Deciphering and reversing tumor immune suppression. Immunity. 2013;39:61-73. [PMID: 23890064 DOI: 10.1016/j.immuni.2013.07.005]

SPARC Is a New Myeloid-Derived Suppressor Cell Marker Licensing Suppressive Activities

Myeloid-derived suppressor cells (MDSC) are well-known key negative regulators of the immune response during tumor growth, however scattered is the knowledge of their capacity to influence and adapt to the different tumor microenvironments and of the markers that identify those capacities. Here we show that the secreted protein acidic and rich in cysteine (SPARC) identifies in both human and mouse MDSC with immune suppressive capacity and pro-tumoral activities including the induction of epithelial-to-mesenchymal transition (EMT) and angiogenesis. In mice the genetic deletion of SPARC reduced MDSC immune suppression and reverted EMT. Sparc^−/− MDSC were less suppressive overall and the granulocytic fraction was more prone to extrude neutrophil extracellular traps (NET). Surprisingly, arginase-I and NOS2, whose expression can be controlled by STAT3, were not down-regulated in Sparc^−/− MDSC, although less suppressive than wild type (WT) counterpart. Flow cytometry analysis showed equal phosphorylation of STAT3 but reduced ROS production that was associated with reduced nuclear translocation of the NF-kB p50 subunit in Sparc^−/− than WT MDSC. The limited p50 in nuclei reduce the formation of the immunosuppressive p50:p50 homodimers in favor of the p65:p50 inflammatory heterodimers. Supporting this hypothesis, the production of TNF by Sparc^−/− MDSC was significantly higher than by WT MDSC. Although associated with tumor-induced chronic inflammation, TNF, if produced at high doses, becomes a key factor in mediating tumor rejection. Therefore, it is foreseeable that an unbalance in TNF production could skew MDSC toward an inflammatory, anti-tumor phenotype. Notably, TNF is also required for inflammation-driven NETosis. The high level of TNF in Sparc^−/− MDSC might explain their increased spontaneous NET formation as that we detected both in vitro and in vivo, in association with signs of endothelial damage. We propose SPARC as a new potential marker of MDSC, in both human and mouse, with the additional feature of controlling MDSC suppressive activity while preventing an excessive inflammatory state through the control of NF-kB signaling pathway.

Pathophysiological Role of Histamine H4 Receptor in Cancer: Therapeutic Implications

Cancer is a leading cause of death in both developed and developing countries. Although advances in cancer research lead to improved anti-neoplastic therapies, they continue to have unfavorable outcomes, including poor response and severe toxicity. Thus, the challenge for the new therapeutic approaches is to increase anti-tumor efficacy by targeting different molecules encompassed in the tumor and its microenvironment, as well as their specific interactions. The histamine H4 receptor (H4R) is the last discovered histamine receptor subtype and it modulates important immune functions in innate and in adaptive immune responses. Several ligands have been developed and some of them are being used in clinical trials for immune disorders with promising results. When searched in The Cancer Genome Atlas (TCGA) database, human H4R gene was found to be expressed in bladder cancer, kidney cancer, breast cancer, gastrointestinal cancers, lung cancer, endometrial cancer, and skin cancer. In the present work, we aimed to briefly summarize current knowledge in H4R's pharmacology and in the clinical use of H4R ligands before focusing on recent data reporting the expression of H4R and its pathophysiological role in cancer, representing a potential molecular target for cancer therapeutics. H4R gene and protein expression in different types of cancers compared with normal tissue as well as its relationship with patient prognosis in terms of survival will be described.

Combinations of Bevacizumab With Cancer Immunotherapy

Cancer immunotherapy (CIT) has transformed cancer treatment. In particular, immunotherapies targeting the programmed death ligand 1 (PD-L1)/programmed death 1 pathway have demonstrated durable clinical benefit in some patients. However, CIT combinations may create a more favorable environment in which to maximize the potential of the immune system to eliminate cancer. Here we describe 3 key mechanisms related to vascular endothelial growth factor (VEGF)-mediated immunosuppression: inhibition of dendritic cell maturation, reduction of T-cell tumor infiltration, and promotion of inhibitory cells in the tumor microenvironment; supporting data are also described. In addition, we discuss immunomodulatory properties observed within tumors following bevacizumab treatment. Combining anti-PD-L1 and anti-VEGF therapies has shown synergy and positive outcomes in phases I to III studies, particularly in settings where high VEGF levels are known to play an important role in tumor growth. We also review data from key studies supporting combination of bevacizumab and CIT, with a focus on PD-L1/programmed death 1 inhibitors.

Design, synthesis and biological evaluation of novel aryl-acrylic derivatives as novel indoleamine-2,3-dioxygenase 1 (IDO1) inhibitors

Two series of novel aryl-acrylic derivatives were designed, synthesized, and screened in enzymatic and cellular inhibitory activities. All compounds showed moderate to significant potency. The SAR analyses indicated that the semicarbazone linker is better than the 1,2,3-triazole linker. Among semicarbazone compounds that R₁ bearing di-chain amino groups exhibited superior activities to those with morpholino group. Furthermore, compounds with electron-withdrawing groups at the 2-position or 4-position on the terminal phenyl ring were more active. Among these, compounds 7g, 7i, 7m and 7n exhibited the inhibitory potency in the low micromolar range and displayed negligible level of cytotoxicity against normal HeLa cells. In addition, the study suggested that the aryl-acrylic is an interesting novel scaffold for IDO1 inhibition for further development.

Oncolytic virotherapy enhances the efficacy of a cancer vaccine by modulating the tumor microenvironment

The efficacy of cancer vaccines has been limited by the immunosuppressive tumor microenvironment, which can be alleviated by immune checkpoint inhibitor (ICI) therapy. Here, we tested if oncolytic viruses (OVs), similar to ICI, can also synergize with cancer vaccines by modulating the tumor microenvironment. VSV‐GP, a chimeric vesicular stomatitis virus (VSV) pseudotyped with the glycoprotein (GP) of the lymphocytic choriomeningitis virus, is a promising new OV candidate. Here, we show that in mouse B16‐OVA melanoma, combination treatment of VSV‐GP with an ovalbumin (OVA) peptide‐loaded dendritic cell (DC) vaccine (DCVacc) significantly enhanced survival over the single agent therapies, although both DCVacc and DCVacc/VSV‐GP treatments induced comparable levels of OVA‐specific CD8 T cell responses. Virus replication was minimal so that direct viral oncolysis in B16‐OVA did not contribute to this synergism. The strong therapeutic effect of the DCVacc/VSV‐GP combination treatment was associated with high numbers of tumor‐infiltrating, highly activated T cells and the relative reduction of regulatory T cells in treated and contra‐lateral nontreated tumors. Accordingly, depletion of CD8 T cells but not natural killer cells abrogated the therapeutic effect of DCVacc/VSV‐GP supporting the crucial role of CD8 T cells. In addition, a drastic increase in several proinflammatory cytokines was observed in VSV‐GP‐treated tumors. Taken together, OVs, similar to ICI, have the potential to markedly increase the efficacy of cancer vaccines by alleviating local immune suppression in the tumor microenvironment.

What's new?

