The combination of a novel immunomodulator with a regulatory T cell suppressing antibody (DTA-1) regress advanced stage B16F10 solid tumor by repolarizing tumor associated macrophages in situ

Targeting the macrophage immunocheckpoint: a novel insight into solid tumor immunotherapy

Tumor immunotherapy, which targets immune checkpoints, presents a promising strategy for the treatment of various cancer types. However, current clinical data indicate challenges in its application to solid tumors. Recent studies have revealed a significant correlation between the degree of immune response in immunotherapy and the tumor microenvironment, particularly with regard to tumor-infiltrating immune cells. Among these immune cells, macrophages, a critical component, are playing an increasingly vital role in tumor immunotherapy. This review focuses on elucidating the role of macrophages within solid tumors and provides an overview of the progress in immunotherapy approaches centered around modulating macrophage responses through various immune factors. Video Abstract.

Tumor-associated macrophages as a potential therapeutic target in thyroid cancers

Macrophages are important precursor cell types of the innate immune system and bridge adaptive immune responses through the antigen presentation system. Meanwhile, macrophages constitute substantial portion of the stromal cells in the tumor microenvironment (TME) (referred to as tumor-associated macrophages, or TAMs) and exhibit conflicting roles in the development, invasion, and metastasis of thyroid cancer (TC). Moreover, TAMs play a crucial role to the behavior of TC due to their high degree of infiltration and prognostic relevance. Generally, TAMs can be divided into two subgroups; M1-like TAMs are capable of directly kill tumor cells, and recruiting and activating other immune cells in the early stages of cancer. However, due to changes in the TME, M2-like TAMs gradually increase and promote tumor progression. This review aims to discuss the impact of TAMs on TC, including their role in tumor promotion, gene mutation, and other factors related to the polarization of TAMs. Finally, we will explore the M2-like TAM-centered therapeutic strategies, including chemotherapy, clinical trials, and combinatorial immunotherapy.

Role of immunotherapy in chondrosarcoma: A case report and review of the literature

Chondrosarcomas (CSs) consist of a heterogenous group of primary bone cancers arising from malignant cells which produce cartilaginous matrix. As the second most common primary bone cancer, CS are often resistant to systemic chemotherapy due to poor vascularization, slow proliferation, and expression of multidrug-resistant pumps. Immune checkpoint inhibitors have transformed the field of oncology and are now designated as frontline therapy for many solid tumor cancers. Several studies have demonstrated increased expression of programed cell death 1 (PD-1) and PD-L1 in CS tissue in vitro, which has led to the development of multiple clinical trials for immunotherapy in patients with aggressive CS. In this review, we highlight the ongoing investigation into the role for immunotherapy in CS. We also report the case of a 44-year-old female with a history of stage IV primary CS of the right shoulder who underwent radical resection with recurrence and demonstrated a spectacular sustained response to pembrolizumab at our center. Our review highlights the need for further studies investigating the role of immunotherapy in the treatment of aggressive bone sarcomas that are resistant to standard surgical resection, chemotherapy, and radiation treatment.

Immunopathology of Extracellular Vesicles in Macrophage and Glioma Cross-Talk

Glioblastomas (GBM) are a devastating disease with extremely poor clinical outcomes. Resident (microglia) and infiltrating macrophages are a substantial component of the tumor environment. In GBM and other cancers, tumor-derived extracellular vesicles (EVs) suppress macrophage inflammatory responses, impairing their ability to identify and phagocytose cancerous tissues. Furthermore, these macrophages then begin to produce EVs that support tumor growth and migration. This cross-talk between macrophages/microglia and gliomas is a significant contributor to GBM pathophysiology. Here, we review the mechanisms through which GBM-derived EVs impair macrophage function, how subsequent macrophage-derived EVs support tumor growth, and the current therapeutic approaches to target GBM/macrophage EV crosstalk.

