Emerging role of tumor-associated macrophages as therapeutic targets in patients with metastatic renal cell carcinoma

An update to experimental and clinical aspects of tumor-associated macrophages in cancer development: hopes and pitfalls

Tumor-associated macrophages (TAMs) represent one of the most abundant tumor-infiltrating stromal cells, and their normal function in tumor microenvironment (TME) is to suppress tumor cells by producing cytokines which trigger both direct cell cytotoxicity and antibody-mediated immune response. However, upon prolonged exposure to TME, the classical function of these so-called M1-type TAMs can be converted to another type, "M2-type," which are recruited by tumor cells so that they promote tumor growth and metastasis. This is the reason why the accumulation of TAMs in TME is correlated with poor prognosis in cancer patients. Both M1- and M2-types have high degree of plasticity, and M2-type cells can be reprogrammed to M1-type for therapeutic purposes. This characteristic introduces TAMs as promising target for developing novel cancer treatments. In addition, inhibition of M2-type cells and blocking their recruitment in TME, as well as their depletion by inducing apoptosis, are other approaches for effective immunotherapy of cancer. In this review, we summarize the potential of TAMs to be targeted for cancer immunotherapy and provide an up-to-date about novel strategies for targeting TAMs.

Extracellular matrix stiffness and tumor-associated macrophage polarization: new fields affecting immune exclusion

In the malignant progression of tumors, there is deposition and cross-linking of collagen, as well as an increase in hyaluronic acid content, which can lead to an increase in extracellular matrix stiffness. Recent research evidence have shown that the extracellular matrix plays an important role in angiogenesis, cell proliferation, migration, immunosuppression, apoptosis, metabolism, and resistance to chemotherapeutic by the alterations toward both secretion and degradation. The clinical importance of tumor-associated macrophage is increasingly recognized, and macrophage polarization plays a central role in a series of tumor immune processes through internal signal cascade, thus regulating tumor progression. Immunotherapy has gradually become a reliable potential treatment strategy for conventional chemotherapy resistance and advanced cancer patients, but the presence of immune exclusion has become a major obstacle to treatment effectiveness, and the reasons for their resistance to these approaches remain uncertain. Currently, there is a lack of exact mechanism on the regulation of extracellular matrix stiffness and tumor-associated macrophage polarization on immune exclusion. An in-depth understanding of the relationship between extracellular matrix stiffness, tumor-associated macrophage polarization, and immune exclusion will help reveal new therapeutic targets and guide the development of clinical treatment methods for advanced cancer patients. This review summarized the different pathways and potential molecular mechanisms of extracellular matrix stiffness and tumor-associated macrophage polarization involved in immune exclusion and provided available strategies to address immune exclusion.

Prognostic significance of annexin A2 and tumor associated macrophages (TAMs) in metastatic renal cell carcinoma and their relation to Sunitinib resistance

Sunitinib, an antiangiogenic tyrosine kinase inhibitor, is the main treatment for metastatic renal cell carcinoma (mRCC). Development of resistance is a major obstacle against therapy success. The aim of this study was to assess annexin A2 and CD163+ tumor associated macrophages (TAMs) immunohistochemical expression in 50 mRCC cases as regard to patients' prognosis and Sunitinib response. Also, to assess the correlation between annexin A2 and TAMs expression. High annexin A2 expression and TAMs density were associated with serum calcium level (P = 0.024 and 0.037, respectively), larger tumor size (P < 0.001), high tumor grade (P = 0.014 and <0.001, respectively), and the presence of tumor necrosis (P < 0.001). High annexin A2 and TAMs expressions were related to shorter patients' overall survival (P = 0.009 and 0.001, respectively) and progression-free survival (P = 0.003 and 0.001, respectively). Annexin A2 was correlated with TAMs density (r = 0.890). Annexin A2 and TAMs are associated with poor prognostic parameters in mRCC patients, including high nuclear grade, increased tumor size, and the presence of tumor necrosis, together with shorter patients' survivals and poor response to Sunitinib. Annexin A2 expression is correlated with TAMs density suggesting immunomodulatory role of annexin A2.

MiR-548t-5p regulates pancreatic ductal adenocarcinoma metastasis through an IL-33-dependent crosstalk between cancer cells and M2 macrophages

IL-33 has been associated with pro- and anticancer functions in cancer. However, its role in pancreatic cancer metastasis remains unknown. This study aimed to explore the role of miR-548t-5p/IL-33 axis in the metastasis of pancreatic cancer. Luciferase activity assay, qRT-PCR, Western blot and ELISA were performed to prove whether IL-33 is the target of miR-548t-5p. In vivo metastasis assay and cellular transwell assay were performed to explore the role of miR-548t-5p/IL-33 axis in the invasion and metastasis of pancreatic cancer. Co-culture experiments and immunohistochemistry were performed to observe whether IL-33 affects cell invasion and metastasis dependent on the involvement of M2 macrophages. THP-1 cell induction experiment and flow cytometry were performed to explore the effect of IL-33 on macrophage polarization. CCK-8, colony formation, cell apoptosis, cell cycle, cell wound healing and transwell assay were performed to investigate the effect of IL-33 induced M2 macrophages on cell malignant biological behavior by coculturing pancreatic cancer cells with the conditioned medium (CM) from macrophages. We found that miR-548t-5p regulated the expression and secretion of IL-33 in pancreatic cancer cells by directly targeting IL-33 mRNA. IL-33 secreted by cancer cells promoted the recruitment and activation of macrophages to a M2-like phenotype. In turn, IL-33 induced M2 macrophages promoted the migration and invasion of cancer cells. Moreover, IL-33 affected pancreatic cancer cell invasion dependent on the involvement of M2 macrophages in the co-culture system. Thus, our study suggested that manipulation of this IL-33-dependent crosstalk has a therapeutic potential for the treatment of pancreatic cancer metastasis.

CHEK2 is a potential prognostic biomarker associated with immune infiltration in clear cell renal cell carcinoma

Checkpoint kinase 2 (CHEK2) plays a crucial role in responding to DNA damage and is linked to diverse cancer types. However, its significance in the prediction of prognosis and impacts on the immune status of clear cell renal cell carcinoma (ccRCC) remains unclear. This study aimed to identify the role of CHEK2 in prognosis and immune microenvironment of ccRCC. We analyzed transcriptome and clinicopathological data from the cancer genome atlas (TCGA) database and conducted functional enrichment analysis to explore molecular mechanisms. The relationship between CHEK2 and immune infiltration was evaluated, and drug sensitivity analysis was performed using the CellMiner database. The results showed that CHEK2 was an independent predictor of ccRCC prognosis and was closely associated with immune-related processes. Additionally, high expression of CHEK2 was linked to resistance to certain targeted drugs. These findings suggest that CHEK2 could serve as a biomarker for ccRCC, providing insights into tumor immune microenvironment alterations and immunotherapeutic response. Further investigation is needed to fully understand the potential of CHEK2 as a prognostic predictor and therapeutic target for ccRCC.

Novel insights into STAT3 in renal diseases

Signal transducer and activator of transcription 3 (STAT3) is a cell-signal transcription factor that has attracted considerable attention in recent years. The stimulation of cytokines and growth factors can result in the transcription of a wide range of genes that are crucial for several cellular biological processes involved in pro- and anti-inflammatory responses. STAT3 has attracted considerable interest as a result of a recent upsurge in study because of their role in directing the innate immune response and sustaining inflammatory pathways, which is a key feature in the pathogenesis of many diseases, including renal disorders. Several pathological conditions which may involve STAT3 include diabetic nephropathy, acute kidney injury, lupus nephritis, polycystic kidney disease, and renal cell carcinoma. STAT3 is expressed in various renal tissues under these pathological conditions. To better understand the role of STAT3 in the kidney and provide a theoretical foundation for STAT3-targeted therapy for renal disorders, this review covers the current work on the activities of STAT3 and its mechanisms in the pathophysiological processes of various types of renal diseases.

