Antiangiogenesis beyond VEGF inhibition: a journey from antiangiogenic single-target to broad-spectrum agents

Recombinant human endostatin as a potential anti-angiogenic agent: therapeutic perspective and current status

Angiogenesis is the physiological process that results in the formation of new blood vessels develop from pre-existing vasculature and plays a significant role in several physiological and pathological processes. Inhibiting angiogenesis, a crucial mechanism in the growth and metastasis of cancer, has been proposed as a potential anticancer therapy. Different studies showed the beneficial effects of angiogenesis inhibitors either in patients suffering from different cancers, alone or in combination with conventional therapies. Even though there are currently a number of efficient anti-angiogenic drugs, including monoclonal antibodies and kinase inhibitors, the associated toxicity profile and their affordability constraints are prompting researchers to search for a safe and affordable angiostatic agent for cancer treatment. Endostatin is one of the endogenous anti-angiogenic candidates that have been extensively pursued for the treatment of cancer, but even over three decades after its discovery, we have not made much advancement in employing it as an anticancer therapeutic despite of its remarkable anti-angiogenic effect with low toxicity profile. A recombinant human endostatin (rh-Es) variant for non-small cell lung cancer was approved by China in 2006 and has since been used effectively. Several other successful clinical trials related to endostatin for various malignancies are either ongoing or have already been completed with promising results. Thus, in this review, we have provided an overview of existing anti-angiogenic drugs developed for cancer therapy, with a summary of tumour angiogenesis in the context of Endostatin, and clinical status of rh-Es in cancer treatment. Furthermore, we briefly discuss the various strategies to improve endostatin features (poor pharmacokinetic properties) for developing rh-Es as a safe and effective agent for cancer treatment.

The mechanism of rh-endostatin-induced cardiotoxicity and its protection by dihydromyricetin[in vivo/in vitro, C57BL/6 mice, AC16 and hiPSC-CMs]

Recombinant human endostatin (rh-endostatin) is an anti-angiogenic drug, which is used for the treatment of advanced non-small-cell lung cancer (NSCLC) and other cancers. However, its side effects, especially the cardiotoxicity with unclear mechanisms limit its wide application in clinical practice. In this study, human cardiomyocyte cell line AC16 and human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) treated with different doses of rh-endostatin were used to analyze its effect on cardiac cell toxicity. The results revealed that rh-endostatin dose-dependently enhanced cardiomyocyte apoptosis through Apaf-1 apoptotic factor and apoptosis-related proteins such as p53. rh-endostatin-induced changes of mitochondrial function and mitophagy were involved in rh-endostatin-mediated cardiac cell toxicity. Rh-endostatin-induced cardiotoxicity was further verified in vivo in mice. Interestingly, Rh-endostatin-induced cardiotoxicity was inhibited by dihydromyricetin (DHM) both in cultured cells in vitro and in mouse hearts in vivo. The study provides new inside into rh-endostatin-induced cardiotoxicity and identified a novel potential medication DHM to overcome the serious adverse effect.

Mitochondrial targeting half-sandwich iridium(III) and ruthenium(II) dppf complexes and in vitro anticancer assay

Considering the potential application of half-sandwich and ferrocenyl-containing organometallic complexes in the area of anticancer, four half-sandwich iridium(III) (Ir^III) and ruthenium(II) (Ru^II) diphenylphosphino ferrocene (dppf) complexes were prepared in this study. Complexes showed favorable anti-proliferation activity towards A549 cell lines compared to cisplatin, meanwhile, which could effectively inhibit cell migration. These complexes followed an energy dependence uptake mechanism, effectively accumulated in mitochondria with a Pearson's Colocalization Coefficient (PCC) of 0.77, decreased the mitochondrial membrane potential, induced a surge of reactive oxygen species, disturbed cell cycle, and eventually led to apoptosis. Western blot assay further confirmed that these complexes induced apoptosis following a mitochondrial pathway. Above all, half-sandwich Ir^III and Ru^II dppf complexes show the prospect of becoming a new multifunctional therapeutic platform for mitochondrial targeted imaging and anticancer drugs.