Exosome-mediated crosstalk between tumor cells and innate immune cells: implications for cancer progression and therapeutic strategies

The increasing number of cancer-associated deaths despite the substantial improvement in diagnosis and treatment has sparked discussions on the need for novel biomarkers and therapeutic strategies for cancer. Exosomes have become crucial players in tumor development and progression, largely due to the diverse nature of their cargo content released to recipient cells. Importantly, exosome-mediated crosstalk between tumor and stromal cells is essential in reprogramming the tumor microenvironment to facilitate tumor progression. As a result, exosomes have gradually become a marker for the early diagnosis of many diseases and an important tool in drug delivery systems. However, the precise mechanisms by which exosomes participate in tumor progression remain elusive, multifaceted, and a double-edged sword, thus requiring further clarification. The available evidence suggests that exosomes can facilitate communication between innate immune cells and tumor cells to either support or inhibit tumor progression. Herein, this review focused on exosome-mediated intercellular communication between tumor cells and macrophages, neutrophils, mast cells, monocytes, dendritic cells, and natural killer cells. Specifically, how such intercellular communication affects tumor progression has been described. It has also been discussed that, depending on their cargo, exosomes can suppress or promote tumor cell progression. In addition, the potential application of exosomes and strategies to target exosomes in cancer treatment has been comprehensively discussed.

Immunotherapy for anaplastic thyroid carcinoma: the present and future

Anaplastic thyroid carcinoma (ATC) is the most malignant tumor of endocrine system, which is an urgent medical problem to be solved. At present, immunotherapy studies on ATC mainly include cutting off the recruitment of tumor-associated macrophage (TAM), inducing the reprogramming of TAM and restoring its phagocytic function, targeting related immune checkpoints on T cells and natural killer cells, tumor vaccines based on oncolytic viruses and dendritic cells, and adoptive immunotherapy. Among them, immunotherapy strategies represented by targeted blocking of programmed death-1/programmed death ligand-1 at immune checkpoint have been preliminarily confirmed to benefit ATC patients, especially the combination of molecular targeted inhibitors and immunotherapy has shown excellent therapeutic effects. Due to the great heterogeneity of ATC, it is expected to provide more therapeutic strategies for patients of ATC by carrying out various immunotherapy studies including biological, immune and cellular therapies and exploring the therapeutic potential of the next generation of immune checkpoint inhibitors. This article reviews the potential immunotherapeutic targets of ATC and the progress of immunotherapy.

Immunotherapy for cancer: effects of iron oxide nanoparticles on polarization of tumor-associated macrophages

Cancer immunotherapy is the most promising trend in oncology, focusing on helping or activating the patient's immune system to identify and fight against cancer. In the last decade, interest in metabolic reprogramming of tumor-associated macrophages from M2-like phenotype (promoting tumor progression) to M1-like phenotypes (suppressing tumor growth) as a therapeutic strategy against cancer has increased considerably. Iron metabolism has been standing out as a target for the reprogramming of tumor-associated macrophages to M1-like phenotype with therapeutic purposes against cancer. Due to the importance of the iron levels in macrophage polarization states, iron oxide nanoparticles can be used to change the activation state of tumor-associated macrophages for a tumor suppressor phenotype and as an anti-tumor strategy.

Crucial role of glucosylceramide synthase in the regulation of stem cell-like cancer cells in B16F10 murine melanoma

Cancer stem cells render a complex cascade of events that facilitates highly invasive melanoma malignancy. Interplay between immunocytes and cancer stem cells within tumor microenvironment with the participation of sphingolipid signaling mediators skews the immune evasion strategies toward metastatic neoplasm. In this context, we aimed to explore the functional aspect of glucosylceramide synthase (GCS), a key enzyme of sphingolipid biosynthesis in the maintenance of melanoma stem cell-like cancer cells (CSCs). Our findings demonstrated that tumor hypoxia was responsible for elevated GCS expression in melanoma, which was correlated with substantially increased melanoma CSCs. Moreover, hypoxia-induced TGF-β from TAMs and Tregs promoted GCS induction in B16F10 murine melanoma CSCs via PKCα signaling and facilitated the expansion of melanoma CSCs. Interestingly, GCS ablation hindered the immunosuppressiveness of TAMs and Tregs. Therefore, our study for the first time demonstrated a novel paracrine pathway of melanoma CSC maintenance and tumorigenicity, exploiting the bidirectional signaling with immunocytes. Furthermore, our study showed that the combinatorial immunotherapy involving immunomodulators like Mw and DTA-1 repressed CSC pool affecting GCS functions in advanced-stage B16F10 murine melanoma tumor. Moreover, GCS inhibition sensitized conventional chemotherapeutic drug-resistant melanoma CSCs to the genotoxic drugs paving the way toward selective melanoma treatment. Better therapeutic efficacy with inhibition of GCS and CSC depletion suggests a crucial role of GCS in melanoma treatment, therefore, implying its application concerning clinical challenges of chemotherapy resistance leading to prolonged survival.