Cancer vaccine efficacy has been limited by the immunosuppressive tumor microenvironment. By inducing cancer cell death with the release of tumor‐related antigens, oncolytic viruses may have an adjuvant effect. Here, the authors show that a combination of the oncolytic rhabdovirus VSV‐GP and a dendritic cell vaccine is highly effective in the treatment of mouse melanoma, most likely because VSV‐GP reprograms the tumor microenvironment to enhance the effectivity of the vaccine‐induced immune response. Oncolytic viruses have the potential to dramatically increase the efficacy of cancer vaccines by alleviating local immune suppression in the tumor microenvironment.

Immunometabolism: A new target for improving cancer immunotherapy

Fundamental metabolic pathways are essential for mammalian cells to provide energy, precursors for biosynthesis of macromolecules, and reducing power for redox regulation. While dysregulated metabolism (e.g., aerobic glycolysis also known as the Warburg effect) has long been recognized as a hallmark of cancer, recent discoveries of metabolic reprogramming in immune cells during their activation and differentiation have led to an emerging concept of "immunometabolism." Considering the recent success of cancer immunotherapy in the treatment of several cancer types, increasing research efforts are being made to elucidate alterations in metabolic profiles of cancer and immune cells during their interplays in the setting of cancer progression and immunotherapy. In this review, we summarize recent advances in studies of metabolic reprogramming in cancer as well as differentiation and functionality of various immune cells. In particular, we will elaborate how distinct metabolic pathways in the tumor microenvironment cause functional impairment of immune cells and contribute to immune evasion by cancer. Lastly, we highlight the potential of metabolically reprogramming the tumor microenvironment to promote effective and long-lasting antitumor immunity for improved immunotherapeutic outcomes.

Tumor-Associated Lymphatic Vessel Features and Immunomodulatory Functions

The lymphatic system comprises a network of lymphoid tissues and vessels that drains the extracellular compartment of most tissues. During tumor development, lymphatic endothelial cells (LECs) substantially expand in response to VEGFR-3 engagement by VEGF-C produced in the tumor microenvironment, a process known as tumor-associated lymphangiogenesis. Lymphatic drainage from the tumor to the draining lymph nodes consequently increases, powering interstitial flow in the tumor stroma. The ability of a tumor to induce and activate lymphatic growth has been positively correlated with metastasis. Much effort has been made to identify genes responsible for tumor-associated lymphangiogenesis. Inhibition of lymphangiogenesis with soluble VEGFR-3 or with specific monoclonal antibodies decreases tumor spread to LNs in rodent models. Importantly, tumor-associated lymphatics do not only operate as tumor cell transporters but also play critical roles in anti-tumor immunity. Therefore, metastatic as well as primary tumor progression can be affected by manipulating tumor-associated lymphatic remodeling or function. Here, we review and discuss our current knowledge on the contribution of LECs immersed in the tumor microenvironment as immunoregulators, as well as a possible functional remodeling of LECs subsets depending on the organ microenvironment.

Advances in immunotherapy delivery from implantable and injectable biomaterials

Macroscale biomaterials, such as preformed implantable scaffolds and injectable soft materials, possess powerful synergies with anti-cancer immunotherapies. Immunotherapies on their own typically have poor delivery properties, and often require repeated high-dose injections that result in serious off-tumor effects and/or limited efficacy. Rationally designed biomaterials allow for discrete localization and controlled release of immunotherapeutic agents, and have been shown in a large number of applications to improve outcomes in the treatment of cancers via immunotherapy. Among various strategies, macroscale biomaterial delivery systems can take the form of robust tablet-like scaffolds that are surgically implanted into a tumor resection site, releasing programmed immune cells or immunoregulatory agents. Alternatively they can be developed as soft gel-like materials that are injected into solid tumors or sites of resection to stimulate a potent anti-tumor immune response. Biomaterials synthesized from diverse components such as polymers and peptides can be combined with any immunotherapy in the modern toolbox, from checkpoint inhibitors and stimulatory adjuvants, to cancer antigens and adoptive T cells, resulting in unique synergies and improved therapeutic efficacy. The field is growing rapidly in size as publications continue to appear in the literature, and biomaterial-based immunotherapies are entering clinical trials and human patients. It is unarguably an exciting time for cancer immunotherapy and biomaterial researchers, and further work seeks to understand the most critical design considerations in the development of the next-generation of immunotherapeutic biomaterials. This review will discuss recent advances in the delivery of immunotherapies from localized biomaterials, focusing on macroscale implantable and injectable systems. STATEMENT OF SIGNIFICANCE: Anti-cancer immunotherapies have shown exciting clinical results in the past few decades, yet they suffer from a few distinct limitations, such as poor delivery kinetics, narrow patient response profiles, and systemic side effects. Biomaterial systems are now being developed that can overcome many of these problems, allowing for localized adjuvant delivery, focused dose concentrations, and extended therapy presentation. The field of biocompatible carrier materials is uniquely suited to be combined with immunotherapy, promising to yield significant improvements in treatment outcomes and clinical care. In this review, the first pioneering efforts and most recent advances in biomaterials for immunotherapeutic applications are explored, with a specific focus on implantable and injectable biomaterials such as porous scaffolds, cryogels, and hydrogels.

Augmenting the synergies of chemotherapy and immunotherapy through drug delivery

Despite the recent approvals of multiple cancer immunotherapies, low tumor immunogenicity and immunosuppressive tumor microenvironments prevent a large portion of patients from responding to these treatment modalities. Given the immunomodulatory and adjuvant effects of conventional chemotherapy as well as its widespread clinical use, the use of chemotherapy in combination with immunotherapy (so-called chemoimmunotherapy) is an attractive approach to potentiate the effects of immunotherapy in more patient populations. However, due to the limited extent of tumor accumulation, poorly controlled interactions with the immune system, and effects on systemic healthy tissues by chemotherapeutic drugs, the incorporation of anti-cancer agents into biomaterial-based structures, such as nanocarriers, is highly attractive to improve the safety and efficacy of chemoimmunotherapy. Herein, we review the recent progress in drug delivery systems (DDSs) for potentiating the immunomodulatory effects of chemotherapeutics in chemoimmunotherapy, which represent among the most promising next generation strategies for cancer treatment in the immunotherapy era. STATEMENT OF SIGNIFICANCE: Given the benefits of cancer immunotherapy in inducing durable, albeit low rates, of patient response, interest in the immunomodulatory and adjuvant effects of conventional chemotherapy has been re-invigorated. This review article discusses the recent progress towards understanding the synergies between these two treatment types, how they can be used in combination (so-called chemoimmunotherapy), and the potential for drug delivery systems to optimize their effects in translational settings.

Phenotype of POLE-mutated endometrial cancer

Background and purpose

Individualized therapy in endometrial cancer, the most common gynaecologic cancer in the developed world, focuses on identifying specific molecular subtypes. Mutations in the exonuclease domain of the DNA polymerase epsilon (POLE) gene define one such subtype, which causes an ultra-mutated tumour phenotype. These tumours may have an improved progression-free survival and may be receptive to specific therapies. However, the clinical phenotype of these tumours is unknown. The objective of this study was to evaluate the clinical and genetic features of POLE-mutated tumours from a large cohort of women whose cases are characterized by: (1) the availability of detailed clinical and lifestyle data; (2) mutation analysis; and (3) long-term follow-up.

Methods

A total of 604 patients with endometrial cancer were included in the study. Data from a detailed questionnaire, including lifestyle and family history information, provided extensive pertinent information on the patients. Sequencing of exons 9–14 of the POLE gene was performed. Follow-up data were gathered and analysed.

