Modification of the tumor microenvironment as a novel target of renal cell carcinoma therapeutics. Cancer J. 2013;19:353-364. [PMID: 23867518 DOI: 10.1097/ppo.0b013e31829da0ae]

Sunitinib resistance in renal cell carcinoma: From molecular mechanisms to predictive biomarkers

Currently, renal cell carcinoma (RCC) is the most prevalent type of kidney cancer. Targeted therapy has replaced radiation therapy and chemotherapy as the main treatment option for RCC due to the lack of significant efficacy with these conventional therapeutic regimens. Sunitinib, a drug used to treat gastrointestinal tumors and renal cell carcinoma, inhibits the tyrosine kinase activity of a number of receptor tyrosine kinases, including vascular endothelial growth factor receptor (VEGFR), platelet-derived growth factor receptor (PDGFR), c-Kit, rearranged during transfection (RET) and fms-related receptor tyrosine kinase 3 (Flt3). Although sunitinib has been shown to be efficacious in the treatment of patients with advanced RCC, a significant number of patients have primary resistance to sunitinib or acquired drug resistance within the 6-15 months of therapy. Thus, in order to develop more efficacious and long-lasting treatment strategies for patients with advanced RCC, it will be crucial to ascertain how to overcome sunitinib resistance that is produced by various drug resistance mechanisms. In this review, we discuss: 1) molecular mechanisms of sunitinib resistance; 2) strategies to overcome sunitinib resistance and 3) potential predictive biomarkers of sunitinib resistance.

Tumoral CD105 promotes immunosuppression, metastasis, and angiogenesis in renal cell carcinoma

CD105 (endoglin) is a transmembrane protein that functions as a TGF-beta coreceptor and is highly expressed on endothelial cells. Unsurprisingly, preclinical and clinical evidence strongly suggests that CD105 is an important contributor to tumor angiogenesis and tumor progression. Emerging evidence suggests that CD105 is also expressed by tumor cells themselves in certain cancers such as renal cell carcinoma (RCC). In human RCC tumor cells, CD105 expression is associated with stem cell-like properties and contributes to the malignant phenotype in vitro and in xenograft models. However, as a regulator of TGF-beta signaling, there is a striking lack of evidence for the role of tumor-expressed CD105 in the anti-tumor immune response and the tumor microenvironment. In this study, we report that tumor cell-expressed CD105 potentiates both the in vitro and in vivo tumorigenic potential of RCC in a syngeneic murine RCC tumor model. Importantly, we find that tumor cell-expressed CD105 sculpts the tumor microenvironment by enhancing the recruitment of immunosuppressive cell types and inhibiting the polyfunctionality of tumor-infiltrating CD4⁺ and CD8⁺ T cells. Finally, while CD105 expression by endothelial cells is a well-established contributor to tumor angiogenesis, we also find that tumor cell-expressed CD105 significantly contributes to tumor angiogenesis in RCC.

Glycoconjugate Nanoparticle-Based Systems in Cancer Immunotherapy: Novel Designs and Recent Updates

For many years, cell-surface glycans (in particular, Tumor-Associated Carbohydrate Antigens, TACAs) have been the target of both passive and active anticancer immunotherapeutic design. Recent advances in immunotherapy as a treatment for a variety of malignancies has revolutionized anti-tumor treatment regimens. Checkpoint inhibitors, Chimeric Antigen Receptor T-cells, Oncolytic virus therapy, monoclonal antibodies and vaccines have been developed and many approvals have led to remarkable outcomes in a subset of patients. However, many of these therapies are very selective for specific patient populations and hence the search for improved therapeutics and refinement of techniques for delivery are ongoing and fervent research areas. Most of these agents are directed at protein/peptide epitopes, but glycans-based targets are gaining in popularity, and a handful of approved immunotherapies owe their activity to oligosaccharide targets. In addition, nanotechnology and nanoparticle-derived systems can help improve the delivery of these agents to specific organs and cell types based on tumor-selective approaches. This review will first outline some of the historical beginnings of this research area and subsequently concentrate on the last 5 years of work. Based on the progress in therapeutic design, predictions can be made as to what the future holds for increasing the percentage of positive patient outcomes for optimized systems.

Determinants of resistance to VEGF-TKI and immune checkpoint inhibitors in metastatic renal cell carcinoma

Vascular endothelial growth factor tyrosine kinase inhibitors (VEGF-TKIs) have been the mainstay of treatment for patients with advanced renal cell carcinoma (RCC). Despite its early promising results in decreasing or delaying the progression of RCC in patients, VEGF-TKIs have provided modest benefits in terms of disease-free progression, as 70% of the patients who initially respond to the treatment later develop drug resistance, with 30% of the patients innately resistant to VEGF-TKIs. In the past decade, several molecular and genetic mechanisms of VEGF-TKI resistance have been reported. One of the mechanisms of VEGF-TKIs is inhibition of the classical angiogenesis pathway. However, recent studies have shown the restoration of an alternative angiogenesis pathway in modulating resistance. Further, in the last 5 years, immune checkpoint inhibitors (ICIs) have revolutionized RCC treatment. Although some patients exhibit potent responses, a non-negligible number of patients are innately resistant or develop resistance within a few months to ICI therapy. Hence, an understanding of the mechanisms of VEGF-TKI and ICI resistance will help in formulating useful knowledge about developing effective treatment strategies for patients with advanced RCC. In this article, we review recent findings on the emerging understanding of RCC pathology, VEGF-TKI and ICI resistance mechanisms, and potential avenues to overcome these resistance mechanisms through rationally designed combination therapies.