Type IV collagen-derived angiogenesis inhibitor: canstatin low expressing in brain-invasive meningiomas using liquid chromatography-mass spectrometry (LC-MS/MS)

PURPOSE

Brain invasion in meningiomas is considered an indicator of more aggressive behavior and worse prognosis. But the precise definition and the prognostic role of brain invasion remains unsolved duo to lacking a standardized workflow of surgical sampling and the histopathological detection. Searching for molecular biomarker expression correlating with brain invasion, could contribute to establish a molecular pathological diagnosis without problems of subjective interobserver variation and deeply understand the mechanism of brain invasion and develop innovative therapeutic strategies.

METHODS

We utilized liquid chromatography tandem mass spectrometry to quantify protein abundances between non-invasive meningiomas (n = 21) and brain-invasive meningiomas (n = 21) spanning World Health Organization grades I and III. After proteomic discrepancies were analyzed, the 14 most up-regulated or down-regulated proteins were recorded. Immunohistochemical staining for glial fibrillary acidic protein and most likely brain invasion-related proteins was performed in both groups.

RESULTS

A total of 6498 unique proteins were identified in non-invasive and brain-invasive meningiomas. Canstatin expression in the non-invasive group was 2.1-fold that of the brain-invasive group. The immunohistochemical staining showed canstatin expressed in both groups, and the non-invasive group showed stronger staining for canstatin in the tumor mass (p = 0.0132) than the brain-invasive group, which showed moderate intensity.

CONCLUSION

This study demonstrated the low expression of canstatin in meningiomas with brain invasion, a finding that provide a basis for understanding the mechanism of brain invasion of meningiomas and may contribute to establish molecular pathological diagnosis and identify novel therapeutic targets for personalized care.

Recombinant Human Arresten and Canstatin Inhibit Angiogenic Behaviors of HUVECs via Inhibiting the PI3K/Akt Signaling Pathway

Angiogenetic inhibitors are crucial in tumor therapy, and endogenous angiogenesis inhibitors have attracted considerable attention due to their effectiveness, safety, and multi-targeting ability. Arresten and canstatin, which have anti-angiogenesis effects, are the c-terminal fragments of the α1 and α2 chains of type IV collagen, respectively. In this study, human arresten and canstatin were recombinantly expressed in Escherichia coli (E. coli), and their effects on the proliferation, migration and tube formation of human umbilical vein endothelial cells (HUVECs) were evaluated. Regarding the cell cycle distribution test and 5-ethynyl-2′-deoxyuridine (EdU) assays, arresten and canstatin could repress the proliferation of HUVECs at a range of concentrations. Transwell assay indicated that the migration of HUVECs was significantly decreased in the presence of arresten and canstatin, while tube formation assays suggested that the total tube length and junction number of HUVECs were significantly inhibited by these two proteins; moreover, they could also reduce the expression of vascular endothelial growth factor (VEGF) and the phosphorylation levels of PI3K and Akt, which indicated that the activation of the 3-kinase/serine/threonine-kinase (PI3K/Akt) signaling pathway was inhibited. These findings may have important implications for the soluble recombinant expression of human arresten and canstatin, and for the related therapy of cancer.

Investigation of the optimal platinum-based regimen in the postoperative adjuvant chemotherapy setting for early-stage resected non-small lung cancer: a Bayesian network meta-analysis

OBJECTIVE

This study aimed to compare the efficacy and safety of different platinum adjuvant chemotherapy regimens for early-stage resected non-small-cell lung cancer (NSCLC).

DESIGN

Systematic review with network meta-analysis of randomised trials.

DATA SOURCES

PubMed, EMBASE, The Cochrane Library, Web of Science and Scopus Google Scholar were searched through 12 March 2021.

ELIGIBILITY CRITERIA

Eligible randomised controlled trials (RCTs) comparing the postoperative platinum chemotherapy regimen with the observation-controlled group or comparing two platinum chemotherapy regimens head-to-head were included.

