Controlling escape from angiogenesis inhibitors

CDC20 Knockdown and Acidic Microenvironment Collaboratively Promote Tumorigenesis through Inhibiting Autophagy and Apoptosis

The reconstitution of the tumorigenesis process would shed light on the tumor development study and further drug selection strategies. To construct a tumorigenesis model and explore potential mechanism is of great importance. In our study, we observed that CDC20-knockdown cells cultured in acidic environment exhibited chromosomal instability and better survival ability. The tumorigenic metabolism transformation was confirmed through the increase of the extracellular acidification rate (ECAR) and decrease of the oxygen consumption rate (OCR) in CDC20-knockdown cells. After a long-term culture for 3–4 months, CDC20-knockdown cells in acidic medium showed a strong tumor formation ability by subcutaneous injection into mice that is similar to that of tumor cells. Meanwhile, transcriptome analysis of cells from different stages showed that stage D cells almost resembled the phenotype of immortal cancer cells. The oncogene accumulation laid a firm foundation in the development of the tumorigenesis process by suppressing autophagy and p53-induced apoptosis. Several autophage- and apoptosis-related genes showed inhibition during this tumorigenesis process. In summary, chromosomal instability induced by CDC20 knockdown and acidic microenvironment could collaboratively promote cell tumorigenesis through the downregulation of autophagy and apoptosis.

GT198 Is a Target of Oncology Drugs and Anticancer Herbs

Tumor angiogenesis is a hallmark of cancer. Therapeutic drug inhibitors targeting angiogenesis are clinically effective. We have previously identified GT198 (gene symbol PSMC3IP, also known as Hop2) as an oncoprotein that induces tumor angiogenesis in human cancers, including oral cancer. In this study, we show that the GT198 protein is a direct drug target of more than a dozen oncology drugs and several clinically successful anticancer herbs. GT198 is a DNA repair protein that binds to DNA. Using an in vitro DNA-binding assay, we tested the approved oncology drug set VII from the National Cancer Institute containing 129 oncology drugs. Identified GT198 inhibitors include but are not limited to mitoxantrone, doxorubicin, paclitaxel, etoposide, dactinomycin, and imatinib. Paclitaxel and etoposide have higher binding affinities, whereas doxorubicin has higher binding efficacy due to competitive inhibition. GT198 shares protein sequence homology with DNA topoisomerases, which are known drug targets, so that GT198 is likely a new drug target previously unrecognized. To seek more powerful GT198 inhibitors, we further tested several anticancer herbal extracts. The positive anticancer herbs with high affinity and high efficacy are all clinically successful ones, including allspice from Jamaica, Gleditsia sinensis or honey locust from China, and BIRM from Ecuador. Partial purification of allspice using an organic chemical approach demonstrated great feasibility of natural product purification, when the activity is monitored by the in vitro DNA-binding assay using GT198 as a target. Together, our study reveals GT198 as a new targeting mechanism for existing oncology drugs. The study also delivers an excellent drug target suitable for compound identification and natural product purification. In particular, this study opens an opportunity to rapidly identify drugs with high efficacy and low toxicity from nature.

A Novel Antitumor Strategy: Simultaneously Inhibiting Angiogenesis and Complement by Targeting VEGFA/PIGF and C3b/C4b

Therapeutic antibodies targeting vascular endothelial growth factor (VEGF) have become a critical regimen for tumor therapy, but the efficacy of monotherapy is usually limited by drug resistance and multiple angiogenic mechanisms. Complement proteins are becoming potential candidates for cancer-targeted therapy based on their role in promoting cancer progression and angiogenesis. However, the antitumor abilities of simultaneous VEGF and complement blockade were unknown. We generated a humanized soluble VEGFR-Fc fusion protein (VID) binding VEGFA/PIGF and a CR1-Fc fusion protein (CID) targeting C3b/C4b. Both VID and CID had good affinities to their ligands and showed effective bioactivities. In vitro, angiogenesis effects induced by VEGF and hemolysis induced by complement were inhibited by VID and CID, respectively. Further, VID and CID confer a synergetic therapeutic effect in a colitis-associated colorectal cancer (CAC) model and an orthotopic 4T1 breast cancer model. Mechanically, combination therapy inhibited tumor angiogenesis, cell proliferation, and MDSC infiltration in the tumor microenvironment and promoted tumor cell apoptosis. Our study offers a novel therapeutic strategy for anti-VEGF-resistant tumors and chronic-inflammation-associated tumors.

Endoplasmic Reticulum Stress Signaling in Cancer Cells

To survive, cancer cells must resist numerous internal and environmental insults associated with neoplasia that jeopardize proteostasis within the endoplasmic reticulum (ER). Solid and hematopoietic tumors often experience genomic instability, oncogene activation, increased protein secretion demands, and somatic mutations in proteins handled by the secretory pathway that impede their folding. Invasion or metastasis into foreign environments can expose tumor cells to hypoxia, oxidative stress, lack of growth signals, inadequate amino acid supplies, glucose deprivation, and lactic acidosis, all of which pose challenges for protein processing in the ER. Together, these conditions can promote the buildup of misfolded proteins in the ER to cause ER stress, which then activates the unfolded protein response (UPR). An intracellular signaling network largely initiated by three ER transmembrane proteins, the UPR constantly surveils protein folding conditions within the ER lumen and when necessary initiates counteractive measures to maintain ER homeostasis. Under mild or moderate levels of ER stress, the homeostatic UPR sets in motion transcriptional and translational changes that promote cell adaption and survival. However, if these processes are unsuccessful at resolving ER stress, a terminal UPR program dominates and actively signals cell suicide. This article summarizes the mounting evidence that cancer cells are predisposed to ER stress and vulnerable to targeted interventions against ongoing UPR signaling.

Protein kinase inhibitor-based cancer therapies: Considering the potential of nitric oxide (NO) to improve cancer treatment

The deregulation of a wide variety of protein kinases is associated with cancer cell initiation and tumor progression. Owing to their indispensable function in signaling pathways driving malignant cell features, protein kinases constitute major therapeutic targets in cancer. Over the past two decades, intense efforts in drug development have been dedicated to this field. The development of protein kinase inhibitors (PKIs) have been a real breakthrough in targeted cancer therapy. Despite obvious successes across patients with different types of cancer, the development of PKI resistance still prevails. Combination therapies are part of a comprehensive approach to address the problem of drug resistance. The therapeutic use of nitric oxide (NO) donors to bypass PKI resistance in cancer has never been tested in clinic yet but several arguments suggest that the combination of PKIs and NO donors may exert a potential anticancer effect. The present review summarized the current state of knowledge on common targets to both PKIs and NO. Herein, we attempt to provide the rationale underlying a potential combination of PKIs and NO donors for future directions and design of new combination therapies in cancer.

The Warburg metabolism fuels tumor metastasis

The Warburg effect is prevalent in human cancer. Accordingly, most cancer cells display highly elevated glycolysis without proportionally increasing pyruvate oxidation. The metastatic process imposes strong selective pressure on cancer cells, and metastasizing cancer cells experience heightened oxidative stress. By constraining mitochondrial oxidative metabolism, the Warburg effect helps cancer cells to minimize oxidative stress, thereby facilitating metastatic dissemination. The PGC1α transcriptional coactivator is a central coordinator of oxidative metabolism. While promoting oxidative metabolism and reversing the Warburg effect, PGC1α critically activates antioxidant genes and protects cells against oxidative damage. Therefore, depending on the context, PGC1α may promote or suppress tumor metastasis. Cancer cells generally retain metabolic flexibility and can resist antiglycolysis treatment by undergoing metabolic reprogramming. Synthetic lethal combination therapies are thus essential to attack the liabilities of the Warburg metabolism for therapeutic benefit.

