"Vessels in the Storm": Searching for Prognostic and Predictive Angiogenic Factors in Colorectal Cancer

NF-κB pathway and angiogenesis: insights into colorectal cancer development and therapeutic targets

Colorectal cancer (CRC) is currently ranked as the third most common type of cancer, contributing significantly to mortality and morbidity worldwide. Epigenetic and genetic changes occurred during CRC progression resulted in the cell proliferation, cancer progression, angiogenesis, and invasion. Angiogenesis is one of the crucial steps during cancer progression required for the delivery of essential nutrients to cancer cells and removes metabolic waste. During angiogenesis, different molecules are secreted from tumoral cells to trigger vascular formation including epidermal growth factor and the vascular endothelial growth factor (VEGF). The production and regulation of the secretion of these molecules are modulated by different subcellular pathways such as NF-κB. NF-κB is involved in regulation of different homeostatic pathways including apoptosis, cell proliferation, inflammation, differentiation, tumor migration, and angiogenesis. Investigation of different aspects of this pathway and its role in angiogenesis could provide a comprehensive overview about the underlying mechanisms and could be used for development of further therapeutic targets. In this review of literature, we comprehensively reviewed the current understanding and potential of NF-κB-related angiogenesis in CRC. Moreover, we explored the treatments that are based on the NF-κB pathway.

Elucidating the role of angiogenesis-related genes in colorectal cancer: a multi-omics analysis

Background

Angiogenesis plays a pivotal role in colorectal cancer (CRC), yet its underlying mechanisms demand further exploration. This study aimed to elucidate the significance of angiogenesis-related genes (ARGs) in CRC through comprehensive multi-omics analysis.

Methods

CRC patients were categorized according to ARGs expression to form angiogenesis-related clusters (ARCs). We investigated the correlation between ARCs and patient survival, clinical features, consensus molecular subtypes (CMS), cancer stem cell (CSC) index, tumor microenvironment (TME), gene mutations, and response to immunotherapy. Utilizing three machine learning algorithms (LASSO, Xgboost, and Decision Tree), we screen key ARGs associated with ARCs, further validated in independent cohorts. A prognostic signature based on key ARGs was developed and analyzed at the scRNA-seq level. Validation of gene expression in external cohorts, clinical tissues, and blood samples was conducted via RT-PCR assay.

Results

Two distinct ARC subtypes were identified and were significantly associated with patient survival, clinical features, CMS, CSC index, and TME, but not with gene mutations. Four genes (S100A4, COL3A1, TIMP1, and APP) were identified as key ARCs, capable of distinguishing ARC subtypes. The prognostic signature based on these genes effectively stratified patients into high- or low-risk categories. scRNA-seq analysis showed that these genes were predominantly expressed in immune cells rather than in cancer cells. Validation in two external cohorts and through clinical samples confirmed significant expression differences between CRC and controls.

Conclusion

This study identified two ARG subtypes in CRC and highlighted four key genes associated with these subtypes, offering new insights into personalized CRC treatment strategies.

Prognostic value of the tumor-to-liver density ratio in patients with metastatic colorectal cancer treated with bevacizumab-based chemotherapy. A post-hoc study of the STIC-AVASTIN trial

BACKGROUND

The Response Evaluation Criteria in Solid Tumors (RECIST) are often inadequate for the early assessment of the response to cancer therapy, particularly bevacizumab-based chemotherapy. In a first cohort of patients with colorectal cancer liver metastases (CRLM), we showed that variations of the tumor-to-liver density (TTLD) ratio and modified size-based criteria determined using computed tomography (CT) data at the first restaging were better prognostic criteria than the RECIST. The aims of this study were to confirm the relevance of these radiological biomarkers as early predictors of the long-term clinical outcome and to assess their correlation with contrast-enhanced ultrasound (CEUS) parameters in a new patient cohort.

METHODS

In this post-hoc study of the multicenter STIC-AVASTIN trial, we retrospectively reviewed CT data of patients with CRLM treated with bevacizumab-based regimens. We determined the size, density and TTLD ratio of target liver lesions at baseline and at the first restaging and also performed a morphologic evaluation according to the MD Anderson criteria. We assessed the correlation of these parameters with progression-free survival (PFS) and overall survival (OS) using the log-rank test and a Cox proportional hazard model. We also examined the association between TTLD ratio and quantitative CEUS parameters.

RESULTS

This analysis concerned 79 of the 137 patients included in the STIC-AVASTIN trial. PFS and OS were significantly longer in patients with tumor size reduction > 15% at first restaging, but were not correlated with TTLD ratio variations. However, PFS was longer in patients with TTLD ratio > 0.6 at baseline and first restaging than in those who did not reach this threshold. In the multivariate analysis, only baseline TTLD ratio > 0.6 was a significant survival predictor. TTLD ratio > 0.6 was associated with improved perfusion parameters.

CONCLUSIONS

Although TTLD ratio variations did not correlate with the long-term clinical outcomes, TTLD absolute values remained a good predictor of survival at baseline and first restaging, and may reflect tumor microvascular features that might influence bevacizumab-based treatment efficiency.

TRIAL REGISTRATION

NCT00489697, registration number of the STIC-AVASTIN trial.