DATA EXTRACTION AND SYNTHESIS

The primary outcome was the efficacy of adjuvant chemotherapy regimens including relapse-free survival (RFS), overall survival (OS), 2-year, 3-year, 5-year RFS rate and OS rate. The secondary outcome was the rate of grade 3-4 toxicity assessments. Cochrane Handbook (V.5) was used for the risk of bias assessment. Analyses were performed using R software V.4.3.1.

RESULTS

20 RCTs with a sample size of 5483 were enrolled in meta-analysis. The chemotherapy group had a significant RFS and OS advantage compared with the observation group (HR 0.67; 95% CI 0.56 to 0.81, p<0.0001; HR 0.80; 95% CI, 0.73 to 0.88, p<0.0001, respectively). Compared with the observation arm, only the 'cisplatin_vinorelbine' regimen had a significant RFS and OS advantage (HR 0.63; 95% CI 0.43 to 0.87; HR 0.74; 95% CI 0.63 to 0.87, respectively) while the remaining chemotherapy regimens had no significant difference of efficacy compared with the observation group. In terms of the safety of adjuvant chemotherapy, the incidence of haematological toxicities and nausea/vomiting was not significantly higher in the 'cisplatin_vinorelbine' arm than in other chemotherapy group.

CONCLUSION

This study summarised the adjuvant cytotoxicity chemotherapy regimens for patients with early-stage resected NSCLC. Our analysis may provide some guiding significance for the clinicians when determining the optimal chemotherapy regimen.

A first-in-human Phase I dose-escalation trial of the novel therapeutic peptide, ALM201, demonstrates a favourable safety profile in unselected patients with ovarian cancer and other advanced solid tumours

Background

We aimed to assess the safety, tolerability and pharmacokinetics of a novel anti-angiogenic peptide.

Methods

We used an open-label, multicentre, dose-escalation Phase I trial design in patients with solid tumours. ALM201 was administered subcutaneously once daily for 5 days every week in unselected patients with solid tumours.

Results

Twenty (8 male, 12 female) patients with various solid tumours were treated (18 evaluable for toxicity) over eight planned dose levels (10–300 mg). ALM201 was well-tolerated at all dose levels without CTCAE grade 4 toxicities. Adverse events were predominantly grades 1–2, most commonly, localised injection-site reactions (44.4%), vomiting (11%), fatigue (16.7%), arthralgia (5.6%) and headache (11%). Thrombosis occurred in two patients at the 100 mg and 10 mg dose levels. The MTD was not reached, and a recommended Phase II dose (RP2D) based on feasibility was declared. Plasma exposure increased with dose (less than dose-proportional at the two highest dose levels). No peptide accumulation was evident. The median treatment duration was 11.1 (range 3–18) weeks. Four of 18 evaluable patients (22%) had stable disease.

Conclusions

Doses up to 300 mg of ALM201 subcutaneously are feasible and well-tolerated. Further investigation of this agent in selected tumour types/settings would benefit from patient-selection biomarkers.

The impacts of government reimbursement negotiation on targeted anticancer medication price, volume and spending in China

INTRODUCTION

New targeted therapies have changed cancer treatment in the past decades. However, high prices of targeted anticancer medications have increased economic burden for both patients and health insurance systems. In July 2017, China implemented combined medication price negotiation and mandatory reimbursement policies for 15 targeted anticancer medications. This study assesses effects of the policy on hospital procurement prices, volumes and spending.

METHODS

Using a quasi-experimental interrupted time series design, we analysed procurement data from the Chinese Medical Economic Information of 789 public hospitals in 30 provinces between January 2016 and September 2018. The intervention group consisted of 15 targeted anticancer medications with negotiated prices in 2017. The comparison group consisted of six targeted anticancer medications without negotiated prices by 2018. The effective date of the policy was September 2017.