Results

Hotspot pathogenic POLE mutations were identified in N = 38/599 patients (6.3%). Patients with a POLE-mutated tumour were significantly younger, were more often nulliparous, and had a history of smoking. POLE-mutated tumours were more frequently aneuploid. Prognosis for patients with hotspot POLE-mutated tumours was significantly better in comparison with patients with non-mutated tumours; however careful selection of pathogenic mutations is essential to the definition of this prognostically favourable group.

Conclusions

This study demonstrates that POLE-mutated endometrial cancer is significantly associated with previously unknown clinicopathologic characteristics. Outcome in POLE-mutated tumours was excellent in cases with hotspot mutations. Our results suggest that prediction of excellent outcome in cases of POLE-mutated EMCA should be restricted to cases of EMCA with hotspot mutations until further data are available on the rising number of mutations with unknown significance.

Mast cells: A double-edged sword in cancer

Mast cells (MCs), a type of innate immune cells, are derived from myeloid stem cells, sometimes known as mastocytes or labrocytes, and contain many granules rich in histamine and heparin. The mentioned cells are able to release various mediators such as cytokines, leukotrienes, and a large number of proteases into the environment. Many studies and experiments have established the infiltration of MCs into the tumor site. However, the findings are highly controversial to determine whether these immune cells contribute to the growth and development of the tumor or cause anti-tumor immune responses. Various studies have revealed that MCs have a pro-tumorigenic or anti-tumorigenic role depending on the type of cancer, the degree of tumor progression, and the location of these immune cells in the tumor bulk. Although these types of immune cells cause angiogenesis and tumor progression in some cancers, they have a significant anti-tumor role in some other types of cancers. In general, although a number of studies have specified the protective role of MCs in cancers, the increased number of MCs in the blood and microenvironment of tumors, as well as the increased level of angiogenesis and tumor progression, has been indicated in another array of studies. The function of MCs against or in favor of the cancers still requires further investigations to more accurately and specifically determine the role of MCs in the cancers. The function of MCs in tumors and their various roles in case of exposure to the cancer cells have been addressed in the present review. The concluding section of the present study recommends a number of methods for modification of MCs in cancer immunotherapy.

Immunotherapy of gynecological cancers

Oncology treatments have evolved from intuitive, via empiric, to the present precision medicine, with the integration of molecular targeted therapies in our treatment arsenal. The use of the patients' powerful immune system has long been contemplated and recently led to the integration of immunotherapy to overturn the well-documented inhibitory effects of the tumor on the immune system and restore it to a state of activity against the cancer. Recent favorable results have shown the value and effectiveness of immunotherapy against gynecological cancers. In particular, the checkpoint inhibitors, targeting the programmed death-1 (PD-1) pathway, have shown durable clinical responses with manageable toxicity. Several phase II and III clinical trials testing the association of different regimen of chemotherapy and immunotherapy are ongoing in gynecological cancers, and important results are expected. In this chapter, we outline the main principles of immunotherapy for gynecological cancers and summarize the current strategies used in clinical trials.

Highly efficient cascading synergy of cancer photo-immunotherapy enabled by engineered graphene quantum dots/photosensitizer/CpG oligonucleotides hybrid nanotheranostics

Currently, photoimmunotherapy based on a theranostic nanoplatform emerges as a promising modality in advanced cancer therapy. In this study, a new type of versatile nanoassemblies (denoted as PC@GCpD(Gd)) was rationally designed by integrating the polydopamine stabilized graphene quantum dots (GQD)-photosensitizer nanocomposites (denoted as GCpD), immunostimulatory polycationic polymer/CpG oligodeoxynucleotide (CpG ODN) nanoparticles (denoted as PC) and Gd³⁺/Cy3 imaging probes for dual magnetic resonance/fluorescence imaging-guided photoimmunotherapy. PC@GCpD(Gd) effectively killed the tumor cells through the amplified photothermal and photodynamic effects mediated by GCpD, and contemporaneously delivered CpG ODN to the targeted endosomal Toll-like receptor 9 (TLR9) to continuously stimulate the secretion of proinflammatory cytokines and the maturation of dendritic cells, thereby resulting in the activation and infiltration of T lymphocytes. As a result, PC@GCpD(Gd) achieved robust inhibition efficiency to almost completely suppress the EMT6 murine mammary cancer model under laser irradiation, implying the superior synergy of combined photoimmunotherapy. Moreover, the in vivo delivery and biodistribution of PC@GCpD(Gd) could be tracked using the high-quality bimodal magnetic resonance imaging/fluorescence imaging. This study highlighted the potent prospect of hybrid PC@GCpD(Gd) nanoassemblies for precise cancer photoimmunotherapy with a cascading effect.

Effect of Multiple Vaccinations with Tumor Cell-Based Vaccine with Codon-Modified GM-CSF on Tumor Growth in a Mouse Model

Ectopic expression of codon-modified granulocyte-macrophage colony-stimulating factor (cGM-CSF) in TC-1 cells (TC-1/cGM-CSF), a model cell line for human papillomavirus (HPV)-infected cervical cancer cells, increased the expression level of GM-CSF and improved the efficacy of tumor cell-based vaccines in a cervical cancer mouse model. The number of vaccine doses required to induce a long-term immune response in a cervical cancer mouse model is poorly understood. Here, we investigated one, three, and five doses of the irradiated TC-1/cGM-CSF vaccine to determine which dose was effective in inducing a greater immune response and the suppression of tumors. Our findings showed that three doses of irradiated TC-1/cGM-CSF vaccine elicited slower tumor growth rates and enhanced survival rates compared with one dose or five doses of irradiated TC-1/cGM-CSF vaccine. Consistently, mice vaccinated with three doses of irradiated TC-1/cGM-CSF vaccine exhibited stronger interferon gamma (IFN-γ) production in HPV E7-specific CD8⁺ T cells and CD4⁺ T cells. A higher percentage of natural killer cells and interferon-producing killer dendritic cells (IKDCs) appeared in the splenocytes of the mice vaccinated with three doses of irradiated TC-1/cGM-CSF vaccine compared with those of the mice vaccinated with one dose or five doses of irradiated TC-1/cGM-CSF vaccine. Our findings demonstrate that single or multiple vaccinations, such as five doses, with irradiated TC-1/cGM-CSF vaccine suppressed the immune response, whereas three doses of irradiated TC-1/cGM-CSF vaccine elicited a greater immune response and subsequent tumor suppression.

VEGF in Signaling and Disease: Beyond Discovery and Development

The discovery of vascular endothelial-derived growth factor (VEGF) has revolutionized our understanding of vasculogenesis and angiogenesis during development and physiological homeostasis. Over a short span of two decades, our understanding of the molecular mechanisms by which VEGF coordinates neurovascular homeostasis has become more sophisticated. The central role of VEGF in the pathogenesis of diverse cancers and blinding eye diseases has also become evident. Elucidation of the molecular regulation of VEGF and the transformative development of multiple therapeutic pathways targeting VEGF directly or indirectly is a powerful case study of how fundamental research can guide innovation and translation. It is also an elegant example of how agnostic discovery and can transform our understanding of human disease. This review will highlight critical nodal points in VEGF biology, including recent developments in immunotherapy for cancer and multitarget approaches in neovascular eye disease.