Landscape of Immunotherapy in Genitourinary Malignancies

The past decade has witnessed a revolution in the development of immune checkpoint inhibitors for the treatment of multiple tumor types, including genitourinary cancers. Immune checkpoint inhibitors have notably improved the treatment outcomes of patients with metastatic renal cell carcinoma and metastatic urothelial carcinoma. In prostate cancer, the role of immunotherapy with checkpoint inhibitors is not yet established except for microsatellite instability high (MSI-H) tumors. Other immunotherapeutic approaches that have been explored in these malignancies include cytokines, vaccines, and cellular therapy. Ongoing studies are exploring the use of immunotherapy combinations as well as combination with chemotherapy and targeted therapy in these types of tumors. The use of immunotherapy beyond the metastatic setting is an active area of research. Moreover, there is great interest in biomarker development to predict response to immunotherapy and risk of toxicity. This book chapter is a comprehensive review of immunotherapeutic approaches, both approved and investigational, for the treatment of renal cell carcinoma, urothelial carcinoma, and prostate cancer.

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.

Pembrolizumab in Combination with Axitinib as First-Line Treatment for Patients with Renal Cell Carcinoma (RCC): Evidence to Date

Over the last 18 months, 3 immunotherapy combination regimens (ipilimumab + nivolumab, pembrolizumab + axitinib, and axitinib + avelumab) were approved by the US Food and Drug Administration for the first-line treatment of metastatic renal cell carcinoma (mRCC), making selection of the optimal first-line treatment regimen very challenging. As of April 2020, preferred first-line treatment options for mRCC are pembrolizumab + axitinib and ipilimumab + nivolumab, based on the improvement in overall survival and progression-free survival compared to sunitinib, as observed in pivotal phase III clinical trials. Because the combination of 2 drugs is typically more toxic than a monotherapy, careful attention must be given to overlapping toxicities. The pembrolizumab + axitinib combination led to grade ≥3 adverse events in 75.8% of patients (vs 70.6% in the sunitinib group), while grade ≥3 adverse events were less frequent in the nivolumab + ipilimumab group compared to the sunitinib group. Discontinuation rates due to toxicity were 10.7% for pembrolizumab + axitinib (both drugs), 22% for ipilimumab + nivolumab and were comparable with sunitinib in both studies (13.9% and 12%, respectively). The combination of pembrolizumab + axitinib may have immune-modulating functions that may provide clinical benefit without the additional toxicity observed with ipilimumab + nivolumab. In addition, this tyrosine kinase inhibitor + immune checkpoint combination should have faster treatment response in patients with larger disease burden or in more symptomatic patients, which makes this combination an excellent choice for the first-line treatment regimen for mRCC. These combinations have proven to be tolerable, though long-term results are still lacking. As treatment options for mRCC are rapidly expanding, immunotherapy combinations could potentially change the treatment paradigm, with the ultimate goal of prolonging life and eventually curing mRCC.

Conversion of extracellular ATP into adenosine: a master switch in renal health and disease

ATP and its ultimate degradation product adenosine are potent extracellular signalling molecules that elicit a variety of pathophysiological functions in the kidney through the activation of P2 and P1 purinergic receptors, respectively. Extracellular purines can modulate immune responses, balancing inflammatory processes and immunosuppression; indeed, alterations in extracellular nucleotide and adenosine signalling determine outcomes of inflammation and healing processes. The functional activities of ectonucleotidases such as CD39 and CD73, which hydrolyse pro-inflammatory ATP to generate immunosuppressive adenosine, are therefore pivotal in acute inflammation. Protracted inflammation may result in aberrant adenosinergic signalling, which serves to sustain inflammasome activation and worsen fibrotic reactions. Alterations in the expression of ectonucleotidases on various immune cells, such as regulatory T cells and macrophages, as well as components of the renal vasculature, control purinergic receptor-mediated effects on target tissues within the kidney. The role of CD39 as a rheostat that can have an impact on purinergic signalling in both acute and chronic inflammation is increasingly supported by the literature, as detailed in this Review. Better understanding of these purinergic processes and development of novel drugs targeting these pathways could lead to effective therapies for the management of acute and chronic kidney disease.

Anti-angiogenesis and Immunotherapy: Novel Paradigms to Envision Tailored Approaches in Renal Cell-Carcinoma

Although decision making strategy based on clinico-histopathological criteria is well established, renal cell carcinoma (RCC) represents a spectrum of biological ecosystems characterized by distinct genetic and molecular alterations, diverse clinical courses and potential specific therapeutic vulnerabilities. Given the plethora of drugs available, the subtype-tailored treatment to RCC subtype holds the potential to improve patient outcome, shrinking treatment-related morbidity and cost. The emerging knowledge of the molecular taxonomy of RCC is evolving, whilst the antiangiogenic and immunotherapy landscape maintains and reinforces their potential. Although several prognostic factors of survival in patients with RCC have been described, no reliable predictive biomarkers of treatment individual sensitivity or resistance have been identified. In this review, we summarize the available evidence able to prompt more precise and individualized patient selection in well-designed clinical trials, covering the unmet need of medical choices in the era of next-generation anti-angiogenesis and immunotherapy.

Angiogenesis and Immunity in Renal Carcinoma: Can We Turn an Unhappy Relationship into a Happy Marriage?

The frontline treatment options for patients with metastatic renal cell carcinoma (mRCC) are evolving rapidly since the approval of combination immunotherapies by the U.S. Food and Drug Administration (USFDA) and the European Medicines Agency (EMA). In particular, in combination with vascular endothelial growth factor receptor (VEGFR) tyrosine-kinase inhibitors (TKIs), immune checkpoint inhibitors (ICIs) have significantly improved the outcome of patients with mRCC compared to TKI monotherapy. Here, we review the preclinical data supporting the combination of ICIs with VEGFR TKIs. The VEGF-signaling inhibition could ideally sustain immunotherapy through a positive modulation of the tumor microenvironment (TME). Antiangiogenetics, in fact, with their inhibitory activity on myelopoiesis that indirectly reduces myeloid-derived suppressor cells (MDSCs) and regulatory T cells' (Tregs) frequency and function, could have a role in determining an effective anti-tumor immune response. These findings are relevant for the challenges posed to clinicians concerning the clinical impact on treatment strategies for mRCC.