RESULTS

After the implementation of the 2017 medication price negotiation and reimbursement policy, cost per defined daily dose (DDD) of the 15 targeted anticancer medications dropped US$71.21 on average from an average US$169.24/DDD before (p=0.000). Compared with what would have happened without the intervention, cost/DDD of price-negotiated medications decreased by 48.9% (p=0.000), procurement volumes increased by 143.0% (p=0.000) and hospital medication spending decreased by 6.9% (p=0.146).

CONCLUSIONS

The 2017 medication price negotiation and reimbursement policy decreased targeted medication procurement costs per DDD, increased volumes procured and at least temporarily contained spending. These changes should result in better access to and affordability of targeted anticancer medications in China.

Discovery of 4,6-Disubstituted Pyrimidine Derivatives as Novel Dual VEGFR2/FGFR1 Inhibitors

Abnormalities in the FGFRs signaling pathway and VEGFR2 amplification often occur in a variety of tumors, and they synergistically promote tumor angiogenesis. Studies have shown that the up-regulation of FGF-2 is closely related to the resistance of VEGFR2 inhibitors. Activation of the FGFRs signal is a signal of compensatory angiogenesis after VEGFR2 resistance. Dual VEGFR2/FGFR1 inhibitors contribute to overcoming the resistance of VEGFR2 inhibitors and inhibit tumor growth significantly. Based on this, we designed and synthesized a series of 4,6-disubstituted pyrimidine derivatives as dual VEGFR2/FGFR1 inhibitors by the molecular hybridization strategy. 3-(2,6-Dichloro-3,5-dimethoxyphenyl)-1-{6-[(4-methoxyphenyl)amino]pyrimidin-4-yl}-1-methylurea (8b) had the best inhibitory activities against VEGFR2 and FGFR1 at 10 μM (82.2 % and 101.0 %, respectively), it showed moderate antiproliferative activities against A549 and KG-1 cell lines as well. Besides, molecular docking was also carried out to study the binding mode of 3-(2,6-dichloro-3,5-dimethoxyphenyl)-1-{6-[(4-methoxyphenyl)-amino]-pyrimidin-4-yl}-1-methylurea (8b) with VEGFR2 and FGFR1. These studies reveal that this series of compounds deserve further optimization.

Synthesis and Antitumor Application of Antiangiogenetic Gold Nanoclusters

Conventional antiangiogenetic inhibitors suffered from poor delivery problems that result in unsatisfactory antitumor treatment efficacy. Although the liposomes or nanomaterial-based delivery systems can improve the therapeutic efficacy of antiangiogenic molecules, the assembly process is far too complex. Herein, a nanomaterial or a new nanodrug that could work without the help of a carrier and could be easily synthesized is needed. Au nanoclusters (AuNCs) are a kind of ideal nanostructures that could spontaneously enter into the cell and could be synthesized by a relatively easy one-pot method. Here, changing the traditional ligand glutathione (GSH) into an anti-Flt1 peptide (AF) has enriched the newly synthesized AF@AuNCs with targeted antiangiogenic properties. Based on the specific binding between AF and vascular endothelial growth factor receptor 1 (VEGFR1), the interaction between VEGFR1 and its ligands could be blocked. Furthermore, the expression of VEGFR2 could be downregulated. Compared with pure AF peptide- and GSH-participated AuNCs (GSH@AuNCs), AF@AuNCs were more effective in inhibiting both tube formation and migration of the endothelial cells in vitro. Furthermore, the in vivo chick embryo chorioallantoic membrane (CAM) experiment and antitumor experiment were conducted to further verify the enhanced antiangiogenesis and tumor inhibition effect of AF@AuNCs. Our findings provide promising evidence of a carrier-free nanodrug for tumors and other vascular hyperproliferative diseases.

