineering

The assembly of robust, modular biological components into complex functional systems is central to synthetic biology. Here, we apply modular "plug and play" design principles to a solid-phase protein display system that facilitates protein purification and functional assays. Specifically, we capture proteins on polyacrylamide hydrogel display beads (PHD beads) made in microfluidic droplet generators. These monodisperse PHD beads are decorated with predefined amounts of anchors, methacrylate-PEG-benzylguanine (BG) and methacrylate-PEG-chloroalkane (CA), that react covalently with SNAP-/Halo-tag fusion proteins, respectively, in a specific, orthogonal, and stable fashion. Anchors, and thus proteins, are distributed throughout the entire bead volume, allowing attachment of ∼10⁹ protein molecules per bead (⌀ 20 μm) -a higher density than achievable with commercial surface-modified beads. We showcase a diverse array of protein modules that enable the secondary capture of proteins, either noncovalently (IgG and SUMO-tag) or covalently (SpyCatcher, SpyTag, SnpCatcher, and SnpTag), in mono- and multivalent display formats. Solid-phase protein binding and enzymatic assays are carried out, and incorporating the photocleavable protein PhoCl enables the controlled release of modules via visible-light irradiation for functional assays in solution. We utilize photocleavage for valency engineering of an anti-TRAIL-R1 scFv, enhancing its apoptosis-inducing potency ∼50-fold through pentamerization.

An overview on display systems (phage, bacterial, and yeast display) for production of anticancer antibodies; advantages and disadvantages

Antibodies as ideal therapeutic and diagnostic molecules are among the top-selling drugs providing considerable efficacy in disease treatment, especially in cancer therapy. Limitations of the hybridoma technology as routine antibody generation method in conjunction with numerous developments in molecular biology led to the development of alternative approaches for the streamlined identification of most effective antibodies. In this regard, display selection technologies such as phage display, bacterial display, and yeast display have been widely promoted over the past three decades as ideal alternatives to traditional methods. The display of antibodies on phages is probably the most widespread of these methods, although surface display on bacteria or yeast have been employed successfully, as well. These methods using various sizes of combinatorial antibody libraries and different selection strategies possessing benefits in screening potency, generating, and isolation of high affinity antibodies with low risk of immunogenicity. Knowing the basics of each method assists in the design and retrieval process of antibodies suitable for different diseases, including cancer. In this review, we aim to outline the basics of each library construction and its display method, screening and selection steps. The advantages and disadvantages in comparison to alternative methods, and their applications in antibody engineering will be explained. Finally, we will review approved or non-approved therapeutic antibodies developed by employing these methods, which may serve as therapeutic antibodies in cancer therapy.

Harnessing TRAIL-Induced Apoptosis Pathway for Cancer Immunotherapy and Associated Challenges

The immune cytokine tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) has attracted rapidly evolving attention as a cancer treatment modality because of its competence to selectively eliminate tumor cells without instigating toxicity in vivo. TRAIL has revealed encouraging promise in preclinical reports in animal models as a cancer treatment option; however, the foremost constraint of the TRAIL therapy is the advancement of TRAIL resistance through a myriad of mechanisms in tumor cells. Investigations have documented that improvement of the expression of anti-apoptotic proteins and survival or proliferation involved signaling pathways concurrently suppressing the expression of pro-apoptotic proteins along with down-regulation of expression of TRAILR1 and TRAILR2, also known as death receptor 4 and 5 (DR4/5) are reliable for tumor cells resistance to TRAIL. Therefore, it seems that the development of a therapeutic approach for overcoming TRAIL resistance is of paramount importance. Studies currently have shown that combined treatment with anti-tumor agents, ranging from synthetic agents to natural products, and TRAIL could result in induction of apoptosis in TRAIL-resistant cells. Also, human mesenchymal stem/stromal cells (MSCs) engineered to generate and deliver TRAIL can provide both targeted and continued delivery of this apoptosis-inducing cytokine. Similarly, nanoparticle (NPs)-based TRAIL delivery offers novel platforms to defeat barricades to TRAIL therapeutic delivery. In the current review, we will focus on underlying mechanisms contributed to inducing resistance to TRAIL in tumor cells, and also discuss recent findings concerning the therapeutic efficacy of combined treatment of TRAIL with other antitumor compounds, and also TRAIL-delivery using human MSCs and NPs to overcome tumor cells resistance to TRAIL.

Therapeutics Targeting the Core Apoptotic Machinery

Simple Summary

Cancer develops when the balance between cell death and cell division in tissues is dysregulated. A key focus of cancer drug discovery is identifying therapeutic agents which will selectively kill and eliminate cancer cells from the body. A number of proteins can prevent the death of cancer cells and developing inhibitors against these proteins to promote cancer cell death is a focus of recent drug discovery efforts. This review aims to summarize the key targets being explored, the drug development approaches being adopted, and the success or limitations of agents currently approved or in clinical development.

Abstract

Therapeutic targeting of the apoptotic pathways for the treatment of cancer is emerging as a valid and exciting approach in anti-cancer therapeutics. Accumulating evidence demonstrates that cancer cells are typically “addicted” to a small number of anti-apoptotic proteins for their survival, and direct targeting of these proteins could provide valuable approaches for directly killing cancer cells. Several approaches and agents are in clinical development targeting either the intrinsic mitochondrial apoptotic pathway or the extrinsic death receptor mediated pathways. In this review, we discuss the main apoptosis pathways and the key molecular targets which are the subject of several drug development approaches, the clinical development of these agents and the emerging resistance factors and combinatorial treatment approaches for this class of agents with existing and emerging novel targeted anti-cancer therapeutics.