Tumor-educated B cells promote renal cancer metastasis via inducing the IL-1β/HIF-2α/Notch1 signals

While B cells in the tumor microenvironment (TME) might play important roles in cancer progression, their impacts on the renal cell carcinoma (RCC) metastasis remained unclear, which drew our attention to further explore. We found that RCC tissues could recruit more B cells than the surrounding normal renal tissues from human clinical RCC samples. Wound healing assay, transwell assay and 3D invasion assays demonstrated that recruited B cells, also known as tumor-educated B cells (TEB), could significantly increase the RCC cell migration and invasion. In addition, in vivo data from xenograft RCC mouse model also confirmed that TEB could enhance RCC cell invasive and metastatic capability. Mechanism dissection revealed that TEB activated IL-1β/HIF-2α signals in RCC cells that could induce the downstream Notch1 signaling pathway. The above results demonstrated the key roles of TEB within renal cancer associated tumor microenvironment were metastasis-promotor and might help us to develop the potential therapies via targeting these newly identified IL-1β/HIF-2α/Notch1 signals in RCC progression.

Toward Normalization of the Tumor Microenvironment for Cancer Therapy

The tumor microenvironment (TME) is a complex ecosystem, including blood vessels, immune cells, fibroblasts, extracellular matrix, cytokines, hormones, and so on. The TME differs from the normal tissue environment (NTE) in many aspects, such as tissue architecture, chronic inflammation, level of oxygen and pH, nutritional state of the cells, as well as tissue firmness. The NTE can inhibit the growth of cancer at the early tumorigenesis phase, whereas the TME promotes the growth of cancer in general, although it may have some anticancer effects. In particular, the TME plays a crucial role in the generation and maintenance of cancer stem cells, which lie at the root of cancer growth. Therefore, normalization of the TME to the NTE may inhibit cancer growth or improve cancer therapeutic efficiency. This review focuses on the recent emerging approaches for this normalization and the action mechanisms.

Cytoreductive Nephrectomy for Metastatic Renal Cell Carcinoma: How to Apply New Evidence in Clinical Practice

Cytoreductive nephrectomy (CN) followed by systemic therapy had been considered the standard of care for metastatic renal cell carcinoma (mRCC) patients since two clinical trials established its role during the cytokines era. With introduction of new and effective drugs, such as vascular endothelial growth factor-targeted therapies, the role of CN started to be challenged. Retrospective studies conducted during the targeted therapy era pointed to better outcomes when CN was associated with systemic treatment, although certain patients with poor risk features did not seem to benefit. Therefore, prospective clinical trials supporting CN were needed. Recently, with the publication of two randomized trials evaluating CN in the targeted therapy era, it has been made clear that patient selection and multidisciplinary discussion are of paramount importance in order to achieve the best outcomes. We reviewed the available literature on the role of CN among mRCC patients, commenting on how to apply the new evidence into clinical practice and providing future perspectives.

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.

Current Status and Future Directions of Immunotherapy in Renal Cell Carcinoma

PURPOSE OF REVIEW

Renal cell carcinoma (RCC) was recognized as an immunologically sensitive cancer over 30 years ago. The first therapies to affect the course of RCC were cytokines (interferon alfa-2B and interleukin-2). Subsequently, drugs that inhibit HIF (hypoxia-inducible factor)/VEGF (vascular endothelial growth factor) signaling demonstrated overall survival advantages (tyrosine kinase inhibitors and mTor inhibitors).

RECENT FINDINGS

In the last 3 years, the immune checkpoint inhibitors (ICIs) have become the standard of care treatments in the first and second lines for RCC. Emerging data show that combinations of ICI, HIF signaling inhibitors, and cytokines are potentially powerful regimens. How to combine and sequence these types of therapies and how to integrate new approaches into the management of RCC are now the key questions for the field. Treatment of RCC is likely to change dramatically in the next few years.

Differential expression of TIM-3 between primary and metastatic sites in renal cell carcinoma

Background

Due to the significant heterogeneity of renal cell carcinoma (RCC), immune checkpoints may express differently between primary and metastatic tumor. We aimed to evaluate the differential expression of TIM-3 between the primary and metastatic sites of RCC.

Methods

Cases of RCC with metastases resected or biopsied at West China Hospital between January 2009 and November 2016 were included. Clinicopathological parameters were retrospectively extracted. SPPS 22.0, GraphPad Prism 6 and R statistical software were applied for data analysis.

Results

A total of 163 cases were included. Immunohistochemical results showed that the overall detection rate of TIM-3 was 56.4% (92/163). The detection rate of TIM-3 in the primary (53.0%, 44/83) was numerically higher than that of the metastasis (42.6%,79/174). Although the concordance rate of TIM-3 between the primary and metastasis was as high as 66.3% (55/83) in the paired cohort, a significant statistically difference of TIM-3 expression between the primary and metastasis was observed (χ2 = 4.664, p = 0.002), with a poor consistency (Kappa = 0.331, p = 0.002). Subsequent survival analysis suggested that TIM-3 expression either in the primary or metastatic tumor was associated with longer progression-free survival (PFS) (HR: 0.67, 95% CI 0.45–0.99, P = 0.02) and overall survival (OS) (HR: 0.52, 95% CI 0.33–0.82, P < 0.001). The expressions of TIM-3 in the primary, metastatic tumors and patients treated with targeted agents all played as favorable factors for PFS and OS. Further multivariate analysis showed that, in the whole cohort, TIM-3 expression in metastatic tumor increased the predicted accuracy (PA) of the whole model of PFS from 74.7 to 75.6% (P = 0.02). For OS, the PA of whole model was increased from 78.1 to 81.1% by adding TIM-3 expression in the metastasis (P = 0.005). The same trends were also observed in paired patients and patients treated with targeted agents. In conclusion, the expression difference between the primary and metastatic tumor of TIM-3 was significant. Biopsy or resection of the metastases may provide a more accurate biological information for clinician’s decision-making and the patient’s prognosis. What’s more, the role of TIM-3 in the RCC still remains controversy, further study are needed to verify the conclusion.

