Combination therapy of established tumors by antibodies targeting immune activating and suppressing molecules

Recent research and clinical progress of CTLA-4-based immunotherapy for breast cancer

Breast cancer is characterized by a high incidence rate and its treatment challenges, particularly in certain subtypes. Consequently, there is an urgent need for the development of novel therapeutic approaches. Immunotherapy utilizing immune checkpoint inhibitors (ICIs) is currently gaining momentum for the treatment of breast cancer. Substantial progress has been made in clinical studies employing cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) inhibitors for breast cancer, but the cure rates are relatively low. To improve the efficacy of CTLA-4-based therapy for breast cancer, further research is imperative to explore more effective immune-based treatment strategies. In addition to monotherapy, CTLA-4 inhibitors are also being investigated in combination with other ICIs or alternative medications. However, it should be noted that immune-based treatments may cause adverse events. This review focuses on the mechanisms of CTLA-4 inhibitor monotherapy or combination therapy in breast cancer. We systematically summarize the latest research and clinical advances in CTLA-4-based immunotherapy for breast cancer, providing new perspectives on the treatment of breast cancer. In addition, this review highlights the immune-related adverse events (irAEs) associated with CTLA-4 inhibitors, providing insights into the development of appropriate clinical tumor immunotherapy regimens and intervention strategies.

Update on immunotherapy in the management of gallbladder cancer

Gallbladder cancer (GBC) is a relatively infrequent but highly lethal cancer with a poor prognosis. Management remains challenging and controversial, and most patients are diagnosed at an advanced stage. However, with the progressive advances in the use of immunotherapies, new treatment modalities are being implemented. In September 2022, the US FDA approved durvalumab (a PD-L1 inhibitor) in combination with chemotherapy for adult patients with locally advanced or metastatic GBC. This groundbreaking news is the first FDA approval for the use of immunotherapy in biliary tract cancers. This article reviews the newest advances and trials regarding immunotherapy for GBC.

Tsunami of immunotherapies in the management of esophageal cancer

Esophageal cancer (EC) is relatively frequent and highly lethal cancer, being the sixth most common cause of cancer death worldwide. The progressive approvals of immunotherapy as first-line and second-line treatment options have paved the way for an evolving new approach to the treatment of this disease. Management of EC is challenging and requires a multimodality approach. Treatment options include surgery, chemoradiotherapy (CRT) and, recently, immunotherapy. The newest guidelines and FDA approvals regarding immunotherapy for EC are reviewed here.

Anti-CTLA-4 and anti-PD-1 immunotherapies repress tumor progression in preclinical breast and colon model with independent regulatory T cells response

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Anti-PD-1 and anti-CTLA-4 induced anti-tumor response in breast cancer mouse model.

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Anti-PD-1 and anti-CTLA-4 induced anti-tumor response in colon cancer mouse model.

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Anti-CTLA-4 reduced colon cancer–derived lung metastasis formation in a mouse model.

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We identified specific T cell response between anti-PD-1 and anti-CTLA-4.

The recent development of immunotherapy represents a significant breakthrough in cancer therapy. Several immunotherapies provide robust efficacy gains in a wide variety of cancers. However, in some patients the immune checkpoint blockade remains ineffective due to poor therapeutic response and tumor relapse. An improved understanding of the mechanisms underlying tumor-immune system interactions can improve clinical management of cancer. Here, we report preclinical data evaluating two murine antibodies corresponding to recent FDA-approved antibodies for human therapy, e.g. anti-CTLA-4 and anti-PD-1. We demonstrated in two mouse syngeneic grafting models of triple negative breast or colon cancer that the two antibodies displayed an efficient anticancer activity, which is enhanced by combination treatment in the breast cancer model. We also demonstrated that CTLA-4 targeting reduced metastasis formation in the colon cancer metastasis model. In addition, using cytometry-based multiplex analysis, we showed that anti-CTLA-4 and anti-PD-1 affected the tumor immune microenvironment differently and in particular the tumor immune infiltration. This work demonstrated anti-cancer effect of CTLA-4 or PD-1 blockade on mouse colon and triple negative breast and on tumor-infiltrating immune cell subpopulations that could improve our knowledge and benefit the breast and colon cancer tumor research community.

Fine-Tuning the Tumour Microenvironment: Current Perspectives on the Mechanisms of Tumour Immunosuppression

Immunotherapy has revolutionised the treatment of cancers by harnessing the power of the immune system to eradicate malignant tissue. However, it is well recognised that some cancers are highly resistant to these therapies, which is in part attributed to the immunosuppressive landscape of the tumour microenvironment (TME). The contexture of the TME is highly heterogeneous and contains a complex architecture of immune, stromal, vascular and tumour cells in addition to acellular components such as the extracellular matrix. While understanding the dynamics of the TME has been instrumental in predicting durable responses to immunotherapy and developing new treatment strategies, recent evidence challenges the fundamental paradigms of how tumours can effectively subvert immunosurveillance. Here, we discuss the various immunosuppressive features of the TME and how fine-tuning these mechanisms, rather than ablating them completely, may result in a more comprehensive and balanced anti-tumour response.

An Agonistic Anti-CD137 Antibody Disrupts Lymphoid Follicle Structure and T-Cell-Dependent Antibody Responses

CD137 is a costimulatory receptor expressed on natural killer cells, T cells, and subsets of dendritic cells. An agonistic monoclonal antibody (mAb) against CD137 has been used to reduce tumor burden or reverse autoimmunity in animal models and clinical trials. Here, we show that mice treated with an agonistic anti-CD137 mAb have reduced numbers of germinal center (GC) B cells and follicular dendritic cells (FDCs) in lymphoid tissues, which impair antibody responses to multiple T-cell-dependent antigens, including infectious virus, viral proteins, and conjugated haptens. These effects are not due to enhanced apoptosis or impaired proliferation of B cells but instead correlate with changes in lymphoid follicle structure and GC B cell dispersal and are mediated by CD137 signaling in CD4⁺ and CD8⁺ T cells. Our experiments in mice suggest that agonistic anti-CD137 mAbs used in cancer and autoimmunity therapy may impair long-term antibody and B cell memory responses.

Anti-CD137 antibody impairs B cell responses during chikungunya virus infection

Anti-CD137 antibody impairs T-cell-dependent antibody responses to subunit vaccines

Anti-CD137 antibody alters lymphoid follicle structure during virus infection

Enhanced CD137 signaling in T cells results in defects in germinal B cell responses

Therapeutic strategies for the costimulatory molecule OX40 in T-cell-mediated immunity

The T cell co-stimulatory molecule OX40 and its cognate ligand OX40L have attracted broad research interest as a therapeutic target in T cell-mediated diseases. Accumulating preclinical evidence highlights the therapeutic efficacy of both agonist and blockade of the OX40-OX40L interaction. Despite this progress, many questions about the immuno-modulator roles of OX40 on T cell function remain unanswered. In this review we summarize the impact of the OX40-OX40L interaction on T cell subsets, including Th1, Th2, Th9, Th17, Th22, Treg, Tfh, and CD8+ T cells, to gain a comprehensive understanding of anti-OX40 mAb-based therapies. The potential therapeutic application of the OX40-OX40L interaction in autoimmunity diseases and cancer immunotherapy are further discussed; OX40-OX40L blockade may ameliorate autoantigen-specific T cell responses and reduce immune activity in autoimmunity diseases. We also explore the rationale of targeting OX40-OX40L interactions in cancer immunotherapy. Ligation of OX40 with targeted agonist anti-OX40 mAbs conveys activating signals to T cells. When combined with other therapeutic treatments, such as anti-PD-1 or anti-CTLA-4 blockade, cytokines, chemotherapy, or radiotherapy, the anti-tumor activity of agonist anti-OX40 treatment will be further enhanced. These data collectively suggest great potential for OX40-mediated therapies.