Apoptosis-Inducing TNF Superfamily Ligands for Cancer Therapy

Cancer is a complex disease with apoptosis evasion as one of its hallmarks; therefore, apoptosis induction in transformed cells seems a promising approach as a cancer treatment. TNF apoptosis-inducing ligands, which are naturally present in the body and possess tumoricidal activity, are attractive candidates. The most studied proteins are TNF-α, FasL, and TNF-related apoptosis-inducing ligand (TRAIL). Over the years, different recombinant TNF family-derived apoptosis-inducing ligands and agonists have been designed. Their stability, specificity, and half-life have been improved because most of the TNF ligands have the disadvantages of having a short half-life and affinity to more than one receptor. Here, we review the outlook on apoptosis-inducing ligands as cancer treatments in diverse preclinical and clinical stages and summarize strategies of overcoming their natural limitations to improve their effectiveness.

Hexavalent TRAIL Fusion Protein Eftozanermin Alfa Optimally Clusters Apoptosis-Inducing TRAIL Receptors to Induce On-Target Antitumor Activity in Solid Tumors

TRAIL can activate cell surface death receptors, resulting in potent tumor cell death via induction of the extrinsic apoptosis pathway. Eftozanermin alfa (ABBV-621) is a second generation TRAIL receptor agonist engineered as an IgG1-Fc mutant backbone linked to two sets of trimeric native single-chain TRAIL receptor binding domain monomers. This hexavalent agonistic fusion protein binds to the death-inducing DR4 and DR5 receptors with nanomolar affinity to drive on-target biological activity with enhanced caspase-8 aggregation and death-inducing signaling complex formation independent of FcγR-mediated cross-linking, and without clinical signs or pathologic evidence of toxicity in nonrodent species. ABBV-621 induced cell death in approximately 36% (45/126) of solid cancer cell lines in vitro at subnanomolar concentrations. An in vivo patient-derived xenograft (PDX) screen of ABBV-621 activity across 15 different tumor indications resulted in an overall response (OR) of 29% (47/162). Although DR4 (TNFSFR10A) and/or DR5 (TNFSFR10B) expression levels did not predict the level of response to ABBV-621 activity in vivo, KRAS mutations were associated with elevated TNFSFR10A and TNFSFR10B and were enriched in ABBV-621-responsive colorectal carcinoma PDX models. To build upon the OR of ABBV-621 monotherapy in colorectal cancer (45%; 10/22) and pancreatic cancer (35%; 7/20), we subsequently demonstrated that inherent resistance to ABBV-621 treatment could be overcome in combination with chemotherapeutics or with selective inhibitors of BCL-X_L. In summary, these data provide a preclinical rationale for the ongoing phase 1 clinical trial (NCT03082209) evaluating the activity of ABBV-621 in patients with cancer. SIGNIFICANCE: This study describes the activity of a hexavalent TRAIL-receptor agonistic fusion protein in preclinical models of solid tumors that mechanistically distinguishes this molecular entity from other TRAIL-based therapeutics.

Phage Display Derived Monoclonal Antibodies: From Bench to Bedside

Monoclonal antibodies (mAbs) have become one of the most important classes of biopharmaceutical products, and they continue to dominate the universe of biopharmaceutical markets in terms of approval and sales. They are the most profitable single product class, where they represent six of the top ten selling drugs. At the beginning of the 1990s, an in vitro antibody selection technology known as antibody phage display was developed by John McCafferty and Sir. Gregory Winter that enabled the discovery of human antibodies for diverse applications, particularly antibody-based drugs. They created combinatorial antibody libraries on filamentous phage to be utilized for generating antigen specific antibodies in a matter of weeks. Since then, more than 70 phage–derived antibodies entered clinical studies and 14 of them have been approved. These antibodies are indicated for cancer, and non-cancer medical conditions, such as inflammatory, optical, infectious, or immunological diseases. This review will illustrate the utility of phage display as a powerful platform for therapeutic antibodies discovery and describe in detail all the approved mAbs derived from phage display.

Suppressed humoral immunity is associated with dengue nonstructural protein NS1-elicited anti-death receptor antibody fractions in mice

Dengue virus (DENV) infections may cause life-threatening dengue hemorrhagic fever (DHF). Suppressed protective immunity was shown in these patients. Although several hypotheses have been formulated, the mechanism of DENV-induced immunosuppression remains unclear. Previously, we found that cross-reactive antibodies against tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) receptor 1 (death receptor 4 [DR4]) were elicited in DHF patients, and that anti-DR4 autoantibody fractions were elicited by nonstructural protein 1 (NS1) immunizations in experimental mice. In this study, we found that anti-DR4 antibodies could suppress B lymphocyte function in vitro and in vivo. Treatment with the anti-DR4 immunoglobulin (Ig) induced caspase-dependent cell death in immortalized B lymphocyte Raji cells in vitro. Anti-DR4 Igs elicited by NS1 and DR4 immunizations markedly suppressed mouse spleen transitional T2 B (IgM+IgD+), bone marrow pre-pro-B (B220+CD43+), pre-B (B220+CD43-), and mature B cell (B220+IgD+) subsets in mice. Furthermore, functional analysis revealed that the pre-elicitation of anti-NS1 and anti-DR4 Ig titers suppressed subsequently neutralizing antibody production by immunization with DENV envelop protein. Our data suggest that the elicitation of anti-DR4 titers through DENV NS1 immunization plays a suppressive role in humoral immunity in mice.

Phage Display Derived Monoclonal Antibodies: From Bench to Bedside

Monoclonal antibodies (mAbs) have become one of the most important classes of biopharmaceutical products, and they continue to dominate the universe of biopharmaceutical markets in terms of approval and sales. They are the most profitable single product class, where they represent six of the top ten selling drugs. At the beginning of the 1990s, an in vitro antibody selection technology known as antibody phage display was developed by John McCafferty and Sir. Gregory Winter that enabled the discovery of human antibodies for diverse applications, particularly antibody-based drugs. They created combinatorial antibody libraries on filamentous phage to be utilized for generating antigen specific antibodies in a matter of weeks. Since then, more than 70 phage-derived antibodies entered clinical studies and 14 of them have been approved. These antibodies are indicated for cancer, and non-cancer medical conditions, such as inflammatory, optical, infectious, or immunological diseases. This review will illustrate the utility of phage display as a powerful platform for therapeutic antibodies discovery and describe in detail all the approved mAbs derived from phage display.