Distinct Responsiveness of Tumor-Associated Macrophages to Immunotherapy of Tumors with Different Mechanisms of Major Histocompatibility Complex Class I Downregulation

Simple Summary

Tumor-associated macrophages (TAMs) are one of the major cell subpopulations in the tumor microenvironment (TME) where they can either be pro-tumorigenic or contribute to an anti-tumor immunity. The TME and TAM phenotype were analyzed after combined immuno-therapy (IT) in tumor models characterized by distinct expression of major histocompatibility class I complex (MHC-I) molecules, i.e., tumors induced with TC-1 (MHC-I-proficient), TC-1/A9 (reversibly downregulated), and TC-1/dB2m (irreversibly downregulated) cells. We found out that combined IT highly activated immune reactions in the TME of TC-1 and TC-1/A9 tumors, but the TME of TC-1/dB2m tumors remained almost unchanged. Correspondingly, TAMs from TC-1/A9 tumors were able to destroy tumor cells in vitro, while TAMs isolated from TC-1/dB2m tumors showed profoundly decreased cytotoxicity. Hence, various capabilities of TAMs in tumors with distinct expression of MHC-I molecules should be considered when applying IT, particularly IT focused on TAMs.

Abstract

Tumor-associated macrophages (TAMs) plentifully infiltrate the tumor microenvironment (TME), but their role in anti-tumor immunity is controversial. Depending on the acquired polarization, they can either support tumor growth or participate in the elimination of neoplastic cells. In this study, we analyzed the TME by RNA-seq and flow cytometry and examined TAMs after ex vivo activation. Tumors with normal and either reversibly or irreversibly decreased expression of major histocompatibility complex class I (MHC-I) molecules were induced with TC-1, TC-1/A9, and TC-1/dB2m cells, respectively. We found that combined immunotherapy (IT), composed of DNA immunization and the CpG oligodeoxynucleotide (ODN) ODN1826, evoked immune reactions in the TME of TC-1- and TC-1/A9-induced tumors, while the TME of TC-1/dB2m tumors was mostly immunologically unresponsive. TAMs infiltrated both tumor types with MHC-I downregulation, but only TAMs from TC-1/A9 tumors acquired the M1 phenotype upon IT and were cytotoxic in in vitro assay. The anti-tumor effect of combined IT was markedly enhanced by a blockade of the colony-stimulating factor-1 receptor (CSF-1R), but only against TC-1/A9 tumors. Overall, TAMs from tumors with irreversible MHC-I downregulation were resistant to the stimulation of cytotoxic activity. These data suggest the dissimilarity of TAMs from different tumor types, which should be considered when utilizing TAMs in cancer IT.

Exosome-mediated communication between tumor cells and tumor-associated macrophages: implications for tumor microenvironment

Exosomes are extracellular vesicles released from numerous types of cells that are involved in multiple tumors development. Exosomes contribute to the modulation of tumor microenvironment (TME) through intercellular communication. As essential immune stromal cells in the TME, tumor-associated macrophages (TAMs) participate in tumor development by mediating angiogenesis, metastasis, chemoresistance, and immune escape. Due to communication with multiple cells in the TME, they exhibit plasticity and heterogeneity during the progress of polarization from monocytes to macrophages. Previous studies suggest that targeting TAMs is a promising therapeutic strategy; however, the detailed mechanism by which TAMs regulate tumor development still remains unclear. In this review, we provide an overview of the roles of exosomes as messengers in the communication between tumor cells and polarization of TAMs; we also describe the effects of their interaction on tumor development. Finally, we comprehensively discussed the potential application of exosomes as the promising tumor immunotherapy strategy.