Tumor regression and potentiation of polymeric vascular disrupting therapy through reprogramming of a hypoxia microenvironment with temsirolimus

To relieve a tumor hypoxia microenvironment, the mTOR inhibitor temsirolimus was employed to modulate the tumor microenvironment when treated with CA4-NPs.

Vessel co-option and resistance to anti-angiogenic therapy

Vessel co-option is a non-angiogenic mechanism of tumour vascularisation in which cancer cells utilise pre-existing blood vessels instead of inducing new blood vessel formation. Vessel co-option has been observed across a range of different tumour types, in both primary cancers and metastatic disease. Importantly, vessel co-option is now implicated as a major mechanism that mediates resistance to conventional anti-angiogenic drugs and this may help to explain the limited efficacy of this therapeutic approach in certain clinical settings. This includes the use of anti-angiogenic drugs to treat advanced-stage/metastatic disease, treatment in the adjuvant setting and the treatment of primary disease. In this article, we review the available evidence linking vessel co-option with resistance to anti-angiogenic therapy in numerous tumour types, including breast, colorectal, lung and pancreatic cancer, glioblastoma, melanoma, hepatocellular carcinoma, and renal cell carcinoma. The finding that vessel co-option is a significant mechanism of resistance to anti-angiogenic therapy may have important implications for the future of anti-cancer therapy, including (a) predicting response to anti-angiogenic drugs, (b) the need to develop therapies that target both angiogenesis and vessel co-option in tumours, and (c) predicting the response to other therapeutic modalities, including immunotherapy.

Interplay Between Macrophages and Angiogenesis: A Double-Edged Sword in Liver Disease

During chronic liver disease, macrophages support angiogenesis, not only by secreting proangiogenic growth factors and matrix-remodeling proteases, but also by physically interacting with the sprouting vasculature to assist the formation of complex vascular networks. In the liver, macrophages acquire specific characteristics becoming Kupffer cells and working to ensure protection and immunotolerance. Angiogenesis is another double-edged sword in health and disease and it is the biggest ally of macrophages allowing its dissemination. Angiogenesis and fibrosis may occur in parallel in several tissues as macrophages co-localize with newly formed vessels and secrete cytokines, interleukins, and growth factors that will activate other cell types in the liver such as hepatic stellate cells and liver sinusoidal endothelial cells, promoting extracellular matrix accumulation and fibrogenesis. Vascular endothelial growth factor, placental growth factor, and platelet-derived growth factor are the leading secreted factors driving pathological angiogenesis and consequently increasing macrophage infiltration. Tumor development in the liver has been widely linked to macrophage-mediated chronic inflammation in which epidermal growth factors, STAT3 and NF-kβ are some of the most relevant signaling molecules involved. In this article, we review the link between macrophages and angiogenesis at molecular and cellular levels in chronic liver disease.

Autophagy is essential for the endothelial differentiation of breast cancer stem‑like cells

Blood vessels serve an important role in tumor growth and metastasis, and recent studies have shown that certain tumor cancer stem cells may differentiate into endothelial cells and contribute to angiogenesis. In the present study, vascular endothelial growth factor (VEGF) was used to induce endothelial differentiation of breast cancer stem‑like cells (BCSLCs), and methods including flow cytometry, western blotting and immunofluorescence were used to study the relationship between autophagy and the endothelial differentiation of BCSLCs. The results showed that BCSLCs could differentiate into endothelial cells under the induction of VEGF in vitro. Subsequently, the role of autophagy in the endothelial differentiation of BCSLCs was examined. Autophagic activity was measured during endothelial differentiation of BCSLCs, and the association between autophagy and endothelial differentiation was investigated using autophagy activators, autophagy inhibitors and autophagy related 5 (Atg5)‑knockdown BCSLCs. Autophagy was increased during endothelial differentiation of BCSLCs, and there was a positive association between autophagy and endothelial differentiation. The ability of cells to undergo endothelial differentiation was reduced in BCSLCs with Atg5 knockdown. Therefore, autophagy was essential for endothelial differentiation of BCSLCs, and the findings of the present study may highlight novel potential avenues for reducing angiogenesis and improving treatment of breast cancer.

Tumor vasculature remolding by thalidomide increases delivery and efficacy of cisplatin

Background

A promising strategy to overcome the chemoresistance is the tumor blood vessel normalization, which restores the physiological perfusion and oxygenation of tumor vasculature. Thalidomide (Thal) has been shown to increase the anti-tumor effect of chemotherapy agents in solid tumors. However, it is not yet known whether the synergistic effect of Thal combined with other cytotoxic drugs is attributable to tumor vascular normalization.

Methods

We used two homograft mice models (4 T1 breast tumor model and CT26 colorectal tumor model) to investigate the effect of Thal on tumor growth, microvessel density, vascular physiology, vascular maturity and function, drug delivery and chemosensitivity. Immunofluorescence, immunohistochemistry and scanning electron microscopy were performed to determine the vessel changes. Protein array assay, qPCR and western blotting were used to detect the molecular mechanism by which Thal regulates tumor vascular.

Results

Here we report that Thal potently suppressed tumor growth, angiogenesis, hypoxia, and vascular permeability in animal models. Thal also induced a regular monolayer of endothelial cells in tumor vessels, inhibiting vascular instability, and normalized tumor vessels by increasing vascular maturity, pericyte coverage and endothelial junctions. The tumor vessel stabilization effect of Thal resulted in a decrease in tumor vessel tortuosity and leakage, and increased vessel thickness and tumor perfusion. Eventually, the delivery of cisplatin was highly enhanced through the normalized tumor vasculature, thus resulting in profound anti-tumor and anti-metastatic effects. Mechanistically, the effects of Thal on tumor vessels were caused in part by its capability to correct the imbalance between pro-angiogenic factors and anti-angiogenic factors.

Conclusions

Our findings provide direct evidence that Thal remodels the abnormal tumor vessel system into a normalized vasculature. Our results may lay solid foundation for the development of Thal as a novel candidate agent to maximize the therapeutic efficacy of chemotherapeutic drugs for solid tumors.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1366-x) contains supplementary material, which is available to authorized users.

Volumetric response quantified using T1 subtraction predicts long-term survival benefit from cabozantinib monotherapy in recurrent glioblastoma

Background

To overcome challenges with traditional response assessment in anti-angiogenic agents, the current study uses T1 subtraction maps to quantify volumetric radiographic response in monotherapy with cabozantinib, an orally bioavailable tyrosine kinase inhibitor with activity against vascular endothelial growth factor receptor 2 (VEGFR2), hepatocyte growth factor receptor (MET), and AXL, in an open-label, phase II trial in patients with recurrent glioblastoma (GBM) (NCT00704288).

Methods

A total of 108 patients with adequate imaging data and confirmed recurrent GBM were included in this retrospective study from a phase II multicenter trial of cabozantinib monotherapy (XL184-201) at either 100 mg (N = 87) or 140 mg (N = 21) per day. Contrast enhanced T1-weighted digital subtraction maps were used to define volume of contrast-enhancing tumor at baseline and subsequent follow-up time points. Volumetric radiographic response (>65% reduction in contrast-enhancing tumor volume from pretreatment baseline tumor volume sustained for more than 4 wk) was tested as an independent predictor of overall survival (OS).

Results

Volumetric response rate for all therapeutic doses was 38.9% (41.4% and 28.6% for 100 mg and 140 mg doses, respectively). A log-linear association between baseline tumor volume and OS (P = 0.0006) and a linear correlation between initial change in tumor volume and OS (P = 0.0256) were observed. A significant difference in OS was observed between responders (median OS = 20.6 mo) and nonresponders (median OS = 8.0 mo) (hazard ratio [HR] = 0.3050, P < 0.0001). Multivariable analyses showed that continuous measures of baseline tumor volume (HR = 1.0233, P < 0.0001) and volumetric response (HR = 0.2240, P < 0.0001) were independent predictors of OS.