Trimer form of tumor necrosis factor-related apoptosis inducing ligand induces apoptosis in canine cell lines derived from mammary tumors

We evaluated the cytotoxic effect of isoleucine-zipper tumor necrosis factor-related apoptosis inducing ligand (izTRAIL) against cell lines, B101592, Cha, and C090115, derived from canine mammary gland tumors. These cells were derived from three dogs diagnosed with mammary adenoma or carcinoma. All three cells were positive for vimentin, while B101592 and C090115 were positive for cytokeratin (CK) AE1/AE3 and CK CAM5.2. Treatment with izTRAIL decreased the viability of the three cell lines. The proportion of annexin V+/propidium iodide- cells increased in all three cell lines after treatment with izTRAIL. Additionally, cell cycle analysis revealed that izTRAIL treatment increased the number of cells in sub-G1 phase. Moreover, izTRAIL treatment activated caspase-8 and caspase-3 and enhanced the levels of cleaved poly (ADP-ribose) polymerase. The cytotoxic effect of izTRAIL was mitigated upon co-treatment with caspase-8 or caspase-3 inhibitor. These results indicated that izTRAIL induces apoptosis in cell lines derived from canine mammary tumor, which was also previously reported in canine hemangiosarcoma cell lines. This suggested that canine tumor cells have conserved TRAIL receptors. This study will provide the basis for further studies on TRAIL receptors and TRAIL-related molecules.

Transient stabilization, rather than inhibition, of MYC amplifies extrinsic apoptosis and therapeutic responses in refractory B-cell lymphoma

Therapeutic targeting of initiating oncogenes is the mainstay of precision medicine. Considerable efforts have been expended toward silencing MYC, which drives many human cancers including Burkitt lymphomas (BL). Yet, the effects of MYC silencing on standard-of-care therapies are poorly understood. Here we found that inhibition of MYC transcription renders B-lymphoblastoid cells refractory to chemotherapeutic agents. This suggested that in the context of chemotherapy, stabilization of Myc protein could be more beneficial than its inactivation. We tested this hypothesis by pharmacologically inhibiting glycogen synthase kinase 3β (GSK-3β), which normally targets Myc for proteasomal degradation. We discovered that chemorefractory BL cell lines responded better to doxorubicin and other anti-cancer drugs when Myc was transiently stabilized. In vivo, GSK3 inhibitors (GSK3i) enhanced doxorubicin-induced apoptosis in BL patient-derived xenografts (BL-PDX), as well as in murine MYC-driven lymphoma allografts. This enhancement was accompanied by and required deregulation of several key genes acting in the extrinsic, death-receptor-mediated apoptotic pathway. Consistent with this mechanism of action, GSK3i also facilitated lymphoma cell killing by a death ligand TRAIL and by a death receptor agonist mapatumumab. Thus, GSK3i synergizes with both standard chemotherapeutics and direct engagers of death receptors and could improve outcomes in patients with refractory lymphomas.

Novel Apoptosis-Inducing Agents for the Treatment of Cancer, a New Arsenal in the Toolbox

Evasion from apoptosis is an important hallmark of cancer cells. Alterations of apoptosis pathways are especially critical as they confer resistance to conventional anti-cancer therapeutics, e.g., chemotherapy, radiotherapy, and targeted therapeutics. Thus, successful induction of apoptosis using novel therapeutics may be a key strategy for preventing recurrence and metastasis. Inhibitors of anti-apoptotic molecules and enhancers of pro-apoptotic molecules are being actively developed for hematologic malignancies and solid tumors in particular over the last decade. However, due to the complicated apoptosis process caused by a multifaceted connection with cross-talk pathways, protein–protein interaction, and diverse resistance mechanisms, drug development within the category has been extremely challenging. Careful design and development of clinical trials incorporating predictive biomarkers along with novel apoptosis-inducing agents based on rational combination strategies are needed to ensure the successful development of these molecules. Here, we review the landscape of currently available direct apoptosis-targeting agents in clinical development for cancer treatment and update the related biomarker advancement to detect and validate the efficacy of apoptosis-targeted therapies, along with strategies to combine them with other agents.

Molecular Mode of Action of TRAIL Receptor Agonists-Common Principles and Their Translational Exploitation

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and its death receptors TRAILR1/death receptor 4 (DR4) and TRAILR2/DR5 trigger cell death in many cancer cells but rarely exert cytotoxic activity on non-transformed cells. Against this background, a variety of recombinant TRAIL variants and anti-TRAIL death receptor antibodies have been developed and tested in preclinical and clinical studies. Despite promising results from mice tumor models, TRAIL death receptor targeting has failed so far in clinical studies to show satisfying anti-tumor efficacy. These disappointing results can largely be explained by two issues: First, tumor cells can acquire TRAIL resistance by several mechanisms defining a need for combination therapies with appropriate sensitizing drugs. Second, there is now growing preclinical evidence that soluble TRAIL variants but also bivalent anti-TRAIL death receptor antibodies typically require oligomerization or plasma membrane anchoring to achieve maximum activity. This review discusses the need for oligomerization and plasma membrane attachment for the activity of TRAIL death receptor agonists in view of what is known about the molecular mechanisms of how TRAIL death receptors trigger intracellular cell death signaling. In particular, it will be highlighted which consequences this has for the development of next generation TRAIL death receptor agonists and their potential clinical application.