Glycyrrhizic acid facilitates anti-tumor immunity by attenuating Tregs and MDSCs: An immunotherapeutic approach

Melanoma is one of the most aggressive malignancies and its treatment remains challenging due to its highly metastatic property and availability of limited effective drugs. In addition, immunosuppresive tumor microenvironment (TME) has been identified as major barrier to evoke anti-tumor response in melanoma. Recent studies revealed that immunosuppressive TME is directly correlated with heightened activations of T regulatory cells (Tregs) and Myeloid derived suppressor cells (MDSCs) functions. In this study, we investigated the anti-cancer effect of a triterpenoid, glycyrrhizic acid (GA) on melanoma. Our study revealed that GA not only exhibited anti-proliferative effects on melanoma cells it significantly restricted progression of melanoma tumor. However, the therapeutic efficacy of GA in impressive regression of tumor was found to be directly correlated with induction of apoptosis and modulation of cytokines from Th2 to Th1 type. To unravel the mechanism of anti-melanoma effect of GA, it has been delineated that GA inhibits pSTAT3 to evade anti-tumor suppressive function of Tregs and MDSCs. Downregulation of FOXP3, GITR and CTLA4 in tumor-infiltrating Tregs and inhibition of Cox2, PGE2 and Arginase 1 in intra-tumoral MDSC were evidenced as some of the key events during therapeutic intervention of GA in melanoma management. Moreover, GA effectively restricted advanced stage solid tumor while used in combination with Mycobacterium indicus pranii, a known immunomodulator, which alone is reported to be ineffective to restrict advanced stage solid tumor. Thus, our findings may open up a novel insight of GA as a promising agent in cancer immunotherapy or adjuvant therapy in future.

Cancer stem cells and ceramide signaling: the cutting edges of immunotherapy

The multipotent, self renewing "cancer stem cells" (CSCs), a small population within tumor microenvironment facilitates transformed cells to grow and propagate within the body. The CSCs are discovered as resistant to the chemotherapeutic drug with distinct immunological characteristics. In recent years, immunologically targeting CSCs have emerged as an integral part of effective and successful cancer therapy. CSCs notably exhibit dysregulation in conventional sub-cellular sphingolipid metabolism. Recently, ceramide decaying enzymes have been shown to activate alternative ceramide signaling pathways leading to reduction in efficacy of the chemotherapeutic drugs. Therefore, a control over ceramide mediated modulations of CSCs offers an attractive dimension of effective cancer treatment strategy in future. In this review, we focused on the recent findings on broad spectrum of ceramide mediated signaling in CSCs within the tumor niche and their role in potential cancer immunotherapy.

Tumor-Associated Macrophages: Protumoral Macrophages in Inflammatory Tumor Microenvironment

Tumor microenvironment consists of malignant and non-malignant cells. The interaction of these dynamic and different cells is responsible for tumor progression at different levels. The non-malignant cells in TME contain cells such as tumor-associated macrophages (TAMs), cancer associated fibroblasts, pericytes, adipocytes, T cells, B cells, myeloid-derived suppressor cells (MDSCs), tumor-associated neutrophils (TANs), dendritic cells (DCs) and Vascular endothelial cells. TAMs are abundant in most human and murine cancers and their presence are associated with poor prognosis. The major event in tumor microenvironment is macrophage polarization into tumor-suppressive M1 or tumor-promoting M2 types. Although much evidence suggests that TAMS are primarily M2-like macrophages, the mechanism responsible for polarization into M1 and M2 macrophages remain unclear. TAM contributes cancer cell motility, invasion, metastases and angiogenesis. The relationship between TAM and tumor cells lead to used them as a diagnostic marker, therapeutic target and prognosis of cancer. This review presents the origin, polarization, role of TAMs in inflammation, metastasis, immune evasion and angiogenesis as well as they can be used as therapeutic target in variety of cancer cells. It is obvious that additional substantial and preclinical research is needed to support the effectiveness and applicability of this new and promising strategy for cancer treatment.