Nanotopography-based lymphatic delivery for improved anti-tumor responses to checkpoint blockade immunotherapy

Rationale: Cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) is a co-inhibitory checkpoint receptor that is expressed by naïve T-cells in lymph nodes (LNs) to inhibit activation against “self” antigens (Ags). In cancer, anti-CTLA-4 blocks inhibitory action, enabling robust activation of T-cells against tumor Ags presented in tumor draining LNs (TDLNs). However, anti-CTLA-4 is administered intravenously with limited exposure within TDLNs and immune related adverse events (irAEs) are associated with over-stimulation of the immune system.

Methods: Herein, we first deliver anti-CTLA-4 in an orthotopic mammary carcinoma murine model using a nanotopographical microneedle-array device to compare its anti-tumor response to that from systemic administration. Additionally, to demonstrate the feasibility of lymphatic delivery in humans using the device, we use near-infrared fluorescence imaging to image delivery of ICG to LNs.

Results: Our data show that lymphatic infusion results in more effective tumor growth inhibition, arrest of metastases, increased tumor infiltrating lymphocytes and complete responses when compared to conventional systemic administration. In clinical studies, we demonstrate for the first time that nanotopographic infusion can deliver ICG through the lymphatics directly to the axilla and inguinal LNs of healthy human volunteers.

Conclusion: Taken together, these results suggest that regional delivery using a nanotopography-based microneedle array could revolutionize checkpoint blockade immunotherapy by reducing systemic drug exposure and maximizing drug delivery to TDLNs where tumor Ags present. Future work is needed to determine whether lymphatic delivery of anti-CTLA-4 can alleviate irAEs that occur with systemic dosing.

Beneficial effects of sunitinib on tumor microenvironment and immunotherapy targeting death receptor5

Tumor-associated blood vessels and lymphatics are abnormal and dysfunctional. These are hallmarks of the tumor microenvironment, which has an immunosuppressive nature, such as through hypoxia. Treatment with anti-death receptor5 (DR5) monoclonal antibody MD5-1, which induces tumor cell death, is a potent anti-tumor immunotherapy. Generally, MD5-1 induces cell death mainly via antigen presenting cells (APCs) and generates tumor-specific effector T cells. To date, the effects of a simultaneous functional improvement of abnormal blood vessels and lymphatics on the immune microenvironment are largely unknown. A combination therapy using sunitinib, vascular endothelial growth factor (VEGF) and platelet-derived growth factor receptor inhibitor, and MD5-1 substantially inhibited tumor growth. Sunitinib improved pericyte coverage on endothelial cells and the expression levels of regulator of G-protein signaling 5, suggesting blood vessel normalization. Sunitinib also increased lymph flow from tumors to central lymph nodes, suggesting improved lymphatic function. In concordance with improved vasculature functions, sunitinib alleviated the tumor hypoxia, suggesting an improved tumor microenvironment. Indeed, the combination therapy induced strong activation of CD8⁺ T cells and dendritic cells in draining lymph nodes. The combination therapy reduced the ratio of immune-suppressive T regulatory cells in the tumors and draining lymph nodes. The combination therapy enhanced the numbers and activation of tumor-infiltrating CD8⁺ T cells. CD4 and/or CD8 depletion, or APC inhibiting experiments showed the contribution of CD8⁺ T cells and APCs to the combination therapy. These findings suggest that targeting blood vessels and lymphatics may have potential benefits for immunotherapy mediated by CD8⁺ T cells and APCs.

Stimulation of natural killer cells with rhCD137 ligand enhances tumor-targeting antibody efficacy in gastric cancer

Although many anticancer agents for gastric cancer have been developed, the prognosis for many patients remains poor. Recently, costimulatory immune molecules that reactivate antitumor immune responses by utilizing the host immune system have attracted attention as new therapeutic strategies. CD137 is a costimulatory molecule that reportedly potentiates the antitumor activity of tumor-targeting monoclonal antibodies (mAbs) by enhancing antibody-dependent cellular cytotoxicity. However, it remains unclear whether CD137 stimulates tumor-regulatory activity in gastric cancer. In this study, we investigated the antitumor effects of CD137 stimulation on gastric cancer cells administered tumor-targeting mAbs. Our results showed that human natural killer (NK) cells were activated by expressing CD137 after encountering trastuzumab-coated gastric cancer cells, and that stimulation of activated NK cells in the presence of trastuzumab and recombinant human CD137 ligand (rhCD137L) enhanced cytotoxicity and release of cytokines (IFN-γ, TNF, granzyme A, or granzyme B) as compared with activated NK cells with trastuzumab alone (p < 0.05). By combination treatment with rhCD137L, similar effects were obtained regarding cancer cell cytotoxicity in the presence of cetuximab (p < 0.01). Moreover, we revealed that CD137 expression was dependent upon the affinity between the Fc portion of the antibodies and FcγRIIIa of NK cells based on results indicating that human IgG1 and IgG3 subclasses enhanced CD137 expression (p < 0.001). These results confirmed that FcγRIIIA polymorphisms (158 V/V) enhanced CD137 expression to a greater degree than 158 F polymorphisms (p = 0.014). Our results suggested that CD137 stimulation could promote the effects of tumor-targeting mAbs in gastric cancer, and that further investigation of antibody binding affinity and in vivo activities might improve therapeutic strategies related to the treatment of gastric cancer patients.

Quantitative T-cell repertoire analysis of peripheral blood mononuclear cells from lung cancer patients following long-term cancer peptide vaccination

Therapeutic cancer peptide vaccination is an immunotherapy designed to elicit cytotoxic T-lymphocyte (CTL) responses in patients. A number of therapeutic vaccination trials have been performed, nevertheless there are only a few reports that have analyzed the T-cell receptors (TCRs) expressed on tumor antigen-specific CTLs. Here, we use next-generation sequencing (NGS) to analyze TCRs of vaccine-induced CTL clones and the TCR repertoire of bulk T cells in peripheral blood mononuclear cells (PBMCs) from two lung cancer patients over the course of long-term vaccine therapy. In both patients, vaccination with two epitope peptides derived from cancer/testis antigens (upregulated lung cancer 10 (URLC10) and cell division associated 1 (CDCA1)) induced specific CTLs expressing various TCRs. All URLC10-specific CTL clones tested showed Ca2+ influx, IFN-γ production, and cytotoxicity when co-cultured with URLC10-pulsed tumor cells. Moreover, in CTL clones that were not stained with the URLC10/MHC-multimer, the CD3 ζ chain was not phosphorylated. NGS of the TCR repertoire of bulk PBMCs demonstrated that the frequency of vaccine peptide-specific CTL clones was near the minimum detectable threshold level. These results demonstrate that vaccination induces antigen-specific CTLs expressing various TCRs at different time points in cancer patients, and that some CTL clones are maintained in PBMCs during long-term treatment, including some with TCRs that do not bind peptide/MHC-multimer.

Immunotherapy for Gastric Cancer: Time for a Personalized Approach?

Over the last decade, our understanding of the mechanisms underlying immune modulation has greatly improved, allowing for the development of multiple therapeutic approaches that are revolutionizing the treatment of cancer. Immunotherapy for gastric cancer (GC) is still in the early phases but is rapidly evolving. Recently, multi-platform molecular analyses of GC have proposed a new classification of this heterogeneous group of tumors, highlighting subset-specific features that may more reliably inform therapeutic choices, including the use of new immunotherapeutic drugs. The clinical benefit and improved survival observed in GC patients treated with immunotherapeutic strategies and their combination with conventional therapies highlighted the importance of the immune environment surrounding the tumor. A thorough investigation of the tumor microenvironment and the complex and dynamic interaction between immune cells and tumor cells is a fundamental requirement for the rational design of novel and more effective immunotherapeutic approaches. This review summarizes the pre-clinical and clinical results obtained so far with immunomodulatory and immunotherapeutic treatments for GC and discusses the novel combination strategies that are being investigated to improve the personalization and efficacy of GC immunotherapy.