Involvement of p38 Activation and Mitochondria in Death of Human Leukemia Cells Induced by an Agonistic Human Monoclonal Antibody Fab Specific to TRAIL Receptor 1

The tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) induces cancer cell death with minimal damage to normal cells; however, some cancer cells are resistant to TRAIL. TRAIL resistance may be overcome by agonistic antibodies to TRAIL receptors. In this study, we report the toxic effects of a novel recombinant agonistic human anti-TRAIL receptor 1 (DR4) monoclonal antibody Fab fragment, DR4-4, on various TRAIL-resistant and -sensitive cancer cell lines. The mechanisms of DR4-4 Fab-induced cell death in a human T cell leukemia cell line (Jurkat) were investigated using cell viability testing, immunoblotting, immunoassays, flow cytometry, and morphological observation. DR4-4 Fab-induced caspase-independent necrosis was observed to occur in Jurkat cells in association with p38 mitogen-activated protein kinase activation, cellular FLICE (FADD-like IL-1β-converting enzyme)-inhibitory protein degradation, decreased mitochondrial membrane potential, and increased mitochondrial reactive oxygen species production. Increased cytotoxic effects of DR4-4 Fab were observed in combination with TRAIL or γ-irradiation. Our results indicate that the novel DR4-4 Fab might overcome TRAIL-resistance and induce death in leukemia cells via cellular mechanisms different from those activated by TRAIL. DR4-4 Fab may have application as a potential therapeutic antibody fragment in single or combination therapy for cancer.

Tumor Necrosis Factor-Alpha as Differential Diagnostic Marker for Patients with Fever of Unknown Origin

Febrile conditions of unidentified origin are still unknown in modern medicine despite the development of diagnostic procedures. There are various agents of long-term temperature encompassing numerous infectious or non-infectious diseases.

The aim of this study was to determine if there was a statistically significant difference in the values of proinflammatory cytokines (IL-1, TNFα, IL-6) in patients who meet the criteria for febrile conditions of unidentified origin, between the group of infectious, malignant, rheumatic, “other” diseases and undiagnosed patients.

The study was conducted in the Immunology laboratory of the Center for Molecular Medicine and Stem Cells Research of the Faculty of Medical Sciences in Kragujevac. Blood samples were taken from patients tested at the Clinic for Infectious Diseases, of the Clinical Center of Kragujevac, in the period from 2014 to 2016. The study included 70 patients.

The measured values of the level of TNFα showed significantly higher values in a group of malignant diseases than in the group of infectious diseases, while the values of IL-1 and IL-6 did not show statistical significance.

TNFα can improve diagnosing in case of patients with an unknown febrile condition, which can shorten the length of the hospital stay and reduce the volume of performance of diagnostic procedures.

DR5 mAb-conjugated, DTIC-loaded immuno-nanoparticles effectively and specifically kill malignant melanoma cells in vivo

We combined chemo- and immunotherapies by constructing dual therapeutic function immuno-nanoparticles (NPs) consisting of death receptor 5 monoclonal antibody (DR5 mAb)-conjugated nanoparticles loaded with dacarbazine (DTIC) (DTIC-NPs-DR5 mAb). We determined the in vivo targeting specificity of DTIC-NPs-DR5 mAb by evaluating distribution in tumor-bearing nude mice using a real-time imaging system. Therapeutic efficacy was assessed in terms of its effect on tumor volume, survival time, histomorphology, microvessel density (MVD), and apoptotic index (AI). Systemic toxicity was evaluated by measuring white blood cells (WBC) counts, alanine aminotransferase (ALT) levels, and creatinine clearance (CR).In vivo and ex vivo imaging indicates that DR5 mAb modification enhanced the accumulation of NPs within the xenograft tumor. DTIC-NPs-DR5 mAb inhibited tumor growth more effectively than DTIC or DR5 mAb alone, indicating that combining DTIC and DR5 mAb through pharmaceutical engineering achieves a better therapeutic effect. Moreover, the toxicity of DTIC-NPs-DR5 mAb was much lower than that of DTIC, implying that DR5 mAb targeting reduces nonspecific uptake of DTIC into normal tissue and thus decreases toxic side effects. These results demonstrate that DTIC-NPs-DR5 mAb is a safe and effective nanoparticle formulation with the potential to improve the efficacy and specificity of melanoma treatment.

Monoclonal Antibody Therapies for Hematological Malignancies: Not Just Lineage-Specific Targets

Today, monoclonal antibodies (mAbs) are a widespread and necessary tool for biomedical science. In the hematological cancer field, since rituximab became the first mAb approved by the Food and Drug Administration for the treatment of B-cell malignancies, a number of effective mAbs targeting lineage-specific antigens (LSAs) have been successfully developed. Non-LSAs (NLSAs) are molecules that are not restricted to specific leukocyte subsets or tissues but play relevant pathogenic roles in blood cancers including the development, proliferation, survival, and refractoriness to therapy of tumor cells. In consequence, efforts to target NLSAs have resulted in a plethora of mAbs-marketed or in development-to achieve different goals like neutralizing oncogenic pathways, blocking tumor-related chemotactic pathways, mobilizing malignant cells from tumor microenvironment to peripheral blood, modulating immune-checkpoints, or delivering cytotoxic drugs into tumor cells. Here, we extensively review several novel mAbs directed against NLSAs undergoing clinical evaluation for treating hematological malignancies. The review focuses on the structure of these antibodies, proposed mechanisms of action, efficacy and safety profile in clinical studies, and their potential applications in the treatment of hematological malignancies.

Cancer vaccines and immunotherapeutic approaches in hepatobiliary and pancreatic cancers

Hepatobiliary and pancreatic cancers along with other gastrointestinal malignancies remain the leading cause of cancer-related deaths worldwide. Strategies developed in the recent years on immunotherapy and cancer vaccines in the setting of primary liver cancer as well as in pancreatic cancer are the scope of this review. Significance of orthotopic and autochthonous animal models which mimic and/or closely reflect human malignancies allowing for a prompt and trustworthy analysis of new therapeutics is underlined. Combinational approaches that on one hand, specifically target a defined cancer-driving pathway, and on the other hand, restore the functions of immune cells, which effector functions are often suppressed by a tumor milieu, are shown to have the strongest perspectives and future directions. Among combinational immunotherapeutic approaches a personalized- and individual cancer case-based therapy is of special importance.