Immunotherapy in anaplastic thyroid cancer

Anaplastic thyroid cancer (ATC) is one of the worst human malignancies, with an associated median survival of only 5 months. It is resistant to conventional thyroid cancer therapies, including radioiodine and thyroid-stimulating hormone suppression. Cancer immunotherapy has emerged over the past few decades as a transformative approach to treating a wide variety of cancers. However, immunotherapy for ATC is still in the experimental stage. This review will cover several strategies of immunotherapy and discuss the possible application of these strategies in the treatment of ATC (such as targeted therapy for tumor-associated macrophages, cancer vaccines, adoptive immunotherapy, monoclonal antibodies and immune checkpoint blockade) with the hope of improving the prognosis of ATC in the future.

Tumor-Associated Macrophages: Recent Insights and Therapies

Macrophages, which have functions of engulfing and digesting foreign substances, can clear away harmful matter, including cellular debris and tumor cells. Based on the condition of the internal environment, circulating monocytes give rise to mature macrophages, and when they are recruited into the tumor microenvironment and in suitable conditions, they are converted into tumor-associated macrophages (TAMs). Generally, macrophages grow into two main groups called classically activated macrophages (M1) and alternatively activated macrophages (M2). M2 and a small fraction of M1 cells, also known as TAMs, not only lack the function of phagocytizing tumor cells but also help these tumor cells escape from being killed and help them spread to other tissues and organs. In this review, we introduce several mechanisms by which macrophages play a role in the immune regulation of tumor cells, including both killing factors and promoting effects. Furthermore, the targeted therapy for treating tumors based on macrophages is also referred to in our review. We confirm that further studies of macrophage-focused therapeutic strategies and their use in clinical practice are needed to verify their superior efficacy and potential in cancer treatment.

PKCζ mediated anti-proliferative effect of C2 ceramide on neutralization of the tumor microenvironment and melanoma regression

Immunotherapy, which has advantages over chemotherapy due to lesser toxicity and higher specificity, is on the rise to treat cancer. Recently, pro-apoptotic glycolipid, ceramide has emerged as a key regulator in cancer immunotherapy. The present study elucidated the potential anti-melanoma efficacy of cell-permeable, exogenous C2 ceramide on cell death and amelioration of tumor microenvironment (TME). We, for the first time, demonstrated that C2 ceramide triggered apoptosis of melanoma cells by augmenting PKCζ along with pro-inflammatory cytokines and signaling factors. C2 ceramide showed a PKCζ-mediated tumor-suppressive role in melanoma without exhibiting hepatotoxicity and nephrotoxicity. Moreover, PKCζ was revealed as one of the key regulators of Akt and ceramide during C2 ceramide-mediated apoptosis. C2 ceramide was effective in repolarization of M2 macrophage phenotype and reduction of angiogenic factors such as VEGF, VEGFR1, VEGFR2, HIF1α. Interestingly, PKCζ knockdown attenuated C2 ceramide-mediated inhibition of melanoma progression. Restoration of the Th1 type TME by C2 ceramide enhanced cytotoxic T cell-mediated killing of melanoma cells. Altogether, the study unraveled that C2 ceramide-induced PKCζ was associated with favorable immune cell functioning in TME leading to melanoma regression. Thus, our findings explored a novel mechanistic insight into C2 ceramide as a promising immunotherapeutic agent in melanoma treatment.

Tumor-Associated Macrophages (TAMs): A Critical Activator In Ovarian Cancer Metastasis

Tumor-associated macrophages (TAMs) that appear in every stage of cancer progression are usually tumor-promoting cells and are present abundantly in the tumor-associated microenvironment. In ovarian cancer, the overall and intratumoral M1/M2 ratio is a relatively efficient TAM parameter for predicting the prognosis of patients, especially for serous tissue type cancer. TAMs exhibit immunological checkpoint modulators, such as the B7 family and programmed death-ligand 1 (PD-L1), and play a key role in the development, metastasis and invasion of ovarian cancer, but the underlying mechanism is barely understood. Ovarian cancer is a severe gynecological malignancy with high mortality. Ovarian cancer-associated death can primarily be attributed to cancer metastasis. The majority of patients are diagnosed with wide dissemination in the peritoneum and omentum, limiting the effectiveness of surgery and chemotherapy. In addition, unlike other well-documented cancers, metastasis through vasculature is not a usual dissemination pathway in ovarian cancer. This review sheds light on TAMs and the main process and mechanism of ovarian cancer metastasis.