Next generation immune-checkpoints for cancer therapy

The discovery and clinical application of immune-checkpoint inhibitors has dramatically improved the treatments, outcomes and therapeutic concepts in multiple tumor settings. This breakthrough was mainly based on monoclonal antibodies blocking the inhibitory molecule CTLA-4 and or the PD-1/PD-L1 axis, with the aim of counteracting major tumor immune evasion mechanisms. Even acknowledging these important successes, not all the patients benefit from these treatments. Translational and clinical research efforts are ongoing to explore the potentialities of a new generation of immune-modulatory molecules to extend current clinical applications and contrast the unsolved issues of resistance and disease relapse that still affects a considerable rate of patients. New immune-checkpoints, with either stimulatory or inhibitory functions are emerging with key roles in regulating T cell response but also affecting other crucial effectors belonging to the innate immune response (e.g., natural killer). Their therapeutic exploitation, either alone or in strategical combinations, is providing important preclinical results, holding promises currently explored in initial clinical trials. The first results point toward favorable safety profiles with selective hints of activity in challenging settings. Important issues regarding the dose, schedule and rational combinations remain open and data from the clinical studies are needed. Here we provide an overview of the main emerging stimulatory or inhibitory immune-checkpoints exploitable in cancer treatment, briefly reporting their biological function, preclinical activity and preliminary clinical data.

Next generation of immune checkpoint therapy in cancer: new developments and challenges

Immune checkpoints consist of inhibitory and stimulatory pathways that maintain self-tolerance and assist with immune response. In cancer, immune checkpoint pathways are often activated to inhibit the nascent anti-tumor immune response. Immune checkpoint therapies act by blocking or stimulating these pathways and enhance the body's immunological activity against tumors. Cytotoxic T lymphocyte-associated molecule-4 (CTLA-4), programmed cell death receptor-1 (PD-1), and programmed cell death ligand-1(PD-L1) are the most widely studied and recognized inhibitory checkpoint pathways. Drugs blocking these pathways are currently utilized for a wide variety of malignancies and have demonstrated durable clinical activities in a subset of cancer patients. This approach is rapidly extending beyond CTLA-4 and PD-1/PD-L1. New inhibitory pathways are under investigation, and drugs blocking LAG-3, TIM-3, TIGIT, VISTA, or B7/H3 are being investigated. Furthermore, agonists of stimulatory checkpoint pathways such as OX40, ICOS, GITR, 4-1BB, CD40, or molecules targeting tumor microenvironment components like IDO or TLR are under investigation. In this article, we have provided a comprehensive review of immune checkpoint pathways involved in cancer immunotherapy, and discuss their mechanisms and the therapeutic interventions currently under investigation in phase I/II clinical trials. We also reviewed the limitations, toxicities, and challenges and outline the possible future research directions.

The promise of 4-1BB (CD137) mediated immunomodulation and immunotherapy for viral diseases

The T-cell surface receptor, 4-1BB (CD137), has been of increasing interest to immunologists as a co-stimulatory immune checkpoint molecule over the last two decades. Ligation of 4-1BB can activate signals in CD8+ T cells and NK cells, resulting in increased proinflammatory cytokine secretion, cytolytic function and antibody-dependent cell-mediated cytotoxicity. Targeting 4-1BB, using a 4-1BB ligand (4-1BBL) or agonistic monoclonal antibodies, has delivered a new strategy to fight against cancer, autoimmune diseases and viral infections. In this review, different aspects of 4-1BB mediated antiviral responses, the mechanistic basis of such responses and future directions are discussed.

Cytokines and metabolic factors regulate tumoricidal T-cell function during cancer immunotherapy

Recent advances in cancer biology and genetics have fostered precision therapies targeting tumor-specific attributes. Immune-based therapies that elicit cytolytic T cells (CTL) specific for tumor antigens can provide therapeutic benefit to cancer patients, however, cure rates are typically low. This largely results from immunosuppressive mechanisms operating within the tumor microenvironment, many of which inflict metabolic stresses upon CTL. Conversely, immunotherapies can mitigate specific metabolic stressors. For instance, dual costimulation immunotherapy with CD134 (OX40) plus CD137 (4-1BB) agonists appears to mediate tumor control in part by engaging cytokine networks that enable infiltrating CTL to compete for limiting supplies of glucose. Future efforts combining modalities that endow CTL with complimentary metabolic advantages should improve therapeutic efficacies.

Second- and third-generation drugs for immuno-oncology treatment-The more the better?

Recent success in cancer immunotherapy (anti-CTLA-4, anti-PD1/PD-L1) has confirmed the hypothesis that the immune system can control many cancers across various histologies, in some cases producing durable responses in a way not seen with many small-molecule drugs. However, only less than 25% of all patients do respond to immuno-oncology drugs and several resistance mechanisms have been identified (e.g. T-cell exhaustion, overexpression of caspase-8 and β-catenin, PD-1/PD-L1 gene amplification, MHC-I/II mutations). To improve response rates and to overcome resistance, novel second- and third-generation immuno-oncology drugs are currently evaluated in ongoing phase I/II trials (either alone or in combination) including novel inhibitory compounds (e.g. TIM-3, VISTA, LAG-3, IDO, KIR) and newly developed co-stimulatory antibodies (e.g. CD40, GITR, OX40, CD137, ICOS). It is important to note that co-stimulatory agents strikingly differ in their proposed mechanism of action compared with monoclonal antibodies that accomplish immune activation by blocking negative checkpoint molecules such as CTLA-4 or PD-1/PD-1 or others. Indeed, the prospect of combining agonistic with antagonistic agents is enticing and represents a real immunologic opportunity to 'step on the gas' while 'cutting the brakes', although this strategy as a novel cancer therapy has not been universally endorsed so far. Concerns include the prospect of triggering cytokine-release syndromes, autoimmune reactions and hyper immune stimulation leading to activation-induced cell death or tolerance, however, toxicity has not been a major issue in the clinical trials reported so far. Although initial phase I/II clinical trials of agonistic and novel antagonistic drugs have shown highly promising results in the absence of disabling toxicity, both in single-agent studies and in combination with chemotherapy or other immune system targeting drugs; however, numerous questions remain about dose, schedule, route of administration and formulation as well as identifying the appropriate patient populations. In our view, with such a wealth of potential mechanisms of action and with the ability to fine-tune monoclonal antibody structure and function to suit particular requirements, the second and third wave of immuno-oncology drugs are likely to provide rapid advances with new combinations of novel immunotherapy (especially co-stimulatory antibodies). Here, we will review the mechanisms of action and the clinical data of these new antibodies and discuss the major issues facing this rapidly evolving field.