Conclusions

T1 subtraction maps provide value in determining response in recurrent GBM treated with cabozantinib and correlated with survival benefit.

Trends and Challenges in Tumor Anti-Angiogenic Therapies

Excessive abnormal angiogenesis plays a pivotal role in tumor progression and is a hallmark of solid tumors. This process is driven by an imbalance between pro- and anti-angiogenic factors dominated by the tissue hypoxia-triggered overproduction of vascular endothelial growth factor (VEGF). VEGF-mediated signaling has quickly become one of the most promising anti-angiogenic therapeutic targets in oncology. Nevertheless, the clinical efficacy of this approach is severely limited in certain tumor types or shows only transient efficacy in patients. Acquired or intrinsic therapy resistance associated with anti-VEGF monotherapeutic approaches indicates the necessity of a paradigm change when targeting neoangiogenesis in solid tumors. In this context, the elaboration of the conceptual framework of “vessel normalization” might be a promising approach to increase the efficacy of anti-angiogenic therapies and the survival rates of patients. Indeed, the promotion of vessel maturation instead of regressing tumors by vaso-obliteration could result in reduced tumor hypoxia and improved drug delivery. The implementation of such anti-angiogenic strategies, however, faces several pitfalls due to the potential involvement of multiple pro-angiogenic factors and modulatory effects of the innate and adaptive immune system. Thus, effective treatments bypassing relapses associated with anti-VEGF monotherapies or breaking the intrinsic therapy resistance of solid tumors might use combination therapies or agents with a multimodal mode of action. This review enumerates some of the current approaches and possible future directions of treating solid tumors by targeting neovascularization.

[68Ga]RGD Versus [18F]FDG PET Imaging in Monitoring Treatment Response of a Mouse Model of Human Glioblastoma Tumor with Bevacizumab and/or Temozolomide

PURPOSE

The aim of this study was to evaluate positron emission tomography (PET) imaging with [⁶⁸Ga]NODAGA-c(RGDfK) ([⁶⁸Ga]RGD), in comparison with 2-deoxy-2-[¹⁸F]fluoro-D-glucose ([¹⁸F]FDG), for early monitoring of the efficacy of an antiangiogenic agent associated or not with chemotherapy, in a mouse model of glioblastoma (GB).

PROCEDURES

Mice bearing U87MG human GB cells line were parted into five groups of five mice each. One group was imaged at baseline before the treatment phase; another group was treated with bevacizumab (BVZ), another group with temozolomide (TMZ), another group with both agents, and the last one was the control group. Tumors growth and biological properties were evaluated by caliper measurements and PET imaging at three time points (baseline, during treatment t1 = 4-6 days and t2 = 10-12 days). At the end of the study, tumors were counted and analyzed by immunohistochemistry (CD31 to evaluate microvessel density).

RESULTS

The tumor volume assessed by caliper measurements was significantly greater at t1 in the control group than in the TMZ + BVZ-treated group or in the BVZ-treated group. At t2, tumor volume of all treated groups was significantly smaller than that of the control group. [¹⁸F]FDG PET failed to reflect this efficacy of treatment. In contrast, at t1, the [⁶⁸Ga]RGD tumor uptake was concordant with tumor growth in controls and in treated groups. At t2, a significant increase in tumor uptake of [⁶⁸Ga]RGD vs. t1 was only observed in the TMZ-treated group, reflecting a lack of angiogenesis inhibition, whereas TMZ + BVZ resulted in a dramatic tumor arrest, reduction in microvessel density and stable tumor [⁶⁸Ga]RGD uptake.

CONCLUSIONS

[⁶⁸Ga]RGD is a useful PET agent for in vivo angiogenesis imaging and can be useful for monitoring antiangiogenic treatment associated or not with chemotherapy.

Regulatory mechanisms of Robo4 and their effects on angiogenesis

Roundabout4 (Robo4) is a transmembrane receptor that belongs to the Roundabout (Robo) family of axon guidance molecules. Robo4 is an endothelial-specific receptor that participates in endothelial cell migration, proliferation, and angiogenesis and the maintenance of vasculature homeostasis. The purpose of this review is to summarize and analyze three main mechanisms related to the expression and function of Robo4 during developmental and pathological angiogenesis. In this review, static shear stress and the binding of transcription factors such as E26 transformation-specific variant 2 (ETV2) and Slit3 induce Robo4 expression and activate Robo4 during tissue and organ development. Robo4 interacts with Slit2 or UNC5B to maintain vascular integrity, while a disturbed flow and the expression of transcription factors in inflammatory or neoplastic environments alter Robo4 expression levels, although these changes have uncertain functions. Based on the mechanisms described above, we discuss the aberrant expression of Robo4 in angiogenesis-related diseases and propose antiangiogenic therapies targeting the Robo4 signaling pathway for the treatment of ocular neovascularization lesions and tumors. Finally, although many problems related to Robo4 signaling pathways remain to be resolved, Robo4 is a promising and potentially valuable therapeutic target for treating pathological angiogenesis and developmental defects in angiogenesis.

The beginning of the end for conventional RECIST - novel therapies require novel imaging approaches

Owing to improvements in our understanding of the biological principles of tumour initiation and progression, a wide variety of novel targeted therapies have been developed. Developments in biomedical imaging, however, have not kept pace with these improvements and are still mainly designed to determine lesion size alone, which is reflected in the Response Evaluation Criteria in Solid Tumors (RECIST). Imaging approaches currently used for the evaluation of treatment responses in patients with solid tumours, therefore, often fail to detect successful responses to novel targeted agents and might even falsely suggest disease progression, a scenario known as pseudoprogression. The ability to differentiate between responders and nonresponders early in the course of treatment is essential to allowing the early adjustment of treatment regimens. Various imaging approaches targeting a single dedicated tumour feature, as described in the hallmarks of cancer, have been successful in preclinical investigations, and some have been evaluated in pilot clinical trials. However, these approaches have largely not been implemented in clinical practice. In this Review, we describe current biomedical imaging approaches used to monitor responses to treatment in patients receiving novel targeted therapies, including a summary of the most promising future approaches and how these might improve clinical practice.

Long noncoding RNAs, emerging and versatile regulators of tumor-induced angiogenesis

Angiogenesis is an essential step in maintaining tumor growth and facilitating metastasis. The regulatory mechanisms of tumor-induced angiogenesis are extremely complicated, and include sophisticated crosstalk between tumors and surrounding microenvironment cells, oncogenic signaling pathway activation and aberrant expression of angiogenesis-related genes. Recently, emerging evidence demonstrated that long noncoding RNAs (lncRNAs) play crucial roles in angiogenesis. However, there are lack of reports to review the progression in this scientific field. Here, we focus on and summarize the latest findings of lncRNA in angiogenesis in various cancers. Firstly, we introduced how lncRNAs in tumor cells to modulate the cellular signaling axis, interact with proteins and serve as competitive endogenous RNAs (ceRNAs) to alter target gene expression, by which induce endothelial cell to form capillaries. Then, we recapitulated the essential functions of lncRNA in endothelial cells, and how lncRNAs in tumor-associated macrophages to mediate angiogenesis. Next, the angiogenesis mechanism of tumor-derived lncRNAs via exosomes were collectively described. At last, the effects of lncRNAs on vasculogenic mimicry were summarized, which showed that malignant tumor cells acquire dedifferentiated and endothelial properties to form vessel-like structures by themselves. This review provides new insights into the complexity of angiogenesis, and suggests that lncRNAs may become promising biomarkers and targets for enhancing the efficacy of anti-angiogenesis therapy in cancer.