TNFα mediated ceramide generation triggers cisplatin induced apoptosis in B16F10 melanoma in a PKCδ independent manner

Ceramide is one of the important cellular components involved in cancer regulation and exerts its pleiotropic role in the protective immune response without exhibiting any adverse effects during malignant neoplasm. Although, the PKCδ-ceramide axis in cancer cells has been an effective target in reduction of cancer, involvement of PKCδ in inducing nephrotoxicity have become a major questionnaire. In the present study, we have elucidated the mechanism by which cisplatin exploits the ceramide to render cancer cell apoptosis leading to the abrogation of malignancy in a PKCδ independent pathway with lesser toxicity. Our study revealed that cisplatin treatment in PKCδ silenced melanoma cells induces ceramide mediated apoptosis. Moreover, cisplatin induced upregulation of the transcription factor IRF1 leading to the induction of the transcriptional activity of the TNFα promoter was evident from the pharmacological inhibition and RNA interference studies. Increased cellular expression of TNFα resulted in an elevated ceramide generation by stimulating acid-sphingomyelinase and cPLA₂. Furthermore, reciprocity in the regulation of sphingosine kinase 1 (Sphk1) and sphingosine kinase 2 (Sphk2) during PKCδ independent ceramide generation was also observed during cisplatin treatment. PKCδ inhibited murine melanoma model showed reduction in nephrotoxicity along with tumor regression by ceramide generation. Altogether, the current study emphasized the unexplored signaling cascade of ceramide generation by cisplatin during PKCδ silenced condition, which is associated with increased TNFα generation. Our findings enlightened the detailed mechanistic insight of ceramide mediated signaling by chemotherapeutic drugs in cancer therapy exploring a new range of targets for cancer treatment strategies.

Molecular Repolarisation of Tumour-Associated Macrophages

The tumour microenvironment (TME) is composed of extracellular matrix and non-mutated cells supporting tumour growth and development. Tumour-associated macrophages (TAMs) are among the most abundant immune cells in the TME and are responsible for the onset of a smouldering inflammation. TAMs play a pivotal role in oncogenic processes as tumour proliferation, angiogenesis and metastasis, and they provide a barrier against the cytotoxic effector function of T lymphocytes and natural killer (NK) cells. However, TAMs are highly plastic cells that can adopt either pro- or anti-inflammatory roles in response to environmental cues. Consequently, TAMs represent an attractive target to recalibrate immune responses in the TME. Initial TAM-targeted strategies, such as macrophage depletion or disruption of TAM recruitment, have shown beneficial effects in preclinical models and clinical trials. Alternatively, reprogramming TAMs towards a proinflammatory and tumouricidal phenotype has become an attractive strategy in immunotherapy. This work summarises the molecular wheelwork of macrophage biology and presents an overview of molecular strategies to repolarise TAMs in immunotherapy.

In vivo cancer vaccination: Which dendritic cells to target and how?

The field of cancer immunotherapy has been revolutionized with the use of immune checkpoint blockade antibodies such as anti-programmed cell death 1 protein (PD-1) and chimeric antigen receptor T cells. Significant clinical benefits are observed in different cancer types with these treatments. While considerable efforts are made in augmenting tumor-specific T cell responses with these therapies, other immunotherapies that actively stimulate endogenous anti-tumor T cells and generating long-term memory have received less attention. Given the high cost of cancer immunotherapies especially with chimeric antigen receptor T cells, not many patients will have access to such treatments. The next-generation of cancer immunotherapy could entail in vivo cancer vaccination to activate both the innate and adaptive anti-tumor responses. This could potentially be achieved via in vivo targeting of dendritic cells which are an indispensable link between the innate and adaptive immunities. Dendritic cells highly expressed toll-like receptors for recognizing and eliminating pathogens. Synthetic toll-like receptors agonists could be synthesized at a low cost and have shown promise in preclinical and clinical trials. As different subsets of human dendritic cells exist in the immune system, activation with different toll-like receptor agonists could exert profound effects on the quality and magnitude of anti-tumor T cell responses. Here, we reviewed the different subsets of human dendritic cells. Using published preclinical and clinical cancers studies available on PubMed, we discussed the use of clinically approved and emerging toll-like receptor agonists to activate dendritic cells in vivo for cancer immunotherapy. Finally, we searched www.clinicaltrials.gov and summarized the active cancer trials evaluating toll-like receptor agonists as an adjuvant.