Effective Combination of Innate and Adaptive Immunotherapeutic Approaches in a Mouse Melanoma Model

Most cancer immunotherapies include activation of either innate or adaptive immune responses. We hypothesized that the combined activation of both innate and adaptive immunity will result in better antitumor efficacy. We have previously shown the synergy of an agonistic anti-CD40 mAb (anti-CD40) and CpG-oligodeoxynucleotides in activating macrophages to induce tumor cell killing in mice. Separately, we have shown that a direct intratumoral injection of immunocytokine (IC), an anti-GD2 Ab linked to IL-2, can activate T and NK cells resulting in antitumor effects. We hypothesized that activation of macrophages with anti-CD40/CpG, and NK cells with IC, would cause innate tumor destruction, leading to increased presentation of tumor Ags and adaptive T cell activation; the latter could be further augmented by anti-CTLA-4 Ab to achieve tumor eradication and immunological memory. Using the mouse GD2⁺ B78 melanoma model, we show that anti-CD40/CpG treatment led to upregulation of T cell activation markers in draining lymph nodes. Anti-CD40/CpG + IC/anti-CTLA-4 synergistically induced regression of advanced s.c. tumors, resulting in cure of some mice and development of immunological memory against B78 and wild type B16 tumors. Although the antitumor effect of anti-CD40/CpG did not require T cells, the antitumor effect of IC/anti-CTLA-4 was dependent on T cells. The combined treatment with anti-CD40/CpG + IC/anti-CTLA-4 reduced T regulatory cells in the tumors and was effective against distant solid tumors and lung metastases. We suggest that a combination of anti-CD40/CpG and IC/anti-CTLA-4 should be developed for clinical testing as a potentially effective novel immunotherapy strategy.

Engineering antibody therapeutics

The successful introduction of antibody-based protein therapeutics into the arsenal of treatments for patients has within a few decades fostered intense innovation in the production and engineering of antibodies. Reviewed here are the methods currently used to produce antibodies along with how our knowledge of the structural and functional characterization of immunoglobulins has resulted in the engineering of antibodies to produce protein therapeutics with unique properties, both biological and biophysical, that are leading to novel therapeutic approaches. Antibody engineering includes the introduction of the antibody combining site (variable regions) into a host of architectures including bi and multi-specific formats that further impact the therapeutic properties leading to further advantages and successes in patient treatment.

Frequent co-expression of EGFR and NeuGcGM3 ganglioside in cancer: it's potential therapeutic implications

Interaction between epidermal growth factor receptor (EGFR) signaling with GM3 ganglioside expression has been previously described. However, little is known about EGFR and NeuGcGM3 co-expression in cancer patients and their therapeutic implications. In this paper, we evaluate the co-expression of EGFR and NeuGcGM3 ganglioside in tumors from 92 patients and in two spontaneous lung metastasis models of mice (Lewis lung carcinoma (3LL-D122) in C57BL/6 and mammary carcinoma (4T1) in BALB/c). As results, co-expression of EGFR and NeuGcGM3 ganglioside was frequently observed in 63 of 92 patients (68 %), independently of histological subtype. Moreover, EGFR is co-expressed with NeuGcGM3 ganglioside in the metastasis of 3LL-D122 and 4T1 murine models. Such dual expression appears to be therapeutically relevant, since combined therapy with mAbs against these two molecules synergistically increase the survival of mice treated. Overall, our results suggest that NeuGcGM3 and EGFR may coordinately contribute to the tumor cell biology and that therapeutic combinations against these two targets might be a valid strategy to explore.

Gp96-Ig/Costimulator (OX40L, ICOSL, or 4-1BBL) Combination Vaccine Improves T-cell Priming and Enhances Immunity, Memory, and Tumor Elimination

T-cell costimulation typically occurs in a defined microenvironment that is not recapitulated by agonistic antibody therapy. To deliver such stimulation under more favorable conditions, we investigated whether an allogeneic cell-based vaccine that secreted Fc-OX40L, Fc-ICOSL, or Fc-4-1BBL would activate and expand T cells comparably with systemically administered agonist antibodies. Among these costimulators, locally secreted Fc-OX40L provided superior priming of antigen-specific CD8(+) T cells, compared with combinations with OX40 antibodies or vaccine alone. Vaccine-expressed Fc-OX40L also stimulated IFNγ, TNFα, granzyme B, and IL2 by antigen-specific CD8(+) T cells similarly to OX40 antibodies, without off-target consequences such as proinflammatory cytokine induction. Vaccine-secreted Fc-OX40L increased CD127(+)KLRG-1(-) memory precursor cells during the contraction phase, resulting in improved proliferation upon secondary antigen challenge, as compared with OX40 antibody. A cell-based vaccine cosecreting gp96-Ig and Fc-OX40L led to even more pronounced tumor control, complete tumor rejection, and increased tumor antigen-specific T-cell proliferation, including in tumor-infiltrating lymphocytes, as compared with combinations of gp96-Ig vaccine and OX40 antibodies, in mice with established melanoma or colorectal carcinoma. These data suggest that local modulation of the vaccine microenvironment has unexpected advantages over systemic costimulation with agonistic antibodies, which may simplify the clinical translation of such combination immunotherapies into humans. Cancer Immunol Res; 4(9); 766-78. ©2016 AACR.

Doxil synergizes with cancer immunotherapies to enhance antitumor responses in syngeneic mouse models

Based on the previously described roles of doxorubicin in immunogenic cell death, both doxorubicin and liposomal doxorubicin (Doxil) were evaluated for their ability to boost the antitumor response of different cancer immunotherapies including checkpoint blockers (anti-PD-L1, PD-1, and CTLA-4 mAbs) and TNF receptor agonists (OX40 and GITR ligand fusion proteins) in syngeneic mouse models. In a preventative CT26 mouse tumor model, both doxorubicin and Doxil synergized with anti-PD-1 and CTLA-4 mAbs. Doxil was active when CT26 tumors were grown in immunocompetent mice but not immunocompromised mice, demonstrating that Doxil activity is increased in the presence of a functional immune system. Using established tumors and maximally efficacious doses of Doxil and cancer immunotherapies in either CT26 or MCA205 tumor models, combination groups produced strong synergistic antitumor effects, a larger percentage of complete responders, and increased survival. In vivo pharmacodynamic studies showed that Doxil treatment decreased the percentage of tumor-infiltrating regulatory T cells and, in combination with anti-PD-L1, increased the percentage of tumor-infiltrating CD8(+) T cells. In the tumor, Doxil administration increased CD80 expression on mature dendritic cells. CD80 expression was also increased on both monocytic and granulocytic myeloid cells, suggesting that Doxil may induce these tumor-infiltrating cells to elicit a costimulatory phenotype capable of activating an antitumor T-cell response. These results uncover a novel role for Doxil in immunomodulation and support the use of Doxil in combination with checkpoint blockade or TNFR agonists to increase response rates and antitumor activity.

Cancer immunotherapy: the beginning of the end of cancer?

These are exciting times for cancer immunotherapy. After many years of disappointing results, the tide has finally changed and immunotherapy has become a clinically validated treatment for many cancers. Immunotherapeutic strategies include cancer vaccines, oncolytic viruses, adoptive transfer of ex vivo activated T and natural killer cells, and administration of antibodies or recombinant proteins that either costimulate cells or block the so-called immune checkpoint pathways. The recent success of several immunotherapeutic regimes, such as monoclonal antibody blocking of cytotoxic T lymphocyte-associated protein 4 (CTLA-4) and programmed cell death protein 1 (PD1), has boosted the development of this treatment modality, with the consequence that new therapeutic targets and schemes which combine various immunological agents are now being described at a breathtaking pace. In this review, we outline some of the main strategies in cancer immunotherapy (cancer vaccines, adoptive cellular immunotherapy, immune checkpoint blockade, and oncolytic viruses) and discuss the progress in the synergistic design of immune-targeting combination therapies.