CRISPR/Cas9-mediated PD-1 disruption enhances human mesothelin-targeted CAR T cell effector functions

The interaction between programmed cell death protein 1 (PD-1) on activated T cells and its ligands on a target tumour may limit the capacity of chimeric antigen receptor (CAR) T cells to eradicate solid tumours. PD-1 blockade could potentially enhance CAR T cell function. Here, we show that mesothelin is overexpressed in human triple-negative breast cancer cells and can be targeted by CAR T cells. To overcome the suppressive effect of PD-1 on CAR T cells, we utilized CRISPR/Cas9 ribonucleoprotein-mediated editing to disrupt the programmed cell death-1 (PD-1) gene locus in human primary T cells, resulting in a significantly reduced PD-1hi population. This reduction had little effect on CAR T cell proliferation but strongly augmented CAR T cell cytokine production and cytotoxicity towards PD-L1-expressing cancer cells in vitro. CAR T cells with PD-1 disruption show enhanced tumour control and relapse prevention in vivo when compared with CAR T cells with or without αPD-1 antibody blockade. Our study demonstrates a potential advantage of integrated immune checkpoint blockade with CAR T cells in controlling solid tumours and provides an alternative CAR T cell strategy for adoptive transfer therapy.

Programmed death ligand 1 expression in prostate cancer cells is associated with deep changes of the tumor inflammatory infiltrate composition

BACKGROUND

The main aim of this study was to investigate the putative correlation between the composition of intratumoral inflammatory infiltrate and the expression of programmed death ligand 1 (PD-L1) by prostate cancer cells. In addition, we evaluated the correlation between the expression of PD-L1 and PTX3.

METHODS

We enrolled 100 patients from which we collected one surgical sample each. Paraffin serial sections were obtained to perform histological classifications and tissues microarray construction. Serial tissues microarray paraffin sections were also used for PD-L1 analysis and intratumoral inflammatory infiltrate characterization (CD4, CD8, CD57, CD3, PD1, PSGL-1, TIGIT, CD20, CD38, CD68, CD163, and PTX3) by immunohistochemistry .

RESULTS

Our result showed a significant increase of the number of both PD-L1 and PTX3 positive cells in prostate tumors respect to benign lesions. Inflammatory infiltrate of PD-L1 positive prostate cancer lesions was characterized by a decrease of both PD1 positive lymphocytes and tumor-infiltrated macrophages, mainly M2 subpopulation. Also, PTX3 expression showed an inverse correlation with the number of PD-L1 positive prostate cancer cells.

CONCLUSIONS

If confirmed, our data could be useful to predict the variations of the inflammatory population related to PD-L1 expression in prostate cancer. This can lay the foundation to establish therapeutic protocols able to inhibit the PD-L1 activity and, at the same time, to reactivate the antitumor inflammatory process.

Fueling Cancer Immunotherapy With Common Gamma Chain Cytokines

Adoptive T cell transfer therapy (ACT) using tumor infiltrating lymphocytes or lymphocytes redirected with antigen receptors (CAR or TCR) has revolutionized the field of cancer immunotherapy. Although CAR T cell therapy mediates robust responses in patients with hematological malignancies, this approach has been less effective for treating patients with solid tumors. Additionally, toxicities post T cell infusion highlight the need for safer ACT protocols. Current protocols traditionally expand T lymphocytes isolated from patient tumors or from peripheral blood to large magnitudes in the presence of high dose IL-2 prior to infusion. Unfortunately, this expansion protocol differentiates T cells to a full effector or terminal phenotype in vitro, consequently reducing their long-term survival and antitumor effectiveness in vivo. Post-infusion, T cells face further obstacles limiting their persistence and function within the suppressive tumor microenvironment. Therapeutic manipulation of T cells with common γ chain cytokines, which are critical growth factors for T cells, may be the key to bypass such immunological hurdles. Herein, we discuss the primary functions of the common γ chain cytokines impacting T cell survival and memory and then elaborate on how these distinct cytokines have been used to augment T cell-based cancer immunotherapy.

Intratumoral IL17-producing cells infiltration correlate with antitumor immune contexture and improved response to adjuvant chemotherapy in gastric cancer

BACKGROUND

Tumor IL17-producing (IL17A+) cells infiltration has different prognostic values among various cancers. The objective of this study was to assess the effect of IL17A+ cells in gastric cancer.

PATIENTS AND METHODS

The study included two patient cohorts, the Cancer Genome Atlas cohort (TCGA, n = 351) and the Zhongshan Hospital cohort (ZSHC, n = 458). The TCGA and ZSHC were used for mRNA-related and cells infiltration-related analyses, respectively. The roles of IL17A mRNA and IL17A+ cells in overall survival (OS), response to adjuvant chemotherapy (ACT), and immune contexture were evaluated. Another independent cohort was included to identify the correlation between mRNA of IL17A and IL17A+ cells infiltration (the preliminary Zhongshan Hospital cohort, PZSHC, n = 21).

RESULTS

The infiltration of IL17A+ cells was positively correlated with the expression of IL17A mRNA (Spearman's ρ = 0.811; P < 0.001). High IL17A mRNA expression and intratumoral IL17A+ cells were correlated with improved OS and remained to be significant after adjusted for confounders. Patients with TNM II/III disease whose tumor present higher intratumoral IL17A+ cells or lower peritumoral IL17A+ cells can benefit more from ACT. Elevated IL17A mRNA expression and increased intratumoral IL17A+ cells infiltration was associated with more antitumor mast cells and nature killer cells infiltration and less pro-tumor M2 macrophages infiltration. High IL17A mRNA expression represented a Th17 cells signature and immune response process and was correlated with increased cytotoxic GZMA, GZMB, IFNG, PRF1, and TNFSF11 expression.

CONCLUSIONS

IL17A mRNA expression and intratumoral IL17A+ cells infiltration were correlated with antitumor immune contexture. IL17A+ cells infiltration could be used as an independent prognostic biomarker for OS and predictive biomarker for superior response to ACT, and further prospective validation needs to be conducted.

Compound-therapy based on cancer-immunity cycle: promising prospects for antitumor regimens

Immunotherapy has made a significant impact on the survival of patients with different tumor. However, it has become clear that they are not sufficiently active durable responses for many tumor patients, but only in a fraction of tumor patients. In order to improve this, combination regimens revealed impressive synergistic effects by combination of doublet or triplet immune agents. In this article, we will summarize the cancer-immunity cycle (CIC) and propose a rationale for the design of synergistic antitumor combinations. In addition, key issues in the development of these strategies are further discussed. Overall, we wish to highlight the backbone principles of combination regimens design at different points of the CIC, with the ultimate goal to guide better designs for future cancer combination therapies.

Checkpoint-modulating immunotherapies in tumor treatment: Targets, drugs, and mechanisms

Tumor immunotherapy, as a new treatment of cancer, has been developing on the basis of tumor immunology. Tumor immunotherapy stimulates and enhances the function of immune system in human bodies, in order to control and kill tumor cells. It is often used as an adjuvant therapy combined with surgery, chemotherapy, radiotherapy and other conventional methods. Cancer immunotherapies involve cells, antibodies and cytokines, etc. Some immunotherapies are widely used to activate the immune system, while some others precisely target at different tumor antigens. With the development of tumor immunotherapy, immune regulation activities of small molecules and biological agents have been gradually becoming a hot research area these years. In this review, we summarize the therapeutic targets, drugs, biologics, and their mechanisms in tumor immunotherapies.