Redirecting tumor-associated macrophages to become tumoricidal effectors as a novel strategy for cancer therapy

Cancer research in recent decades has highlighted the potential influence of the tumor microenvironment on the progression and metastasis of most known cancer types. Within the established microenvironment, tumor-associated macrophages (TAMs) are one of the most abundant and crucial non-neoplastic cell types. The polarization of macrophages into tumor-suppressive M1 or tumor-promoting M2 types is a fundamental event in the establishment of the tumor microenvironment. Although ample evidence indicates that TAMs are primarily M2 polarized, the mechanisms responsible for the regulation and maintenance of M1 and M2 polarization imbalance remain unclear. The manipulation of this critical axis through three main approaches may provide new strategies for cancer therapy - (I) specific interference with M2-like TAM survival or inhibiting their signaling cascades, (II) repression of macrophage recruitment to tumors, and (III) repolarization of tumor-promoting M2-like TAMs to a tumoricidal M1-like phenotype. This review summarizes current strategies for cancer intervention via manipulation of macrophage polarization, with particular focus on composition of the tumor microenvironment and its influence on cancer progression and metastasis. It is clear that additional fundamental and preclinical research is required to confirm the efficacy and practicality of this novel and promising strategy for treating cancer.

A randomized trial of TLR-2 agonist CADI-05 targeting desmocollin-3 for advanced non-small-cell lung cancer

Background

Randomized controlled trial to evaluate synergy between taxane plus platinum chemotherapy and CADI-05, a Toll like receptor-2 agonist targeting desmocollin-3 as a first-line therapy in advanced non-small-cell lung cancer (NSCLC).

Patients and methods

Patients with advanced NSCLC (stage IIIB or IV) were randomized to cisplatin-paclitaxel (chemotherapy group, N = 112) or cisplatin-paclitaxel plus CADI-05 (chemoimmunotherapy group, N = 109). CADI-05 was administered a week before chemotherapy and on days 8 and 15 of each cycle and every month subsequently for 12 months or disease progression. Overall survival was compared using a log-rank test. Computed tomography was carried out at baseline, end of two cycles and four cycles. Response rate was evaluated using Response Evaluation Criteria in Solid Tumors criteria by an independent radiologist.

Results

As per intention-to-treat analysis, no survival benefit was observed between two groups [208 versus 196 days; hazard ratio, 0.86; 95% confidence interval (CI) 0.63-1.19; P = 0.3804]. In a subgroup analysis, improvement in median survival by 127 days was observed in squamous NSCC with chemoimmunotherapy (hazard ratio, 0.55; 95% CI 0.32-0.95; P = 0.046). In patients receiving planned four cycles of chemotherapy, there was improved median overall survival by 66 days (299 versus 233 days; hazard ratio, 0.64; 95% CI 0.41 to 0.98; P = 0.04) in the chemoimmunotherapy group compared with the chemotherapy group. This was associated with the improved survival by 17.48% at the end of 1 year, in the chemoimmunotherapy group. Systemic adverse events were identical in both the groups.

Conclusion

There was no survival benefit with the addition of CADI-05 to the combination of cisplatin-paclitaxel in patients with advanced NSCLC; however, the squamous cell subset did demonstrate a survival advantage.

Human papillomavirus-driven immune deviation: challenge and novel opportunity for immunotherapy