Deciphering CD137 (4-1BB) signaling in T-cell costimulation for translation into successful cancer immunotherapy

CD137 (4-1BB, TNF-receptor superfamily 9) is a surface glycoprotein of the TNFR family which can be induced on a variety of leukocyte subsets. On T and NK cells, CD137 is expressed following activation and, if ligated by its natural ligand (CD137L), conveys polyubiquitination-mediated signals via TNF receptor associated factor 2 that inhibit apoptosis, while enhancing proliferation and effector functions. CD137 thus behaves as a bona fide inducible costimulatory molecule. These functional properties of CD137 can be exploited in cancer immunotherapy by systemic administration of agonist monoclonal antibodies, which increase anticancer CTLs and enhance NK-cell-mediated antibody-dependent cell-mediated cytotoxicity. Reportedly, anti-CD137 mAb and adoptive T-cell therapy strongly synergize, since (i) CD137 expression can be used to select the T cells endowed with the best activities against the tumor, (ii) costimulation of the lymphocyte cultures to be used in adoptive T-cell therapy can be done with CD137 agonist antibodies or CD137L, and (iii) synergistic effects upon coadministration of T cells and antibodies are readily observed in mouse models. Furthermore, the signaling cytoplasmic tail of CD137 is a key component of anti-CD19 chimeric antigen receptors that are used to redirect T cells against leukemia and lymphoma in the clinic. Ongoing phase II clinical trials with agonist antibodies and the presence of CD137 sequence in these successful chimeric antigen receptors highlight the importance of CD137 in oncoimmunology.

Combination OX40 agonism/CTLA-4 blockade with HER2 vaccination reverses T-cell anergy and promotes survival in tumor-bearing mice

Immunotherapy is gathering momentum as a primary therapy for cancer patients. However, monotherapies have limited efficacy in improving outcomes and benefit only a subset of patients. Combination therapies targeting multiple pathways can augment an immune response to improve survival further. Here, we demonstrate that dual aOX40 (anti-CD134)/aCTLA-4 (anti-cytotoxic T-lymphocyte-associated protein 4) immunotherapy generated a potent antigen-specific CD8 T-cell response, enhancing expansion, effector function, and memory T-cell persistence. Importantly, OX40 and CTLA-4 expression on CD8 T cells was critical for promoting their maximal expansion following combination therapy. Animals treated with combination therapy and vaccination using anti-DEC-205 (dendritic and epithelial cells, 205 kDa)-HER2 (human epidermal growth factor receptor 2) had significantly improved survival in a mammary carcinoma model. Vaccination with combination therapy uniquely restricted Th2-cytokine production by CD4 cells, relative to combination therapy alone, and enhanced IFNγ production by CD8 and CD4 cells. We observed an increase in MIP-1α (macrophage inflammatory protein-1α)/CCL3 [chemokine (C-C motif) ligand 3], MIP-1β/CCL4, RANTES (regulated on activation, normal T-cell expressed and excreted)/CCL5, and GM-CSF production by CD8 and CD4 T cells following treatment. Furthermore, this therapy was associated with extensive tumor destruction and T-cell infiltration into the tumor. Notably, in a spontaneous model of prostate adenocarcinoma, vaccination with combination therapy reversed anergy and enhanced the expansion and function of CD8 T cells recognizing a tumor-associated antigen. Collectively, these data demonstrate that the addition of a vaccine with combined aOX40/aCTLA-4 immunotherapy augmented antitumor CD8 T-cell function while limiting Th2 polarization in CD4 cells and improved overall survival.

Engineering high-affinity PD-1 variants for optimized immunotherapy and immuno-PET imaging

Signaling through the immune checkpoint programmed cell death protein-1 (PD-1) enables tumor progression by dampening antitumor immune responses. Therapeutic blockade of the signaling axis between PD-1 and its ligand programmed cell death ligand-1 (PD-L1) with monoclonal antibodies has shown remarkable clinical success in the treatment of cancer. However, antibodies have inherent limitations that can curtail their efficacy in this setting, including poor tissue/tumor penetrance and detrimental Fc-effector functions that deplete immune cells. To determine if PD-1:PD-L1-directed immunotherapy could be improved with smaller, nonantibody therapeutics, we used directed evolution by yeast-surface display to engineer the PD-1 ectodomain as a high-affinity (110 pM) competitive antagonist of PD-L1. In contrast to anti-PD-L1 monoclonal antibodies, high-affinity PD-1 demonstrated superior tumor penetration without inducing depletion of peripheral effector T cells. Consistent with these advantages, in syngeneic CT26 tumor models, high-affinity PD-1 was effective in treating both small (50 mm(3)) and large tumors (150 mm(3)), whereas the activity of anti-PD-L1 antibodies was completely abrogated against large tumors. Furthermore, we found that high-affinity PD-1 could be radiolabeled and applied as a PET imaging tracer to efficiently distinguish between PD-L1-positive and PD-L1-negative tumors in living mice, providing an alternative to invasive biopsy and histological analysis. These results thus highlight the favorable pharmacology of small, nonantibody therapeutics for enhanced cancer immunotherapy and immune diagnostics.

Combined treatment with dabrafenib and trametinib with immune-stimulating antibodies for BRAF mutant melanoma

The combination of targeted therapy with BRAF and MEK inhibitors has become the standard of care in patients with BRAF^V600E mutant melanoma, but responses are not durable. In addition, the impressive clinical benefits with anti-PD-1 and anti-PD-L1 antibodies (Ab) in patients with heavily pretreated metastatic melanoma and the synergistic effect of dabrafenib, trametinib and anti-PD-1 compared with single therapy alone groups support the idea that combining dabrafenib, trametinib and immunotherapy based on PD-1 blockade could be an interesting approach in the treatment of metastatic melanoma. With our mouse model of syngeneic BRAF^V600E driven melanoma (SM1), we tested whether the addition of an immunostimulatory Ab targeting CD137 (4-1BB) and/or CD134 (OX40) would enhance the antitumor effect of dabrafenib, trametinib and anti-PD-1 or anti-PD-L1 therapy. In vitro studies showed that the combination group of dabrafenib, trametinib and anti-PD-1 increases CD8⁺ tumor infiltrating lymphocytes (TILs), as well as CD4⁺ T cells and tumor-associated macrophages (TAMs). An upregulation of PD-L1 was observed in the combination of dabrafenib, trametinib and anti-PD-1 therapy. Combination of dabrafenib, trametinib and anti-PD-1, with either anti-CD137 or anti-CD134, showed a superior antitumor effect, but the five-agent combination was not superior to the four-agent combinations. In conclusion, the combination of dabrafenib, trametinib, anti-PD1 or anti-PD-L1 therapy results in robust antitumor activity, which is further improved by adding the immune-stimulating Ab anti-CD137 or anti-CD134. Our findings support the testing of these combinations in patients with BRAF^V600E mutant metastatic melanoma.

Evolving synergistic combinations of targeted immunotherapies to combat cancer

Immunotherapy has now been clinically validated as an effective treatment for many cancers. There is tremendous potential for synergistic combinations of immunotherapy agents and for combining immunotherapy agents with conventional cancer treatments. Clinical trials combining blockade of cytotoxic T lymphocyte-associated antigen 4 (CTLA4) and programmed cell death protein 1 (PD1) may serve as a paradigm to guide future approaches to immuno-oncology combination therapy. In this Review, we discuss progress in the synergistic design of immune-targeting combination therapies and highlight the challenges involved in tailoring such strategies to provide maximal benefit to patients.

Boosting Cancer Immunotherapy with Anti-CD137 Antibody Therapy

In the past 5 years, immunomodulatory antibodies have revolutionized cancer immunotherapy. CD137, a member of the tumor necrosis factor receptor superfamily, represents a promising target for enhancing antitumor immune responses. CD137 helps regulate the activation of many immune cells, including CD4(+) T cells, CD8(+) T cells, dendritic cells, and natural killer cells. Recent studies indicate that the antitumor efficacy of therapeutic tumor-targeting antibodies can be augmented by the addition of agonistic antibodies targeting CD137. As ligation of CD137 provides a costimulatory signal in multiple immune cell subsets, combination therapy of CD137 antibody with therapeutic antibodies and/or vaccination has the potential to improve cancer treatment. Recently, clinical trials of combination therapies with agonistic anti-CD137 mAbs have been launched. In this review, we discuss the recent advances and clinical promise of agonistic anti-CD137 monoclonal antibody therapy.