Résistance aux inhibiteurs des tyrosines kinases dans le cancer du rein

FOCUS ON RESISTANCE TO TYROSINE KINASE INHIBITORS IN RENAL CANCER: The last decade has seen significant advances in understanding the biology and genetics of kidney cancer, some of which have radically changed treatment standards, including the emergence of targeted therapies. TKIs have significantly improved outcome in patients with metastatic disease. Nevertheless, a subset of patients (approximately 25 %) does not show any clinical benefit from targeted therapies. In many cases, patients initially respond to therapy but resistance to targeted agents has been shown to develop after a median of 6-12 months of treatment. Two general models of tumor resistance to anti-angiogenic agents targeting the VEGF pathway have been proposed: an adaptive (evasive) resistance, which occurs after a prolonged application of a drug (providing a period of tumor control), or intrinsic one (preexisting) non-responsiveness despite the presence of an active agent, showing no therapeutic benefit. Intrinsic resistance is related to tumor redundancy of pro-angiogenic pathways. Acquired resistance is associated with activation of alternative pathways either by upregulation of the VEGF pathway or by recruitment of alternative angiogenic factors responsible for tumor revascularization. Because different combinations and sequences of TKI are tested in clinical trials and immunotherapy (alone or in combination) radically alters patient management in its metastatic disease, the current effort aims at identifying resistance processes, evaluating their importance and proposing rational therapeutic approaches in order to obtain an additional clinical benefit. Our article summarizes the different mechanisms of resistance described in the literature.

The use of alpha-fetoprotein for the treatment of autoimmune diseases and cancer

Alpha-fetoprotein is a shuttle protein that delivers nutrients through receptor-mediated endocytosis to embryotic cells. In adults, alpha-fetoprotein can shuttle drugs into alpha-fetoprotein receptor-positive myeloid-derived suppressor, regenerating and also cancer cells. Drugs with high-binding affinity to alpha-fetoprotein can activate or deplete targeted cells. Myeloid-derived suppressor cells activation leads to immune suppression that can be used for treating autoimmune diseases. On the other hand, toxins delivered by alpha-fetoprotein can damage myeloid-derived suppressor cells and consequently unleash innate and adaptive immunity to destroy cancer cells. Innate immunity natural killers reduce cancer stem cells and metastases. The new alpha-fetoprotein drug noncovalent complexes for immunotherapy change the local immune balance and has potential in oncology, autoimmune and infectious diseases treatment, inflammation, transplantation, vaccination, etc.

Immune consequences of anti-angiogenic therapyin renal cell carcinoma

Current therapies of renal cell carcinoma (RCC), a highly vascularised tumour, mostly rely on anti-angiogenic treatment options. These include tyrosine kinase inhibitors (TKIs) and anti-VEGF monoclonal antibodies. Although these strategies aim at restraining vascularisation to control tumour growth, the effects of such therapies are much wider, as affecting the vessel structure deeply modifies the microenvironment of the tumour mass. The aim of this review is to provide an overview of current knowledge on the global effects of anti-angiogenic treatment, mostly TKIs, on the shaping of the immune component of the RCC microenvironment. The data supporting the modification of immunity by anti-angiogenic therapies are collected to reveal the potential of angiogenesis modulation as a strategy for the adjuvant anti-cancer approach in immunotherapy.

Targeting tumor-infiltrating Ly6G+ myeloid cells improves sorafenib efficacy in mouse orthotopic hepatocellular carcinoma

Sorafenib, a multikinase inhibitor with antiangiogenic activity, is an approved therapy for hepatocellular carcinoma (HCC). It is unclear whether the proinflammatory and immunosuppressive mechanisms may limit the therapeutic efficacy of sorafenib in HCC. We used a syngeneic mouse liver cancer cell line to establish orthotopic liver or subcutaneous tumors to study how proinflammatory and immunosuppressive mechanisms impact on the efficacy of sorafenib. We found sorafenib exhibited a potent therapeutic effect in subcutaneous tumors, but a less potent effect in orthotopic liver tumors. The protein levels of interleukin-6 (IL-6) and vascular endothelial growth factor A (VEGF-A) were persistently elevated in orthotopic liver tumors, but not in subcutaneous tumors, treated with sorafenib. Likewise, the tumor-infiltrating Ly6G⁺ myeloid-derived suppressor cells (MDSCs) and immune suppressors were increased in orthotopic liver tumors, not in subcutaneous tumors, treated with sorafenib. The tumor-infiltrating Ly6G⁺ MDSCs of sorafenib-treated orthotopic liver tumors significantly induced IL-10 and TGF-β expressing CD4⁺ T cells, and downregulated the cytotoxic activity of CD8⁺ T cells. IL-6, but not VEGF-A, protected Ly6G⁺ MDSCs from sorafenib-induced cell death in vitro. The combination of anti-Ly6G antibody or anti-IL-6 antibody with sorafenib significantly reduced the cell proportion of Ly6G⁺ MDSCs in orthotopic liver tumors, enhanced the T cells proliferation and improved the therapeutic effect of sorafenib synergistically. Modulating tumor microenvironment through targeting tumor-infiltrating Ly6G⁺ MDSCs represents a potential strategy to improve the anti-HCC efficacy of sorafenib.

Adoptive T-Cell Therapy for Solid Tumors

Chimeric antigen receptor (CAR) T-cell therapy is an innovative form of immunotherapy wherein autologous T cells are genetically modified to express chimeric receptors encoding an antigen-specific single-chain variable fragment and various costimulatory molecules. Upon administration, these modified T cells traffic to, and recognize, cancer cells in an HLA-independent manner. CAR T-cell therapy has shown remarkable success in the treatment of CD-19-expressing B-cell acute lymphocytic leukemia. However, clinical gains to the same magnitude have not been reported in solid tumors. Several known obstacles to CAR T-cell therapy for solid tumors include target antigen identification, effective trafficking to the tumor, robust activation, proliferation, and in vivo cytotoxicity. Beyond these T-cell intrinsic properties, a complex and dynamic immunosuppressive tumor microenvironment in solid tumors hinders T-cell efficacy. Notable advancements in CAR design to include multiple costimulatory molecules, ligands, and soluble cytokines have shown promise in preclinical models, and some of these are currently in early-phase clinical trials. In this review, we discuss selected solid tumor malignancies and relevant preclinical data and highlight clinical trial results that are available. Furthermore, we outline some obstacles to CAR T-cell therapy for each tumor and propose strategies to overcome some of these limitations.