Enhancing Anti-PD-1/PD-L1 Immune Checkpoint Inhibitory Cancer Therapy by CD276-Targeted Photodynamic Ablation of Tumor Cells and Tumor Vasculature

Antiangiogenic therapies have been demonstrated to improve the efficacy of immune checkpoint inhibition by overcoming the immunosuppressive status of the tumor microenvironment. However, most of the current antiangiogenic agents cannot discriminate tumor angiogenesis from physiological angiogenesis. The aim of this study was to investigate whether a photodynamic therapy (PDT) agent that targets CD276, a receptor overexpressed in various tumor cells and tumor vasculature but with limited expression in normal tissue vasculature, could improve the tumor inhibitory efficacy of a PD-1/PD-L1 blockade. A CD276-targeting agent (IRD-αCD276/Fab) was synthesized by conjugating the Fab fragment of an anti-CD276 antibody with a photosensitizer IRDye700. The in vivo tumor-targeting efficacy and therapeutic effects of IRD-αCD276/Fab with or without an anti-PD-1/PD-L1 blockade were tested in subcutaneous and lung metastatic tumor models. PDT using IRD-αCD276/Fab significantly suppressed the growth of subcutaneous 4T1 tumor and inhibited its lung metastasis. Moreover, it triggered in vivo antitumor immunity by increasing the activation and maturation of dendritic cells. Tumor PD-L1 levels were also markedly increased after PDT using IRD-αCD276/Fab, as evidenced by noninvasive PD-L1-targeted small-animal PET imaging. In combination with an anti-PD-1/PD-L1 blockade, IRD-αCD276/Fab PDT markedly suppressed the growth of tumors and prevented their metastasis to the lung by recruiting the tumor infiltration of CD8⁺ T cells. Our data provide evidence for the role of CD276-targeted PDT for local immune modulation, and its combination with PD-L1/PD-1 axis inhibition is a promising strategy for eliminating primary tumors as well as disseminated metastases, by generating local and systemic antitumor responses.

Pre- and post-operative anti-PD-L1 plus anti-angiogenic therapies in mouse breast or renal cancer models of micro- or macro-metastatic disease

BACKGROUND

There are phase 3 clinical trials underway evaluating anti-PD-L1 antibodies as adjuvant (postoperative) monotherapies for resectable renal cell carcinoma (RCC) and triple-negative breast cancer (TNBC); in combination with antiangiogenic VEGF/VEGFR2 inhibitors (e.g., bevacizumab and sunitinib) for metastatic RCC; and in combination with chemotherapeutics as neoadjuvant (preoperative) therapies for resectable TNBC.

METHODS

This study investigated these and similar clinically relevant drug combinations in highly translational preclinical models of micro- and macro-metastatic disease that spontaneously develop after surgical resection of primary kidney or breast tumours derived from orthotopic implantation of murine cancer cell lines (RENCA^luc or EMT-6/CDDP, respectively).

RESULTS

In the RENCA^luc model, adjuvant sunitinib plus anti-PD-L1 improved overall survival compared to either drug alone, while the same combination was ineffective as early therapy for unresected primary tumours or late-stage therapy for advanced metastatic disease. In the EMT-6/CDDP model, anti-PD-L1 was highly effective as an adjuvant monotherapy, while its combination with paclitaxel chemotherapy (with or without anti-VEGF) was most effective as a neoadjuvant therapy.

CONCLUSIONS

Our preclinical data suggest that anti-PD-L1 plus sunitinib may warrant further investigation as an adjuvant therapy for RCC, while anti-PD-L1 may be improved by combining with chemotherapy in the neoadjuvant but not the adjuvant setting of treating breast cancer.

Non-hematopoietic Control of Peripheral Tissue T Cell Responses: Implications for Solid Tumors

In response to pathological challenge, the host generates rapid, protective adaptive immune responses while simultaneously maintaining tolerance to self and limiting immune pathology. Peripheral tissues (e.g., skin, gut, lung) are simultaneously the first site of pathogen-encounter and also the location of effector function, and mounting evidence indicates that tissues act as scaffolds to facilitate initiation, maintenance, and resolution of local responses. Just as both effector and memory T cells must adapt to their new interstitial environment upon infiltration, tissues are also remodeled in the context of acute inflammation and disease. In this review, we present the biochemical and biophysical mechanisms by which non-hematopoietic stromal cells and extracellular matrix molecules collaborate to regulate T cell behavior in peripheral tissue. Finally, we discuss how tissue remodeling in the context of tumor microenvironments impairs T cell accumulation and function contributing to immune escape and tumor progression.

Is It Possible to Develop Cancer Vaccines to Neoantigens, What Are the Major Challenges, and How Can These Be Overcome? Targeting the Right Antigens in the Right Patients

Recent advances in genomic sequencing and bioinformatics have empowered a revolution in immuno-oncology that has led to numerous unambiguous demonstrations of spontaneous and therapy-induced T-cell responses in patients against a subset of immunogenic tumor-specific somatic mutations known as neoantigens. These findings raise the exciting possibility that patients could be therapeutically treated with personalized vaccines against the mutations expressed by their own tumor. A central challenge for the broader clinical application of this approach will be to define the best antigens to target, to determine the subset of patients most likely to derive significant clinical benefit, and, finally, to discover both the best method of vaccine delivery and the optimal time in the disease course to do so. A growing number of translational immunologists believe that these challenges can be overcome and this perspective will discuss strategies to achieve this.

PDGFRα expression as a novel therapeutic marker in well-differentiated neuroendocrine tumors

AIMS

To evaluate the biological significance of dense vascular networks associated with low-grade NENs, we assessed the impact of PDGFRα tissue expression in 77 GEP/NEN patients, associating PDGFRα expression with the morphological characterization in low-grade tumors.

METHODS AND RESULTS

Paraffin-embedded specimens of 77 GEP- NEN tissues, collected from January 2006 to March 2018, were evaluated for PDGFRα tissue expression and correlations with clinicopathological characteristics. PDGFRα tissue expression was significantly correlated with grade and the NEN growth pattern (p < 0.001) but not with gender, primary site or lymph nodes metastatic status. PDGFRα staining was mainly localized in the vascular pole of the neuroendocrine cells and in Enterochromaffin (EC) cells. In particular PDGFRα tissue expression was significantly more expressed in G2 (p < 0.001) than G1 and G3 cases (p 0.004; p < 0.0002;) and correlated with an insular growth pattern. PDGFRα tissue expression was associated with the Ki67 index and we found a significant negative trend of association with the Ki67 proliferation index (P < 0.001): thus PDGFRα expression is referred to morphological and not to proliferative data.

CONCLUSIONS

PDGFRα represents an effective target for new anti-angiogenic treatment in WD- GEP-NENs, in particular in G2 cases, and in G3 cases only when there is a mixed insular-acinar pattern. In this context, it is important to carefully delineate those tumors that might better respond to this type of treatment alone or in combination. Further investigation of the relationship between PD-L1 and PDGFRa is warranted, and may contribute to optimize the therapeutic approach in patients with GEP-NENs.