Differential expression of angiogenesis-related genes 'VEGF' and 'angiopoietin-1' in metastatic and EMAST-positive colorectal cancer patients

Abnormal angiogenesis leads to tumor progression and metastasis in colorectal cancer (CRC). This study aimed to elucidate the association between angiogenesis-related genes, including VEGF-A, ANGPT-1, and ANGPT-2 with both metastatic and microsatellite alterations at selected tetranucleotide repeats (EMAST) subtypes of CRC. We conducted a thorough assessment of the ANGPT-1, ANGPT-2, and VEGF-A gene expression utilizing publicly available RNA sequencing and microarray datasets. Then, the experimental validation was performed in 122 CRC patients, considering their disease metastasis and EMAST+/- profile by using reverse transcription polymerase chain reaction (RT-PCR). Subsequently, a competing endogenous RNA (ceRNA) network associated with these angiogenesis-related genes was constructed and analyzed. The expression level of VEGF-A and ANGPT-2 genes were significantly higher in tumor tissues as compared with normal adjacent tissues (P-value < 0.001). Nevertheless, ANGPT-1 had a significantly lower expression in tumor samples than in normal colon tissue (P-value < 0.01). We identified a significantly increased VEGF-A (P-value = 0.002) and decreased ANGPT-1 (P-value = 0.04) expression in EMAST+ colorectal tumors. Regarding metastasis, a significantly increased VEGF-A and ANGPT-2 expression (P-value = 0.001) and decreased ANGPT-1 expression (P-value < 0.05) were established in metastatic CRC patients. Remarkably, co-expression analysis also showed a strong correlation between ANGPT-2 and VEGF-A gene expressions. The ceRNA network was constructed by ANGPT-1, ANGPT-2, VEGF-A, and experimentally validated miRNAs (hsa-miR-190a-3p, hsa-miR-374c-5p, hsa-miR-452-5p, and hsa-miR-889-3p), lncRNAs (AFAP1-AS1, KCNQ1OT1 and MALAT1), and TFs (Sp1, E2F1, and STAT3). Network analysis revealed that colorectal cancer is amongst the 82 significant pathways. We demonstrated a significant differential expression of VEGF-A and ANGPT-1 in colorectal cancer patients exhibiting the EMAST+ phenotype. This finding provides novel insights into the molecular pathogenesis of colorectal cancer, specifically in EMAST subtypes. Yet, the generalization of in silico findings to EMAST+ colorectal cancer warrants future experimental investigations. In the end, this study proposes that the EMAST biomarker could serve as an additional perspective on CMS4 biology which is well-defined by activated angiogenesis and worse overall survival.

Anti-angiogenesis in colorectal cancer therapy

The morbidity of colorectal cancer (CRC) has risen to third place among malignant tumors worldwide. In addition, CRC is a common cancer in China whose incidence increases annually. Angiogenesis plays an important role in the development of tumors because it can bring the nutrients that cancer cells need and take away metabolic waste. Various mechanisms are involved in the formation of neovascularization, and vascular endothelial growth factor is a key mediator. Meanwhile, angiogenesis inhibitors and drug resistance (DR) are challenges to consider when formulating treatment strategies for patients with different conditions. Thus, this review will discuss the molecules, signaling pathways, microenvironment, treatment, and DR of angiogenesis in CRC.

Current Status of Angiogenesis Inhibitors as Second-Line Treatment for Unresectable Colorectal Cancer

Colorectal cancer is the third most common disease and the second most common cause of death around the world. The drug for second-line treatment depends on the drugs used in first-line treatment and the biomarker status. As biomarkers, the RAS gene, BRAF gene, and dMMR/MSI-H, TMB-H, and HER2 statuses have been established in clinical practice, and the corresponding molecularly targeted therapeutic agents are selected based on the biomarker status. Given the frequency of biomarkers, it is assumed that when patients move on to second-line treatment, an angiogenesis inhibitor is selected in many cases. For second-line treatment, three angiogenesis inhibitors, bevacizumab (BEV), ramucirumab (RAM), and aflibercept (AFL), are available, and one of them is combined with cytotoxic agents. These three angiogenesis inhibitors are known to inhibit angiogenesis through different mechanisms of action. Although no useful biomarkers have been established for the selection of angiogenesis inhibitors, previous biomarker studies have suggested that angiogenesis-related factors such as VEGF-A and VEGF-D might be predictors of the therapeutic efficacy of angiogenesis inhibitors. These biomarkers are measured as protein levels in plasma and are considered to be promising biomarkers. We consider that the rationale for selecting among these three angiogenesis inhibitors should be clarified to benefit patients.

Xerna™ TME Panel is a machine learning-based transcriptomic biomarker designed to predict therapeutic response in multiple cancers

Introduction

Most predictive biomarkers approved for clinical use measure single analytes such as genetic alteration or protein overexpression. We developed and validated a novel biomarker with the aim of achieving broad clinical utility. The Xerna™ TME Panel is a pan-tumor, RNA expression-based classifier, designed to predict response to multiple tumor microenvironment (TME)-targeted therapies, including immunotherapies and anti-angiogenic agents.

Methods

The Panel algorithm is an artificial neural network (ANN) trained with an input signature of 124 genes that was optimized across various solid tumors. From the 298-patient training data, the model learned to discriminate four TME subtypes: Angiogenic (A), Immune Active (IA), Immune Desert (ID), and Immune Suppressed (IS). The final classifier was evaluated in four independent clinical cohorts to test whether TME subtype could predict response to anti-angiogenic agents and immunotherapies across gastric, ovarian, and melanoma datasets.