Adoptive T-Cell Therapy for Solid Tumors

Chimeric antigen receptor (CAR) T-cell therapy is an innovative form of immunotherapy wherein autologous T cells are genetically modified to express chimeric receptors encoding an antigen-specific single-chain variable fragment and various costimulatory molecules. Upon administration, these modified T cells traffic to, and recognize, cancer cells in an HLA-independent manner. CAR T-cell therapy has shown remarkable success in the treatment of CD-19-expressing B-cell acute lymphocytic leukemia. However, clinical gains to the same magnitude have not been reported in solid tumors. Several known obstacles to CAR T-cell therapy for solid tumors include target antigen identification, effective trafficking to the tumor, robust activation, proliferation, and in vivo cytotoxicity. Beyond these T-cell intrinsic properties, a complex and dynamic immunosuppressive tumor microenvironment in solid tumors hinders T-cell efficacy. Notable advancements in CAR design to include multiple costimulatory molecules, ligands, and soluble cytokines have shown promise in preclinical models, and some of these are currently in early-phase clinical trials. In this review, we discuss selected solid tumor malignancies and relevant preclinical data and highlight clinical trial results that are available. Furthermore, we outline some obstacles to CAR T-cell therapy for each tumor and propose strategies to overcome some of these limitations.

Sorafenib combined with HER-2 targeted vaccination can promote effective T cell immunity in vivo

The tumor microenvironment (TME) is established and maintained through complex interactions between tumor cells and host stromal elements. Therefore, therapies that target multiple cellular components of the tumor may be most effective. Sorafenib, a multi-kinase inhibitor, alters signaling pathways in both tumor cells and host stromal cells. Thus, we explored the potential immune-modulating effects of sorafenib in a murine HER-2-(neu) overexpressing breast tumor model alone and in combination with a HER-2 targeted granulocyte-macrophage colony-stimulating factor (GM-CSF)-secreting vaccine (3T3neuGM). In vitro, sorafenib inhibited the growth of HER-2 overexpressing NT2.5 tumor cells, inducing apoptosis. Sorafenib also interfered with ERK MAPK, p38 MAPK, and STAT3 signaling, as well as cyclin D expression, but did not affect HER-2 or AKT signaling. In vivo, single agent sorafenib disrupted the tumor-associated vasculature and induced tumor cell apoptosis, effectively inducing the regression of established NT2.5 tumors in immune competent FVB/N mice. Immune depletion studies demonstrated that both CD4⁺ and CD8⁺ T cells were required for tumor regression. Sorafenib treatment did not impact the rate of tumor clearance induced by vaccination with 3T3neuGM in tumor-bearing FVB/N mice relative to either sorafenib treatment or vaccination alone. In vivo studies further demonstrated that sorafenib enhanced the accumulation of both CD4⁺ and CD8⁺ T cells into the TME of vaccinated mice. Together, these findings suggest that GM-CSF-secreting cellular immunotherapy may be integrated with sorafenib without impairing vaccine-based immune responses.

Portal Venous Blood Circulation Supports Immunosuppressive Environment and Pancreatic Cancer Circulating Tumor Cell Activation

OBJECTIVES

Aggressive spread and liver metastases are predominant features of pancreatic ductal adenocarcinoma (PDAC). This study investigates activation of PDAC circulating tumor cells (CTC) and immunosuppression in the portal venous system.

METHODS

Portal venous and peripheral blood were collected during pancreaticoduodenectomy from patients with PDAC (n = 21) or other non-PDAC pancreatic conditions (n = 20). Circulating tumor cells were isolated by fluorescence-activated cell sorting and characterized for messenger RNA (mRNA) expression and acetylated chromatin encoding K-RAS exon 12 mutation (K-RASmut). Myeloid-derived suppressor cells (MDSC) were identified using flow cytometry.

RESULTS

Pancreatic ductal adenocarcinoma K-RASmut mRNA expression in portal venous blood CTC was significantly elevated compared with preoperative and postoperative peripheral blood (P = 0.0123 and P = 0.0246, respectively). There was no significant variation in total CTC numbers between portal and peripheral blood.Portal venous M-MDSC were elevated compared with peripheral blood in PDAC patients (P = 0.0065). M-MDSC increases correlated with K-RASmut mRNA-expressing CTC present in PDAC portal blood (P < 0.0001).

CONCLUSIONS

Association of MDSC with active CTC in portal venous blood may support immunosuppression within the portal venous circulation to promote PDAC CTC survival.

VHL-dependent alterations in the secretome of renal cell carcinoma: Association with immune cell response?

Secreted proteins could modulate the interaction between tumor, stroma and immune cells within the tumor microenvironment thereby mounting an immunosuppressive tumor microenvironment. In order to determine the secretome-mediated, von Hippel Lindau (VHL)-regulated cross-talk between tumor cells and T lymphocytes peripheral blood mononuclear cells (PBMC) from healthy donors were either cultured in conditioned media obtained from normoxic and hypoxic human VHL-deficient renal cell carcinoma (RCC) cell line (786-0^VHL−) and its wild type (wt) VHL-transfected counterpart (786-0^VHL+) or directly co-cultured with both cell lines. An increased T cell proliferation was detected in the presence of 786-0^VHL+-conditioned medium. By applying a quantitative proteomic-based approach using differential gel electrophoresis followed by mass spectrometry fourteen proteins were identified to be differentially expressed within the secretome of 786-0^VHL− cells when compared to that of 786-0^VHL+ cells. All proteins identified were involved in multiple tumor-associated biological functions including immune responses. Functional studies on manganese superoxide dismutase 2 (MnSOD2) demonstrated that it was a regulator of T cell activation-induced oxidative signaling and cell death. Direct effects of soluble MnSOD2 on the growth properties and interleukin 2 (IL-2) secretion of T cells could be demonstrated underlining the critical role of extracellular MnSOD2 levels for T cell proliferation and activation.