HEYL Regulates Neoangiogenesis Through Overexpression in Both Breast Tumor Epithelium and Endothelium

Blocking tumor angiogenesis is an appealing therapeutic strategy, but to date, success has been elusive. We previously identified HEYL, a downstream target of Notch signaling, as an overexpressed gene in both breast cancer cells and as a tumor endothelial marker, suggesting that HEYL overexpression in both compartments may contribute to neoangiogenesis. Carcinomas arising in double transgenic Her2-neu/HeyL mice showed higher tumor vessel density and significantly faster growth than tumors in parental Her2/neu mice. Providing mechanistic insight, microarray-based mRNA profiling of HS578T-tet-off-HEYL human breast cancer cells revealed upregulation of several angiogenic factors including CXCL1/2/3 upon HEYL expression, which was validated by RT-qPCR and protein array analysis. Upregulation of the cytokines CXCL1/2/3 occurred through direct binding of HEYL to their promoter sequences. We found that vessel growth and migration of human vascular endothelial cells (HUVECs) was promoted by conditioned medium from HS578T-tet-off-HEYL carcinoma cells, but was blocked by neutralizing antibodies against CXCL1/2/3. Supporting these findings, suppressing HEYL expression using shRNA in MDA-MB-231 cells significantly reduced tumor growth. In addition, suppressing the action of proangiogenic cytokines induced by HEYL using a small molecule inhibitor of the CXCl1/2/3 receptor, CXCR2, in combination with the anti-VEGF monoclonal antibody, bevacizumab, significantly reduced tumor growth of MDA-MB-231 xenografts. Thus, HEYL expression in tumor epithelium has a profound effect on the vascular microenvironment in promoting neoangiogenesis. Furthermore, we show that lack of HEYL expression in endothelial cells leads to defects in neoangiogenesis, both under normal physiological conditions and in cancer. Thus, HeyL-/- mice showed impaired vessel outgrowth in the neonatal retina, while the growth of mammary tumor cells E0771 was retarded in syngeneic HeyL-/- mice compared to wild type C57/Bl6 mice. Blocking HEYL's angiogenesis-promoting function in both tumor cells and tumor-associated endothelium may enhance efficacy of therapy targeting the tumor vasculature in breast cancer.

Vascular toxicity associated with anti-angiogenic drugs

Over the past two decades, the treatment of cancer has been revolutionised by the highly successful introduction of novel molecular targeted therapies and immunotherapies, including small-molecule kinase inhibitors and monoclonal antibodies that target angiogenesis by inhibiting vascular endothelial growth factor (VEGF) signaling pathways. Despite their anti-angiogenic and anti-cancer benefits, the use of VEGF inhibitors (VEGFi) and other tyrosine kinase inhibitors (TKIs) has been hampered by potent vascular toxicities especially hypertension and thromboembolism. Molecular processes underlying VEGFi-induced vascular toxicities still remain unclear but inhibition of endothelial NO synthase (eNOS), reduced nitric oxide (NO) production, oxidative stress, activation of the endothelin system, and rarefaction have been implicated. However, the pathophysiological mechanisms still remain elusive and there is an urgent need to better understand exactly how anti-angiogenic drugs cause hypertension and other cardiovascular diseases (CVDs). This is especially important because VEGFi are increasingly being used in combination with other anti-cancer dugs, such as immunotherapies (immune checkpoint inhibitors (ICIs)), other TKIs, drugs that inhibit epigenetic processes (histone deacetylase (HDAC) inhibitor) and poly (adenosine diphosphate-ribose) polymerase (PARP) inhibitors, which may themselves induce cardiovascular injury. Here, we discuss vascular toxicities associated with TKIs, especially VEGFi, and provide an up-to-date overview on molecular mechanisms underlying VEGFi-induced vascular toxicity and cardiovascular sequelae. We also review the vascular effects of VEGFi when used in combination with other modern anti-cancer drugs.