A Phase Ib Study of Axitinib in Combination with Crizotinib in Patients with Metastatic Renal Cell Cancer or Other Advanced Solid Tumors

Lessons Learned.

The combination of axitinib and crizotinib has a manageable safety and tolerability profile, consistent with the profiles of the individual agents when administered as monotherapy.

The antitumor activity reported here for the combination axitinib/crizotinib does not support further study of this combination treatment in metastatic renal cell carcinoma given the current treatment landscape.

Background.

Vascular endothelial growth factor (VEGF) inhibitors have been successfully used to treat metastatic renal cell carcinoma (mRCC); however, resistance eventually develops in most cases. Tyrosine protein kinase Met (MET) expression increases following VEGF inhibition, and inhibition of both has shown additive effects in controlling tumor growth and metastasis. We therefore conducted a study of axitinib plus crizotinib in advanced solid tumors and mRCC.

Methods.

This phase Ib study included a dose‐escalation phase (starting doses: axitinib 3 mg plus crizotinib 200 mg) to estimate maximum tolerated dose (MTD) in patients with solid tumors and a dose‐expansion phase to examine preliminary efficacy in treatment‐naïve patients with mRCC. Safety, pharmacokinetics, and biomarkers were also assessed.

Results.

No patients in the dose‐escalation phase (n = 22) experienced dose‐limiting toxicity; MTD was estimated to be axitinib 5 mg plus crizotinib 250 mg. The most common grade ≥3 adverse events were hypertension (18.2%) and fatigue (9.1%). In the dose‐expansion phase, overall response rate was 30% (95% confidence interval [CI], 11.9–54.3), and progression‐free survival was 5.6 months (95% CI, 3.5–not reached).

Conclusion.

The combination of axitinib plus crizotinib, at estimated MTD, had a manageable safety profile and showed evidence of modest antitumor activity in mRCC.

The small GTPase Rab5c is a key regulator of trafficking of the CD93/Multimerin-2/β1 integrin complex in endothelial cell adhesion and migration

Background

In the endothelium, the single-pass membrane protein CD93, through its interaction with the extracellular matrix protein Multimerin-2, activates signaling pathways that are critical for vascular development and angiogenesis. Trafficking of adhesion molecules through endosomal compartments modulates their signaling output. However, the mechanistic basis coordinating CD93 recycling and its implications for endothelial cell (EC) function remain elusive.

Methods

Human umbilical vein ECs (HUVECs) and human dermal blood ECs (HDBEC) were used in this study. Fluorescence confocal microscopy was employed to follow CD93 retrieval, recycling, and protein colocalization in spreading cells. To better define CD93 trafficking, drug treatments and transfected chimeric wild type and mutant CD93 proteins were used. The scratch assay was used to evaluate cell migration. Gene silencing strategies, flow citometry, and quantification of migratory capability were used to determine the role of Rab5c during CD93 recycling to the cell surface.

Results

Here, we identify the recycling pathway of CD93 following EC adhesion and migration. We show that the cytoplasmic domain of CD93, by its interaction with Moesin and F-actin, is instrumental for CD93 retrieval in adhering and migrating cells and that aberrant endosomal trafficking of CD93 prevents its localization at the leading edge of migration. Moreover, the small GTPase Rab5c turns out to be a key component of the molecular machinery that is able to drive CD93 recycling to the EC surface. Finally, in the Rab5c endosomal compartment CD93 forms a complex with Multimerin-2 and active β1 integrin, which is recycled back to the basolaterally-polarized cell surface by clathrin-independent endocytosis.

Conclusions

Our findings, focusing on the pro-angiogenic receptor CD93, unveil the mechanisms of its polarized trafficking during EC adhesion and migration, opening novel therapeutic opportunities for angiogenic diseases.

Electronic supplementary material

The online version of this article (10.1186/s12964-019-0375-x) contains supplementary material, which is available to authorized users.

Inula L. Secondary Metabolites against Oxidative Stress-Related Human Diseases

An imbalance in the production of reactive oxygen species in the body can cause an increase of oxidative stress that leads to oxidative damage to cells and tissues, which culminates in the development or aggravation of some chronic diseases, such as inflammation, diabetes mellitus, cancer, cardiovascular disease, and obesity. Secondary metabolites from Inula species can play an important role in the prevention and treatment of the oxidative stress-related diseases mentioned above. The databases Scopus, PubMed, and Web of Science and the combining terms Inula, antioxidant and secondary metabolites were used in the research for this review. More than 120 articles are reviewed, highlighting the most active compounds with special emphasis on the elucidation of their antioxidative-stress mechanism of action, which increases the knowledge about their potential in the fight against inflammation, cancer, neurodegeneration, and diabetes. Alantolactone is the most polyvalent compound, reporting interesting EC50 values for several bioactivities, while 1-O-acetylbritannilactone can be pointed out as a promising lead compound for the development of analogues with interesting properties. The Inula genus is a good bet as source of structurally diverse compounds with antioxidant activity that can act via different mechanisms to fight several oxidative stress-related human diseases, being useful for development of new drugs.

Lenvatinib, a molecule with versatile application: from preclinical evidence to future development in anti-cancer treatment

Lenvatinib is an emerging multi-kinase inhibitor with a preferential anti-angiogenic activity, which has shown efficacy in the treatment of renal cell carcinoma, differentiated thyroid cancer and hepatocellular carcinoma. It inhibits vascular endothelial growth factor receptor family (VEGFR1–3), fibroblast growth factor receptor family (FGFR1–4), platelet-derived growth factor receptor–alpha (PDGFRα), tyrosine-kinase receptor (KIT) and rearranged during transfection receptor (RET). In this review we have evaluated the development from bench to bedside of lenvatinib. PubMed, MEDLINE and clinicaltrials.gov are the sources of data. Furthermore, the preclinical in vitro and in vivo data, as well as efficacy and toxicity results of lenvatinib in the clinic, are presented and discussed. Treatment with lenvatinib causes side effects (hypertension, proteinuria, fatigue and diarrhea), which are predominantly related to the inhibition of angiogenesis. For these reasons, the identification of biomarkers of efficacy and resistance to lenvatinib is a key challenge in order to select responsive patients. This review provides an overview on lenvatinib's clinical use, perspectives and indications for future development.

An in vivo wound healing model for the characterization of the angiogenic process and its modulation by pharmacological interventions

Angiogenesis during wound healing is essential for tissue repair and also affected during cancer treatment by anti-angiogenic drugs. Here, we introduce a minimally invasive wound healing model in the mouse ear to assess angiogenesis with high spatiotemporal resolution in a longitudinal manner in vivo using two-photon microscopy in mice expressing GCaMP2 in arterial endothelial cells. The development of vascular sprouts occurred in a highly orchestrated manner within a time window of 8 days following wounding. Novel sprouts developed exclusively from the distal stump of the transsected arteries, growing towards the proximal arterial stump. This was in line with the incidence of Ca2+ transients in the arterial endothelial cells, most probably a result of VEGF stimulation, which were more numerous on the distal part. Functional analysis revealed perfusion across the wound site via arterial sprouts developed between days 6 and 8 following the incision. At day 8, proximal and distal arteries were structurally and functionally connected, though only 2/3 of all sprouts detected were actually perfused. Treatment with the FDA approved drug, sunitinib, the preclinical drug AZD4547, as well as with the combination of the two agents had significant effects on both structural and functional readouts of neo-angiogenesis. The simplicity and high reproducibility of the model makes it an attractive tool for elucidating migratory activity, phenotype and functionality of endothelial cells during angiogenesis and for evaluating specific anti-angiogenic drug interventions.