Results

The TME subtypes represent stromal phenotypes defined by angiogenesis and immune biological axes. The model yields clear boundaries between biomarker-positive and -negative and showed 1.6-to-7-fold enrichment of clinical benefit for multiple therapeutic hypotheses. The Panel performed better across all criteria compared to a null model for gastric and ovarian anti-angiogenic datasets. It also outperformed PD-L1 combined positive score (>1) in accuracy, specificity, and positive predictive value (PPV), and microsatellite-instability high (MSI-H) in sensitivity and negative predictive value (NPV) for the gastric immunotherapy cohort.

Discussion

The TME Panel's strong performance on diverse datasets suggests it may be amenable for use as a clinical diagnostic for varied cancer types and therapeutic modalities.

A Fc-VEGF chimeric fusion enhances PD-L1 immunotherapy via inducing immune reprogramming and infiltration in the immunosuppressive tumor microenvironment

BACKGROUND

Immunotherapy is an emerging cancer therapy with potential great success; however, immune checkpoint inhibitor (e.g., anti-PD-1) has response rates of only 10-30% in solid tumor because of the immunosuppressive tumor microenvironment (TME). This affliction can be solved by vascular normalization and TME reprogramming.

METHODS

By using the single-cell RNA sequencing (scRNAseq) approach, we tried to find out the reprogramming mechanism that the Fc-VEGF chimeric antibody drug (Fc-VFD) enhances immune cell infiltration in the TME.

RESULTS

In this work, we showed that Fc-VEGF121-VEGF165 (Fc-VEGF chimeric antibody drug, Fc-VFD) arrests excess angiogenesis and tumor growth through vascular normalization using in vitro and in vivo studies. The results confirmed that the treatment of Fc-VFD increases immune cell infiltration including cytotoxic T, NK, and M1-macrophages cells. Indeed, Fc-VFD inhibits Lon-induced M2 macrophages polarization that induces angiogenesis. Furthermore, Fc-VFD inhibits the secretion of VEGF-A, IL-6, TGF-β, or IL-10 from endothelial, cancer cells, and M2 macrophage, which reprograms immunosuppressive TME. Importantly, Fc-VFD enhances the synergistic effect on the combination immunotherapy with anti-PD-L1 in vivo.

CONCLUSIONS

In short, Fc-VFD fusion normalizes intratumor vasculature to reprogram the immunosuppressive TME and enhance cancer immunotherapy.

Endothelial cells-directed angiogenesis in colorectal cancer: Interleukin as the mediator and pharmacological target

Enhanced angiogenesis is a cancer hallmark and critical for colorectal cancer (CRC) invasion and metastasis. Upon exposure to proangiogenic factors, therefore, targeting tumor-associated proangiogenic factors/receptors hold great promise as a therapeutic modality to treat CRC, particularly metastatic CRC. Accumulating evidence from numerous studies suggests that tumor endothelial cells (ECs) are not only the target of proangiogenic factors, but also function as the cellular source of proangiogenic factors. Studies showed that ECs can produce different proangiogenic factors to participate in the regulation of angiogenesis process, in which ECs-derived interleukins (ILs) show a potential stimulatory effect on angiogenesis via either an direct action on their receptors expressed on progenitor of ECs or an indirect way through enhanced production of other proangiogenic factors. Although a great deal of attention is given to the effects of tumor-derived and immune cell-derived ILs, few studies describe the potential effects of vascular ECs-derived ILs on the tumor angiogenesis process. This review provides an updated summary of available information on proangiogenic ILs, such as IL-1, IL-6, IL-8, IL-17, IL-22, IL-33, IL-34, and IL-37, released by microvascular ECs as potential drivers of the tumor angiogenesis process and discusses their potential as a novel candidate for antiangiogenic target for the treatment of CRC patients.

A novel form of docetaxel polymeric micelles demonstrates anti-tumor and ascites-inhibitory activities in animal models as monotherapy or in combination with anti-angiogenic agents

Malignant ascites (MA) is caused by intraperitoneal spread of solid tumor cells and results in a poor quality of life. Chemotherapy is a common first-line treatment for patients with MA. Taxotere ^® (DTX) is widely used in solid tumor therapies. However, the low water solubility and side effects caused by additives in the formulation restrict the clinical application of docetaxel. HT001 is a clinical stage docetaxel micelle developed to overcome the solubility issue with improved safety profiles. To support clinical development and expand clinical application of HT001, this study used in vitro and in vivo approaches to investigate the anti-tumor effects of HT001 when applied as monotherapy or in combination with anti-angiogenic agents. HT001 demonstrated comparable anti-proliferative activities as docetaxel in a broad range of cancer cell lines in vitro. Furthermore, HT001 suppressed tumor growth in a dose-dependent manner in A549, MCF-7, and SKOV-3 xenograft tumor mouse models in vivo. In a hepatocellular carcinoma H22 malignant ascites-bearing mouse model, HT001 presented a dose-dependent inhibition of ascites production, prolonged animal survival, and reduced VEGF levels. When dosed at 20 mg/kg, the HT001-treated group exhibited curative results, with no ascites formation in 80% of mice at the end of the study while all the mice in the vehicle control group succumbed. Similar results were obtained in HT001 treatment of mice bearing malignant ascites produced by human ovarian cancer ES-2 cells. Notably, the combination of HT001 with Endostar not only significantly reduced ascites production but also prolonged survival of H22 ascites-bearing mice. HT001 showed similar PK and tissue distribution profiles as DTX in non-rodent hosts. Collectively, these results demonstrate potent anti-tumor activity of HT001 in multiple solid tumor models or malignant ascites models, and reveal synergistic effects with anti-angiogenic agents, supporting the clinical development and clinical expansion plans for HT001.