Hepatocyte Growth Factor and Macrophage-stimulating Protein "Hinge" Analogs to Treat Pancreatic Cancer

Pancreatic cancer (PC) ranks twelfth in frequency of diagnosis but is the fourth leading cause of cancer related deaths with a 5 year survival rate of less than 7 percent. This poor prognosis occurs because the early stages of PC are often asymptomatic. Over-expression of several growth factors, most notably vascular endothelial growth factor (VEGF), has been implicated in PC resulting in dysfunctional signal transduction pathways and the facilitation of tumor growth, invasion and metastasis. Hepatocyte growth factor (HGF) acts via the Met receptor and has also received research attention with ongoing efforts to develop treatments to block the Met receptor and its signal transduction pathways. Macrophage-stimulating protein (MSP), and its receptor Ron, is also recognized as important in the etiology of PC but is less well studied. Although the angiotensin II (AngII)/AT1 receptor system is best known for mediating blood pressure and body water/electrolyte balance, it also facilitates tumor vascularization and growth by stimulating the expression of VEGF. A metabolite of AngII, angiotensin IV (AngIV) has sequence homology with the "hinge regions" of HGF and MSP, key structures in the growth factor dimerization processes necessary for Met and Ron receptor activation. We have developed AngIV-based analogs designed to block dimerization of HGF and MSP and thus receptor activation. Norleual has shown promise as tested utilizing PC cell cultures. Results indicate that cell migration, invasion, and pro-survival functions were suppressed by this analog and tumor growth was significantly inhibited in an orthotopic PC mouse model.

Cooperation of Indian Hedgehog and Vascular Endothelial Growth Factor in Tumor Angiogenesis and Growth in Human Hepatocellular Carcinomas, an Immunohistochemical Study

The Hedgehog pathway was recently shown to be involved in vascular development and neovascularization in human embryogenesis and disease. However, the role of Hedgehog pathway in modulating tumor angiogenesis is still unexplored. In the current study, we investigated the expression of Indian Hedgehog (Ihh) and vascular endothelial cell growth factor (VEGF) in human hepatocellular carcinomas (HCCs) with immunohistochemical staining and compared the immunoreaction data with various clinicopathologic characteristics. Immunoreactivity of Ihh and VEGF proteins was observed in 61.5% (56/91) and 64.5% (59/91) cases of HCC tumor tissues, respectively, which was considerably higher than the adjacent nonmalignant tissues. Ihh protein was observed predominantly in the cytoplasm of the tumor cells with a staining pattern of which was sparse and dot-like, or circular around the cell membrane. VEGF protein was expressed heterogenously in the cytoplasm in tumor cells and was negative in peritumoral areas in all cases. CD34 showed diffuse staining in the tumor parenchyma in most HCC specimens. The association of expression of Ihh and VEGF with tumor size was statistically significant (P<0.05), but there was no significant association with other clinicopathologic parameters. Moreover, there was a significant association of the expressions of Ihh and VEGF proteins in HCC (r=0.6, P<0.0001), and of Ihh and CD34 staining (r=0.261, P=0.012). Our findings suggest that Ihh is involved in the development of HCC. These findings are also consistent with the concept that cooperation of Ihh and VEGF modulate HCC tumor angiogenesis and growth.

Primary Preclinical and Clinical Evaluation of 68Ga-DOTA-TMVP1 as a Novel VEGFR-3 PET Imaging Radiotracer in Gynecological Cancer

PURPOSE

Tumor periphery and lymph nodes of tumor-induced lymphangiogenesis often abundantly express VEGFR-3. In our previous study, we identified a 5-amino acid peptide named TMVP1, which binds specifically to VEGFR-3. The objective of this study was to develop a novel ⁶⁸Ga-labeled TMVP1 for VEGFR-3 PET imaging and to investigate its safety, biodistribution, and tumor-localizing efficacy in xenograft tumor models and a small cohort of patients with recurrent ovarian and cervical cancer.

EXPERIMENTAL DESIGN

The DOTA-conjugated TMVP1 peptide was labeled with radionuclide ⁶⁸Ga. SPR and saturation binding assays were used for the receptor-binding studies. Gynecologic xenograft tumors were employed for small-animal PET imaging and biodistribution of ⁶⁸Ga-DOTA-TMVP1 in vivo. In the clinical study, 5 healthy volunteers and 8 patients with gynecologic cancer underwent whole-body PET/CT after being injected with ⁶⁸Ga-DOTA-TMVP1.