Myeloid-derived suppressor cells increase and inhibit donor-reactive T cell responses to graft intestinal epithelium in intestinal transplant patients

Recent advances in immunosuppressive regimens have decreased acute cellular rejection (ACR) rates and improved intestinal and multivisceral transplant (ITx) recipient survival. We investigated the role of myeloid-derived suppressor cells (MDSCs) in ITx. We identified MDSCs as CD33⁺ CD11b⁺ lineage(CD3/CD56/CD19)^- HLA-DR^-/low cells with 3 subsets, CD14^- CD15^- (e-MDSCs), CD14⁺ CD15^- (M-MDSCs), and CD14^- CD15⁺ (PMN-MDSCs), in peripheral blood mononuclear cells (PBMCs) and mononuclear cells in the grafted intestinal mucosa. Total MDSC numbers increased in PBMCs after ITx; among MDSC subsets, M-MDSC numbers were maintained at a high level after 2 months post ITx. The MDSC numbers decreased in ITx recipients with ACR. MDSC numbers were positively correlated with serum interleukin (IL)-6 levels and the glucocorticoid administration index. IL-6 and methylprednisolone enhanced the differentiation of bone marrow cells to MDSCs in vitro. M-MDSCs and e-MDSCs expressed CCR1, -2, and -3; e-MDSCs and PMN-MDSCs expressed CXCR2; and intestinal grafts expressed the corresponding chemokine ligands after ITx. Of note, the percentage of MDSCs among intestinal mucosal CD45⁺ cells increased after ITx. A novel in vitro assay demonstrated that MDSCs suppressed donor-reactive T cell-mediated destruction of donor intestinal epithelial organoids. Taken together, our results suggest that MDSCs accumulate in the recipient PBMCs and the grafted intestinal mucosa in ITx, and may regulate ACR.

The reciprocal function and regulation of tumor vessels and immune cells offers new therapeutic opportunities in cancer

Tumor angiogenesis and escape of immunosurveillance are two cancer hallmarks that are tightly linked and reciprocally regulated by paracrine signaling cues of cell constituents from both compartments. Formation and remodeling of new blood vessels in tumors is abnormal and facilitates immune evasion. In turn, immune cells in the tumor, specifically in context with an acidic and hypoxic environment, can promote neovascularization. Immunotherapy has emerged as a major therapeutic modality in cancer but is often hampered by the low influx of activated cytotoxic T-cells. On the other hand, anti-angiogenic therapy has been shown to transiently normalize the tumor vasculature and enhance infiltration of T lymphocytes, providing a rationale for a combination of these two therapeutic approaches to sustain and improve therapeutic efficacy in cancer. In this review, we discuss how the tumor vasculature facilitates an immunosuppressive phenotype and vice versa how innate and adaptive immune cells regulate angiogenesis during tumor progression. We further highlight recent results of antiangiogenic immunotherapies in experimental models and the clinic to evaluate the concept that targeting both the tumor vessels and immune cells increases the effectiveness in cancer patients.

Mechanism and Management of Cancer Chemotherapy-Induced Atherosclerosis

The advent of new chemotherapeutic and immunotherapeutic treatments has markedly improved outcomes in patients with cancer. However, increasing numbers of elderly patients with cancer and prolonged periods of treatment have made the management of cardiovascular complications and treatment-induced cardiotoxicity an important concern, and onco-cardiology has received increasing attention. The number of patients with cardiotoxicity, particularly atherosclerotic lesions, and the usage of angiogenesis inhibitors have increased, making the involvement of onco-cardiologists essential for effective disease management. A paradigm shift in immunotherapy was caused by the development of immune checkpoint inhibitors. Because vascular endothelial growth factors (VEGF) in the cancer microenvironment and cancer immune function are interrelated angiogenesis inhibitors will most likely play an increasingly important role in combined immunotherapy. To ensure the optimal long-term diagnosis and long-term treatment of cancer and the effective management of treatment-related atherosclerotic diseases, the long-term continuous participation of onco-cardiologists is essential.

Expression of PD-1 and PD-L1 increase in consecutive biopsies in patients with classical Hodgkin lymphoma

High expression of programmed death receptor 1 (PD-1) and its ligand (PD-L1) by leukocytes in primary classical Hodgkin lymphoma (cHL) is associated with inferior outcome. However, it is unclear how expression varies during disease progression, and in the event of relapse. Our aim was to study PD-1 and PD-L1 in consecutive biopsies from untreated and treated cHL patients. We screened pathology registries from 3500 cHL patients. Eleven patients had a diagnostic cHL biopsy and a previous benign lymph node biopsy reclassified as cHL when reviewed and designated as the untreated. Thirty patients had a primary and a relapse biopsy, designated as the treated. Biopsies were immunostained to detect PD-1+ and PD-L1+ leukocytes, and PD-L1+ tumor cells. In the untreated, none of the markers were statistically significantly different when biopsies 1 and 2 were compared. In the treated, 19, 22, and 18 of 30 cases had increased proportions of PD-1+ leukocytes, PD-L1+ leukocytes and PD-L1+ tumor cells, respectively, and were all statistically significantly increased when primary and relapse biopsies were compared. PD-1 and PD-L1 most likely increase due to primary treatment with chemotherapy and radiotherapy, which could have implications regarding treatment with PD-1 inhibitors.

Autophagosome-based strategy to monitor apparent tumor-specific CD8 T cells in patients with prostate cancer

The immune system plays an essential role in eradicating cancer in concert with various treatment modalities. In the absence of autologous tumor material, no standardized method exists to assess T cell responses against the many antigens that may serve as cancer rejection antigens. Thus, development of methods to screen for therapy-induced anti-tumor responses is a high priority that could help tailor therapy. Here we tested whether a tumor-derived antigen source called DRibbles®, which contain a pool of defective ribosomal products (DRiPs), long-lived and short-lived proteins (SLiPs) and danger-associated molecular patterns (DAMPs), can be used to identify tumor-associated antigen (TAA)-specific responses in patients before or after immunotherapy treatment. Protein content, gene expression and non-synonymous - single nucleotide variants (ns-SNVs) present in UbiLT3 DRibbles were compared with prostate adenocarcinomas and the prostate GVAX vaccine cell lines (PC3/LNCaP). UbiLT3 DRibbles were found to share proteins, as well as match tumor sequences for ns-SNVs with prostate adenocarcinomas and with the cell lines PC3 and LNCaP. UbiLT3 DRibbles were used to monitor anti-tumor responses in patients vaccinated with allogeneic prostate GVAX. UbiLT3-DRibble-reactive CD8+ T-cell responses were detected in post-vaccine PBMC of 6/12 patients (range 0.85-22% of CD8+ cells) after 1 week in vitro stimulation (p = 0.007 vs. pre-vaccine). In conclusion, a cancer-derived autophagosome-enriched preparation, packaging over 100 proteins over-expressed in prostate cancer into microvesicles containing DAMPs, could be used to identify CD8+ T cells in peripheral blood from patients after prostate GVAX vaccination and may represent a general method to monitor anti-cancer T cell responses following immunotherapy.

Combining Vascular Normalization with an Oncolytic Virus Enhances Immunotherapy in a Preclinical Model of Advanced-Stage Ovarian Cancer

PURPOSE

Intravenous delivery of oncolytic viruses often leads to tumor vascular shutdown, resulting in decreased tumor perfusion and elevated tumor hypoxia. We hypothesized that using 3TSR to normalize tumor vasculature prior to administration of an oncolytic Newcastle disease virus (NDV) would enhance virus delivery and trafficking of immunologic cell subsets to the tumor core, resulting in systemically enhanced immunotherapy and regression of advanced-stage epithelial ovarian cancer (EOC).