Mechanisms and clinical implications in renal carcinoma resistance: narrative review of immune checkpoint inhibitors

Clear cell renal cell carcinoma (ccRCC) is the most common histological subtype of renal cell carcinoma. The prognosis for patients with ccRCC has improved over recent years with the use of combination therapies with an anti-programmed death-1 (PD-1) backbone. This has enhanced the quality of life and life expectancy of patients with this disease. Unfortunately, not all patients benefit; eventually, most patients will develop resistance to therapy and progress. Recent molecular, biochemical, and immunological research has extensively researched anti-angiogenic and immune-based treatment resistance mechanisms. This analysis offers an overview of the principles underpinning the resistance pathways related to immune checkpoint inhibitors (ICIs). Additionally, novel approaches to overcome resistance that may be considered for the trial context are discussed.

Identification of immune cell infiltration profiles in renal cell carcinoma and their clinical significance

Renal cell carcinoma (RCC) is the most common malignancy of the urinary system, accounting for 3.7% of all new malignancies. The prognosis of RCC patients is still poor, especially patients in advanced stage. Limited studies have fully clarified the role of immune cell infiltration profiles in the prognosis and immunotherapy of RCC. In current study, we evaluated the abundance of the 22 tumor-infiltrating immune cells (TIICs) with CIBERSORT methods. The correlation between TIICs and clinicopathological parameters, tumor immune dysfunction and exclusion (TIDE) score and immunophenoscore (IPS) of RCC patients were also explored. Significant correlations were obtained between TIICs subpopulation and specific clinicopathologic parameters of RCC, including age, gender, tumor grade, clinical stage, T stage and distant metastasis. Moreover, RCC patients with high level of memory activated CD4 T cells, follicular helper T cells and regulatory T cells had a worse overall survival (OS) rate. RCC patients with high level of CD 8 + T cells and M1 macrophages had a lower TIDE score and higher anti-CTLA IPS, higher anti-PD1 IPS as well as higher anti-PD1/CTLA4 IPS. Our results clarified the immune cell infiltration profiles of RCC. RCC patients with high level of CD 8 + T cell and M1 macrophages had a lower TIDE score and higher IPS, suggesting that RCC patients with high level of CD 8 + T cell and M1 macrophages may benefit from immunotherapy.

Role of Clock Genes and Circadian Rhythm in Renal Cell Carcinoma: Recent Evidence and Therapeutic Consequences

Circadian rhythm regulates cellular differentiation and physiology and shapes the immune response. Altered expression of clock genes might lead to the onset of common malignant cancers, including Renal Cell Carcinoma (RCC). Data from Cancer Genome Atlas (TCGA) indicate that clock genes PER1-3, CRY2, CLOCK, NR1D2 and RORα are overexpressed in RCC tissues and correlate with patients' prognosis. The expression of clock genes could finely tune transcription factor activity in RCC and is associated with the extent of immune cell infiltration. The clock system interacts with hypoxia-induced factor-1α (HIF-1α) and regulates the circadian oscillation of mammalian target of rapamycin (mTOR) activity thereby conditioning the antitumor effect of mTOR inhibitors. The stimulation of natural killer (NK) cell activity exerted by the administration of interferon-α, a cornerstone of the first era of immunotherapy for RCC, relevantly varies according to circadian dosing time. Recent evidence demonstrated that time-of-day infusion directly affects the efficacy of immune checkpoint inhibitors in cancer patients. Compounds targeting the circadian clock have been identified and their role in the era of immunotherapy deserves to be further investigated. In this review, we aimed at addressing the impact of clock genes on the natural history of kidney cancer and their potential therapeutic implications.

Molecular mechanisms of resistance to tyrosine kinase inhibitor in clear cell renal cell carcinoma

Clear cell renal cell carcinoma (ccRCC) is the most common subtype of renal cell carcinoma (RCC). Loss of von Hippel-Lindau tumor suppressor gene is frequently observed in ccRCC and increases the expression of hypoxia-inducible factors and their targets, including epidermal growth factor, vascular endothelial growth factor, and platelet-derived growth factor. Tyrosine kinase inhibitors (TKIs) offer a survival benefit in metastatic renal cell carcinoma (mRCC). Recently, immune checkpoint inhibitors have been introduced in mRCC. Combination therapy with TKIs and immune checkpoint inhibitors significantly improved patient outcomes. Therefore, TKIs still play an essential role in mRCC treatment. However, the clinical utility of TKIs is compromised when primary and acquired resistance are encountered. The mechanism of resistance to TKI is not fully elucidated. Here, we comprehensively reviewed the molecular mechanisms of resistance to TKIs and a potential strategy to overcome this resistance. We outlined the involvement of angiogenesis, non-angiogenesis, epithelial-mesenchymal transition, activating bypass pathways, lysosomal sequestration, non-coding RNAs, epigenetic modifications and tumor microenvironment factors in the resistance to TKIs. Deep insight into the molecular mechanisms of resistance to TKIs will help to better understand the biology of RCC and can ultimately help in the development of more effective therapies.

Tumor-associated macrophages promote migration and invasion via modulating IL-6/STAT3 signaling in renal cell carcinoma

Tumor-associated macrophages (TAMs) promote tumor cell growth and metastasis in various human cancers. However, the role of TAMs in renal cell carcinoma (RCC) is rarely investigated. Herein, we observed that the infiltration of TAMs was obviously elevated in RCC tumor tissues, high infiltration of TAMs was closely associated with tumor progression and poor prognosis in RCC patients. In vitro assays further indicated that the conditioned medium of TAMs (TAMs CM) facilitated migration, invasion, and epithelial-mesenchymal transition (EMT) in RCC cells. Moreover, we found that IL-6 was involved in the functions of TAMs in RCC; IL-6 neutralizing antibody (IL-6NA) partly abolished the effect of TAMs on RCC cells. In addition, we demonstrated that TAMs might exert their roles by activating STAT3 signaling in RCC, and IL-6 was responsible for TAMs-induced STAT3 signaling activation. In conclusion, our results revealed that high infiltration of TAMs may promote RCC cells migration, invasion, and EMT via modulating IL-6/STAT3 signaling, further suggesting a potential of novel treatment strategies targeting TAMs or IL-6 for metastatic RCC.

EGFR-Mutated Non-Small Cell Lung Cancer and Resistance to Immunotherapy: Role of the Tumor Microenvironment

Lung cancer is a leading cause of cancer-related deaths worldwide. About 10–30% of patients with non-small cell lung cancer (NSCLC) harbor mutations of the EGFR gene. The Tumor Microenvironment (TME) of patients with NSCLC harboring EGFR mutations displays peculiar characteristics and may modulate the antitumor immune response. EGFR activation increases PD-L1 expression in tumor cells, inducing T cell apoptosis and immune escape. EGFR-Tyrosine Kinase Inhibitors (TKIs) strengthen MHC class I and II antigen presentation in response to IFN-γ, boost CD8+ T-cells levels and DCs, eliminate FOXP3+ Tregs, inhibit macrophage polarization into the M2 phenotype, and decrease PD-L1 expression in cancer cells. Thus, targeted therapy blocks specific signaling pathways, whereas immunotherapy stimulates the immune system to attack tumor cells evading immune surveillance. A combination of TKIs and immunotherapy may have suboptimal synergistic effects. However, data are controversial because activated EGFR signaling allows NSCLC cells to use multiple strategies to create an immunosuppressive TME, including recruitment of Tumor-Associated Macrophages and Tregs and the production of inhibitory cytokines and metabolites. Therefore, these mechanisms should be characterized and targeted by a combined pharmacological approach that also concerns disease stage, cancer-related inflammation with related systemic symptoms, and the general status of the patients to overcome the single-drug resistance development.