Immuno-regulatory antibodies for the treatment of cancer

INTRODUCTION

After years of limited success, progress of anti-cancer immuno-therapeutics has been considerable over the past decade. Key to this progress has been the application of new biological insights around the importance and nature of immune checkpoints that are able to reverse down-regulation of anti-tumor immunity.

AREAS COVERED

An overview of the preclinical and recent clinical trial data on key immuno-regulatory agents currently in development, including antibody targeting of cytotoxic T-lymphocyte antigen 4 (CTLA-4), programmed death receptor 1 (PD-1) on T-lymphocytes and its principal ligand (PD-L1) on tumor cells as well as immune agonists (e.g., anti-CD40).

EXPERT OPINION

Durable long-term responses in some patients with advanced melanoma, initially with ipilimumab (anti-CTLA-4) and more recently antibodies targeting either PD-1 or PD-L1 in patients with melanoma and renal cancer, non-small-cell lung, bladder and head and neck cancers with less toxicity, have provided real optimism that immunotherapeutic approaches can improve outcomes in a wide range of cancer. The manageable tolerability of PD-1-pathway blockers and their unique mechanism of action are encouraging combination approaches. Current efforts focus on registration trials of single agents plus combinations in many different tumor types and treatment settings and identifying and developing predictive biomarkers of immunological response.

OX40 Agonists and Combination Immunotherapy: Putting the Pedal to the Metal

Recent studies have highlighted the therapeutic efficacy of immunotherapy, a class of cancer treatments that utilize the patient’s own immune system to destroy cancerous cells. Within a tumor the presence of a family of negative regulatory molecules, collectively known as “checkpoint inhibitors,” can inhibit T cell function to suppress anti-tumor immunity. Checkpoint inhibitors, such as CTLA-4 and PD-1, attenuate T cell proliferation and cytokine production. Targeted blockade of CTLA-4 or PD-1 with antagonist monoclonal antibodies (mAbs) releases the “brakes” on T cells to boost anti-tumor immunity. Generating optimal “killer” CD8 T cell responses also requires T cell receptor activation plus co-stimulation, which can be provided through ligation of tumor necrosis factor receptor family members, including OX40 (CD134) and 4-1BB (CD137). OX40 is of particular interest as treatment with an activating (agonist) anti-OX40 mAb augments T cell differentiation and cytolytic function leading to enhanced anti-tumor immunity against a variety of tumors. When used as single agents, these drugs can induce potent clinical and immunologic responses in patients with metastatic disease. However, each of these agents only benefits a subset of patients, highlighting the critical need for more effective combinatorial therapeutic strategies. In this review, we will discuss our current understanding of the cellular and molecular mechanisms by which OX40 agonists synergize with checkpoint inhibitor blockade to augment T cell-mediated anti-tumor immunity and the potential opportunities for clinical translation of combinatorial immunotherapeutic strategies.

Immune checkpoint protein inhibition for cancer: preclinical justification for CTLA-4 and PD-1 blockade and new combinations

Over the last two decades, our understanding of the molecular basis of immunity has revealed the complexity of regulatory pathways involved in immune responses to cancer. A significant body of data support the critical importance of immune checkpoints in the control of the adaptive immune response to malignancy, and suggest that inhibitors of those checkpoints might have significant utility in treating cancer. This has been borne out by the recent US Food and Drug Administration (FDA) approvals of two different antibodies, one against cytotoxic T-lymphocyte antigen-4 (CTLA-4) and one against programmed death-1 (PD-1). Here, we provide a comprehensive review of the literature regarding the preclinical justification for the use of CTLA-4 and PD-1 blockade as monotherapy, and as combination therapy in the treatment of cancer. The animal data strongly supported the use of these drugs in patients, and in many cases suggested strategies that directly led to successful registration trials. In contrast, many of the toxicities, and some of the unusual response patterns seen in patients with these drugs, were not predicted by the preclinical work that we cite, highlighting the importance of early-phase trials with patients to inform future drug development. In addition, we review herein the preclinical data surrounding emerging immune checkpoint proteins, including BTLA, VISTA, CD160, LAG3, TIM3, and CD244 as potential targets for inhibition. The current comprehensive review of the literature regarding CTLA-4 and PD-1, as well as a number of novel checkpoint proteins demonstrates a strong preclinical basis for the use of these antibodies singly and in combination to overcome checkpoint inhibition in the treatment of cancer. We also suggest that the use of these antibodies may augment the efficacy of other activating immune antibodies, cytokines, radiation, and adoptive cell therapy in human cancer.

Therapeutic vaccines for cancer: an overview of clinical trials

The therapeutic potential of host-specific and tumour-specific immune responses is well recognized and, after many years, active immunotherapies directed at inducing or augmenting these responses are entering clinical practice. Antitumour immunization is a complex, multi-component task, and the optimal combinations of antigens, adjuvants, delivery vehicles and routes of administration are not yet identified. Active immunotherapy must also address the immunosuppressive and tolerogenic mechanisms deployed by tumours. This Review provides an overview of new results from clinical studies of therapeutic cancer vaccines directed against tumour-associated antigens and discusses their implications for the use of active immunotherapy.

Targeting 4-1BB costimulation to the tumor stroma with bispecific aptamer conjugates enhances the therapeutic index of tumor immunotherapy

Despite the recent successes of using immune modulatory Abs in patients with cancer, autoimmune pathologies resulting from the activation of self-reactive T cells preclude the dose escalations necessary to fully exploit their therapeutic potential. To reduce the observed and expected toxicities associated with immune modulation, here we describe a clinically feasible and broadly applicable approach to limit immune costimulation to the disseminated tumor lesions of the patient, whereby an agonistic 4-1BB oligonucleotide aptamer is targeted to the tumor stroma by conjugation to an aptamer that binds to a broadly expressed stromal product, VEGF. This approach was predicated on the premise that by targeting the costimulatory ligands to products secreted into the tumor stroma, the T cells will be costimulated before their engagement of the MHC-peptide complex on the tumor cell, thereby obviating the need to target the costimulatory ligands to noninternalizing cell surface products expressed on the tumor cells. Underscoring the potency of stroma-targeted costimulation and the broad spectrum of tumors secreting VEGF, in preclinical murine tumor models, systemic administration of the VEGF-targeted 4-1BB aptamer conjugates engendered potent antitumor immunity against multiple unrelated tumors in subcutaneous, postsurgical lung metastasis, methylcholantrene-induced fibrosarcoma, and oncogene-induced autochthonous glioma models, and exhibited a superior therapeutic index compared with nontargeted administration of an agonistic 4-1BB Ab or 4-1BB aptamer.

Combination anti-CD137 and anti-CD40 antibody therapy in murine myc-driven hematological cancers

In order to stimulate antigen presentation and T cell activity against cancer, we treated three different tumor models in mice with the monoclonal antibodies anti-CD40 plus anti-CD137 (BiMab). In a subcutaneous transplantable MC38 colon cancer model, there was significant enhancement in the survival of mice following BiMab treatment. Anti-CD40 has shown considerable success against lymphoma in previous studies by other investigators, and we also showed in this study that, in a model of Eμ-Myc lymphoma, there was a statistically significant enhancement of survival of mice following BiMab treatment. Following the success of the BiMab treatment in the previous two models, we wished to determine if it would be successful in a mouse model of multiple myeloma. Firstly, we tested a transplantable model of disease in which multiple myeloma cells derived from Vk*MYC mice were injected intravenously. A minor proportion of anti-CD137 and BiMab treated mice experienced prolongation of life beyond 250 days. Then we tested the therapy in a spontaneously occurring multiple myeloma model, in Vk*MYC transgenic mice. The majority of mice treated survived longer than control mice, although statistical significance was not demonstrated.