RESULTS

DOTA-TMVP1 was successfully labeled with ⁶⁸Ga. LECs showed higher binding capacity with ⁶⁸Ga-DOTA-TMVP1 than LEC(shVEGFR-3) and human umbilical vein endothelial cells. In mice with subcutaneous C33-A and SKOV-3 xenografts, the tracer was rapidly eliminated through the kidney to the bladder, and the small-animal PET/CT helped to clearly visualize the tumors. In patients with recurrent ovarian cancer and cervical cancer, tracer accumulation well above the background level was demonstrated in most identified sites of disease; especially with recurrent endodermal sinus tumors, the diagnostic value of ⁶⁸Ga-DOTA-TMVP1 was comparable with that of ¹⁸F-FDG PET/CT.

CONCLUSIONS

⁶⁸Ga-DOTA-TMVP1 is a potential PET tracer for imaging VEGFR-3 with favorable pharmacokinetics.

Baseline platelet counts and derived inflammatory biomarkers: prognostic relevance in metastatic melanoma patients receiving Endostar plus dacarbazine and cisplatin

Background: The clinical efficacy and safety of Endostar combined with chemotherapy in the treatment of metastatic malignant melanoma (MM) were analyzed and the indicators capable of predicting the efficacy of the regimen were identified to guide clinical practice. Patients and methods: The clinical data of 55 patients with metastatic MM without gene mutations who were treated with Endostar combined with dacarbazine and cisplatin were retrospectively analyzed. Efficacy was assessed using RECIST 1.1, and adverse events (AEs) were graded according to NCI-CTCAE 4.0. The log-rank test was used to compare the survival curves of patients in different subgroups, and stepwise multivariate Cox regression analysis was used to determine significant prognostic factors. Differences were considered statistically significant at P<0.05. Results: Of the 55 patients, seven showed a partial response, 20 showed stable disease, and 28 showed progressive disease. The median progression-free survival was 17.9 months. AEs were controllable. Univariate analysis identified biotherapy, clinical stage, clinical classification, low baseline platelet count, platelet to albumin ratio (PAR), and platelet to globulin ratio (PGR) as factors affecting drug efficacy. Multivariate Cox regression analysis identified clinical stage and PAR as independent factors predicting the efficacy of the regimen. Conclusions: Endostar combined with chemotherapy showed a curative effect on metastatic MM without gene mutations, and AEs were controllable. The baseline platelet count and derived PAR and PGR values were associated with the efficacy of the regimen. The potential value of efficacy prediction remains to be further verified by prospective random experiments.

Cardiovascular safety of oncologic agents: a double-edged sword even in the era of targeted therapies - Part 2

INTRODUCTION

Patients with cancer are subject to the cardiotoxic effects of cancer therapy. Improved cancer treatments lead to more cancer-survivors, who though are exposed to various forms of cardiovascular (CV) disease (CVD) as they age. Aging patients are at increased risk of developing both malignancy and CVD or they may have survived some form of CVD as a result of effective CV treatments. Furthermore, patients with CVD may develop cancer and require treatment (and vice versa), all contributing to increased morbidity and mortality. The prevalence of both malignancy and CVD will increase due to the trend toward a longer lifespan.

AREAS COVERED

In part 2 of this review, the discussion of the CV effects of specific oncology drugs is completed with inclusion of additional immunological agents, current hormonal and other agents. Early detection and monitoring of cardiotoxicity, use of biomarkers and other imaging and diagnostic methods and prevention and treatment options are also discussed.

EXPERT OPINION

As outlined in part 1 of this review, oncologists need to be aware of the CV adverse-effects of their treatments and make careful and expectant clinical decisions, especially in patients with preexisting CVD or CV risk factors. Similarly, cardiologists should consider a detailed previous history of treatment for malignant disease, including prior chemotherapy exposure, dose(s) received, and/or combined modality therapy with chest radiotherapy. Both specialists should collaborate in order to minimize the impact of these two ubiquitous diseases (cancer and CVD) and mitigate the adverse effects of treatment modalities.