Genomic Analysis of Immune Cell Infiltrates Across 11 Tumor Types

BACKGROUND

Immune infiltration of the tumor microenvironment has been associated with improved survival for some patients with solid tumors. The precise makeup and prognostic relevance of immune infiltrates across a broad spectrum of tumors remain unclear.

METHODS

Using mRNA sequencing data from The Cancer Genome Atlas (TCGA) from 11 tumor types representing 3485 tumors, we evaluated lymphocyte and macrophage gene expression by tissue type and by genomic subtypes defined within and across tumor tissue of origin (Cox proportional hazards, Pearson correlation). We investigated clonal diversity of B-cell infiltrates through calculating B-cell receptor (BCR) repertoire sequence diversity. All statistical tests were two-sided.

RESULTS

High expression of T-cell and B-cell signatures predicted improved overall survival across many tumor types including breast, lung, and melanoma (breast CD8_T_Cells hazard ratio [HR] = 0.36, 95% confidence interval [CI] = 0.16 to 0.81, P = .01; lung adenocarcinoma B_Cell_60gene HR = 0.71, 95% CI = 0.58 to 0.87, P = 7.80E-04; melanoma LCK HR = 0.86, 95% CI = 0.79 to 0.94, P = 6.75E-04). Macrophage signatures predicted worse survival in GBM, as did B-cell signatures in renal tumors (Glioblastoma Multiforme [GBM]: macrophages HR = 1.62, 95% CI = 1.17 to 2.26, P = .004; renal: B_Cell_60gene HR = 1.17, 95% CI = 1.04 to 1.32, P = .009). BCR diversity was associated with survival beyond gene segment expression in melanoma (HR = 2.67, 95% CI = 1.32 to 5.40, P = .02) and renal cell carcinoma (HR = 0.36, 95% CI = 0.15 to 0.87, P = .006).

CONCLUSIONS

These data support existing studies suggesting that in diverse tissue types, heterogeneous immune infiltrates are present and typically portend an improved prognosis. In some tumor types, BCR diversity was also associated with survival. Quantitative genomic signatures of immune cells warrant further testing as prognostic markers and potential biomarkers of response to cancer immunotherapy.

miR-29b and miR-198 overexpression in CD8+ T cells of renal cell carcinoma patients down-modulates JAK3 and MCL-1 leading to immune dysfunction

Background

Mammalian microRNAs (miR) regulate the expression of genes relevant for the development of adaptive and innate immunity against cancer. Since T cell dysfunction has previously been reported in patients with renal cell carcinoma (RCC; clear cell type), we aimed to analyze these immune cells for genetic and protein differences when compared to normal donor T cells freshly after isolation and 35 days after in vitro stimulation (IVS) with HLA-matched RCC tumor cells.

Methods

We investigated gene expression profiles of tumor-reactive CD8⁺ T cells obtained from RCC patient and compared with their HLA-matched healthy sibling donors using a microarray approach. In addition, miRNAs analysis was performed in a validation cohort of peripheral blood CD8⁺ T cells from 25 RCC patients compared to 15 healthy volunteers.

Results

We observed that CD8⁺ T cells from RCC patients expressed reduced levels of anti-apoptotic and proliferation-associated gene products when compared with normal donor T cells both pre- and post-IVS. In particular, JAK3 and MCL-1 were down-regulated in patient CD8⁺ T cells versus their normal counterparts, likely due to defective suppressor activity of miR-29b and miR-198 in RCC CD8⁺ T cells. Indeed, specific inhibition of miR-29b or miR-198 in peripheral blood mononuclear cells (PBMCs) isolated from RCC patients, resulted in the up-regulation of JAK3 and MCL-1 proteins and significant improvement of cell survival in vitro.

Conclusions

Our results suggest that miR-29b and miR-198 dysregulation in RCC patient CD8⁺ T cells is associated with dysfunctional immunity and foreshadow the development of miR-targeted therapeutics to correct such T cell defects in vivo.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-016-0841-9) contains supplementary material, which is available to authorized users.

CXCL10 and CCL2 mRNA expression in monocytes is inversely correlated with the HLA-DR lower fraction of monocytes in patients with renal cell carcinoma

Circulating cluster of differentiation (CD)14+ human leukocyte antigen (HLA)-DRlow/- monocytes, those with a lower HLA-DR expression or are negative for HLA-DR, are considered to be involved in systemic immunosuppression in patients with several malignant tumors. However, few studies have investigated in detail the gene expression profile of CD14+HLA-DRlow/- monocytes. In the present study, the mRNA expression levels of immune-associated molecules in CD14+ monocytes isolated from healthy donors and patients with renal cell carcinoma (RCC) were analyzed. Consistent with previous studies, the percentage of HLA-DRlow/- cells in CD14+ monocytes was significantly increased in patients with RCC compared with healthy donors. In 3 of the 4 patients who underwent surgical resection of the primary tumor, the percentage of CD14+HLA-DRlow/- cells was significantly decreased following surgery. The mRNA expression levels of cyclooxygenase 2, transforming growth factor β, interleukin 6R, chemokine (C-C motif) ligand 2 (CCL2), chemokine (C-X-C motif) ligand 10 (CXCL10), oncostatin M, and vascular endothelial growth factor-A in CD14+ monocytes were quantified using reverse transcription-quantitative polymerase chain reaction. The results of the present study revealed that increased expression levels of CCL2 and CXCL10 were inversely correlated with the percentage of CD14+HLA-DRlow/- monocytes. This suggested that monocytes in RCC patients were immunologically suppressed, and that immunosuppression in RCC patients may be due, in part, to the dysfunction of circulating monocytes.