Antibodies and Derivatives Targeting DR4 and DR5 for Cancer Therapy

Developing therapeutics that induce apoptosis in cancer cells has become an increasingly attractive approach for the past 30 years. The discovery of tumor necrosis factor (TNF) superfamily members and more specifically TNF-related apoptosis-inducing ligand (TRAIL), the only cytokine of the family capable of eradicating selectively cancer cells, led to the development of numerous TRAIL derivatives targeting death receptor 4 (DR4) and death receptor 5 (DR5) for cancer therapy. With a few exceptions, preliminary attempts to use recombinant TRAIL, agonistic antibodies, or derivatives to target TRAIL agonist receptors in the clinic have been fairly disappointing. Nonetheless, a tremendous effort, worldwide, is being put into the development of novel strategic options to target TRAIL receptors. Antibodies and derivatives allow for the design of novel and efficient agonists. We summarize and discuss here the advantages and drawbacks of the soar of TRAIL therapeutics, from the first developments to the next generation of agonistic products, with a particular insight on new concepts.

Enhancement of death receptor 4-mediated apoptosis and cytotoxicity in renal cell carcinoma cells by anisomycin

Renal cell carcinoma (RCC) is one of the most drug-resistant malignancies, and an effective therapy is lacking for metastatic RCC. Anisomycin is known to inhibit protein synthesis and induce ribotoxic stress. The aim of this study was to explore whether anisomycin enhances the cytotoxic effects of mapatumumab, a human agonistic monoclonal antibody specific for death receptor 4 (DR4), in human RCC cells. We examined the cytotoxicity of anisomycin alone and in combination with mapatumumab in human RCC cell lines and primary RCC cell cultures. RCC cells treated with anisomycin showed cytotoxicity in a dose-dependent manner. Anisomyin in combination with mapatumumab showed a synergistic effect not only in two human RCC cell lines but also in five primary RCC cell cultures. The synergy between anisomycin and mapatumumab for cytotoxicity was also observed for apoptosis. Interestingly, anisomycin significantly increased DR4 expression at both the mRNA and the protein level. Furthermore, the combination-induced cytotoxicity was significantly suppressed by a human recombinant DR4:Fc chimeric protein. The combination of anisomycin and mapatumumab also enhanced the activity of caspases 8 and 3, the downstream molecules of death receptors. These findings indicate that anisomycin sensitizes RCC cells to DR4-mediated apoptosis through the induction of DR4, suggesting that combinational treatment with anisomycin and mapatumumab might represent a novel therapeutic strategy for the treatment of RCC.

Identification of Novel Epitopes with Agonistic Activity for the Development of Tumor Immunotherapy Targeting TRAIL-R1

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) receptor-1/2 (TRAIL-R1/R2), also known as death receptors, are expressed in a wide variety of tumor cells. Although TRAIL can induce cell apoptosis by engaging its cognate TRAIL-R1/R2, some tumor cells are or become resistant to TRAIL treatment. Monoclonal antibodies (mAbs) against TRAIL-R1/R2 have been developed to use as potential antitumor therapeutic agents instead of TRAIL. However, TRAIL-R1/R2-based tumor therapy has not yet been realized. We previously generated a series of fully human monoclonal antibodies against TRAIL-R1 (TR1-mAbs) that induced tumor cell apoptosis. In this study, we identified the antigenic binding sites of these TR1-mAbs and proposed two major epitopes on the extracellular domain of TRAIL-R1. The analysis revealed that the epitopes of some TR1-mAbs partially overlaps with the beginning of TRAIL-binding sites, and other epitopes are located within the TRAIL-binding region. Among these mAbs, TR1-422 and TR1-419 mAbs have two antigenic binding sites that bound to the same binding region, but they have different essential amino acid residues and binding site sizes. Furthermore, we investigated the apoptosis activity of TR1-419 and TR1-422 mAbs in the form of IgG and IgM. In contrast to the IgG-type TR1-419 and TR1-422 mAbs, which enhanced and inhibited TRAIL-induced apoptosis, respectively, both IgM-type TR1-419 and TR1-422 mAb strongly induced cell apoptosis with or without soluble TRAIL (sTRAIL). Moreover, the results showed that IgM-type TR1-419 and TR1-422 mAbs alone can sufficiently activate the extrinsic and intrinsic apoptosis signaling pathways and suppress tumor growth in vivo. Consequently, we identified two antigenic binding sites with agonistic activity, and their specific IgM-type mAbs exhibited strong cytotoxic activity in tumor cells in vitro and in vivo. Thus, these agonistic antigenic binding sites may be useful for the development of effective Ab-based drugs or Ab-based cell immunotherapy for various human solid tumors.

Improvement of Pharmacokinetic Profile of TRAIL via Trimer-Tag Enhances its Antitumor Activity in vivo

TNF-related apoptosis-inducing ligand (TRAIL/Apo2L) has long been considered a tantalizing target for cancer therapy because it mediates activation of the extrinsic apoptosis pathway in a tumor-specific manner by binding to and trimerizing its functional receptors DR4 or DR5. Despite initial promise, both recombinant human TRAIL (native TRAIL) and dimeric DR4/DR5 agonist monoclonal antibodies (mAbs) failed in multiple human clinical trials. Here we show that in-frame fusion of human C-propeptide of α1(I) collagen (Trimer-Tag) to the C-terminus of mature human TRAIL leads to a disulfide bond-linked homotrimer which can be expressed at high levels as a secreted protein from CHO cells. The resulting TRAIL-Trimer not only retains similar bioactivity and receptor binding kinetics as native TRAIL in vitro which are 4-5 orders of magnitude superior to that of dimeric TRAIL-Fc, but also manifests more favorable pharmacokinetic and antitumor pharmacodynamic profiles in vivo than that of native TRAIL. Taken together, this work provides direct evidence for the in vivo antitumor efficacy of TRAIL being proportional to systemic drug exposure and suggests that the previous clinical failures may have been due to rapid systemic clearance of native TRAIL and poor apoptosis-inducing potency of dimeric agonist mAbs despite their long serum half-lives.