Molecular Mechanisms of Resistance to Immunotherapy and Antiangiogenic Treatments in Clear Cell Renal Cell Carcinoma

Clear cell renal cell carcinoma (ccRCC) is the most common histological subtype arising from renal cell carcinomas. This tumor is characterized by a predominant angiogenic and immunogenic microenvironment that interplay with stromal, immune cells, and tumoral cells. Despite the obscure prognosis traditionally related to this entity, strategies including angiogenesis inhibition with tyrosine kinase inhibitors (TKIs), as well as the enhancement of the immune system with the inhibition of immune checkpoint proteins, such as PD-1/PDL-1 and CTLA-4, have revolutionized the treatment landscape. This approach has achieved a substantial improvement in life expectancy and quality of life from patients with advanced ccRCC. Unfortunately, not all patients benefit from this success as most patients will finally progress to these therapies and, even worse, approximately 5 to 30% of patients will primarily progress. In the last few years, preclinical and clinical research have been conducted to decode the biological basis underlying the resistance mechanisms regarding angiogenic and immune-based therapy. In this review, we summarize the insights of these molecular alterations to understand the resistance pathways related to the treatment with TKI and immune checkpoint inhibitors (ICIs). Moreover, we include additional information on novel approaches that are currently under research to overcome these resistance alterations in preclinical studies and early phase clinical trials.

Beyond Promoter: The Role of Macrophage in Invasion and Progression of Renal Cell Carcinoma

Renal cell carcinoma (RCC) is one of the common urologic neoplasms, and its incidence has been increasing over the past several decades; however, its pathogenesis is still unknown up to now. Recent studies have found that in addition to tumor cells, other cells in the tumor microenvironment also affect the biological behavior of the tumor. Among them, macrophages exist in a large amount in tumor microenvironment, and they are generally considered to play a key role in promoting tumorigenesis. Therefore, we summarized the recent researches on macrophage in the invasiveness and progression of RCC in latest years, and we also introduced and discussed many studies about macrophage in RCC to promote angiogenesis by changing tumor microenvironment and inhibit immune response in order to activate tumor progression. Moreover, macrophage interactes with various cytokines to promote tumor proliferation, invasion and metastasis, and it also promotes tumor stem cell formation and induces drug resistance in the progression of RCC. The highlight of this review is to make a summary of the roles of macrophage in the invasion and progression of RCC; at the same time to raise some potential and possible targets for future RCC therapy.

Hypoxic TAM-derived exosomal miR-155-5p promotes RCC progression through HuR-dependent IGF1R/AKT/PI3K pathway

Hypoxic tumor-associated macrophages (TAMs) are related to poor prognosis of patients with clear cell renal cell carcinoma (ccRCC). Exosomes are small lipid-bilayer vesicles that implicated in tumor progression and metastasis. However, whether hypoxic TAM-derived exosomes affect RCC progression within the hypoxic tumor microenvironment has not been elucidated. GSE analysis identified miR-155-5p was upregulated in RCC. Moreover, we quantified levels of miR-155-5p using RT-qPCR, performed immunohistochemical staining in 79 pairs of primary RCC specimens and related them to clinicopathological parameters. Higher miR-155-5p levels were related to more CD163 + TAM infiltration and elevated HIF-1a expression in our cohort. In the in vitro studies, we initially purified and characterized the exosomes from the supernatant of TAMs subjected to normoxia or hypoxia, and then transfected antagomiR-155-5p or control into these TAMs to produce corresponding exosomes. Gain and loss-of-function studies further investigated the effect of transferred hypoxic exosomal miR-155-5p on the cross-talk between TAMs and RCC cells in xenograft model and in vitro co-culture experiments. The results of RNA immunoprecipitation analyses elucidated that miR-155-5p could directly interact with human antigen R (HuR), thus increasing IGF1R mRNA stability. Mechanistically, hypoxic TAM-Exo transferred miR-155-5p promoted RCC progression partially through activating IGF1R/PI3K/AKT cascades. Taken together, transfer of miR-155-5p from hypoxic TAMs by exosomes to renal cancer cells explains the oncogenic manner, in which M2 macrophages confer the malignant phenotype to RCC cells by enhancing HuR-mediated mRNA stability of IGF1R.

Aspects of the Tumor Microenvironment Involved in Immune Resistance and Drug Resistance

The tumor microenvironment (TME) is a complex and ever-changing "rogue organ" composed of its own blood supply, lymphatic and nervous systems, stroma, immune cells and extracellular matrix (ECM). These complex components, utilizing both benign and malignant cells, nurture the harsh, immunosuppressive and nutrient-deficient environment necessary for tumor cell growth, proliferation and phenotypic flexibility and variation. An important aspect of the TME is cellular crosstalk and cell-to-ECM communication. This interaction induces the release of soluble factors responsible for immune evasion and ECM remodeling, which further contribute to therapy resistance. Other aspects are the presence of exosomes contributed by both malignant and benign cells, circulating deregulated microRNAs and TME-specific metabolic patterns which further potentiate the progression and/or resistance to therapy. In addition to biochemical signaling, specific TME characteristics such as the hypoxic environment, metabolic derangements, and abnormal mechanical forces have been implicated in the development of treatment resistance. In this review, we will provide an overview of tumor microenvironmental composition, structure, and features that influence immune suppression and contribute to treatment resistance.

Renal cell carcinoma pathology in 2021: 'new need for renal cancer immune profiling'

PURPOSE OF REVIEW

The aim of this review is to outline characteristics of the renal cell carcinoma (RCC) tumor immune microenvironment (TIME), the potential impact of tumor intrinsic alterations on the TIME and the value of metastatic tissue assessment in this context.

RECENT FINDINGS

According to the latest European Association of Urology, European Society for Medical Oncology and National Comprehensive Cancer Network guidelines immune checkpoint inhibition represents a new core treatment strategy in advanced clear cell RCC (ccRCC). Despite its success, the prognosis of many RCC patients remains unsatisfactory most likely because of resistance mechanisms within the TIME. Moreover, most studies assess the primary tumor even though the advanced metastatic disease is targeted. Overall, metastatic RCC has hardly been investigated. First insights into the complexity of the genomic and immune landscape in RCC were recently provided. The functional impact of tumor intrinsic alterations on the TIME has just been described potentially contributing to therapy response in RCC.

SUMMARY

The complexity of the RCC TIME and its potential interdependence with tumor intrinsic alterations has only just been recognized. A deeper understanding of the TIME may reveal predictive and prognostic biomarkers long-awaited in RCC, improve RCC patient stratification and could possibly be most instructive if assessed in metastatic tissue.