EXPERIMENTAL DESIGN

Using an orthotopic, syngeneic mouse model of advanced-stage EOC, we pretreated mice with 3TSR (4 mg/kg per day) alone or followed by combination with fusogenic NDV(F3aa) (1.0 × 10⁸ plaque-forming units).

RESULTS

Treatment with 3TSR normalized tumor vasculature, enhanced blood perfusion of primary EOC tumors, and induced disease regression. Animals treated with combination therapy had the greatest reduction in primary tumor mass, ascites accumulation, and secondary lesions (50% of mice were completely devoid of peritoneal metastases). Combining 3TSR + NDV(F3aa) led to enhanced trafficking of immunologic cells into the primary tumor core.

CONCLUSIONS

We have shown, for the first time, that NDV, like other oncolytic viruses, is a potent mediator of acute vascular shutdown and that preventing this through vascular normalization can promote regression in a preclinical model of advanced-stage ovarian cancer. This challenges the current focus on induction of intravascular thrombosis as a requisite for successful oncolytic virotherapy.See related commentary by Bykov and Zamarin, p. 1446.

The impact of inflationary cytomegalovirus-specific memory T cells on anti-tumour immune responses in patients with cancer

Human cytomegalovirus (CMV) is a ubiquitous, persistent beta herpesvirus. CMV infection contributes to the accumulation of functional antigen-specific CD8⁺ T-cell pools with an effector-memory phenotype and enrichment of these immune cells in peripheral organs. We review here this 'memory T-cell inflation' phenomenon and associated factors including age and sex. 'Collateral damage' due to CMV-directed immune reactivity may occur in later stages of life - arising from CMV-specific immune responses that were beneficial in earlier life. CMV may be considered an age-dependent immunomodulator and a double-edged sword in editing anti-tumour immune responses. Emerging evidence suggests that CMV is highly prevalent in patients with a variety of cancers, particularly glioblastoma. A better understanding of CMV-associated immune responses and its implications for immune senescence, especially in patients with cancer, may aid in the design of more clinically relevant and tailored, personalized treatment regimens. 'Memory T-cell inflation' could be applied in vaccine development strategies to enrich for immune reactivity where long-term immunological memory is needed, e.g. in long-term immune memory formation directed against transformed cells.

Next Generation Cancer Vaccines-Make It Personal!

Dramatic success in cancer immunotherapy has been achieved over the last decade with the introduction of checkpoint inhibitors, leading to response rates higher than with chemotherapy in certain cancer types. These responses are often restricted to cancers that have a high mutational burden and show pre-existing T-cell infiltrates. Despite extensive efforts, therapeutic vaccines have been mostly unsuccessful in the clinic. With the introduction of next generation sequencing, the identification of individual mutations is possible, enabling the production of personalized cancer vaccines. Combining immune check point inhibitors to overcome the immunosuppressive microenvironment and personalized cancer vaccines for directing the host immune system against the chosen antigens might be a promising treatment strategy.

Personalized cancer neoantigen vaccines come of age

Cancer vaccines have encountered their ideal personalized partner along with evidence for great breakthroughs in the identification and synthesis of neoantigens. Individual cancer neoantigen vaccines are capable of eliciting robust T-cell responses and have been demonstrated to achieve striking clinical efficacy due to their high immunogenicity and central thymic tolerance escape of neoantigens. Two recent phase I clinical trials have provided support for the hypothesis and have heralded a nascent era of personalized vaccines in the field of immunotherapy. This review aims to address the identification of neoepitopes and describes advances made in personalized vaccines. In addition, this review discusses the challenges related to the exploitation of vaccine therapy, and provides potential thoughts for the improvement of vaccine design and applications.

Cancer initiation and progression within the cancer microenvironment

Within the cancer microenvironment, the growth and proliferation of cancer cells in the primary site as well as in the metastatic site represent a global biological phenomenon. To understand the growth, proliferation and progression of cancer either by local expansion and/or metastasis, it is important to understand the cancer microenvironment and host response to cancer growth. Melanoma is an excellent model to study the interaction of cancer initiation and growth in relationship to its microenvironment. Social evolution with cooperative cellular groups within an organism is what gives rise to multicellularity in the first place. Cancer cells evolve to exploit their cellular environment. The foundations of multicellular cooperation break down in cancer because those cells that misbehave have an evolutionary advantage over their normally behaving neighbors. It is important to classify evolutionary and ecological aspects of cancer growth, thus, data for cancer growth and outcomes need to be collected to define these parameters so that accurate predictions of how cancer cells may proliferate and metastasize can be developed.

B lymphocytes can be activated to act as antigen presenting cells to promote anti-tumor responses

Immune evasion by tumors includes several different mechanisms, including the inefficiency of antigen presenting cells (APCs) to trigger anti-tumor T cell responses. B lymphocytes may display a pro-tumoral role but can also be modulated to function as antigen presenting cells to T lymphocytes, capable of triggering anti-cancer immune responses. While dendritic cells, DCs, are the best APC population to activate naive T cells, DCs or their precursors, monocytes, are frequently modulated by tumors, displaying a tolerogenic phenotype in cancer patients. In patients with cervical cancer, we observed that monocyte derived DCs are tolerogenic, inhibiting allogeneic T cell activation compared to the same population obtained from patients with precursor lesions or cervicitis. In this work, we show that B lymphocytes from cervical cancer patients respond to treatment with sCD40L and IL-4 by increasing the CD80+CD86+ population, therefore potentially increasing their ability to activate T cells. To test if B lymphocytes could actually trigger anti-tumor T cell responses, we designed an experimental model where we harvested T and B lymphocytes, or dendritic cells, from tumor bearing donors, and after APC stimulation, transplanted them, together with T cells into RAG1-/- recipients, previously injected with tumor cells. We were able to show that anti-CD40 activated B lymphocytes could trigger secondary T cell responses, dependent on MHC-II expression. Moreover, we showed that dendritic cells were resistant to the anti-CD40 treatment and unable to stimulate anti-tumor responses. In summary, our results suggest that B lymphocytes may be used as a tool for immunotherapy against cancer.

Injectable Bioresponsive Gel Depot for Enhanced Immune Checkpoint Blockade

Although cancer immunotherapy based on immune checkpoint inhibitors holds great promise toward many types of cancers, several challenges still remain, associated with low objective response of patient rate as well as systemic side effects. Here, a combination immunotherapy strategy is developed based on a thermogelling reactive oxygen species (ROS)-responsive polypeptide gel for sustained release of anti-programmed cell death-ligand 1 antibody and dextro-1-methyl tryptophan, inhibitor of indoleamine-2,3-dioxygenase with leveraging the ROS level in the tumor microenvironment. This bioresponsive gel depot can effectively reduce the local ROS level and facilitate release of immunotherapeutics, which leads to enhanced anti-melanoma efficacy in vivo.