Pharmacology of ME-344, a novel cytotoxic isoflavone

Isoflavones isolated from members of the Fabaceae (primarily Leguminosae) family have been characterized for their phytoestrogenic properties, but certain derivatives have also shown potential as possible cancer therapeutic agents. ME-344, related to phenoxodiol (Fig. 1), is a second generation isoflavone with a recent history of both preclinical and early clinical testing. The drug has unusual cytotoxicity profiles, where cancer cell lines can be categorized as either intrinsically sensitive or resistant to the drug. Evolving studies show that the cytotoxic properties of the drug are enacted through targeting mitochondrial bioenergetics. While the drug has undergone early Phase I/II trials in solid tumors with confined dose limiting effects and some evidence of disease response, there is a continuing need to define specific cellular targets that determine sensitivity, with the long-term goal of applying such information to individualized therapy. This review article details some of the existing and ongoing studies that are assisting in the continued drug development processes that may lead to new drug application (NDA) status.

Macrophages enhance Vegfa-driven angiogenesis in an embryonic zebrafish tumour xenograft model

Tumour angiogenesis has long been a focus of anti-cancer therapy; however, anti-angiogenic cancer treatment strategies have had limited clinical success. Tumour-associated myeloid cells are believed to play a role in the resistance of cancer towards anti-angiogenesis therapy, but the mechanisms by which they do this are unclear. An embryonic zebrafish xenograft model has been developed to investigate the mechanisms of tumour angiogenesis and as an assay to screen anti-angiogenic compounds. In this study, we used cell ablation techniques to remove either macrophages or neutrophils and assessed their contribution towards zebrafish xenograft angiogenesis by quantitating levels of graft vascularisation. The ablation of macrophages, but not neutrophils, caused a strong reduction in tumour xenograft vascularisation and time-lapse imaging demonstrated that tumour xenograft macrophages directly associated with the migrating tip of developing tumour blood vessels. Finally, we found that, although macrophages are required for vascularisation in xenografts that either secrete VEGFA or overexpress zebrafish vegfaa, they are not required for the vascularisation of grafts with low levels of VEGFA, suggesting that zebrafish macrophages can enhance Vegfa-driven tumour angiogenesis. The importance of macrophages to this angiogenic response suggests that this model could be used to further investigate the interplay between myeloid cells and tumour vascularisation.

Summary: Zebrafish embryonic macrophages associate with the distal tips of tumour xenograft blood vessels and are required for Vegfa-driven angiogenesis.

Plasma Tie2 is a tumor vascular response biomarker for VEGF inhibitors in metastatic colorectal cancer

Oncological use of anti-angiogenic VEGF inhibitors has been limited by the lack of informative biomarkers. Previously we reported circulating Tie2 as a vascular response biomarker for bevacizumab-treated ovarian cancer patients. Using advanced MRI and circulating biomarkers we have extended these findings in metastatic colorectal cancer (n = 70). Bevacizumab (10 mg/kg) was administered to elicit a biomarker response, followed by FOLFOX6-bevacizumab until disease progression. Bevacizumab induced a correlation between Tie2 and the tumor vascular imaging biomarker, Ktrans (R:-0.21 to 0.47) implying that Tie2 originated from the tumor vasculature. Tie2 trajectories were independently associated with pre-treatment tumor vascular characteristics, tumor response, progression free survival (HR for progression = 3.01, p = 0.00014; median PFS 248 vs. 348 days p = 0.0008) and the modeling of progressive disease (p < 0.0001), suggesting that Tie2 should be monitored clinically to optimize VEGF inhibitor use. A vascular response is defined as a 30% reduction in Tie2; vascular progression as a 40% increase in Tie2 above the nadir. Tie2 is the first, validated, tumor vascular response biomarker for VEGFi.

AutoTube: a novel software for the automated morphometric analysis of vascular networks in tissues

Due to their involvement in many physiologic and pathologic processes, there is a great interest in identifying new molecular pathways that mediate the formation and function of blood and lymphatic vessels. Vascular research increasingly involves the image-based analysis and quantification of vessel networks in tissue whole-mounts or of tube-like structures formed by cultured endothelial cells in vitro. While both types of experiments deliver important mechanistic insights into (lymph)angiogenic processes, the manual analysis and quantification of such experiments are typically labour-intensive and affected by inter-experimenter variability. To bypass these problems, we developed AutoTube, a new software that quantifies parameters like the area covered by vessels, vessel width, skeleton length and branching or crossing points of vascular networks in tissues and in in vitro assays. AutoTube is freely downloadable, comprises an intuitive graphical user interface and helps to perform otherwise highly time-consuming image analyses in a rapid, automated and reproducible manner. By analysing lymphatic and blood vascular networks in whole-mounts prepared from different tissues or from gene-targeted mice with known vascular abnormalities, we demonstrate the ability of AutoTube to determine vascular parameters in close agreement to the manual analyses and to identify statistically significant differences in vascular morphology in tissues and in vascular networks formed in in vitro assays.

1-Methoxycarbony-β-carboline from Picrasma quassioides exerts anti-angiogenic properties in HUVECs in vitro and zebrafish embryos in vivo

Angiogenesis is a crucial process in the development of inflammatory diseases, including cancer, psoriasis and rheumatoid arthritis. Recently, several alkaloids from Picrasma quassioides had been screened for angiogenic activity in the zebrafish model, and the results indicated that 1-methoxycarbony-β-carboline (MCC) could effectively inhibit blood vessel formation. In this study, we further confirmed that MCC can inhibit, in a concentration-dependent manner, the viability, migration, invasion, and tube formation of human umbilical vein endothelial cells (HUVECs) in vitro, as well as the regenerative vascular outgrowth of zebrafish caudal fin in vivo. In the zebrafish xenograft assay, MCC inhibited the growth of tumor masses and the metastatic transplanted DU145 tumor cells. The proteome profile array of the MCC-treated HUVECs showed that MCC could down-regulate several angiogenesis-related self-secreted proteins, including ANG, EGF, bFGF, GRO, IGF-1, PLG and MMP-1. In addition, the expression of two key membrane receptor proteins in angiogenesis, TIE-2 and uPAR, were also down-regulated after MCC treatment. Taken together, these results shed light on the potential therapeutic application of MCC as a potent natural angiogenesis inhibitor via multiple molecular targets.

Role of monocyte-to-lymphocyte ratio in predicting sorafenib response in patients with advanced hepatocellular carcinoma

Purpose

Sorafenib is the first-line treatment for patients with unresectable hepatocellular carcinoma (HCC), and its clinical response rate is only about 10%. In clinical practice, some HCC patients obtain favorable overall survival (OS) to the treatment of sorafenib while some patients do not demonstrate a sensitive response to sorafenib. Therefore, it is valuable to determine the subgroups of patients who respond well as well as poorly to sorafenib. Thus, clinical variables of advanced HCC patients with sorafenib treatment were compiled to investigate whether monocyte-to-lymphocyte ratio (MLR) could be a biomarker for predicting sorafenib response.

Patients and methods

In this study, a total of 142 patients with advanced HCC were enrolled from January 1, 2013 to December 31, 2016 at the Fudan University Shanghai Cancer Center. MLR was analyzed using a ROC curve. A Cox regression model and log-rank test were performed to analyze the relationship between clinical factors and OS, as well as progression free survival (PFS).