The platelet to lymphocyte ratio predicts overall survival better than the neutrophil to lymphocyte ratio in metastatic renal cell carcinoma

Background/aim

The prognostic values of systemic inflammatory markers, neutrophil to lymphocyte ratio (NLR), and platelet to lymphocyte ratio (PLR) on overall survival (OS) of metastatic renal cell carcinoma patients (mRCC) treated with tyrosine kinase inhibitors (TKI) remain unclear. Thus, the present study aimed to investigate the prognostic impact of these markers on OS of mRCC patients.

Materials and methods

A total of 150 patients receiving TKIs were retrospectively analyzed. Progression-free survival and OS times were analyzed with the Kaplan–Meier method, and the log‐rank test was used for comparison. Univariable and multivariable Cox regression models evaluated the impact of NLR and PLR on OS of the patients. The receiver operating characteristic curve analysis determined that the optimal cut-off values of NL, and PLR in predicting OS were 2 and 204, respectively.

Results

Patient with PLR > 204 had significantly lower median OS time than those with PLR ≤ 204 (14.6 months vs. 31.6 months, P < 0.001). While the univariate analyses showed that both NLR and PLR associated with OS (NLR: P = 0.002; PLR: P < 0.001), PLR, not NLR, was an independent determinant for OS in the multivariate analyses (Hazard Ratio: 2.535, 95% CI: 1.564-4.108, P < 0.001). Additionally, the presence of brain metastases and International Metastatic Renal Cell Carcinoma Database Consortium (IMDC) prognostic scoring system were identified as independent prognostic factors for OS (brain metastases: P = 0.040; IMDC: P < 0.001).

Conclusion

The PLR is a readily and inexpensively obtained marker, which may predict OS in patients with mRCC treated with TKIs.

Manipulating macrophage polarization in cancer patients: From nanoparticles to human chimeric antigen receptor macrophages

Chimeric antigen receptor (CAR) T cell treatment has provided notable results in hematological tumors. Unfortunately, this evidence has not been translated into improved outcomes in solid malignancies so far, where several reports have suggested that T cells encounter substantial difficulties in penetrating and surviving in the tumor microenvironment (TME). Thus, researchers have recently investigated other immune cell types as CAR platforms, in order to overcome the limitations of CAR T cells. Among them, CAR-macrophages (M) technology has emerged as a novel perspective for cancer patients, on the basis of preclinical studies observing that CAR expression in human macrophages could play a crucial role in enhancing phagocytosis, polarizing M2 to M1 phenotype, and stimulating T cell anti-tumor activity. Herein, we provide an overview of current scenario of CAR-Ms in several solid tumors, also focusing on the biological rationale behind this promising therapeutic approach and future research directions in this setting.

An update on investigational therapies that target STAT3 for the treatment of cancer

INTRODUCTION

Signal transducer and activator of transcription 3 (STAT3) is involved in cancer initiation and resistance to chemo-radiation therapies and targeted agents. The role of STAT3 in inflammation and immunity together with its involvement in a variety of diseases including genitourinary, gastrointestinal, lung, ovarian and brain tumors makes STAT3 an ideal candidate for therapeutic strategies.

AREAS COVERED

The authors provided an overview on STAT3 inhibitors and examined the most recent results obtained by these agents in cancer patients. The authors discussed the results published since 2015 and the ongoing clinical trials on anti-STAT3 agents in cancer patients. The authors also provide our opinion on the future perspectives of this therapeutic approach in this context. The manuscript includes information from trial databases and scientific literature.

EXPERT OPINION

Future challenges include the development of non-peptide small-molecule inhibitors of STAT3 designed to directly inhibit STAT3 activity. In addition, inhibitors of STAT3/STAT3 nuclear translocation or DNA binding activity are also emerging as novel promising therapeutic approaches A better comprehension of the role of STAT3 in modulating immune response together with advances in understanding the mechanisms of STAT3-induced chemo and/or radio-resistance will also help the design of combined strategies in cancer patients.

Cellular and physical microenvironments regulate the aggressiveness and sunitinib chemosensitivity of clear cell renal cell carcinoma

Renal cell carcinoma (RCC) is the most predominant type of kidney cancer in adults and is responsible for approximately 85% of clinical cases. The tumor‐specific microenvironment includes both cellular and physical factors, and it regulates the homeostasis and function of cancer cells. Perirenal adipose tissue and tumor‐associated macrophages are the major cellular components of the RCC microenvironment. The RCC microvasculature network generates interstitial fluid flow, which is the movement of fluid through the extracellular compartments of tissues. This fluid flow is a specific physical characteristic of the microenvironment of RCC. We hypothesized that there may be an interaction between the cellular and physical microenvironments and that these two factors may play an important role in regulating the behavior of RCC. To elucidate the effects of adipose tissue, macrophages, and fluid flow stimulation on RCC and to investigate the relationships between these factors, we used a collagen gel culture method to generate cancer–stroma interactions and a gyratory shaker to create fluid flow stimulation. Adipose‐related cells, monocytes, and fluid flow influenced the proliferative potential and invasive capacity of RCC cells. Extracellular signal‐regulated kinase and p38 signaling were regulated either synergistically or independently by both fluid flow and cellular interactions between RCC and adipose tissue fragments or macrophages. Fluid flow stimulation synergistically enhanced the anti‐proliferative effect of sunitinib on RCC cells, but macrophages abolished the synergistic anti‐proliferative effect related to fluid flow stimulation. In conclusion, we established a reconstructed model to investigate the cellular and physical microenvironments of RCC in vitro. Our alternative culture model may provide a promising tool for further therapeutic investigations into many types of cancer. © 2021 The Authors. The Journal of Pathology published by John Wiley & Sons, Ltd. on behalf of The Pathological Society of Great Britain and Ireland.

Possible Roles of Interleukin-4 and -13 and Their Receptors in Gastric and Colon Cancer

Interleukin (IL)-4 and -13 are structurally and functionally related cytokines sharing common receptor subunits. They regulate immune responses and, moreover, are involved in the pathogenesis of a variety of human neoplasms. Three different receptors have been described for IL-4, but only IL-4 receptor type II (IL-4Rα/IL-13Rα1) is expressed in solid tumors. While IL-13 can also bind to three different receptors, IL-13 receptor type I (IL-4Rα/IL-13Rα1/IL-13Rα2) and type II (IL-4Rα/IL-13Rα1) are expressed in solid tumors. After receptor binding, IL-4 and IL-13 can mediate tumor cell proliferation, survival, and metastasis in gastric or colon cancer. This review summarizes the results about the role of IL-4/IL-13 and their receptors in gastric and colon cancer.

Tumor Microenvironment Features as Predictive Biomarkers of Response to Immune Checkpoint Inhibitors (ICI) in Metastatic Clear Cell Renal Cell Carcinoma (mccRCC)

Renal cell carcinoma (RCC) is the seventh most frequently diagnosed malignancy with an increasing incidence in developed countries. Despite a greater understanding of the cancer biology, which has led to an increase of therapeutic options, metastatic clear cell renal cell carcinoma (mccRCC) still have a poor prognosis with a median five-years survival rate lower than 10%. The standard of care for mccRCC has changed dramatically over the past decades with the emergence of new treatments: anti-VEGFR tyrosine kinase inhibitors, mTOR Inhibitors and immune checkpoint inhibitors (ICI) such as anti-Programmed cell-Death 1 (PD-1) and anti-anti-Programmed Death Ligand-1 (PD-L1) used as monotherapy or as a combination with anti CTLA-4 or anti angiogenic therapies. In the face of these rising therapeutic options, the question of the therapeutic sequences is crucial. Predictive biomarkers are urgently required to provide a personalized treatment for each patient. Disappointingly, the usual ICI biomarkers, PD-L1 expression and Tumor Mutational Burden, approved in melanoma or non-small cell lung cancer (NSCLC) have failed to distinguish good and poor mccRCC responders to ICI. The tumor microenvironment is known to be involved in ICI response. Innovative technologies can be used to explore the immune contexture of tumors and to find predictive and prognostic biomarkers. Recent comprehensive molecular characterization of RCC has led to the development of robust genomic signatures, which could be used as predictive biomarkers. This review will provide an overview of the components of the RCC tumor microenvironment and discuss their role in disease progression and resistance to ICI. We will then highlight the current and future ICI predictive biomarkers assessed in mccRCC with a major focus on immunohistochemistry markers and genomic signatures.