Influence of KDR Genetic Variation on the Effectiveness and Safety of Bevacizumab in the First-Line Treatment for Patients with Advanced Colorectal Cancer

Objective

Bevacizumab is usually considered a first-line anti-tumor therapy, which inhibits tumor growth by downregulating the vascular endothelial growth factor (VEGF) that further silences the activity of the kinase insert region receptor (KDR) gene. In the current study, we investigated the treatment response of bevacizumab in advanced colorectal cancer (CRC) patients bearing 889 C>T mutation in the KDR gene.

Methods

A total of 135 advanced CRC patients were treated with bevacizumab along with chemotherapy at the seventh medical center of the People’s Liberation Army general hospital from January 2012 to June 2021 and were analyzed retrospectively. The KDR genotyping and mRNA expression analyses were performed in 57 patients.

Results

The KDR genotyping revealed 97 (71.85%) cases with CC genotype, 34 (25.19%) cases with CT, and 4 (2.96%) cases with TT genotype, while the minor allele frequency of 889 C>T was found as 0.16. The median progression-free survival (PFS) of the patients with CT/TT genotype and CC genotype was found to be 6.1 and 9.7 months, respectively (P = 0.009). The median overall survival (OS) of the two genotypes was 13.7 and 19.7 (P = 0.025), respectively. Multivariable Cox regression analysis of PFS, CT/TT genotype was found to be an independent factor for PFS (odds ratio (OR) = 1.88, P = 0.023). Additionally, the mRNA expression of KDR in 57 biopsies taken from patients with CT/TT genotypes was significantly higher than that of patients with CC genotype (P < 0.001). Additionally, in terms of safety, 55 patients experienced grade 2 or higher fatigue (incidence rate 40.74%) after receiving bevacizumab along with chemotherapy.

Conclusion

The 889 C>T mutation in KDR gene affects the KDR expression in colorectal cancer patients, thereby affecting the effectiveness of bevacizumab therapy.

Hypoxia-Mimetic CoCl2 Agent Enhances Pro-Angiogenic Activities in Ovine Amniotic Epithelial Cells-Derived Conditioned Medium

Amniotic epithelial stem cells (AECs) are largely studied for their pro-regenerative properties. However, it remains undetermined if low oxygen (O₂) levels that AECs experience in vivo can be of value in maintaining their biological properties after isolation. To this aim, the present study has been designed to evaluate the effects of a hypoxia-mimetic agent, cobalt chloride (CoCl₂), on AECs’ stemness and angiogenic activities. First, a CoCl₂ dose-effect was performed to select the concentration able to induce hypoxia, through HIF-1α stabilization, without promoting any cytotoxicity effect assessed through the analysis of cell vitality, proliferation, and apoptotic-related events. Then, the identified CoCl₂ dose was evaluated on the expression and angiogenic properties of AECs’ stemness markers (OCT-4, NANOG, SOX-2) by analysing VEGF expression, angiogenic chemokines’ profiles, and AEC-derived conditioned media activity through an in vitro angiogenic xeno-assay. Results demonstrated that AECs are sensitive to the cytotoxicity effects of CoCl₂. The unique concentration leading to HIF-1α stabilization and nuclear translocation was 10 µM, preserving cell viability and proliferation up to 48 h. CoCl₂ exposure did not modulate stemness markers in AECs while progressively decreasing VEGF expression. On the contrary, CoCl₂ treatment promoted a significant short-term release of angiogenic chemokines in culture media (CM). The enrichment in bio-active factors was confirmed by the ability of CoCl₂-derived CM to induce HUVEC growth and the cells’ organization in tubule-like structures. These findings demonstrate that an appropriate dose of CoCl₂ can be adopted as a hypoxia-mimetic agent in AECs. The short-term, chemical-induced hypoxic condition can be targeted to enhance AECs’ pro-angiogenic properties by providing a novel approach for stem cell-free therapy protocols.

Issues of origin, morphology and clinical significance of tumor microvessels in gastric cancer

Gastric cancer (GC) remains a serious oncological problem, ranking third in the structure of mortality from malignant neoplasms. Improving treatment outcomes for this pathology largely depends on understanding the pathogenesis and biological characteristics of GC, including the identification and characterization of diagnostic, prognostic, predictive, and therapeutic biomarkers. It is known that the main cause of death from malignant neoplasms and GC, in particular, is tumor metastasis. Given that angiogenesis is a critical process for tumor growth and metastasis, it is now considered an important marker of disease prognosis and sensitivity to anticancer therapy. In the presented review, modern concepts of the mechanisms of tumor vessel formation and the peculiarities of their morphology are considered; data on numerous factors influencing the formation of tumor microvessels and their role in GC progression are summarized; and various approaches to the classification of tumor vessels, as well as the methods for assessing angiogenesis activity in a tumor, are highlighted. Here, results from studies on the prognostic and predictive significance of tumor microvessels in GC are also discussed, and a new classification of tumor microvessels in GC, based on their morphology and clinical significance, is proposed for consideration.