Results

The optimal cut-off point for MLR was 0.35, and MLR level had no significant correlation with age, gender, hepatitis B infection, grade, alpha-fetoprotein (AFP) level and state of portal vein tumor thrombus. Multivariate Cox regression model showed that grade (HR: 0.608, 95% CI: 0.409–0.904, P=0.014), AFP (HR: 0.445, 95% CI: 0.307–0.645, P=0.0001), MLR (HR: 0.445, 95% CI: 0.301–0.658, P=0.0001) and aspartate aminotransferase (AST) (HR: 1.005, 95% CI: 1.001–1.009, P=0.007) may serve as independent prognostic predictors for OS, and MLR maintained significant correlation with PFS in HCC patients (HR: 0.457, 95% CI: 0.308–0.678, P=0.0001). By log-rank test, there was longer PFS and OS in patients with low MLR than in those with high MLR (both P=0.0001).

Conclusion

MLR can predict sorafenib response and a high MLR is correlated with poor prognosis in patients with advanced HCC.

Double-Blind Phase III Trial of Adjuvant Chemotherapy With and Without Bevacizumab in Patients With Lymph Node-Positive and High-Risk Lymph Node-Negative Breast Cancer (E5103)

Purpose Bevacizumab improves progression-free survival but not overall survival in patients with metastatic breast cancer. E5103 tested the effect of bevacizumab in the adjuvant setting in patients with human epidermal growth factor receptor 2-negative disease. Patients and Methods Patients were assigned 1:2:2 to receive placebo with doxorubicin and cyclophosphamide (AC) followed by weekly paclitaxel (arm A), bevacizumab only during AC and paclitaxel (arm B), or bevacizumab during AC and paclitaxel followed by bevacizumab monotherapy for 10 cycles (arm C). Random assignment was stratified and bevacizumab dose adjusted for choice of AC schedule. Radiation and hormonal therapy were administered concurrently with bevacizumab in arm C. The primary end point was invasive disease-free survival (IDFS). Results Four thousand nine hundred ninety-four patients were enrolled. Median age was 52 years; 64% of patients were estrogen receptor positive, 27% were lymph node negative, and 78% received dose-dense AC. Chemotherapy-associated adverse events including myelosuppression and neuropathy were similar across all arms. Grade ≥ 3 hypertension was more common in bevacizumab-treated patients, but thrombosis, proteinuria, and hemorrhage were not. The cumulative incidence of clinical congestive heart failure at 15 months was 1.0%, 1.9%, and 3.0% in arms A, B, and C, respectively. Bevacizumab exposure was less than anticipated, with approximately 24% of patients in arm B and approximately 55% of patients in arm C discontinuing bevacizumab before completing planned therapy. Five-year IDFS was 77% (95% CI, 71% to 81%) in arm A, 76% (95% CI, 72% to 80%) in arm B, and 80% (95% CI, 77% to 83%) in arm C. Conclusion Incorporation of bevacizumab into sequential anthracycline- and taxane-containing adjuvant therapy does not improve IDFS or overall survival in patients with high-risk human epidermal growth factor receptor 2-negative breast cancer. Longer duration bevacizumab therapy is unlikely to be feasible given the high rate of early discontinuation.

Oleanolic Acids Inhibit Vascular Endothelial Growth Factor Receptor 2 Signaling in Endothelial Cells: Implication for Anti-Angiogenic Therapy

Angiogenesis must be precisely controlled because uncontrolled angiogenesis is involved in aggravation of disease symptoms. Vascular endothelial growth factor (VEGF)/VEGF receptor 2 (VEGFR-2) signaling is a key pathway leading to angiogenic responses in vascular endothelial cells (ECs). Therefore, targeting VEGF/VEGFR-2 signaling may be effective at modulating angiogenesis to alleviate various disease symptoms. Oleanolic acid was verified as a VEGFR-2 binding chemical from anticancer herbs with similar binding affinity as a reference drug in the Protein Data Bank (PDB) entry 3CJG of model A coordination. Oleanolic acid effectively inhibited VEGF-induced VEGFR-2 activation and angiogenesis in HU-VECs without cytotoxicity. We also verified that oleanolic acid inhibits in vivo angiogenesis during the development and the course of the retinopathy of prematurity (ROP) model in the mouse retina. Taken together, our results suggest a potential therapeutic benefit of oleanolic acid for inhibiting angiogenesis in proangiogenic diseases, including retinopathy.

Silencing NIK potentiates anti-VEGF therapy in a novel 3D model of colorectal cancer angiogenesis

Angiogenesis is essential for colorectal cancer (CRC) progression, as demonstrated by the beneficial clinical effects of therapeutics inhibiting VEGF signaling. However, alternative mechanisms of neovascularization can develop, resulting in treatment failure. Previously we demonstrated NF-κB-inducing kinase (NIK) contributes to pathological angiogenesis. Here, we investigate NIK as a therapeutic target in endothelial cells (EC) in CRC. To determine NIK expression levels in CRC tissues, we immunostained both primary colorectal tumors and tumors metastasized to the liver. Additionally, a 3D tumor-stromal cell interaction model was developed including EC, fibroblasts and CRC cells to study tumor angiogenesis. This model tested efficacy of NIK-targeting siRNA (siNIK) in EC alone or in combination with the anti-VEGF antibody, bevacizumab. Both primary CRC and liver metastases contained blood vessels expressing NIK. In patients receiving chemotherapy plus bevacizumab, immature NIK⁺ vessels (p < 0.05) were increased as compared to chemotherapy alone. Activation of NIK by lymphotoxin-beta receptor (LTβR) induced increases in pro-angiogenic mediators, including interleukin (IL)-6, IL-8, chemokine (C-X-C motif) ligand (CXCL)1 and CXCL5 in EC and fibroblasts, accompanied by sprouting in the 3D model, which was blocked by siNIK in EC. Treatment with bevacizumab plus siNIK in EC resulted in a synergistic effect and reduced VEGF and bFGF-induced sprouting (p < 0.05). Here, we demonstrate a role for NIK in CRC-associated angiogenesis. Targeting NIK in EC in combination with anti-VEGF antibody bevacizumab may hold therapeutic potential to increase efficiency in blocking tumor neovascularization, either to prevent treatment failure due to activation of accessory pathways such as NF-κB signaling or as a rescue treatment.

Induction of chemokine (C-C motif) ligand 5 by Epstein-Barr virus infection enhances tumor angiogenesis in nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is etiologically associated with Epstein–Barr virus (EBV) infection and is known to be highly vascularized. Previous studies have suggested that EBV oncoproteins contribute to NPC angiogenesis. However, the regulatory network of EBV in angiogenesis still remains elusive. Herein, we reveal a novel mechanism of EBV‐induced angiogenesis in NPC. First, we showed that EBV‐infected NPC cell lines generated larger tumors with more microvessels in mouse xenograft models. Subsequent proteomic analysis revealed that EBV infection increased the expression of a series of angiogenic factors, including chemokine (C‐C motif) ligand 5 (CCL5). We then proved that CCL5 was a target of EBV in inducing tumor angiogenesis and growth. Further investigation through transcriptome analysis indicated that the pro‐angiogenic function of CCL5 might be mediated by the PI3K/AKT pathway. Furthermore, we confirmed that activation of the PI3K/AKT and hypoxia‐inducible factor‐1α pathways was essential for CCL5‐promoted angiogenesis. Finally, the immunohistochemical analysis of human NPC specimens also showed that CCL5 was correlated with angiogenesis. Taken together, our study identifies CCL5 as a key EBV‐regulated molecular driver that promotes NPC angiogenesis, suggesting it as a potential therapeutic target.