Bioinformatics analysis to screen key prognostic genes in the breast cancer tumor microenvironment

Increasing evidence has shown that the tumor microenvironment (TME) plays an important role in tumor occurrence and development and can also affect patient prognosis. In this study, we screened key prognostic genes in the breast cancer (BC) TME by analyzing the immune and stromal scores of tumor samples to detect differentially expressed genes (DEGs) and also constructed a TME-related prognostic model. First, we obtained mRNA-Seq and related clinical information for patients with BC from The Cancer Genome Atlas (TCGA) and calculated the stromal and immune scores of tumor tissues using the ESTIMATE algorithm. Next, we performed functional enrichment analysis and generated protein-protein interaction networks from the DEGs that were highly related to the TME. Finally, Cox proportional hazards regression analysis was performed on BC datasets from TCGA, and analyses were conducted on infiltrating immune cells and the human protein atlas. Together, these analyses indicated that the KLRB1 and SIT1 genes could be used as independent prognostic factors for BC, while risk score, age, and clinical stage could be used as prognostic factors. In summary, we found that the prognosis of BC is closely related to immune regulation in the TME.

Impact of inflammation and immunotherapy in renal cell carcinoma

Substantial research attention has been directed at exploring the mechanisms and treatment of renal cell carcinoma (RCC). Indeed, the association between inflammation and tumor phenotypes has been at the center of cancer research. Concomitant with research on the inflammation response and inflammatory molecules involved in RCC, new breakthroughs have emerged. A large body of knowledge now shows that treatments targeting inflammation and immunity in RCC provide substantial clinical benefits. Adequate analysis and a better understanding of the mechanisms of inflammatory factors in the occurrence and progression of RCC are highly desirable. Currently, numerous RCC treatments targeted at inflammation and immunotherapy are available. The current review describes in detail the link between inflammation and RCC.

RCC Immune Microenvironment Subsequent to Targeted Therapy: A Friend or a Foe?

Renal cell carcinoma (RCC) is composed of different subtypes with distinct molecular and histological tumor heterogeneity. Although the advent of various targeted therapies has improved the survival of patients with advanced RCC over the past 15 years (since 2006), few cases experienced complete response due to drug resistance. Recent studies have demonstrated that the outcomes following targeted therapies are potentially associated with intricate cross-links between immune responses and suppressors in the tumor microenvironment (TME). In addition, progress on drug research and development enhances our awareness and understanding about immunotherapy and combined treatment. In this review article, we intend to make a comprehensive summary about TME and its alterations following targeted therapies, provide valid evidence in this aspect, and discuss optimal matches between targeted therapy and immunotherapy.

The tumour microenvironment and metabolism in renal cell carcinoma targeted or immune therapy

Renal cell carcinoma (RCC) is one of the most common tumours of the urinary system, and is insidious and not susceptible to chemoradiotherapy. As the most common subtype of RCC (70-80% of cases), clear cell renal cell carcinoma (ccRCC) is characterized by the loss of von Hippel-Lindau and the accumulation of robust lipid and glycogen. For advanced RCC, molecular-targeted drugs, tyrosine kinase inhibitors (TKIs) and the immune checkpoint inhibitors (ICIs) have been increasingly recommended and investigated. Due to the existence of a highly dynamic, adaptive and heterogeneous tumour microenvironment (TME), and due to the glucose and lipid metabolism in RCC, this cancer may be accompanied by various types of resistance to TKIs and ICIs. With the increased production of lactate, nitric oxide, and other new by-products of metabolism, novel findings of the TME and key metabolic enzymes drived by HIF and other factors have been increasingly clarified in RCC carcinogenesis and therapy. However, there are few summaries of the TME and tumour metabolism for RCC progression and therapy. Here, we summarize and discuss the relationship of the important implicated characteristics of the TME as well as metabolic molecules and RCC carcinogenesis to provide prospects for future treatment strategies to overcome TME-related resistance in RCC.

Resistance to cancer immunotherapy in metastatic renal cell carcinoma

The prognosis of metastatic clear cell renal cell carcinoma (mccRCC) has changed dramatically over the years with the emergence of immune checkpoint inhibitors (ICI) used alone, or in combination with another ICI, or with vascular endothelial growth factor receptor tyrosine kinase inhibitor. Although major response rates have been observed with ICI, many patients do not respond, reflecting primary resistance, and durable responses remain exceptional, reflecting secondary resistance. Factors contributing to primary and acquired resistance are manifold, including patient-intrinsic factors, tumor cell-intrinsic factors and factors associated with the tumoral microenvironment (TME). While some mechanisms of resistance are common to several tumor types, others are specific to mccRCC. Predictive biomarkers and alternative strategies are needed to overcome this resistance. This review provides an overview of the major ICI resistance mechanisms, highlights the potential of the TME to induce resistance to ICI, and discusses the predictive biomarkers available to guide therapeutic choice.

Prognostic value of a nine-gene signature in glioma patients based on tumor-associated macrophages expression profiling

Tumor-associated macrophages (TAMs) are regarded as the most abundantly infiltrating immune cells around the tumor microenvironment in gliomas, which plays an important role in tumorgenesis and immunosuppression. A total of 216 patients diagnosed with primary glioma were obtained from the Chinese Glioma Genome Atlas of which the RNA sequencing data was used as training set. RNA sequencing from the Cancer Genome Atlas was applicated for validation. We found that mesenchymal subtype showed strong positive correlation with macrophage-related genes (MRGs) expression. Survival analysis showed that high expression level of MRG predicted poor prognosis. A TAM-based nine-gene signature was constructed, which divided the samples into high- and low-risk of unfavorable outcome. The result of Cox regression analysis showed that the risk score was an independent prognostic factor in gliomas. Hence, the expression of TAMs was correlated with patient survival. The nine-TAM-related gene signature can predict patient survival efficiently.

Chimeric antigen receptor T cells in solid tumors: a war against the tumor microenvironment

Chimeric antigen receptor (CAR) T cell is a novel approach, which utilizes anti-tumor immunity for cancer treatment. As compared to the traditional cell-mediated immunity, CAR-T possesses the improved specificity of tumor antigens and independent cytotoxicity from major histocompatibility complex molecules through a monoclonal antibody in addition to the T-cell receptor. CAR-T cell has proven its effectiveness, primarily in hematological malignancies, specifically where the CD 19 CAR-T cells were used to treat B-cell acute lymphoblastic leukemia and B-cell lymphomas. Nevertheless, there is little progress in the treatment of solid tumors despite the fact that many CAR agents have been created to target tumor antigens such as CEA, EGFR/EGFRvIII, GD2, HER2, MSLN, MUC1, and other antigens. The main obstruction against the progress of research in solid tumors is the tumor microenvironment, in which several elements, such as poor locating ability, immunosuppressive cells, cytokines, chemokines, immunosuppressive checkpoints, inhibitory metabolic factors, tumor antigen loss, and antigen heterogeneity, could affect the potency of CAR-T cells. To overcome these hurdles, researchers have reconstructed the CAR-T cells in various ways. The purpose of this review is to summarize the current research in this field, analyze the mechanisms of the major barriers mentioned above, outline the main solutions, and discuss the outlook of this novel immunotherapeutic modality.