Anti-tumor enhancement of Fei-Liu-Ping ointment in combination with celecoxib via cyclooxygenase-2-mediated lung metastatic inflammatory microenvironment in Lewis lung carcinoma xenograft mouse model

Background

Fei-Liu-Ping (FLP) ointment is an oral prescription medication that has been widely applied to treat lung cancer patients in China. Regulation of the metastatic microenvironment is an important therapeutic approach for prevention and treatment of tumor recurrence and metastasis. The advantage of Traditional Chinese Medicine management of lung cancer lies in the prevention of recurrence and metastasis. Our previous study has demonstrated that FLP ointment could regulate lung inflammatory microenvironment in vitro. However, the effects of FLP on the tumor microenvironment in vivo are still poorly understood. The objective of this study is to investigate the effect of FLP alone or in combination with celecoxib in the prevention of lung cancer progression by Cyclooxygenase (Cox)-2 mediated tumor inflammatory microenvironment in vivo.

Methods

120 Lewis lung carcinoma xenograft mice were divided equally into four groups: vehicle, FLP, celecoxib, and FLP plus celecoxib. The dynamic growth of the xenografted tumors was observed using an in vivo fluorescence imaging system. Mice were sacrificed on day 14, day 21, and day 28, and tumor specimens and lung tissues were harvested to detect the metastasis-associated protein expression.

Results

Tumor inhibition rate was 15.4, 44.2, 47.4 % at day 14, 37.3, 34.7, 61.5 % at day 21, and 15.5, 10.3, 32.5 % at day 28 after treatment of FLP, celecoxib, and FLP plus celecoxib, respectively. Upon treatment of FLP and celecoxib together, lung metastasis rate was 30 % (8 metastatic nodules) lower than other groups. FLP inhibited Cox-2 expression in a time-dependent manner. Moreover, FLP inhibited N-cadherin, matrix metalloproteinases (MMP)-9, and Vimentin expression. Treatment of FLP in combination with celecoxib was more effective than FLP or celecoxib alone in inhibiting vascular endothelial growth factor, platelet-derived growth factor receptors β, microsomal Prostaglandin E synthase-1, MMP-2, MMP-9, N-cadherin, and Vimentin expression, but increased E-cadherin expression.

Conclusions

FLP inhibited tumor growth and metastasis in a Lewis lung xenograft mice model through the Cox-2 pathway. FLP in combination with celecoxib enhanced the antitumor growth and anti-metastasis effects. Traditional Chinese herbs combined with anti-inflammatory drugs might offer a promising strategy to prevent tumor metastasis.

Inhibition of the angiopoietin/Tie2 axis induces immunogenic modulation, which sensitizes human tumor cells to immune attack

BACKGROUND

The angiopoietin/Tie2 pathway is an attractive target for cancer therapy due to its well-known role in regulating angiogenesis. Trebananib, a recombinant peptide-Fc fusion protein, or peptibody, that binds to angiopoietin-1 (Ang1) and Ang2 to block their interaction with the Tie2 receptor, is under active clinical investigation. We investigated whether suppressing the angiopoietin/Tie2 pathway, using the preclinical version of Trebananib (mL4-3 and L1-7(N)), could increase the sensitivity of human tumor cells to immune-mediated lysis through immunogenic modulation, which would make Trebananib a promising candidate for combination with immunotherapy.

METHODS

We assessed human carcinoma cells for expression and activation of Ang1 and Ang2 and their receptor tyrosine kinase Tie2. In vitro, we exposed tumor cell lines expressing Tie2 to the peptibodies mL4-3 and L1-7(N), which inhibit the binding of Ang1 and Ang2 to Tie2, and assessed the cells for changes in viability, proliferation, surface phenotype, and sensitivity to attack by antigen-specific cytotoxic T lymphocytes (CTLs).

RESULTS

Suppression of the angiopoietin/Tie2 pathway using mL4-3 and L1-7(N) had no effect on the proliferation or viability of tumor cells. However, these inhibitors markedly altered tumor cell phenotype, rendering tumor cells significantly more sensitive to antigen-specific CTL killing. ICAM-1 was shown to be mechanistically involved in these inhibitors' ability to sensitize tumor cells to immune-mediated attack by functional blocking studies.

CONCLUSION

Our findings provide a rationale for the combination of agents targeting the angiopoietin/Tie2 pathway with cancer immunotherapies.

CD8 engineered cytotoxic T cells reprogram melanoma tumor environment

Cytotoxic T lymphocytes (CTL) from CD8β-deficient mice have powerful FasL-mediated cytotoxicity and IFNγ responses, but ablated Ca²⁺ and NFAT signaling, which can be restored by transduction with CD8β. Upon infection with lymphocytic choriomeningitis virus (LCMV), these cells yielded GP33-specific CTL (CD8βR) that exhibited high FasL/Fas-mediated cytotoxicity, IFNγ CXCL9 and 10 chemokine responses. Transfer of these cells in B16-GP33 tumor bearing mice resulted in (i) massive T cell tumor infiltration, (ii) strong reduction of myeloid-derived suppressor cells (MDSCs), regulatory T cells (Treg) and IL-17-expressing T helper cells, (iii) maturation of tumor-associated antigen-presenting cells and (iv) production of endogenous, B16 melanoma-specific CTL that eradicated the tumor long after the transferred CD8βR CTL perished. Our study demonstrates that the synergistic combination of strong Fas/FasL mediated cytotoxicity, IFNγ and CXCL9 and 10 responses endows adoptively transferred CTL to reprogram the tumor environment and to thus enable the generation of endogenous, tumoricidal immunity.

Clinical applications of PD-1-based therapy: a focus on pembrolizumab (MK-3475) in the management of melanoma and other tumor types

Preclinical work has led to an increased understanding of the immunomodulatory mechanisms involved in the regulation of the antitumor response in a variety of tumor types. PD-1 (programmed death 1) appears to be a key checkpoint involved in immune suppression in the tumor microenvironment, even in diseases not previously thought to be sensitive to immune manipulation. More recently, the subsequent clinical development of PD-1-based therapy has resulted in a major breakthrough in the field of oncology. Pembrolizumab, a humanized highly selective IgG4 anti-PD-1 monoclonal antibody, was recently approved for the treatment of advanced melanoma based on promising early-phase clinical data. Encouraging results have also been seen in other malignancies, and PD-1-targeted therapies are likely to markedly change the treatment landscape. Future work will center on rationally designed combination strategies in order to potentiate the antitumor immune response and overcome mechanisms of resistance.