Circulating PTGS2, JAG1, GUCY2C and PGF mRNA in Peripheral Blood and Serum as Potential Biomarkers for Patients with Metastatic Colon Cancer

Genes involved in the angiogenic process have been proposed for the diagnosis and therapeutic response of metastatic colorectal cancer (CRC). This study aimed to investigate the value of PTGS2, JAG1, GUCY2C and PGF-circulating RNA as biomarkers in metastatic CRC. Blood cells and serum mRNA from 59 patients with metastatic CRC and 47 healthy controls were analyzed by digital PCR. The area under the receiver operating characteristic curve (AUC) was used to estimate the diagnostic value of each mRNA alone or mRNA combinations. A significant upregulation of the JAG1, PTGS2 and GUCY2C genes in blood cells and serum samples from metastatic CRC patients was detected. Circulating mRNA levels in the serum of all genes were significantly more abundant than in blood. The highest discrimination ability between metastatic CRC patients and healthy donors was obtained with PTGS2 (AUC of 0.984) and GUCY2C (AUC of 0.896) in serum samples. Biomarker combinations did not improve the discriminatory capacity of biomarkers separately. Analyzed biomarkers showed no correlation with overall survival or progression-free survival, but GUCY2C and GUCY2C/PTGS2 expression in serum correlated significantly with the response to antiangiogenic agents. These findings demonstrate that assessment of genes involved in the angiogenic process may be a potential non-invasive diagnostic tool for metastatic CRC and its response to antiangiogenic therapy.

Aflibercept or bevacizumab in combination with FOLFIRI as second-line treatment of mRAS metastatic colorectal cancer patients: the ARBITRATION study protocol

Background:

The intensive study of predictive factors has strongly ameliorated the therapeutic flow-chart of metastatic colorectal cancer (mCRC) by allowing the selection of patients who benefit from specific therapies. For instance, in mRAS (mutated RAS) mCRC patients, anti-EGFR drugs (cetuximab and panitumumab) are not recommended; in this group of patients, the use of anti-angiogenic drugs (bevacizumab and aflibercept) is predominant. However, at progression to standard bevacizumab-based first-line chemotherapy, still to date, there are no studies to guide oncologists in the choice of the best second-line anti-angiogenic drug (bevacizumab beyond progression versus aflibercept).

Methods:

ARBITRATION is a prospective, observational study assessing efficacy differences between second-line fluorouracil/irinotecan (FOLFIRI)/bevacizumab versus FOLFIRI/aflibercept at progression to fluoropyrimidines, oxaliplatin and bevacizumab in mRAS mCRC patients. A test power of 80%, a median survival of 9 months from second-line treatment start and a hazard ratio of 0.67 between the two schedules were the basis for statistical design. The final sample will be 220 patients (110 per treatment). The significance will be verified with a two-tailed log-rank test with an alpha value of the I-type error of 5%. Time-to-outcome will be described by Kaplan–Meier curves and prognostic factors studied through multivariable analyses based on the Cox model. Secondary objectives include safety, responses’ duration and progression-free survival. A translational research will be conducted to measure several angiogenic proteins in patients’ serum before starting the therapy in order to evidence any angiogenic factor patterns related to outcome.

Discussion:

We present a large, prospective, observational study aiming to answer two scientific questions: (1) outcome differences between second-line treatments with FOLFIRI/bevacizumab beyond progression versus FOLFIRI/aflibercept in mRAS mCRC patients, (2) angiogenic factors’ patterns that could associate with efficacy and help oncologists to apply best the therapeutic anti-angiogenic strategies.

Trial registration:

The ARBITRATION trial (version 0.0, 13 April 2020) has been registered into the clinicaltrials.gov registry on 20 May 2020 with identifier NCT04397601.

Tumor Microenvironment in Metastatic Colorectal Cancer: The Arbitrator in Patients' Outcome

Simple Summary

Colorectal cancer accounts for approximately 10% of all annually diagnosed cancers worldwide being liver metastasis, the most common cause of death in patients with colorectal cancer. The interplay between tumor and stromal cells in the primary tumor microenvironment and at distant metastases are rising in importance as potential mechanisms of the tumor progression. In this review we discuss the new biomarkers derived from tumor microenvironment and liquid biopsy as emerging prognostic and treatments response markers for metastatic colorectal cancer. We also review the developing new clinical strategies based on tumor microenvironmental cells to tackle metastatic disease in metastatic colorectal cancer patients.

Abstract

Colorectal cancer (CRC) is one of the most common cancers in western countries. Its mortality rate varies greatly, depending on the stage of the disease. The main cause of CRC mortality is metastasis, which most commonly affects the liver. The role of tumor microenvironment in tumor initiation, progression and metastasis development has been widely studied. In this review we summarize the role of the tumor microenvironment in the liver pre-metastatic niche formation, paying attention to the distant cellular crosstalk mediated by exosomes. Moreover, and based on the prognostic and predictive capacity of alterations in the stromal compartment of tumors, we describe the role of tumor microenvironment cells and related liquid biopsy biomarkers in the delivery of precise medication for metastatic CRC. Finally, we evaluate the different clinical strategies to prevent and treat liver metastatic disease, based on the targeting of the tumor microenvironment. Specifically, targeting angiogenesis pathways and regulating immune response are two important research pipelines that are being widely developed and promise great benefits.

Updates on the molecular mechanisms of aspirin in the prevention of colorectal cancer: Review

Colorectal cancer is one of the commonest malignancies worldwide. The estimated lifetime risk of the disease is about 5% with an incidence of one million new cases and 600,000 deaths worldwide every year. It is estimated that in 2019, approximately 134,490 new cases of colorectal cancer will be diagnosed with 49,190 mortalities. Though the disease is regarded as a disorder of the more developed world, the occurrence is steadily increasing in many developing countries. Since chronic inflammation is a known aggravating risk factor for colorectal cancer, anti-inflammatory agents such as aspirin have been used to prevent the development of colorectal cancer and related mortality. The potential mechanisms for the effect of aspirin in the prevention of colorectal cancer have been proposed and broadly classified as cyclooxygenase (COX) dependent and COX-independent. Some of the primary effectors of COX-dependent mechanisms in carcinogenesis are likely to be prostaglandins. In contrast to the reversible action of other nonsteroidal anti-inflammatory drugs, aspirin is known to irreversibly inactivate COX enzymes to suppress production of prostaglandins. COX-independent mechanisms of anticancer effects of aspirin include down-regulation of nuclear factor kappa B activity and Akt activation, modulation of Bcl-2 and Bax family proteins, suppression of vascular endothelial growth factor, induction of apoptosis, disruption of DNA repair mechanisms, and induction of spermidine/spermine N¹-acetyltransferase that modulates polyamine catabolism.