Expansion and Antitumor Cytotoxicity of T-Cells Are Augmented by Substrate-Bound CCL21 and Intercellular Adhesion Molecule 1

Adoptive immunotherapy is based on ex vivo expansion and stimulation of T-cells, followed by their transfer into patients. The need for the ex vivo culturing step provides opportunities for modulating the properties of transferred T-cells, enhancing their antitumor abilities, and increasing their number. Here, we present a synthetic immune niche (SIN) that increases the number and antitumor activity of cytotoxic CD8⁺ T-cells. We first evaluated the effect of various SIN compositions that mimic the physiological microenvironment encountered by T-cells during their activation and expansion in the lymph node. We found that substrates coated with the chemokine CCL21 together with the adhesion molecule intercellular adhesion molecule 1 significantly increase the number of ovalbumin-specific murine CD8⁺ T-cells activated by antigen-loaded dendritic cells or activation microbeads. Notably, cells cultured on these substrates also displayed augmented cytotoxic activity toward ovalbumin-expressing melanoma cells, both in culture and in vivo. This increase in specific cytotoxic activity was associated with a major increase in the cellular levels of the killing-mediator granzyme B. Our results suggest that this SIN may be used for generating T-cells with augmented cytotoxic function, for use in cancer immunotherapy.

Noninvasive imaging of the PD-1:PD-L1 immune checkpoint: Embracing nuclear medicine for the benefit of personalized immunotherapy

Molecular imaging of the immune checkpoint receptor PD-1 and its ligand PD-L1 is increasingly investigated as a strategy to guide and monitor PD-1:PD-L1-targeted immune checkpoint therapy. We provide an overview of the current state-of-the-art on PD-1- and PD-L1-specific imaging agents for quantitative, real-time assessment of PD-1:PD-L1 expression in the tumor environment and discuss their potential for clinical translation.

Blood and lymphatic vessels contribute to the impact of the immune microenvironment on clinical outcome in non-small-cell lung cancer

OBJECTIVES

Lymphangiogenesis plays a critical role in the immune response, tumour progression and therapy effectiveness. The aim of this study was to determine whether the interplay between the lymphatic and the blood microvasculature, tumour-infiltrating lymphocytes and the programmed death 1 (PD-1)/programmed death ligand 1 (PD-L1) immune checkpoint constitutes an immune microenvironment affecting the clinical outcome of patients with non-small-cell lung cancer.

METHODS

Samples from 50 squamous cell carcinomas and 42 adenocarcinomas were subjected to immunofluorescence to detect blood and lymphatic vessels. CD3pos, CD8pos and PD-1pos tumour-infiltrating lymphocytes and tumour PD-L1 expression were assessed by immunohistochemical analysis.

RESULTS

Quantification of vascular structures documented a peak of lymphatics at the invasive margin together with a decreasing gradient of blood and lymphatic vessels from the peritumour area throughout the neoplastic core. Nodal involvement and pathological stage were strongly associated with vascularization, and an increased density of vessels was detected in samples with a higher incidence of tumour-infiltrating lymphocytes and a lower expression of PD-L1. Patients with a high PD-L1 to PD-1 ratio and vascular rarefaction had a gain of 10 months in overall survival compared to those with a low ratio and prominent vascularity.

CONCLUSIONS

Microvessels are an essential component of the cancer immune microenvironment. The clinical impact of the PD-1/PD-L1-based immune contexture may be implemented by the assessment of microvascular density to potentially identify patients with non-small-cell lung cancer who could benefit from immunotherapy and antiangiogenic treatment.

Known and novel roles of the MET oncogene in cancer: a coherent approach to targeted therapy

The MET oncogene encodes an unconventional receptor tyrosine kinase with pleiotropic functions: it initiates and sustains neoplastic transformation when genetically altered ('oncogene addiction') and fosters cancer cell survival and tumour dissemination when transcriptionally activated in the context of an adaptive response to adverse microenvironmental conditions ('oncogene expedience'). Moreover, MET is an intrinsic modulator of the self-renewal and clonogenic ability of cancer stem cells ('oncogene inherence'). Here, we provide the latest findings on MET function in cancer by focusing on newly identified genetic abnormalities in tumour cells and recently described non-mutational MET activities in stromal cells and cancer stem cells. We discuss how MET drives cancer clonal evolution and progression towards metastasis, both ab initio and under therapeutic pressure. We then elaborate on the use of MET inhibitors in the clinic with a critical appraisal of failures and successes. Ultimately, we advocate a rationale to improve the outcome of anti-MET therapies on the basis of thorough consideration of the entire spectrum of MET-mediated biological responses, which implicates adequate patient stratification, meaningful biomarkers and appropriate clinical end points.

Armed oncolytic viruses: A kick-start for anti-tumor immunity

Oncolytic viruses (OVs), viruses that specifically result in killing tumor cells, represent a promising class of cancer therapy. Recently, the focus in the OV therapy field has shifted from their direct oncolytic effect to their immune stimulatory effect. OV therapy can function as a "kick start" for the antitumor immune response by releasing tumor associated antigens and release of inflammatory signals. Combining OVs with immune modulators could enhance the efficacy of both immune and OV therapies. Additionally, genetic engineering of OVs allows local expression of immune therapeutics, thereby reducing related toxicities. Different options to modify the tumor microenvironment in combination with OV therapy have been explored. The possibilities and obstacles of these combinations will be discussed in this review.

Abscopal, immunological effects of radiotherapy: Narrowing the gap between clinical and preclinical experiences

Radiotherapy-despite being a local therapy that meanwhile is characterized by an impressively high degree of spatial accuracy-can stimulate systemic phenomena which occasionally lead to regression and rejection of non-irradiated, distant tumor lesions. These abscopal effects of local irradiation have been observed in sporadic clinical case reports since the beginning of the 20th century, and extensive preclinical work has contributed to identify systemic anti-tumor immune responses as the underlying driving forces. Although abscopal tumor regression still remains a rare event in the radiotherapeutic routine, increasing numbers of cases are being reported, particularly since the clinical implementation of immune checkpoint inhibiting agents. Accordingly, interests to systematically exploit the therapeutic potential of radiotherapy-stimulated systemic responses are constantly growing. The present review briefly delineates the history of radiotherapy-induced abscopal effects and the activation of systemic anti-tumor immune responses by local irradiation. We discuss preclinical and clinical reports with specific focus on the corresponding controversies, and we propose issues that should be addressed in the future in order to narrow the gap between preclinical knowledge and clinical experiences.

Antitumor Immunity Is Controlled by Tetraspanin Proteins

Antitumor immunity is shaped by the different types of immune cells that are present in the tumor microenvironment (TME). In particular, environmental signals (for instance, soluble factors or cell–cell contact) transmitted through the plasma membrane determine whether immune cells are activated or inhibited. Tetraspanin proteins are emerging as central building blocks of the plasma membrane by their capacity to cluster immune receptors, enzymes, and signaling molecules into the tetraspanin web. Whereas some tetraspanins (CD81, CD151, CD9) are widely and broadly expressed, others (CD53, CD37, Tssc6) have an expression pattern restricted to hematopoietic cells. Studies using genetic mouse models have identified important immunological functions of these tetraspanins on different leukocyte subsets, and as such, may be involved in the immune response against tumors. While multiple studies have been performed with regards to deciphering the function of tetraspanins on cancer cells, the effect of tetraspanins on immune cells in the antitumor response remains understudied. In this review, we will focus on tetraspanins expressed by immune cells and discuss their potential role in antitumor immunity. New insights in tetraspanin function in the TME and possible prognostic and therapeutic roles of tetraspanins will be discussed.