Targeting tumor-necrosis factor receptor pathways for tumor immunotherapy

With the success of ipilimumab and promise of programmed death-1 pathway-targeted agents, the field of tumor immunotherapy is expanding rapidly. Newer targets for clinical development include select members of the tumor necrosis factor receptor (TNFR) family. Agonist antibodies to these co-stimulatory molecules target both T and B cells, modulating T-cell activation and enhancing immune responses. In vitro and in vivo preclinical data have provided the basis for continued development of 4-1BB, OX40, glucocorticoid-induced TNFR-related gene, herpes virus entry mediator, and CD27 as potential therapies for patients with cancer. In this review, we summarize the immune response to tumors, consider preclinical and early clinical data on select TNFR family members, discuss potential translational challenges and suggest possible combination therapies with the aim of inducing durable antitumor responses.

Radiotherapy-induced anti-tumor immunity contributes to the therapeutic efficacy of irradiation and can be augmented by CTLA-4 blockade in a mouse model

Purpose

There is growing evidence that tumor-specific immune responses play an important role in anti-cancer therapy, including radiotherapy. Using mouse tumor models we demonstrate that irradiation-induced anti-tumor immunity is essential for the therapeutic efficacy of irradiation and can be augmented by modulation of cytotoxic T lymphocyte (CTL) activity.

Methods and Materials

C57BL/6 mice, syngeneic EL4 lymphoma cells, and Lewis lung carcinoma (LL/C) cells were used. Cells were injected into the right femurs of mice. Ten days after inoculation, tumors were treated with 30 Gy of local X-ray irradiation and their growth was subsequently measured. The effect of irradiation on tumor growth delay (TGD) was defined as the time (in days) for tumors to grow to 500 mm³ in the treated group minus that of the untreated group. Cytokine production and serum antibodies were measured by ELISA and flow cytometry.

Results

In the EL4 tumor model, tumors were locally controlled by X-ray irradiation and re-introduced EL4 cells were completely rejected. Mouse EL4-specific systemic immunity was confirmed by splenocyte cytokine production and detection of tumor-specific IgG1 antibodies. In the LL/C tumor model, X-ray irradiation also significantly delayed tumor growth (TGD: 15.4 days) and prolonged median survival time (MST) to 59 days (versus 28 days in the non-irradiated group). CD8(+) cell depletion using an anti-CD8 antibody significantly decreased the therapeutic efficacy of irradiation (TGD, 8.7 days; MST, 49 days). Next, we examined whether T cell modulation affected the efficacy of radiotherapy. An anti-CTLA-4 antibody significantly increased the anti-tumor activity of radiotherapy (TGD was prolonged from 13.1 to 19.5 days), while anti-FR4 and anti-GITR antibodies did not affect efficacy.

Conclusions

Our results indicate that tumor-specific immune responses play an important role in the therapeutic efficacy of irradiation. Immunomodulation, including CTLA-4 blockade, may be a promising treatment in combination with radiotherapy.

Orchestrating immune check-point blockade for cancer immunotherapy in combinations

Inhibitory receptors on immune system cells respond to membrane-bound and soluble ligands to abort or mitigate the intensity of immune responses by raising thresholds of activation, halting proliferation, favoring apoptosis or inhibiting/deviating effector function differentiation. Such evolutionarily selected inhibitory mechanisms are termed check-points and therefore check-point inhibitors empower any ongoing anti-cancer immune response that might have been too weak or exhausted. Monoclonal antibodies (mAb) interfering with CTLA-4-CD80/86, PD-1 - PD-L1, TIM-3-GAL9 and LAG3-MHC-II belong to this category of check-point inhibitors. The anti-CTLA-4 mAb ipilimumab has been approved for metastatic melanoma. Anti-PD-1 and anti-PD-L1 mAbs have shown extremely encouraging clinical activity. The potential of combination strategies with these agents has recently been highlighted by clinical observations on CTLA-4+PD-1 combined blockade in melanoma patients.

Combinations of immunostimulatory antibodies with synergistic effects against spontaneous cancer

Immunostimulatory monoclonal antibodies can be given in combinations, hence modulating the activity of 2 or more receptors of the immune system. Some of these combinations have been shown to synergize at the elicitation of therapeutically relevant immune responses in transgenic mice developing spontaneous, oncogene-driven tumors, including multifocal hepatocellular carcinomas expressing ovalbumin as a surrogate tumor-associated antigen.

Combined immunostimulatory monoclonal antibodies extend survival in an aggressive transgenic hepatocellular carcinoma mouse model

PURPOSE

Immunostimulatory monoclonal antibodies (ISmAb) that unleash antitumor immune responses are showing efficacy in cancer clinical trials. Anti-B7-H1 (PD-L1) monoclonal antibodies (mAb) block a critical inhibitory pathway in T cells, whereas anti-CD137 and OX40 mAbs provide T-cell costimulation. A combination of these ISmAbs (anti-CD137 + anti-OX40 + anti-B7-H1) was tested using a transgenic mouse model of multifocal and rapidly progressing hepatocellular carcinoma, in which c-myc drives transformation and cytosolic ovalbumin (OVA) is expressed in tumor cells as a model antigen.

EXPERIMENTAL DESIGN

Flow-cytometry and immunohistochemistry were used to quantify tumor-infiltrating lymphocytes (TIL) elicited by treatment and assess their activation status and cytolytic potential. Tolerance induction and its prevention/reversal by treatment with the combination of ISmAbs were revealed by in vivo killing assays.

RESULTS

The triple combination of ISmAbs extended survival of mice bearing hepatocellular carcinomas in a CD8-dependent fashion and synergized with adoptive T-cell therapy using activated OVA-specific TCR-transgenic OT-1 and OT-2 lymphocytes. Mice undergoing therapy showed clear increases in tumor infiltration by activated and blastic CD8(+) and CD4(+) T lymphocytes containing perforin/granzyme B and expressing the ISmAb-targeted receptors on their surface. The triple combination of ISmAbs did not result in enhanced OVA-specific cytotoxic T lymphocyte (CTL) activity but other antigens expressed by cell lines derived from such hepatocellular carcinomas were recognized by endogenous TILs. Adoptively transferred OVA-specific OT-1 lymphocytes into tumor-bearing mice were rendered tolerant, unless given the triple mAb therapy.

CONCLUSION

Extension of survival and dense T-cell infiltrates emphasize the translational potential of combinational immunotherapy strategies for hepatocellular carcinoma. Clin Cancer Res; 19(22); 6151-62. ©2013 AACR.

Superior anti-tumor protection and therapeutic efficacy of vaccination with dendritic cell/tumor cell fusion hybrids for murine Lewis lung carcinoma

BACKGROUND

The development of protocols for the ex vivo generation of dendritic cells (DCs) has led to intensive research into their potential use in immunotherapy in the treatment of cancer. In this study, we examined the efficacy of dendritic cell-tumor cell fusion hybrid vaccines in eliciting an immune response against Lewis lung carcinoma (LLC) cells, as compared to other types of tumor vaccines. In addition, we also tested whether the efficacy of the vaccines was affected by the route of administration. Four different tumor vaccines were compared: (1) HC (hybrid cell), consisting of DC/LLC hybrids; (2) DC+LLC (DCs pulsed with apoptotic LLCs); (3) DC without antigen loading/pulsing; (4) LLC (apoptotic/irradiated tumor cells). We also compared four different routes of administration for each vaccine: (1) Preimmunization; (2) Vaccination therapy; (3) Adoptive immunotherapy; (4) Vaccination therapy combined with adoptive immunotherapy. Anti-tumor immunity was assessed in vivo and the CTL (cytotoxic T lymphocyte) response as well as the expression of key cytokines, IFN-γ and IL-10 were further evaluated using in vitro assays.