TRF2 and VEGF-A: an unknown relationship with prognostic impact on survival of colorectal cancer patients

BACKGROUND

Colorectal cancer is one of most common tumors in developed countries and, despite improvements in treatment and diagnosis, mortality rate of patients remains high, evidencing the urgent need of novel biomarkers to properly identify colorectal cancer high-risk patients that would benefit of specific treatments. Recent works have demonstrated that the telomeric protein TRF2 is over-expressed in colorectal cancer and it promotes tumor formation and progression through extra-telomeric functions. Moreover, we and other groups evidenced, both in vitro on established cell lines and in vivo on tumor bearing mice, that TRF2 regulates the vascularization mediated by VEGF-A. In the present paper, our data evidence a tight correlation between TRF2 and VEGF-A with prognostic relevance in colorectal cancer patients.

METHODS

For this study we sampled 185 colorectal cancer patients surgically treated and diagnosed at the Regina Elena National Cancer Institute of Rome and investigated the association between the survival outcome and the levels of VEGF-A and TRF2.

RESULTS

Tissue microarray immunohistochemical analyses revealed that TRF2 positively correlates with VEGF-A expression in our cohort of patients. Moreover, analysis of patients' survival, confirmed in a larger dataset of patients from TCGA, demonstrated that co-expression of TRF2 and VEGF-A correlate with a poor clinical outcome in stage I-III colorectal cancer patients, regardless the mutational state of driver oncogenes.

CONCLUSIONS

Our results permitted to identify the positive correlation between high levels of TRF2 and VEGF-A as a novel prognostic biomarker for identifying the subset of high-risk colorectal cancer patients that could benefit of specific therapeutic regimens.

Evaluation of Second-line Anti-VEGF after First-line Anti-EGFR Based Therapy in RAS Wild-Type Metastatic Colorectal Cancer: The Multicenter "SLAVE" Study

: Background: The optimal anti-angiogenic strategy as second-line treatment in RAS wild-type metastatic colorectal cancer (mCRC) treated with anti-EGFR (Epidermal Growth Factor Receptor) based first-line treatment is still debated.

METHODS

This multicenter, real-world, retrospective study is aimed at evaluating the effectiveness of second-line Bevacizumab- and Aflibercept-based treatments after an anti-EGFR based first-line regimen. Clinical outcomes measured were: objective response rate (ORR), progression free survival (PFS), overall survival (OS) and adverse events (AEs) profiles.

RESULTS

From February 2011 to October 2019, 277 consecutive mCRC patients received Bevacizumab-based (228, 82.3%) or Aflibercept-based (49, 17.7%) regimen. No significant difference was found regarding ORR. The median follow-up was 27.7 months (95%CI: 24.7-34.4). Aflibercept-treated group had a significantly shorter PFS compared to Bevacizumab-treated group (5.6 vs. 7.1 months, respectively) (HR = 1.34 (95%CI: 0.95-1.89); p = 0.0932). The median OS of the Bevacizumab-treated group and Aflibercept-treated group was 16.2 (95%CI: 15.3-18.1) and 12.7 (95%CI: 8.8-17.5) months, respectively (HR= 1.31 (95%CI: 0.89-1.93) p = 0.16). After adjusting for the key covariates (age, gender, performance status, number of metastatic sites and primary tumor side) Bevacizumab-based regimens revealed to be significantly related with a prolonged PFS (HR = 1.44 (95%CI: 1.02-2.03); p = 0.0399) compared to Aflibercept-based regimens, but not with a prolonged OS (HR = 1.47 (95%CI: 0.99-2.17); p = 0.0503). The incidence of G3/G4 VEGF inhibitors class-specific AEs was 7.5% and 26.5% in the Bevacizumab-treated group and the Aflibercept-treated group, respectively (p = 0.0001).

CONCLUSION

Our analysis seems to reveal that Bevacizumab-based regimens have a slightly better PFS and class-specific AEs profile compared to Aflibercept-based regimen as second-line treatment of RAS wild-type mCRC patients previously treated with anti-EGFR based treatments. These results have to be taken with caution and no conclusive considerations are allowed.

Expression of pro-angiogenic factors as potential biomarkers in experimental models of colon cancer

PURPOSE

RAS mutational status in colorectal cancer (CRC) represents a predictive biomarker of response to anti-EGFR therapy, but to date it cannot be considered an appropriate biomarker of response to anti-VEGF therapy. To elucidate the function of K-Ras in promoting angiogenesis, the effect of conditioned media from KRAS mutated and wild type colon cancer cell lines on HUVECs tubule formation ability and the correspondent production of pro-angiogenic factors have been evaluated by a specific ELISA assay.