Antibody targeting intracellular oncogenic Ras mutants exerts anti-tumour effects after systemic administration

Oncogenic Ras mutants, frequently detected in human cancers, are high-priority anticancer drug targets. However, direct inhibition of oncogenic Ras mutants with small molecules has been extremely challenging. Here we report the development of a human IgG1 format antibody, RT11, which internalizes into the cytosol of living cells and selectively binds to the activated GTP-bound form of various oncogenic Ras mutants to block the interactions with effector proteins, thereby suppressing downstream signalling and exerting anti-proliferative effects in a variety of tumour cells harbouring oncogenic Ras mutants. When systemically administered, an RT11 variant with an additional tumour-associated integrin binding moiety for tumour tissue targeting significantly inhibits the in vivo growth of oncogenic Ras-mutated tumour xenografts in mice, but not wild-type Ras-harbouring tumours. Our results demonstrate the feasibility of developing therapeutic antibodies for direct targeting of cytosolic proteins that are inaccessible using current antibody technology.

Journey of TRAIL from Bench to Bedside and its Potential Role in Immuno-Oncology

Induction of apoptosis in cancer cells has increasingly been the focus of many therapeutic approaches in oncology field. Since its identification as a TNF family member, TRAIL (TNF-related apoptosis-inducing ligand) paved a new path in apoptosis inducing cancer therapies. Its selective ability to activate extrinsic and intrinsic cell death pathways in cancer cells only, independently from p53 mutations responsible for conventional therapeutics resistance, spotted TRAIL as a potent cancer apoptotic agent. Many recombinant preparations of TRAIL and death receptor targeting monoclonal antibodies have been developed and being tested pre-clinically and clinically both as a single agent and in combinations. Of note, the monoclonal antibodies were not the only type of antibodies developed to target TRAIL receptors. Recent technology has brought forth several single chain variable domains (scFv) designs fused recombinantly to TRAIL as well. Also, it is becoming progressively more understandable that field of nanotechnology has revolutionized cancer diagnosis and therapy. The recent breakthroughs in materials science and protein engineering have helped considerably in strategically loading drugs into nanoparticles or conjugating drugs to their surface. In this review we aim to comprehensively highlight the molecular knowledge of TRAIL in the context of its pathway, receptors and resistance factors. We also aim to review the clinical trials that have been done using TRAIL based therapies and to review various scFv designs, the arsenal of nano-carriers and molecules available to selectively target tumor cells with TRAIL.

Restoring TRAIL Induced Apoptosis Using Naturopathy. Hercules Joins Hand with Nature to Triumph Over Lernaean Hydra

Cancer is a multifaceted disease. Our deepened knowledge about genetic and biological mechanisms of cancer cells presents an opportunity to explore the inter-individual differences in the body’s ability to metabolize and respond to different nutrients. It is becoming progressively more understandable that the deregulation of several signaling pathways and the alterations in apoptotic response are some of the major determinants that underpin carcinogenesis. Tumor necrosis factor-Related Apoptosis-Inducing Ligand (TRAIL)-mediated signaling has gained a remarkable appreciation because of its ability to selectively induce apoptosis in cancer cells leaving normal cells intact. However, technological advances have started to shed light on underlying mechanisms of resistance against TRAIL-induced apoptosis in cancer cells. The impairment of TRAIL-mediated apoptosis includes various factors ranging from the loss or down regulation of TRAIL receptors or pro-apoptotic proteins to the up regulation of anti-apoptotic proteins. Intriguingly to mention that there is an ever-increasing number of natural herbal extracts (phytometabolites), which have been explored to date for their potential action in restoring apoptosis TRAIL-mediated in cancer cells. In this review, we will highlight the progress in understanding the mechanisms opted by phenolic compounds in overcoming TRAIL resistance.

Hyaluronate-Gold Nanorod/DR5 Antibody Complex for Noninvasive Theranosis of Skin Cancer

Noninvasive transdermal delivery is a promising method with distinct advantages including patient compliance over other delivery routes. Here, hyaluronate-gold nanorod/death receptor 5 antibody (HA-AuNR/DR5 Ab) complex was developed for transdermal theranosis of skin cancer. The successful formation of the complex was corroborated by ¹H nuclear magnetic resonance, UV-vis spectroscopy, dynamic light scattering, zeta potential, and transmission electron microscopy. In vitro biological activity of the complex was verified by ELISA and MTT assay using HCT116 cancer cells. In addition, in vivo photoacoustic imaging and two-photon microscopy clearly visualized the transdermal delivery of HA-AuNR/DR5 Ab complex through the inevitable barrier of stratum corneum in the skin. Furthermore, in vivo antitumor effect on skin cancer model mice was confirmed from statistically significant decrease of tumor-reflecting luciferase expression levels and apoptotic signals in terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay. Taken together, we could confirm the feasibility of HA-AuNR/DR5 Ab complex as a novel theranostic platform for noninvasive transdermal treatment of skin cancers.

Phage display-derived human antibodies in clinical development and therapy

Over the last 3 decades, monoclonal antibodies have become the most important class of therapeutic biologicals on the market. Development of therapeutic antibodies was accelerated by recombinant DNA technologies, which allowed the humanization of murine monoclonal antibodies to make them more similar to those of the human body and suitable for a broad range of chronic diseases like cancer and autoimmune diseases. In the early 1990s in vitro antibody selection technologies were developed that enabled the discovery of “fully” human antibodies with potentially superior clinical efficacy and lowest immunogenicity.