RESULTS

Our data demonstrate that vaccination with HC hybrids provides more effective anti-tumor protective immunity and significantly greater therapeutic immunity than vaccination with DC+LLC, DC or LLC. Most remarkably, vaccination therapy with HC hybrids was more successful than combination (vaccination + adoptive) therapy for the induction of anti-tumor responses. Splenocytes harvested from mice immunized with HC hybrids demonstrated the greatest cytotoxic T lymphocyte (CTL) activity and their production of IFN-γ was high, while their production of IL-10 was very low.

CONCLUSIONS

Our results suggest that vaccination therapy with DC-tumor cell fusion hybrids provides more effective protection against lung cancer.

Targeting immunosuppression for cancer therapy

Failing immunity has been acknowledged for its contribution to cancer development and progression. Recent clinical findings have provided payoffs for significant preclinical evaluation and refinement over the last 20 years, but many questions remain to be answered. In this issue of the JCI, Marabelle et al. describe a novel method for targeting the Tregs that infiltrate tumors, demonstrating that dampening the tumor immunosuppressive environment while activating innate antitumor immunity may be an effective approach to cancer treatment.

Evaluating combinations of costimulatory antibody-ligand fusion proteins for targeted cancer immunotherapy

Combinatory strategies are becoming of increasing interest in cancer immunotherapy. Costimulation by individual members of the immunoglobulin-like (Ig)- and TNF superfamily have already shown promising antitumor potential, thus prompting the exploration of their synergistic abilities in combinatorial approaches. Here, we pursued a targeted strategy with antibody-fusion proteins composed of a tumor-directed antibody and the extracellular domain of the costimulatory ligand B7.1, 4-1BBL, OX40L, GITRL or LIGHT, respectively. Costimulatory activity was assessed in an experimental setting where initial T cell activation was induced by a bispecific antibody (tumor-related antigen × CD3). Advantage of combined targeted costimulation was shown for either B7.1 or 4-1BBL with OX40L, GITRL, LIGHT and 4-1BBL in terms of T cell proliferation and IFN-γ release. Since encouraging results were obtained by the combination of B7.1 and 4-1BBL, we adapted the model system for a time-shift setting. Here, enhanced proliferation and granzyme B expression as well as reduced PD-1 expression on the T cell population demonstrated the benefit of costimulation-assisted restimulation. Finally, the antitumor potential of this combinatorial setting was confirmed in vivo in a lung metastasis mouse model. Thus, combinatorial approaches with costimulatory antibody-ligand fusion proteins seem a promising strategy to be further investigated for cancer immunotherapy.

New insights into the role of the immune microenvironment in breast carcinoma

Recently, immune edition has been recognized as a new hallmark of cancer. In this respect, some clinical trials in breast cancer have reported imppressive outcomes related to laboratory immune findings, especially in the neoadjuvant and metastatic setting. Infiltration by tumor infiltrating lymphocytes (TIL) and their subtypes, tumor-associated macrophages (TAM) and myeloid-derived suppressive cells (MDSC) seem bona fide prognostic and even predictive biomarkers, that will eventually be incorporated into diagnostic and therapeutic algorithms of breast cancer. In addition, the complex interaction of costimulatory and coinhibitory molecules on the immune synapse and the different signals that they may exert represent another exciting field to explore. In this review we try to summarize and elucidate these new concepts and knowledge from a translational perspective focusing on breast cancer, paying special attention to those aspects that might have more significance in clinical practice and could be useful to design successful therapeutic strategies in the future.

Pegylated IL-10 induces cancer immunity: the surprising role of IL-10 as a potent inducer of IFN-γ-mediated CD8(+) T cell cytotoxicity

Recently, the development of several strategies based on immunotherapy has raised hopes for a more promising way to treat cancer patients. Here, we describe how interleukin (IL)-10, a seemingly unlikely candidate, stimulates the immune system in a particularly efficacious way. IL-10, an omnipotent anti-inflammatory cytokine, delivers an equally potent immune stimulation in the context of CD8(+) T cells and tumor immunity. By activation of tumor-resident, tumor-specific CD8(+) T cells, pegylated IL-10 can induce rejection of large and metastasizing tumors in mice. Here, we summarize the mechanisms of action of IL-10, the reasons why the mechanisms may be crucial for the treatment of cancer patients, and the rationale for applying pegylated IL-10 in the clinic.

The TNFRs OX40, 4-1BB, and CD40 as targets for cancer immunotherapy

T cell-mediated rejection of tumors requires signals from the T cell receptor and co-stimulatory molecules to license effector functions of tumor-antigen specific T cells. There is also an array of immune suppressive mechanisms within the tumor microenvironment that can suppress anti-tumor immunity. The use of monoclonal antibodies to overcome this suppression and/or enhance tumor-antigen specific T cell responses has shown promise in clinical trials. In particular, targeting co-stimulatory members of the tumor necrosis factor receptor (TNFR) family with agonist Abs enhances T cell function, which has led to encouraging therapeutic results in cancer-bearing hosts. These encouraging data establish TNFRs as important targets for enhancing tumor-specific immune responses in mice and man. This review will focus on agonists that target the TNFRs OX40, 4-1BB, and CD40.

Coinhibitory molecules in cancer biology and therapy

The adaptive immune response is controlled by checkpoints represented by coinhibitory molecules, which are crucial for maintaining self-tolerance and minimizing collateral tissue damage under physiological conditions. A growing body of preclinical evidence supports the hypothesis that unleashing this immunological break might be therapeutically beneficial in the fight against cancer, as it would elicit an effective antitumor immune response. Remarkably, recent clinical trials have demonstrated that this novel strategy can be highly effective in the treatment of patients with cancer, as shown by the paradigmatic case of ipilimumab (a monoclonal antibody blocking the coinhibitory molecule cytotoxic T lymphocyte associated antigen-4 [CTLA4]) that is opening a new era in the therapeutic approach to a chemoresistant tumor such as cutaneous melanoma. In this review we summarize the biology of coinhibitory molecules, overview the experimental and clinical attempts to interfere with these immune checkpoints to treat cancer and critically discuss the challenges posed by such a promising antitumor modality.

Therapeutic cancer vaccines in prostate cancer: the quest for intermediate markers of response

Despite recent advances in cancer immunotherapy, no prospectively validated intermediate biomarkers exist to predict response. These biomarkers are highly desirable given modern immunotherapy's paradoxical pattern of clinical benefit; that is, improvement in overall survival without short-term change in progression. Immunotherapy clinical trials have evaluated biomarkers that may correlate with clinical outcomes. Many of them are performed on peripheral blood to evaluate the systemic response, such as tumor-targeted humoral and cellular immunity, and cytokine responses. Accumulating evidence suggests that immune infiltrates in tumors may suggest evidence for the therapy's mechanism of action, and have greater potential for providing prognostic and predictive information. In addition, a non-immunologic biomarker, such as tumor growth kinetics, may explain this paradoxical pattern of clinical benefit, and predict survival in patients treated with an immunotherapy. Prospective assessment and validation of these and other intermediate markers would be required to better understand their potential clinical role.