The role of immune infiltrates as prognostic biomarkers in patients with breast cancer

The presence of immune infiltrates in the tumor microenvironment has been documented in many types of cancer. Moreover, the preexistent or endogenous immunity which consists of interactions between intratumoral lymphocytes and tumor cells is mostly relevant for the successful application of various anticancer therapies, including standard chemotherapy, immune checkpoint inhibition-based immunotherapy and targeted therapies. The immunoscore defines densities of intratumoral immune infiltrates which determine poor or favorable prognosis depending on their quantity and quality in the tumor compartments. Results from large clinical studies have demonstrated an association between high densities of cytotoxic and memory TILs in the tumor compartments with improved prognosis. Importantly, we have demonstrated that differential combined densities of immune infiltrates jointly analyzed in the tumor center (TC) and the invasive margin (IM) have a significant prognostic value in breast cancer patients with poor clinicopathological parameters.

Targeting the Tumor Microenvironment in Renal Cell Cancer Biology and Therapy

Renal cell cancer (RCC) is a highly vascularized and immunogenic tumor type. The inhibition of vessel formation by anti-angiogenic therapies, as well as the stimulation of the immune system by immunotherapy has revolutionized the therapeutic landscape of RCC in recent years. Nevertheless, both therapies are associated with therapy resistance due to a highly dynamic, adaptive and heterogeneous tumor microenvironment (TME). The aim of this short review article is to provide an overview of the components of the RCC TME as well as to discuss their contribution to disease progression. In addition, we report on preclinical and clinical findings and how the different TME components can be modulated to impede treatment progression as well as to overcome therapy resistance to anti-angiogenic or immunomodulating therapy concepts. Furthermore, we discuss the predictive and prognostic role of the TME in RCC therapy. We also report on the concept of combinational targeting of anti-angiogenic therapies and immune checkpoint inhibitor therapy, also including the latest results of clinical studies discussed at recent oncological meetings. Finally, promising new therapeutic targets within the TME are mentioned.

Limitations to the Therapeutic Potential of Tyrosine Kinase Inhibitors and Alternative Therapies for Kidney Cancer

Background: Renal cell carcinomas (RCCs) are the most common primary renal tumor. RCCs have a high rate of metastasis and have the highest mortality rate of all genitourinary cancers. They are often diagnosed late when metastases have developed, and these metastases are difficult to treat successfully. Since 2006, the standard first-line treatment for patients with metastatic RCC has been multitargeted tyrosine kinase inhibitors (TKIs) that include mammalian target of rapamycin (mTOR) inhibitors. RCCs are highly vascularized tumors, and their angiogenesis is controlled by tyrosine kinases that play a vital role in growth factor signaling to stimulate this process. TKI therapy was introduced for direct targeting of angiogenesis in RCC. TKIs have been moderately successful in the treatment of metastatic RCC and initially increased cancer-specific survival times. However, RCC rapidly becomes resistant to TKIs, and no current drug has produced a cure for advanced RCC. Methods: We provide an overview of RCC, explain some reasons for therapy resistance in RCC, and describe some therapies that may overcome resistance to TKIs. The key pathways that determine therapy resistance are illustrated. Results: Factors involved in the development and progression of RCC include genetic mutations, activation of hypoxia-inducible factor and related proteins, cellular metabolism, the tumor microenvironment, and growth factors and their receptors. Resistance to the therapeutic potential of TKIs can be acquired or intrinsic. Alternative therapies include other small molecule drugs and immunotherapy based on immune checkpoint blockade. Conclusion: The treatment of RCC is undergoing a paradigm shift from sole use of small molecule antiangiogenesis TKIs as first-line therapy to include newly approved agents for second-line and third-line therapy that now involve the mTOR pathway and immune checkpoint blockade drugs for patients with advanced RCC.

The tumor microenvironment in renal cell cancer

PURPOSE OF REVIEW

In addition to the provision of nutrients and growth factors that facilitate tumor cell proliferation and metastasis, the tumor microenvironment (MEV) restricts immune surveillance of tumor-associated antigens and limits the efficacy of immune checkpoint inhibitors, tumor vaccines, and other immune therapies. This review will focus on the immunosuppressive mechanisms operative within the tumor MVE of renal cell carcinoma.

RECENT FINDINGS

Several of the immunosuppressive mechanisms within the tumor MEV have been identified and are potentially druggable. Clinical trials with agents that target several of these inhibitory pathways are currently underway.

SUMMARY

Although renal cell carcinoma is one of several tumor types responsive to immune checkpoint inhibitors, the effectiveness of these agents is likely to be limited by the various tumor-infiltrating bone marrow-derived myeloid cells that comprise the MEV. Several strategies to combat the recruitment of these cells into tumor tissue or to neutralize their immunosuppressive function have shown encouraging results in animal tumor models and clinical trials.

Tumor microenvironment-driven non-cell-autonomous resistance to antineoplastic treatment

Drug resistance is of great concern in cancer treatment because most effective drugs are limited by the development of resistance following some periods of therapeutic administration. The tumor microenvironment (TME), which includes various types of cells and extracellular components, mediates tumor progression and affects treatment efficacy. TME-mediated drug resistance is associated with tumor cells and their pericellular matrix. Noninherent-adaptive drug resistance refers to a non-cell-autonomous mechanism in which the resistance lies in the treatment process rather than genetic or epigenetic changes, and this mechanism is closely related to the TME. A new concept is therefore proposed in which tumor cell resistance to targeted therapy may be due to non-cell-autonomous mechanisms. However, knowledge of non-cell-autonomous mechanisms of resistance to different treatments is not comprehensive. In this review, we outlined TME factors and molecular events involved in the regulation of non-cell-autonomous resistance of cancer, summarized how the TME contributes to non-cell-autonomous drug resistance in different types of antineoplastic treatment, and discussed the novel strategies to investigate and overcome the non-cell-autonomous mechanism of cancer non-cell-autonomous resistance.

Tumors and Their Microenvironment Dual-Targeting Chemotherapy with Local Immune Adjuvant Therapy for Effective Antitumor Immunity against Breast Cancer

Chemotherapy turns tumor cells into "tumor vaccines" by immunogenic cell death (ICD). However, it remains a challenge to exploit chemotherapy-induced "tumor vaccines" for solid cancer immunotherapy due to the inefficient effector T cells activation and tumor microenvironment immunosuppression. Here, a matrix metalloprotease 2 responsive liposome (PEG-FA-Lip) composed of cleavable PEG chains covering the folate (FA)-modified liposome is developed to deliver ICD inducer doxorubicin. In breast cancer-bearing mice, PEG-FA-Lip targets both 4T1 breast cancer cells and M2-tumor associated macrophages (M2-TAMs) via FA-receptor mediated endocytosis, resulting in abundant "tumor vaccines" and efficient elimination of M2-TAMs. The combination of local cytosine-phosphate-guanine (CpG) therapy facilitates PEG-FA-Lip induced "tumor vaccines" to effectively arouse systematic effector T cells immune response through promoting dendritic cell maturation and immunostimulatory cytokines secretion. The simultaneous elimination of M2-TAMs ensures the activated effector T cells exert antitumor immunity within tumor via decreasing immunosuppressive cytokines secretion and tumor infiltration of Treg cells. After receiving the combined treatment, 30.1% of breast cancer-bearing mice (initial tumor volume > 100 mm3) achieves the goal of tumor eradication. Remarkably, this combination therapy greatly inhibits lung metastasis and controls the growth of already metastasized breast cancers (initial tumor volume > 100 mm3).