Endostar, a Modified Endostatin Induces Vascular Normalization to Improve Chemotherapy Efficacy Through Suppression of Src Signaling Pathway

Pathological angiogenesis can be a significant barrier to effective cancer therapy. Recent evidence suggests that Endostar may induce vascular normalization, thereby improving tumor perfusion and systemic chemotherapy. However, the molecular mechanism by which Endostar makes chemotherapy more effective remains to be fully elucidated. In this study, established 4T1 breast tumor-bearing animals treated with Endostar were evaluated at serial time points for treatment-associated changes in vascular architecture. As a result, Endostar induced a morphologically and functionally normalized vascular network. Combined Endostar and doxorubicin exhibited significant antitumor (34% of control size) and antimetastatic effects (29% of control metastatic nodules) in vivo. Finally, a two-dimensional gel electrophoresis and MALDIQ-TOF MS/MS-based proteomics approach was used to identify differentially expressed proteins involved in vascular normalization during Endostar administration. SRCIN1 was detected as one of the most significantly increased proteins. SRCIN1 is a novel Src-binding protein that regulates Src activation through C-terminal Src kinase, and attenuated Src activation during Endostar treatment was further confirmed by immunoblotting. Collectively, these data provided a molecular basis for vascular normalization, which were associated with the observed synergistic effect in vivo.

The role of tumor microenvironment in resistance to anti-angiogenic therapy

Anti-angiogenic therapy has been demonstrated to increase progression-free survival in patients with many different solid cancers. Unfortunately, the benefit in overall survival is modest and the rapid emergence of drug resistance is a significant clinical problem. Over the last decade, several mechanisms have been identified to decipher the emergence of resistance. There is a multitude of changes within the tumor microenvironment (TME) in response to anti-angiogenic therapy that offers new therapeutic opportunities. In this review, we compile results from contemporary studies related to adaptive changes in the TME in the development of resistance to anti-angiogenic therapy. These include preclinical models of emerging resistance, dynamic changes in hypoxia signaling and stromal cells during treatment, and novel strategies to overcome resistance by targeting the TME.

M2-like tumor-associated macrophages drive vasculogenic mimicry through amplification of IL-6 expression in glioma cells

Vasculogenic mimicry (VM) has offered a new horizon for understanding tumor angiogenesis, but the mechanisms of VM in glioma progression have not been studied explicitly until now. As a significant component of immune infiltration in tumor microenvironment, macrophages have been demonstrated to play an important role in tumor growth and angiogenesis. However, whether macrophages could play a potential key role in glioma VM is still poorly understood. Herein we reported that both VM and CD163⁺ cells were associated with WHO grade and reduced patient survival, and VM channel counting was correlated to the number of infiltrated CD163⁺ cells in glioma specimens. In vitro studies of glioma cell lines implicated that M2-like macrophages (M2) promoted glioma VM. We found that conditional medium derived from M2 amplified IL-6 expression in glioma cells. Furthermore, our data indicated that IL-6 could promote glioma VM, as blocking IL-6 with neutralizing antibodies abrogated M2-mediated VM enhancement. In addition, the potent PKC inhibitor bisindolylmaleimide I could prevent M2-induced IL-6 upregulation and further inhibited glioma VM facilitation. Taken together, our results suggested that M2-like macrophages drove glioma VM through amplifying IL-6 secretion in glioma cells via PKC pathway.

Novel targeted therapies and immunotherapy for advanced thyroid cancers

Thyroid cancer is a frequently encountered endocrine malignancy. Despite the favorable prognosis of this disease, 15–20% of differentiated thyroid cancer (DTC) cases and most anaplastic types, remain resistant to standard treatment options, including radioactive iodine (RAI). In addition, around 30% of medullary thyroid cancer (MTC) cases show resistance after surgery. The evolving understanding of disease-specific molecular therapeutic targets has led to the approval of two targeted therapies (Sorafenib and Lenvatinib) for RAI refractory DTC and another two drugs (Vandetanib and Cabozantinib) for MTC. These advanced therapies exert their effects by blocking the MAPK pathway, which has been widely correlated to different types of thyroid cancers. While these drugs remain reserved for thyroid cancer patients who failed all treatment options, their ability to improve patients’ overall survival remain hindered by their low efficacy and other molecular factors. Among these factors is the tumor’s ability to activate parallel proliferative signaling pathways other than the cascades blocked by these drugs, along with overexpression of some tyrosine kinase receptors (TKR). These facts urge the search for novel different treatment strategies for advanced thyroid cases beyond these drugs. Furthermore, the growing knowledge of the dynamic immune system interaction with tumor microenvironment has revolutionized the cancer immune therapy field. In this review, we aim to discuss the molecular escape mechanisms of thyroid tumors from these drugs. We also highlight novel therapeutic options targeting other pathways than MAPK, including PI3K pathway, ALK translocations and HER2/3 receptors and their clinical impact. We also aim to discuss the usage of targeted therapy in restoring thyroid tumor sensitivity to RAI, and finally turn to extensively discuss the role of immunotherapy as a potential alternative treatment option for advanced thyroid diseases.

Dendritic Cells Pulsed with Exosomes in Combination with PD-1 Antibody Increase the Efficacy of Sorafenib in Hepatocellular Carcinoma Model

Advanced hepatocellular carcinoma (HCC) has limited therapeutic options. Immunotherapy is a promising treatment, while sorafenib is a first-line drug-based treatment for advanced HCC. However, the efficacy of sorafenib and immunotherapy in combination, have not been clearly evaluated. Sorafenib treatment has been shown to promote immunosuppression by increasing hypoxia in orthotopic HCC models. Here, we found that sorafenib treatment in mice with orthotopic HCC increased the expression of inhibitor programmed death-ligand 1 (PD-L1) and T-regulatory cells in tumor tissues. We pulsed dendritic cells with exosomes derived from tumor cells (DC-TEX) and found that the number of T-regulatory cells decreased and the number of CD8+T cells increased. However, combining DC-TEX and sorafenib did not prolong survival in these mice. Moreover, we found that the number of PD-1+CD8+T cells significantly increased after DC-TEX treatment. Therefore, we next added PD-1 antibody (PD-1 Ab) to the treatment regimen to block the PD-1/PD-L1 pathway, and found that the exhausted CD8+T cells were restored, without affecting the number of T-regulatory cells. Thus, our data suggest that the combination of DC-TEX and PD-1 Ab enhanced the efficacy of sorafenib, but treatment with either DC-TEX or PD-1 Ab alone, did not.

A phase 1 trial extension to assess immunologic efficacy and safety of prime-boost vaccination with VXM01, an oral T cell vaccine against VEGFR2, in patients with advanced pancreatic cancer

VXM01 is a first-in-kind orally applied tumor vaccine based on live attenuated Salmonella typhi carrying an expression plasmid encoding VEGFR2, an antigen expressed on tumor vasculature and a stable and accessible target for anti-angiogenic intervention. A recent randomized, placebo-controlled, phase I dose-escalation trial in advanced pancreatic cancer patients demonstrated safety, immunogenicity and transient, T-cell response-related anti-angiogenic activity of four priming vaccinations applied within one week. We here evaluated whether monthly boost vaccinations are safe and can sustain increased frequencies of vaccine-specific T cells. Patients with advanced pancreatic cancer were randomly assigned at a ratio of 2:1 to priming with VXM01 followed by up to six monthly boost vaccinations, or placebo treatment. Vaccinations were applied orally at two alternative doses of either 10⁶ colony-forming units (CFU) or 10⁷ CFU, and concomitant treatment with standard-of-care gemcitabine during the priming phase, and any treatment thereafter, was allowed in the study. Immunomonitoring involved interferon-gamma (IFNγ) ELIspot analysis with long overlapping peptides spanning the entire VEGFR2 sequence. A total of 26 patients were treated. Treatment-related adverse events preferentially associated with VXM01 were decreases in lymphocyte numbers in the blood, increased frequencies of neutrophils and diarrhea. Eight out of 16 patients who received at least one boosting vaccination responded with pronounced, i.e. at least 3-fold, increase in VEGFR2-specific T cell response over baseline levels. In the VXM01 vaccination group, VEGFR2-specific T cells peaked preferentially during the boosting phase with an average 4-fold increase over baseline levels. In conclusion, prime/boost vaccination with VXM01 was safe and immunogenic and increased vaccine specific T cell responses compared with placebo treatment.