METHODS

Ras-activated signaling pathways were compared by western blot analysis and RTq-PCR. In addition, VEGF, IL-8, bFGF and HIF-1α expression was determined in K-RAS silenced cells. Furthermore, we conducted an observational study in a cohort of RAS mutated metastatic CRC patients, treated with first-line bevacizumab-based regimens, evaluating VEGF-A and IL-8 plasma levels at baseline, and during treatment.

RESULTS

K-RAS promotes VEGF production by cancer cell lines. At the transcriptional level, this is reflected to a K-RAS dependent HIF-1α over-expression. Moreover, the HIF-1α, VEGF and FGF expression inhibition in KRAS knocked cells confirmed these results. Within the clinical part, no statistically significant correlation has been found between progression-free survival (PFS) and VEGF-A/IL-8 levels, but we cannot exclude that these biomarkers could be further investigated as predictive or prognostic biomarkers in this setting.

CONCLUSION

Our study confirmed the direct involvement of K-Ras in promoting angiogenesis into colon cancer cell lines.

A nomogram to predict vascular invasion before resection of colorectal cancer

Vascular invasion (VI) is an important feature for systemic recurrence and an indicator for the application of adjuvant therapy in colorectal cancer (CRC). Preoperative knowledge of VI is important in determining whether adjuvant therapy is necessary, as well as the adequacy of surgical resection. In the present study, a predictive nomogram for VI in patients with CRC was constructed. The prediction model consisted of 664 eligible patients with CRC, who were divided into a training set (n=468) and a validation set (n=196). Data were collected between August 2013 and April 2018. The feature selection model was established using the least absolute shrinkage and selection operator regression model. Multivariable logistic regression analysis was used to construct the predictive nomogram. The performance of the nomogram was evaluated by calibration, discrimination and clinical usefulness. Differentiation, computed tomography (CT)-based on N stage (CT N stage), hemameba and tumor distance from the anus (cm) were integrated into the nomogram. The nomogram exhibited good discrimination, with an area under the curve (AUC) of 0.731 and good calibration. Application of the nomogram in the validation cohort showed acceptable discrimination, with an AUC of 0.710 and good calibration. Decision curve analysis revealed that the nomogram was clinically useful. These findings suggests, to the best of our knowledge, that this may be the first nomogram for individual preoperative prediction of VI in patients with CRC, which may promote preoperative optimization strategies for this selected group of patients.

Polymer-based nanoparticles for chemo/gene-therapy: Evaluation its therapeutic efficacy and toxicity against colorectal carcinoma

Combination treatment through simultaneous delivery of anticancer drugs and gene with nano-formulation has been demonstrated to be an elegant and efficient approach for colorectal cancer therapy. Recently, sorafenib being studied in combination therapy in colorectal cancer (CRC) attracted attention of researchers. On the basis of our previous study, pigment epithelium-derived factor (PEDF) loaded nanoparticles showed good effect on CRC in vitro and in vivo. Herein, we designed a combination therapy for sorafenib (Sora), a multi-kinase inhibitor and PEDF, a powerful antiangiogenic gene, in a nano-formulation aimed to increase anti-tumor effect on CRC for the first time. Sora and PEDF were simultaneously encapsulated in PEG-PLGA based nanoparticles by a modified double-emulsion solvent evaporation method. The obtained co-encapsulated nanoparticles (Sora@PEDF-NPs) showed high entrapment efficiency of both Sora and PEDF - and exhibited a uniform spherical morphology. The release profiles of Sora and PEDF were in a sustained manner. The most effective tumor growth inhibition in the C26 cells and C26-bearing mice was observed in the Sora@PEDF-NPs in comparison with none-drug nanoparticles, free Sora, mono-drug nanoparticles (Sora-NPs and PEDF-NPs) and the mixture of Sora-NPs and equivalent PEDF-NPs (Mix-NPs). More importantly, Sora@PEDF-NPs showed lower toxicity than free Sora in mice according to the acute toxicity test. The serologic biochemical analysis and mice body weight during therapeutic period revealed that Sora@PEDF-NPs had no obvious toxicity. All the data demonstrated that the simultaneously loaded nanoparticles with multi-kinase inhibitor and anti-angiogenic gene might be one of the most potential formulations in the treatment of colorectal carcinoma in clinic and worthy of further investigation.

Serum PlGF and EGF are independent prognostic markers in non-metastatic colorectal cancer

The aim of this study was to determine the prognostic value of circulating angiogenic cytokines in non-metastatic colorectal cancer (CRC) patients. Preoperative serum samples of a training (TC) (n = 219) and a validation cohort (VC) (n = 168) were analyzed via ELISA to determine PlGF, EGF, VEGF, Ang1, PDGF-A, PDGF-B, IL-8 and bFGF levels. In addition, survival was correlated with PlGF and EGF expression measured by microarray and RNAseq in two publicly available, independent cohorts (n = 550 and n = 463, respectively). Prognostic values for overall (OS) and disease-free survival (DFS) were determined using uni- and multivariate Cox proportional hazard analyses. Elevated PlGF is predictive for impaired OS (TC: HR 1.056; p = 0.046; VC: HR 1.093; p = 0.001) and DFS (TC: HR 1.052; p = 0.029; VC: HR 1.091; p = 0.009). Conversely, elevated EGF is associated with favorable DFS (TC: HR 0.998; p = 0.045; VC: HR 0.998; p = 0.018) but not OS (TC: p = 0.201; VC: p = 0.453). None of the other angiogenic cytokines correlated with prognosis. The prognostic value of PlGF (OS + DFS) and EGF (DFS) was confirmed in both independent retrospective cohorts. Serum PlGF and EGF may serve as prognostic markers in non-metastatic CRC.