Antibody phage display is the first and most widely used of the in vitro selection technologies. It has proven to be a robust, versatile platform technology for the discovery of human antibodies and a powerful engineering tool to improve antibody properties. As of the beginning of 2016, 6 human antibodies discovered or further developed by phage display were approved for therapy. In 2002, adalimumab (Humira®) became the first phage display-derived antibody granted a marketing approval. Humira® was also the first approved human antibody, and it is currently the best-selling antibody drug on the market. Numerous phage display-derived antibodies are currently under advanced clinical investigation, and, despite the availability of other technologies such as human antibody-producing transgenic mice, phage display has not lost its importance for the discovery and engineering of therapeutic antibodies.

Here, we provide a comprehensive overview about phage display-derived antibodies that are approved for therapy or in clinical development. A selection of these antibodies is described in more detail to demonstrate different aspects of the phage display technology and its development over the last 25 years.

TRAIL-receptor 1 IgM antibodies strongly induce apoptosis in human cancer cells in vitro and in vivo

Agonistic tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL)-receptor-specific antibodies are attractive antitumor therapeutics. Recently, our group has generated several human monoclonal antibodies (mAbs) to TRAIL-receptor-1 (TRAIL-R1) (TR1-IgGs) using ISAAC technology. However, these TR1-IgGs did not demonstrate ideal apoptosis-inducing capacity in the absence of additional antibodies. To overcome this limitation, we class-switched the TR1-IgGs to TRAIL-R1 IgM antibodies (TR1-IgMs); TR1-IgMs might possess high valency and facilitate the crosslinking of the cell surface receptors. We showed that the TR1-IgMs bound TRAIL-R1, activated the caspase signal, and induced strong apoptosis (100-fold higher compared with the IgG form in one case) in human tumor cell lines without any additional crosslinking in vitro. We further demonstrated that these TR1-IgMs dramatically inhibited tumor growth in a xenograft model through the caspase activation cascade. These data suggest that TR1-IgMs may become potential immunotherapeutic agents for cancer therapy.

High-efficiency antibody discovery achieved with multiplexed microscopy

The analysis of secreted antibody from large and diverse populations of B cells in parallel at the clonal level can reveal desirable antibodies for diagnostic or therapeutic applications. By immobilizing B cells in microdroplets with particulate reporters, decoding and isolating them in a microscopy environment, we have recovered panels of antibodies with rare attributes to therapeutically relevant targets. The ability to screen up to 100 million cells in a single experiment can be fully leveraged by accessing primary B-cell populations from evolutionarily divergent species such as chickens.

A randomized, double-blind, placebo-controlled phase II study to assess the efficacy and safety of mapatumumab with sorafenib in patients with advanced hepatocellular carcinoma

BACKGROUND

This randomized, double-blind, placebo-controlled, phase II study evaluated the efficacy and safety of mapatumumab (a human agonistic monoclonal antibody against tumor necrosis factor-related apoptosis-inducing ligand receptor 1) in combination with sorafenib in patients with advanced hepatocellular carcinoma (HCC).

PATIENTS AND METHODS

Patients with advanced HCC (stratified by Barcelona Clinic Liver Cancer stage and Eastern Cooperative Oncology Group performance status) were randomized 1:1 to receive sorafenib (400 mg, twice daily per 21-day cycle) and either placebo (placebo-sorafenib arm) or mapatumumab (30 mg/kg on day 1 per 21-day cycle; mapatumumab-sorafenib arm). The primary end point was time to (radiologic) progression (TTP), assessed by blinded independent central review. Key secondary end points included progression-free survival, overall survival, and objective response.

RESULTS

In total, 101 patients were randomized (placebo-sorafenib arm: N = 51; mapatumumab-sorafenib arm: N = 50). There was no significant difference in median TTP between both arms [5.6 versus 4.1 months, respectively; adjusted hazard ratio (one-sided 90% confidence interval) 1.192 (0-1.737)]. No mapatumumab-related benefit was identified when TTP was evaluated in the stratified subgroups. The addition of mapatumumab to sorafenib did not demonstrate improvement in the secondary efficacy end points. The reported frequency of adverse events (AEs) and serious AEs was comparable in both treatment arms.

CONCLUSIONS

The addition of mapatumumab to sorafenib did not improve TTP or other efficacy end points, nor did it substantially change the toxicity profile of sorafenib in patients with advanced HCC. Based on these results, further development of the combination of mapatumumab and sorafenib in HCC is not planned.

TRAIL-based therapy in pediatric bone tumors: how to overcome resistance

Osteosarcoma and Ewing's sarcoma, the two most frequent malignant primary tumors preferentially arise in children and young adults, and have a poor prognosis. TRAIL represents a promising therapeutic approach for most cancers but in the case of primary bone tumors, osteosarcoma cell lines are highly resistant to this pro-apoptotic cytokine. In addition, another signaling pathway mediating cell proliferation and migration may be even activated in this subset of resistant cells leading to protumoral effect. Therapeutic perspectives are linked to possibility to overcome TRAIL resistance by combining other drugs with TRAIL or death receptors agonistic antibodies. We hypothesized that the bone microenvironment may provide a favorable niche for TRAIL resistance that might be targeted by new resensitizing agents.