Microvascular density, macrophages, and mast cells in human clear cell renal carcinoma with and without bevacizumab treatment

BACKGROUND

Clear cell renal cell carcinoma (ccRCC) represents a highly vascularized aggressive kidney cancer. Due to ccRCC chemotherapy resistance, antiangiogenesis is one of the most innovative targeted therapies for this tumor. The tumor microenvironment exerts important roles in tumor growth, angiogenesis, and metastatic escape.

MATERIALS AND METHODS

In this study, we investigated the composition of tumor cell microenvironment including mast cells, macrophages, and microvascular density in ccRCC tumor tissues collected from patients who underwent nephrectomy treated or not with bevacizumab as neoadjuvant therapy before surgery.

RESULTS

The results of this study indicate that bevacizumab-treated ccRCC samples present reduced microvascular density as well as a lower number of CD68-positive macrophages and tryptase-positive mast cells in comparison with the untreated patients.

CONCLUSIONS

It follows that the antiangiogenic activity of bevacizumab may be due to a direct effect on angiogenic cytokines released by tumor cells and an indirect effect on the release of pro-angiogenic factors by inflammatory stromal cells.

Complement Activation as a Helping Hand for Inflammophilic Pathogens and Cancer

The complement system, an evolutionarily ancient component of innate immunity, is capable of protecting hosts from invading pathogens, either directly, by lysis of target cells, or indirectly, by mobilization of host immune mechanisms. However, this potentially cytotoxic cascade must be tightly regulated, since improperly controlled complement can damage healthy cells and tissues. The practical importance of this axis is highlighted when impairment of complement regulators or bacterial mechanisms of complement evasion result in pathogenic conditions. Recognition of complement as a "double-edged sword" is widely acknowledged, but another, currently underappreciated aspect of complement function has emerged as an important player in homeostatic balance-the dual outcome of complement-mediated inflammation. In most cases, the proinflammatory properties of complement are beneficial to the host. However, certain pathogens have developed the ability to utilize local inflammation as a source of nutrients and as a way to establish a niche for further colonization. Such a strategy can be illustrated in the example of periodontitis. Interestingly, certain tumors also seem to benefit from complement activation products, which promote a proangiogenic and immunosuppressive microenvironment.

Restoration of Peripheral Intermediate and Classical Monocytes Expressing HLA-DR in Patients With Lung Adenocarcinoma After Platinum-Based Chemotherapy

Lung adenocarcinoma represents one of the lung cancer subtypes with major prevalence. Accumulating evidence indicates that the immune system plays an important role in the evolution of the neoplastic process; additionally, several reports suggest that chemotherapy has an immunomodulatory effect. In order to identify the peripheral subpopulations of leukocytes that may change after chemotherapy, we evaluated several peripheral immune subpopulations of monocytes and lymphocytes by multicolor flow cytometry. In addition, we also measured cytokines and growth factors on plasma in order to evaluate the pro-inflammatory context in patients with lung adenocarcinoma after chemotherapy. We found that HLA-DR⁺ classical and intermediate monocytes were decreased in patients before chemotherapy, compared to controls. After chemotherapy, the relative percentage of those subpopulations was restored. In addition, interleukin 1β, interleukin 12, and interleukin 5 were increased after chemotherapy compared to prechemotherapy levels, while MIP-1β was decreased.

The Identification of Immunological Biomarkers in Kidney Cancers

The recent approval of several agents have revolutionized the scenario of therapeutic management of metastatic renal cell carcinoma (RCC) allowing us to reach important clinical end points with extended patients' survival. Actually, every new drug approved has represented an important step forward to the improvement of patient's survival. On the other hand, we now understand that RCC includes a large group of tumor entities, each of them with different genetic and mutational alterations, but also showing different clinical behavior; a reason behind the needs of subtype specific personalized approach to therapy of RCC. Immunotherapy is gradually becoming a key factor in the therapeutic algorithm for patients with locally advanced or metastatic RCC. Due to the combination of potent treatment success and potentially deadly adverse effects from immune checkpoint inhibitors (ICI), gathering prognostic and predictive information about FDA-indicated tumors seems to be prudent. Robust and reliable biomarkers are crucial for patient's selection of treatments with immunomodulatory drugs. PD-L1 expression is a poor prognostic factor and predictive of better responses from both PD-1 and PD-L1 inhibitors in a variety of tumor types including RCC. Each FDA approved PD-1/PD-L1 drug is paired with a PD-L1 Immunohistochemistry (IHC) assay. Thus, there is need for improved knowledge and application of PD-1/PD-L1 IHC biomarkers in daily practice. IHC staining appears in membranous fashion. The atezolizumab approved IHC assay is unique in that only immune cell staining is quantified for the use of this assay in RCC. A single biomarker for patient selection may not be feasible, given that immune responses are dynamic and evolve over time. Biomarker development for ICI drugs will likely require integration of multiple biologic components like PD-L1 expression, TILs and mutational load. New methodological approaches based on digital pathology may be relevant since they will allow recognition of the biomarker and to objectively quantitate its expression, and therefore might produce objective and reproducible cut-off assessment. Multidisciplinary approach is very much needed to fully develop the current and future value of ICI in clinical practice.

Higher Serum C-reactive Protein Level Represents the Immunosuppressive Tumor Microenvironment in Patients With Clear Cell Renal Cell Carcinoma

INTRODUCTION

C-reactive protein (CRP), a representative inflammatory marker, could serve as a biomarker in renal cell carcinoma because CRP is an important prognostic factor. However, its detailed mechanism remains unknown. This study showed that higher CRP levels correlated with the tumor immune microenvironment, which leads to a worse prognosis. These findings can help to clarify the underlying mechanisms between the presence of systemic inflammatory reaction and prognosis. The aim of this study is to investigate the association between tumor immune microenvironment and CRP in patients with renal cell carcinoma (RCC) to explore the underlying mechanisms between CRP level and prognosis.

PATIENTS AND METHODS

Immunohistochemical measurement of CD4, CD8, CD163 (M2 macrophages), and Foxp3 (Regulatory T [Treg] cells) was performed in patients with clear-cell RCC (n = 111) treated with radical or partial nephrectomy at our institution. The association between immunohistochemical status and preoperative serum CRP level and cancer-specific survival (CSS) was analyzed.

RESULTS

Thirty-three patients (30%) had a high CRP level (≥ 5.0 mg/L), and the CSS rate was significantly worse among these patients than among the remaining patients (P < .001). In patients with strong infiltration of CD8+, Foxp3+, or CD163+ cells, CRP levels were significantly higher (P = .041, P = .001, and P = .035, respectively), and CSS was significantly worse compared with patients with weak infiltration (P = .040, P = .026, and P < .001, respectively). In multivariate analysis, strong CD163+ cells infiltration (P = .001) as well as pathologic T3 (P = .036), lymph-node involvement (P = .007), distant metastasis (P < .001), and Fuhrman nuclear grade 4 (P = .003) were independent prognostic factors for CSS.