Tumour and patient factors in renal cell carcinoma-towards personalized therapy

Renal cell carcinoma (RCC) comprises a heterogeneous group of histologically and molecularly distinct tumour subtypes. Current targeted therapies have improved survival in patients with advanced disease but complete response occurs rarely, if at all. The genomic characterization of RCC is central to the development of novel targeted therapies. Large-scale studies employing multiple 'omics' platforms have led to the identification of key driver genes and commonly altered pathways. Specific molecular alterations and signatures that correlate with tumour phenotype and clinical outcome have been identified and can be harnessed for patient management and counselling. RCC seems to be a remarkably diverse malignancy with significant intratumour and intertumour genetic heterogeneity. The tumour microenvironment is increasingly recognized as a vital regulator of RCC tumour biology. Patient factors, including immune response and drug metabolism, vary widely, which can lead to widely divergent responses to drug therapy. Intratumour heterogeneity poses a significant challenge to the development of personalized therapies in RCC as a single biopsy might not accurately represent the clonal population ultimately responsible for aggressive biologic behaviour. On the other hand, the diversity of genomic alterations in RCC could also afford opportunities for targeting unique pathways based on analysis of an individual tumour's molecular composition.

Effects of obesity on immune responses to renal tumors

Kidney cancer incidence in the USA has been steadily increasing over the past several decades. The reasons for this are not completely clear, but an increased prevalence of known predisposing factors may be promoting this trend. Several major risk factors for kidney cancer have been identified. Among these, obesity is notable because its incidence has risen dramatically during this same period of time. Here, we will review the relationship between obesity and kidney cancer, and will explore the idea that obesity-mediated alterations in immune function may render immunotherapies for renal tumors ineffective. To support this idea, we will summarize characteristics of endogenous immune responses to renal tumors, as well as existing and developing immune-based therapies for kidney cancer patients. In doing so, we will highlight the ways in which altered immune function in obese individuals may render these therapies ineffective.

An unexpected increase of toxicity of amino acid-containing ionic liquids

The influence of the structure of cations and anions on the biological activity of ionic liquids is addressed.

Complex role for the immune system in initiation and progression of pancreatic cancer

The immune system plays a complex role in the development and progression of pancreatic cancer. Inflammation can promote the formation of premalignant lesions and accelerate pancreatic cancer development. Conversely, pancreatic cancer is characterized by an immunosuppressive environment, which is thought to promote tumor progression and invasion. Here we review the current literature describing the role of the immune response in the progressive development of pancreatic cancer, with a focus on the mechanisms that drive recruitment and activation of immune cells at the tumor site, and our current understanding of the function of the immune cell types at the tumor. Recent clinical and preclinical data are reviewed, detailing the involvement of the immune response in pancreatitis and pancreatic cancer, including the role of specific cytokines and implications for disease outcome. Acute pancreatitis is characterized by a predominantly innate immune response, while chronic pancreatitis elicits an immune response that involves both innate and adaptive immune cells, and often results in profound systemic immune-suppression. Pancreatic adenocarcinoma is characterized by marked immune dysfunction driven by immunosuppressive cell types, tumor-promoting immune cells, and defective or absent inflammatory cells. Recent studies reveal that immune cells interact with cancer stem cells and tumor stromal cells, and these interactions have an impact on development and progression of pancreatic ductal adenocarcinoma (PDAC). Finally, current PDAC therapies are reviewed and the potential for harnessing the actions of the immune response to assist in targeting pancreatic cancer using immunotherapy is discussed.

Minimal changes in the systemic immune response after nephrectomy of localized renal masses

OBJECTIVES

Renal cell carcinoma (RCC) is an immunogenic tumor, and multiple immunostimulatory therapies are in use or under development for patients with inoperable tumors. However, a major drawback to the use of immunotherapy for RCC is that renal tumors are also immunosuppressive. As a result, current immunotherapies are curative in<10% of patients with RCC. To better understand the systemic immune response to RCC, we performed a comprehensive examination of the leukocyte and cytokine/chemokine composition in the peripheral blood of patients with localized clear cell renal tumors pre- and post-nephrectomy.

METHODS AND MATERIALS

Peripheral blood samples were taken from 53 consented subjects with renal masses before cytoreductive nephrectomy and again at clinic visits approximately 30 days after nephrectomy. Samples were also obtained from 10 healthy age- and gender-matched controls. Blood samples from clear cell RCC subjects were analyzed by multi-parameter flow cytometry to determine leukocyte subset composition and multiplex array to evaluate plasma proteins.

RESULTS

Pre-nephrectomy, clear cell tumors were associated with systemic accumulations of both "exhausted" CD8+ T cells, as indicated by surface BTLA expression, and monocytic CD14(+)HLA-DR(neg)CD33(+) myeloid-derived suppressor cells (MDSC). Subjects with T3 clear cell RCC also had a unique pro-tumorigenic and inflammatory cytokine/chemokine profile characterized by high serum concentrations of IL-1β, IL-2, IL-5, IL-7, IL-8, IL-17, TNF-α, MCP-1 and MIP-1β. At an early post-nephrectomy time point (~30 d), we found the systemic immune response to be largely unaltered. The only significant change was a decrease in the mean percentage of circulating BTLA(+)CD8(+) T cells. All other cellular and soluble immune parameters we examined were unaltered by the removal of the primary tumor.

CONCLUSIONS

In the first month following surgery, nephrectomy may relieve systemic CD8 T cell exhaustion marked by BTLA expression, but continuing inflammation and MDSC presence likely counteract this positive effect. Future determination of how this systemic immune signature becomes altered during metastatic progression could provide novel targets for neoadjuvant immunotherapy in RCC.