The tumor-stromal ratio as a strong prognosticator for advanced gastric cancer patients: proposal of a new TSNM staging system

BACKGROUND

Insufficient attention is paid to the underlying tumor microenvironment (TME) evolution, that resulting in tumor heterogeneity and driving differences in cancer aggressiveness and treatment outcomes. The morphological evaluation of the proportion of the stroma at the most invasive part of primary tumor (tumor-stromal ratio, TSR) in cancer is gaining momentum as evidence strengthens for the clinical relevance.

METHODS

Tissue samples from the most invasive part of the primary gastric cancer (GC) of 494 patients were analyzed for their TSR, and a new TSNM (tumor-stromal node metastasis) staging system based on patho-biological behaviors was established and assessed.

RESULTS

TSR is a new and strong independent prognostic factor for GC patients. The likelihood of tumor invasion is increased significantly for patients in the stromal-high subgroup compared to those in the stromal-low subgroup (P = 0.011). The discrimination ability of TSR was not less than the TNM staging system and was better in patients with stages I and II GC. We integrated the TSR parameter into the TNM staging system and proposed a new TSNM staging system creatively. There were three new subgroups (IC, IIC, IIID). There were four major groups and 10 subgroups in the TSNM system. The difference in overall survival (OS) was statistically significant among all TSNM system (P < 0.005 for all). Deep analyses revealed well predictive performance of the TSNM (P < 0.001).

CONCLUSIONS

This study confirms the TSR as a TME prognostic factor for GC. TSR is a candidate TME parameter that could easily be implemented in routine pathology diagnostics, and the TSNM staging system has been established to optimize risk stratification for GC. The value of the TSNM staging system should be validated in further prospective study.

Targeting hypoxic response for cancer therapy

Hypoxic tumor microenvironment (HTM) is considered to promote metabolic changes, oncogene activation and epithelial mesenchymal transition, and resistance to chemo- and radio-therapy, all of which are hallmarks of aggressive tumor behavior. Cancer cells within the HTM acquire phenotypic properties that allow them to overcome the lack of energy and nutrients supply within this niche. These phenotypic properties include activation of genes regulating glycolysis, glucose transport, acidosis regulators, angiogenesis, all of which are orchestrated through the activation of the transcription factor, HIF1A, which is an independent marker of poor prognosis. Moreover, during the adaptation to a HTM cancer cells undergo deep changes in mitochondrial functions such as “Warburg effect” and the “reverse Warburg effect”.

This review aims to provide an overview of the characteristics of the HTM, with particular focus on novel therapeutic strategies currently in clinical trials, targeting the adaptive response to hypoxia of cancer cells.

The feasibility of 18F-AlF-NOTA-PRGD2 PET/CT for monitoring early response of Endostar antiangiogenic therapy in human nasopharyngeal carcinoma xenograft model compared with 18F-FDG

Purpose

Radiolabeled arginine-glycine-aspartic acid (RGD) peptides have been developed for PET imaging of integrin avβ3 in the tumor vasculature, leading to great potential for noninvasively evaluating tumor angiogenesis and monitoring antiangiogenic treatment. The aim of this study was to investigate a novel one-step labeled integrin-targeted tracer, ¹⁸F-AlF-NOTA-PRGD2, for PET/CT for detecting tumor angiogenesis and monitoring the early therapeutic efficacy of antiangiogenic agent Endostar in human nasopharyngeal carcinoma (NPC) xenograft model.

Experimental design and results

Mice bearing NPC underwent ¹⁸F-AlF-NOTA-PRGD2 PET/CT at baseline and after 2, 4, 7, and 14 days of consecutive treatment with Endostar or PBS, compared with ¹⁸F-FDG PET/CT. Tumors were harvested at all imaging time points for histopathological analysis with H & E and microvessel density (MVD) and integrin avβ3 immunostaining. The maximum percent injected dose per gram of body weight (%ID/gmax) tumor uptake of ¹⁸F-AlF-NOTA-PRGD2 PET/CT was significantly lower than that in the control group starting from day 2 (p < 0.01), much earlier and more accurately than that of ¹⁸F-FDG PET/CT. Moreover, a moderate linear correlation was observed between tumor MVD and the corresponding tumor uptake of ¹⁸F-AlF-NOTA-PRGD2 PET/CT (r = 0.853, p < 0.01).

Conclusions

¹⁸F-AlF-NOTA-PRGD2 PET/CT can be used for in vivo angiogenesis imaging and monitoring early response to Endostar antiangiogenic treatment in NPC xenograft model, favoring its potential clinical translation.

Cancer chemoprevention revisited: Cytochrome P450 family 1B1 as a target in the tumor and the microenvironment

Cancer chemoprevention is the use of synthetic, natural or biological agents to prevent or delay the development or progression of malignancies. Intriguingly, many phytochemicals with anti-inflammatory and anti-angiogenic effects, recently proposed as chemoprevention strategies, are inhibitors of Cytochrome P450 family 1B1 (CYP1B1), an enzyme overexpressed in a wide variety of tumors and associated with angiogenesis. In turn, pro-inflammatory cytokines were reported to boost CYP1B1 expression, suggesting a key role of CYP1B1 in a positive loop of inflammatory angiogenesis. Other well-known pro-tumorigenic activities of CYP1B1 rely on metabolic bioactivation of xenobiotics and steroid hormones into their carcinogenic derivatives. In contrast to initial in vitro observations, in vivo studies demonstrated a protecting role against cancer for the other CYP1 family members (CYP1A1 and CYP1A2), suggesting that the specificity of CYP1 family inhibitors should be carefully taken into account for developing potential chemoprevention strategies. Recent studies also proposed a role of CYP1B1 in multiple cell types found within the tumor microenvironment, including fibroblasts, endothelial and immune cells. Overall, our review of the current literature suggests a positive loop between inflammatory cytokines and CYP1B1, which in turn may play a key role in cancer angiogenesis, acting on both cancer cells and the tumor microenvironment. Strategies aiming at specific CYP1B1 inhibition in multiple cell types may translate into clinical chemoprevention and angioprevention approaches.

Collateral Damage Intended-Cancer-Associated Fibroblasts and Vasculature Are Potential Targets in Cancer Therapy

After oncogenic transformation, tumor cells rewire their metabolism to obtain sufficient energy and biochemical building blocks for cell proliferation, even under hypoxic conditions. Glucose and glutamine become their major limiting nutritional demands. Instead of being autonomous, tumor cells change their immediate environment not only by their metabolites but also by mediators, such as juxtacrine cell contacts, chemokines and other cytokines. Thus, the tumor cells shape their microenvironment as well as induce resident cells, such as fibroblasts and endothelial cells (ECs), to support them. Fibroblasts differentiate into cancer-associated fibroblasts (CAFs), which produce a qualitatively and quantitatively different extracellular matrix (ECM). By their contractile power, they exert tensile forces onto this ECM, leading to increased intratumoral pressure. Moreover, along with enhanced cross-linkage of the ECM components, CAFs thus stiffen the ECM. Attracted by tumor cell- and CAF-secreted vascular endothelial growth factor (VEGF), ECs sprout from pre-existing blood vessels during tumor-induced angiogenesis. Tumor vessels are distinct from EC-lined vessels, because tumor cells integrate into the endothelium or even mimic and replace it in vasculogenic mimicry (VM) vessels. Not only the VM vessels but also the characteristically malformed EC-lined tumor vessels are typical for tumor tissue and may represent promising targets in cancer therapy.