CONCLUSIONS

Infiltration of the immunosuppressive cells known as Tregs and M2 macrophages in the tumor microenvironment is associated with higher CRP and poor prognosis in patients with clear-cell RCC. CRP could reflect an immunosuppressive microenvironment.

Immunotherapy in renal cell carcinoma: latest evidence and clinical implications

Advances in understanding the mechanisms of tumour-induced immunosuppression have led to the development of immune-checkpoint inhibitors in cancer patients, including those with renal cell carcinoma (RCC). The optimal combination between immunotherapy and targeted agents (as well as the possible favourable sequential therapy of these two classes of drugs) remains an open question at this moment. Several trials are currently underway to assess the combination of anti-programmed-death 1 (PD-1) or anti-PD-ligand(L)1 agents with other immunotherapies or with anti-vascular endothelial growth factor receptor (VEGFR) tyrosine kinase inhibitors (TKIs). In this editorial, we described the results of the most recent clinical trials on the use of immunotherapies in RCC and the emerging data on the research for reliable biomarkers of tumour response in this setting. In addition, we have focused on the role of the gut microbiome and tumour microenvironment in the development of future therapeutic strategies for RCC patients.

Targeted Imaging of Tumor-Associated Macrophages by Cyanine 7-Labeled Mannose in Xenograft Tumors

Mannose receptor is considered as a hallmark of M2-oriented tumor-associated macrophages (TAMs), but its utility in TAMs was rarely reported. Therefore, deoxymannose (DM), a high-affinity ligand of mannose receptor, was labeled with near-infrared dye cyanine 7 (Cy7), and its feasibility of targeted imaging on TAMs was evaluated in vitro and in vivo. The Cy7-DM was synthesized, and its binding affinity with induced TAMs in vitro, whole-body imaging in xenograft tumor mouse model in vivo, and the cellular localization in dissected tissues were evaluated. We demonstrated a high uptake of Cy7-DM by induced M2 macrophages and TAMs in tumor tissues. In vivo near-infrared live imaging visualized abundant TAMs in tumor lesions instead of inflammatory sites by Cy7-DM imaging, and the quantity of Cy7-DM signals in tumors was significantly higher than that shown in inflammatory sites from 1 to 8 hours of imaging. Our results suggest that mannose could rapidly and specifically target TAMs and is a promising candidate for targeted diagnosis of tumor with rich TAMs.

Current and Emerging Therapeutic Targets for Metastatic Renal Cell Carcinoma

PURPOSE OF REVIEW

The treatment of advanced renal cell carcinoma has evolved dramatically over recent years. In this review, we will summarize current and emerging therapies based on molecular targets and provide insight into treatment strategy for metastatic renal cell carcinoma.

RECENT FINDINGS

We have witnessed a paradigm shift in the therapeutic landscape as treatment was formerly reliant on cytokine-based agents which have now been replaced with therapies targeting angiogenesis, mammalian target of rapamycin pathways, and immune responses. These dramatic changes are primarily due to our improved understanding of the underlying mutations and molecular mechanisms leading to tumorigenesis and progression. We now have targeted agents in the form of small-molecule tyrosine kinase inhibitors, monoclonal antibodies, and mTOR inhibitors. Moreover, immunotherapy-targeting checkpoints of T-lymphocyte activity has provided increased overall survival and a new class of agents with potential to radically change the treatment options. With these agents and their combination, durable responses are increasingly seen even though treatment resistance remains a huge challenge. New treatment strategies are rapidly developing and the therapeutic landscape is expected for further evolution.

Neutrophil-lymphocyte ratio in the management and prediction of outcomes in renal cell carcinoma

Renal cell carcinoma (RCC) is one of the ten most common malignancies. The prognosis of RCC is poor when the disease is in advanced stages, with five-year survival of less than 10%. However current assessment approaches are limited in their ability to prognosticate and guide therapeutic decision-making. Cellular-mediated inflammatory response is increasingly being recognised to have an important role in carcinogenesis of RCC. Various inflammatory markers have been found to identify patients with RCC at high risk of recurrence and predict survival. Neutrophil-lymphocyte ratio (NLR) is a simple and inexpensive inflammatory marker that has been shown to be of value in the assessment of patients with RCC. An elevated pretreatment NLR has been found to be associated with reduced overall survival, recurrence-free survival and progress-free survival and risk of recurrence in localized RCC. In addition, lower pretreatment NLR has been demonstrated to be associated with better clinical response to systemic therapy including vascular endothelial growth factor inhibitors, among patients with metastatic RCC. However, NLR has not been found to differentiate whether small renal masses of less than 40 mm are benign or malignant. Further research is needed to determine the cut-offs for NLR to predict different clinical outcomes and how post-treatment NLR can be used. In addition, more work is also needed to evaluate combining NLR with other biomarkers in a model to predict patients’ clinical outcome or response to treatment for RCC.

The role of tumor microenvironment in therapeutic resistance

Cancer cells undergo unlimited progression and survival owing to activation of oncogenes. However, support of the tumor microenvironment is essential to the formation of clinically relevant tumors. Recent evidence indicates that the tumor microenvironment is a critical regulator of immune escape, progression, and distant metastasis of cancer. Moreover, the tumor microenvironment is known to be involved in acquired resistance of tumors to various therapies. Despite significant advances in chemotherapy and radiotherapy, occurrence of therapeutic resistance leads to reduced efficacy. This review highlights myeloid cells, cancer-associated fibroblasts, and mesenchymal stem cells consisting of the tumor microenvironment, as well as the relevant signaling pathways that eventually render cancer cells to be therapeutically resistant.

Dual-targeting biomimetic delivery for anti-glioma activity via remodeling the tumor microenvironment and directing macrophage-mediated immunotherapy

A dual-targeting biomimetic codelivery and treatment strategy was developed for anti-glioma activity.

Tumor-associated macrophages (TAMs) are the major components in the tumor microenvironment (TME). The polarization from the protumor M2 (TAM2) to antitumor M1 (TAM1) phenotype can not only lift the immunosuppressive constraints and elicit cytotoxic T-cell immunity but also augment the chemotherapy efficacy. However, the treatment feasibility by TAM modulation in brain tumors and the mechanisms remained unknown. A dual-targeting biomimetic codelivery and treatment strategy was developed for anti-glioma activity. We demonstrated that the albumin nanoparticles modified with dual ligands, a transferrin receptor (TfR)-binding peptide T12 and mannose, efficiently passed through the BBB via the nutrient transporters (i.e., TfR and the albumin-binding receptor SPARC) that were both overexpressed in the BBB and glioma cells, thus achieving biomimetic delivery to glioma. Importantly, after penetrating the BBB, this system can take advantage of the overexpression of the SPARC and mannose receptors on TAM2, thus also targeting the protumor TAM2. With the codelivery disulfiram/copper complex and regorafenib, the system efficiently inhibited the glioma cell proliferation and successfully “re-educated” the protumor TAM2 towards antitumor TAM1. The treatment efficacy was examined in the glioma-bearing nude mice and immunocompetent mice. It showed this system yielded an enhanced treatment outcome, owing to the synergistic combination of chemotherapy and macrophage-directed immunotherapy. The importance of this delivery and therapeutic strategy was to remodel the immune microenvironment and reprogram TAM and trigger macrophage-directed anti-glioma immunotherapy via the interplay of the TAM, Treg, and CD8⁺ T cells and the effector cytokines. The albumin-based biomimetic brain delivery also provides a promising method for the pharmacotherapy of brain diseases.