Novel Insights into the Effect of Hyperforin and Photodynamic Therapy with Hypericin on Chosen Angiogenic Factors in Colorectal Micro-Tumors Created on Chorioallantoic Membrane

Photodynamic therapy with hypericin (HY-PDT) and hyperforin (HP) could be treatment modalities for colorectal cancer (CRC), but evidence of their effect on angiogenic factors in CRC is missing. Convenient experimental model utilization is essential for angiogenesis research. Therefore, not only 2D cell models, but also 3D cell models and micro-tumors were used and compared. The micro-tumor extent and interconnection with the chorioallantoic membrane (CAM) was determined by histological analyses. The presence of proliferating cells and HY penetration into the tumor mass were detected by fluorescence microscopy. The metabolic activity status was assessed by an colorimetric assay for assessing cell metabolic activity (MTT assay) and HY accumulation was determined by flow cytometry. Pro-angiogenic factor expression was determined by Western blot and quantitative real-time polymerase chain reaction (RT-qPCR). We confirmed the cytotoxic effect of HY-PDT and HP and showed that their effect is influenced by structural characteristics of the experimental model. We have pioneered a method for analyzing the effect of HP and cellular targeted HY-PDT on pro-angiogenic factor expression in CRC micro-tumors. Despite the inhibitory effect of HY-PDT and HP on CRC, the increased expression of some pro-angiogenic factors was observed. We also showed that CRC experimental micro-tumors created on quail CAM could be utilized for analyses of gene and protein expression.

Targeting angiogenesis for patients with unresectable malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is a global health issue, the principal cause of which is exposure to asbestos. The prevalence is anticipated to rise over the next 2 decades, particularly in developing countries, due to the 30-50-year latency period between exposure to asbestos and carcinogenic development. Unresectable MPM has a poor prognosis and limited treatment options and, as such, there is a broad range of therapeutic targets of interest, including angiogenesis, immune checkpoints, mesothelin, as well as chemotherapeutic agents. Recently, the results of several randomized trials in the first-line setting combining antiangiogenic agents with chemotherapy have been reported. This review examines the scientific rationale for targeting angiogenesis in the treatment of unresectable MPM and analyzes recent clinical results with antiangiogenic agents in development (bevacizumab, nintedanib, and cediranib) for the management of MPM.

Tumor-associated Macrophages and Neuroendocrine Differentiation Decrease the Efficacy of Bevacizumab Plus Chemotherapy in Patients With Advanced Colorectal Cancer

BACKGROUND

In the present study, we investigated the prognostic and predictive role of neuroendocrine differentiation (NED) and tumor-associated macrophage (TAM) infiltration in tumor tissue from patients with advanced colorectal cancer who had received bevacizumab plus chemotherapy.

PATIENTS AND METHODS

A total of 123 consecutive patients with advanced colorectal cancer who had received bevacizumab plus irinotecan/oxaliplatin-based combination chemotherapy were included in the present study. In addition to the clinicopathologic parameters, the presence of NED and the level of TAM infiltration were studied as covariates for survival analysis.

RESULTS

The median patient age was 57 years (range, 30-76 years). The chemotherapy backbone was FOLFIRI (folinic acid, 5-fluorouracil, irinotecan) for 75% of the patients. Univariate analysis showed that only NED and TAM infiltration were significant predictive factors for progression-free survival. Left-sided tumors and low TAM infiltration were favorable factors for overall survival on univariate analysis. However, the TAM level was the only independent prognostic factor for overall survival (hazard ratio, 0.301; 95% confidence interval, 0.102-0.892).

CONCLUSION

Our results suggest that increased TAM infiltration in tumor tissue and NED could decrease the efficacy of bevacizumab plus combination chemotherapy in patients with advanced colorectal cancer. TAM infiltration in the tumor tissue could be used as a biomarker in patients with advanced colorectal cancer receiving bevacizumab plus chemotherapy.

The Prognostic Value of the Combination of Low VEGFR-1 and High VEGFR-2 Expression in Endothelial Cells of Colorectal Cancer

Research on tumor angiogenesis has mainly focused on the vascular endothelial growth factor (VEGF) family and on methods to block its actions. However, reports on VEGF receptor (VEGFR) expression in tumor-associated endothelial cells (ECs) are limited. Thus, we evaluated VEGF, VEGFR-1 and VEGFR-2 expression in ECs of colorectal cancer (CRC) using immunohistochemistry. VEGF, VEGFR-1 and -2 expression in ECs was quantitatively evaluated by digital image analysis in a retrospective series of 204 tumor tissue samples and related to clinical variables. The data show that the VEGF, VEGFR-1 and VEGFR-2 expression in ECs is heterogeneous. Multivariate analysis including a set of clinicopathological variables reveals that high EC VEGFR-1 expression is an independent prognostic factor for overall survival (OS). The combination of low VEGFR-1 and high VEGFR-2 expression in ECs outperforms models integrating VEGFR-1 and VEGFR-2 as separate markers. Indeed, this VEGFR-1_VEGFR-2 combination is an independent negative prognostic factor for OS (p = 0.012) and metastasis-free survival (p = 0.007). In conclusion, this work illustrates the importance of studying the distribution of VEGF members in ECs of CRC. Interestingly, our preliminary data suggest that high VEGFR-1 and low VEGFR-2 expression in ECs appear to be involved in the progression of CRC, suggesting that targeting EC VEGFR-1 could offer novel opportunities for CRC treatment. However, a prospective validation study is needed.