Dual Agonist Surrobody Simultaneously Activates Death Receptors DR4 and DR5 to Induce Cancer Cell Death

Death receptors of the TNF family are found on the surface of most cancer cells and their activation typically kills cancer cells through the stimulation of the extrinsic apoptotic pathway. The endogenous ligand for death receptors 4 and 5 (DR4 and DR5) is TNF-related apoptosis-inducing ligand, TRAIL (Apo2L). As most untransformed cells are not susceptible to TRAIL-induced apoptosis, death receptor activators have emerged as promising cancer therapeutic agents. One strategy to stimulate death receptors in cancer patients is to use soluble human recombinant TRAIL protein, but this agent has limitations of a short half-life and decoy receptor sequestration. Another strategy that attempted to evade decoy receptor sequestration and to provide improved pharmacokinetic properties was to generate DR4 or DR5 agonist antibodies. The resulting monoclonal agonist antibodies overcame the limitations of short half-life and avoided decoy receptor sequestration, but are limited by activating only one of the two death receptors. Here, we describe a DR4 and DR5 dual agonist produced using Surrobody technology that activates both DR4 and DR5 to induce apoptotic death of cancer cells in vitro and in vivo and also avoids decoy receptor sequestration. This fully human anti-DR4/DR5 Surrobody displays superior potency to DR4- and DR5-specific antibodies, even when combined with TRAIL-sensitizing proapoptotic agents. Moreover, cancer cells were less likely to acquire resistance to Surrobody than either anti-DR4 or anti-DR5 monospecific antibodies. Taken together, Surrobody shows promising preclinical proapoptotic activity against cancer cells, meriting further exploration of its potential as a novel cancer therapeutic agent.

Principles of antibody-mediated TNF receptor activation

From the beginning of research on receptors of the tumor necrosis factor (TNF) receptor superfamily (TNFRSF), agonistic antibodies have been used to stimulate TNFRSF receptors in vitro and in vivo. Indeed, CD95, one of the first cloned TNFRSF receptors, was solely identified as the target of cell death-inducing antibodies. Early on, it became evident from in vitro studies that valency and Fcγ receptor (FcγR) binding of antibodies targeting TNFRSF receptors can be of crucial relevance for agonistic activity. TNFRSF receptor-specific antibodies of the IgM subclass and secondary cross-linked or aggregation prone dimeric antibodies typically display superior agonistic activity compared with dimeric antibodies. Likewise, anchoring of antibodies to cell surface-expressed FcγRs potentiate their ability to trigger TNFRSF receptor signaling. However, only recently has the relevance of oligomerization and FcγR binding for the in vivo activity of antibody-induced TNFRSF receptor activation been straightforwardly demonstrated in vivo. This review discusses the crucial role of oligomerization and/or FcγR binding for antibody-mediated TNFRSF receptor stimulation in light of current models of TNFRSF receptor activation and especially the overwhelming relevance of these issues for the rational development of therapeutic TNFRSF receptor-targeting antibodies.

5-Fluorouracil preferentially sensitizes mutant KRAS non-small cell lung carcinoma cells to TRAIL-induced apoptosis

Mutations in the KRAS gene are very common in non-small cell lung cancer (NSCLC), but effective therapies targeting KRAS have yet to be developed. Interest in tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), a potent inducer of cell death, has increased following the observation that TRAIL can selectively kill a wide variety of human cancer cells without killing normal cells both in vitro and in xenograft models. However, results from clinical trials of TRAIL-based therapy are disappointingly modest at best and many have demonstrated a lack of therapeutic benefit. Current research has focused on selecting a subpopulation of cancer patients who may benefit from TRAIL-based therapy and identifying best drugs to work with TRAIL. In the current study, we found that NSCLC cells with a KRAS mutation were highly sensitive to treatment with TRAIL and 5-fluorouracil (5FU). Compared with other chemotherapeutic agents, 5FU displayed the highest synergy with TRAIL in inducing apoptosis in mutant KRAS NSCLC cells. We also found that, on a mechanistic level, 5FU preferentially repressed survivin expression and induced expression of TRAIL death receptor 5 to sensitize NSCLC cells to TRAIL. The combination of low-dose 5FU and TRAIL strongly inhibited xenograft tumor growth in mice. Our results suggest that the combination of TRAIL and 5FU may be beneficial for patients with mutant KRAS NSCLC.

Small molecule inhibitor of apoptosis proteins antagonists: a patent review

INTRODUCTION

The family of inhibitor of apoptosis proteins (IAPs) plays a key role in the suppression of proapoptotic signaling; hence, a small molecule that disrupts the binding of IAPs with their functional partner should restore apoptotic response to proapoptotic stimuli in cells. The continued publication of new patent applications of IAP antagonists over the past 4 years is a testament to the continued interest surrounding the IAP family of proteins.

AREAS COVERED

This review summarizes the IAP antagonist patent literature from 2010 to 2014. Monovalent and bivalent Smac mimetics will be covered as well as two new developments in the field: IAP antagonists coupled to or merged with other targeted agents and new BIR2 selective IAP antagonists.

EXPERT OPINION

In addition to the well-explored scaffolds for monovalent and bivalent Smac-mimetics, some companies have taken more drastic approaches to explore new chemical space - for example, fragment-based approaches and macrocyclic inhibitors. Furthermore, other companies have designed compounds with alternative biological profiles - tethering to known kinase binding structures, trying to target to the mitochondria or introducing selective binding to the BIR2 domain. An overview of the status for the four small molecule IAP antagonists being evaluated in active human clinical trials is also provided.

Fractional killing arises from cell-to-cell variability in overcoming a caspase activity threshold

When cells are exposed to death ligands such as TRAIL, a fraction undergoes apoptosis and a fraction survives; if surviving cells are re-exposed to TRAIL, fractional killing is once again observed. Therapeutic antibodies directed against TRAIL receptors also cause fractional killing, even at saturating concentrations, limiting their effectiveness. Fractional killing arises from cell-to-cell fluctuations in protein levels (extrinsic noise), but how this results in a clean bifurcation between life and death remains unclear. In this paper, we identify a threshold in the rate and timing of initiator caspase activation that distinguishes cells that live from those that die; by mapping this threshold, we can predict fractional killing of cells exposed to natural and synthetic agonists alone or in combination with sensitizing drugs such as bortezomib. A phenomenological model of the threshold also quantifies the contributions of two resistance genes (c-FLIP and Bcl-2), providing new insight into the control of cell fate by opposing pro-death and pro-survival proteins and suggesting new criteria for evaluating the efficacy of therapeutic TRAIL receptor agonists.