It is now recognized that the immune system can be a key component of restraint and control during the neoplastic process. Human papillomavirus (HPV)-associated cancers of the anogenital tract and oropharynx represent a significant clinical problem but there is a clear opportunity for immune targeting of the viral oncogene expression that drives cancer development. However, high-risk HPV infection of the target epithelium and the expression of the E6/E7 oncogenes can lead to early compromise of the innate immune system (loss of antigen-presenting cells) facilitating viral persistence and increased risk of cancer. In these circumstances, a succession of interacting and self-reinforcing events mediated through modulation of different immune receptors, chemokine and cytokine responses (CCL20; CCL2; CCR2; IL-6; CCR7; IL-12) further promote the generation of an immune suppressive microenvironment [increased levels of Tregs, Th17, myeloid-derived suppressor cells (MDSCs) and PD-L1]. The overexpression of E6/E7 expression also compromises the ability to repair cellular DNA, leading to genomic instability, with the acquisition of genetic changes providing for the selection of advantaged cancer cells including additional strategies for immune escape. Therapeutic vaccines targeting the HPV oncogenes have shown some encouraging success in some recent early-phase clinical trials tested in patients with HPV-associated high-grade anogenital lesions. A significant hurdle to success in more advanced disease will be the local and systemic immune suppressive factors. Interventions targeting the different immunosuppressive components can provide opportunity to release existing or generate new and effective antitumour immunity. Treatments that alter the protumour inflammatory environment including toll-like receptor stimulation, inhibition of IL-6-related pathways, immune-checkpoint inhibition, direct modulation of MDSCs, Tregs and macrophages could all be useful in combination with therapeutic HPV vaccination. Future progress in delivering successful immunotherapy will depend on the configuration of treatment protocols in an insightful and timely combination.

Trial Watch: Immunotherapy plus radiation therapy for oncological indications

Malignant cells succumbing to some forms of radiation therapy are particularly immunogenic and hence can initiate a therapeutically relevant adaptive immune response. This reflects the intrinsic antigenicity of malignant cells (which often synthesize a high number of potentially reactive neo-antigens) coupled with the ability of radiation therapy to boost the adjuvanticity of cell death as it stimulates the release of endogenous adjuvants from dying cells. Thus, radiation therapy has been intensively investigated for its capacity to improve the therapeutic profile of several anticancer immunotherapies, including (but not limited to) checkpoint blockers, anticancer vaccines, oncolytic viruses, Toll-like receptor (TLR) agonists, cytokines, and several small molecules with immunostimulatory effects. Here, we summarize recent preclinical and clinical advances in this field of investigation.

The possible interaction between periostin expressed by cancer stroma and tumor-associated macrophages in developing mycosis fungoides

Mycosis fungoides (MF) starts as an indolent disease, progresses from a patch stage to confluent plaques and ultimately develops skin tumors. Tumor-associated macrophages (TAMs) play roles in maintaining the tumor microenvironment in MF. The purpose of this study was to elucidate the involvement of TAMs in the lesional skin of different stages of MF. First, we immunohistologically examined the percentage of CD163+ macrophages and CD206+ cells, as well as the levels of periostin and IL-4 in cancer stroma. The percentage of CD206+ cells increased in parallel with tumor progression, while there was no significant difference in the percentage of CD163+ cells. Periostin was prominent in the stromal area at the patch and plaque stages but decreased at the tumor stage. In contrast, IL-4 was prominently stained at both plaque and tumor stages. To further elucidate the molecular mechanisms of the effects of these stromal factors on TAMs, we examined their effects on mRNA expression in monocyte-derived macrophages in vitro. Based on microarray analysis and gene ontology, we examined a series of chemokines and MMPs whose expression was strongly connected with periostin stimulation. The DNA microarray results were verified in M2 macrophages using real-time PCR. We further examined the mRNA expression of these chemokines and MMPs in the presence of periostin and IL-4 to simulate the advanced stages of MF and validated their protein expression by ELISA. Our present report suggests possible roles of periostin on TAMs in establishing the tumor microenvironment in MF.

Regulatory T cells in the immunotherapy of melanoma

Patients with melanoma are supposed to develop spontaneous immune responses against specific tumor antigens. However, several mechanisms contribute to the failure of tumor antigen-specific T cell responses, inducing immune escape. Importantly, immunosuppression mediated by regulatory T cells (Tregs) in tumor lesions is a dominant mechanism of tumor immune evasion. Based on this information, several therapies targeting Tregs such as cyclophosphamide, IL-2-based therapies, and antibodies against the surface molecular of Tregs have been developed. However, only some of these strategies showed clinical efficacy in patients with melanoma in spite of their success in shifting immune systems to antitumor responses in animal models. In the future, strategies specifically depleting local Tregs, inhibiting Treg migration to the tumor lesion, and Treg depletion in combination with other chemotherapies or immune modulation will hopefully bring benefits to melanoma patients.