Successful treatment of relapsed testicular embryonal rhabdomyosarcoma with Endostar and traditional chemotherapy: a case report

Embryonal rhabdomyosarcoma (ERMS) has a low prevalence, poor prognosis, and limited treatment efficacy. We report a case of an 18-year-old male whose disease relapsed in the abdominal cavity after a testicular ERMS curative resection. The patient received eight sequential cycles of rescue therapy using cisplatin and isocyclophosphamide in combination with a vascular targeted drug, Endostar. The therapeutic effect of the combination regimen has been evaluated for complete response. This is the first case to report using Endostar and chemotherapy in relapsed ERMS, and the curative effect results in complete response. Endostar, a new vascular targeted drug, combined with chemotherapy may play a synergistic role and provide a reference for the treatment of ERMS.

Efficacy and safety of apatinib in patients with advanced nonsmall cell lung cancer that failed prior chemotherapy or EGFR-TKIs: A pooled analysis

BACKGROUND

Apatinib is a tyrosine kinase inhibitor (TKI) that selectively inhibits the vascular endothelial growth factor receptor-2. A weighted pooled analysis was performed to evaluate the clinical outcome, efficacy, and toxicity of apatinib in patients with advanced nonsmall cell lung cancer (NSCLC) that failed prior treatment with chemotherapy or epidermal growth factor receptor-TKIs (EGFR-TKIs).

METHODS

The literature published in PubMed, Embase, and Cochrane Library databases was searched (from inception to November 30, 2017) for eligible trials using the following search terms: apatinib AND (lung cancer OR NSCLC). Meeting abstracts were also reviewed to identify appropriate studies. Inclusion criteria were as follows: prospective or retrospective studies that evaluated efficacy and/or safety of apatinib in patients with advanced NSCLC that failed prior chemotherapy or EGFR-TKIs; primary outcome included one of these endpoints, progression-free survival (PFS), overall survival (OS), objective response rate (ORR), disease control rate (DCR), or adverse events (AEs); English language; and number of cases in the study ≥10 cases.

RESULTS

A total of 457 patients with advanced NSCLC were treated with apatinib in 14 studies (10 retrospective and 4 prospective studies) and were included in this pooled analysis. The pooled median PFS was 4.77 months [95% confidence interval (CI), 4.11-5.00] in all groups, 4.80 months (95% CI, 4.65-4.95) in the 750 mg apatinib (high-dose) group, and 3.88 months (95% CI, 3.11-4.65) in the 250 to 500 mg apatinib (low-dose) group. Median PFS stratified by single apatinib therapy or apatinib combined with continuous EGFR-TKIs was 4.76 months (95% CI, 3.66-5.06) and 5.20 months (95% CI, 3.66-6.74), respectively. The pooled median OS, ORR, and DCR values were 6.85 months, 18%, and 72%, respectively; pooled median ORR and DCR were 15% and 72% in the 750 mg apatinib group versus 20% and 72% in the 250 to 500 mg apatinib group. ORR and DCR stratified by therapeutic regimens were 14% and 70% for single-agent apatinib, 29% and 88% for apatinib combined with continuous EGFR-TKIs, and 26% and 63% for apatinib combined with chemotherapy, respectively. The pooled AE rates of grade 3/4 were hypertension (7%), proteinuria (3%), hand-foot-skin reaction (6%), fatigue (4%), decreased appetite (1.1%), oral mucositis (3%), and thrombocytopenia (3%).

CONCLUSION

Apatinib has promising antitumor activity and manageable toxicity profile in patients with advanced NSCLC that failed prior chemotherapy or EGFR-TKIs. This result needs to be confirmed through the ongoing Phase III clinical trial.

Tumor endothelial marker 8 promotes cancer progression and metastasis

Every year more than 8 million people suffer from cancer-related deaths worldwide [1]. Metastasis, the spread of cancer to distant sites, accounts for 90% of these deaths. A promising target for blocking tumor progression, without causing severe side effects [2], is Tumor Endothelial Marker 8 (TEM8), an integrin-like cell surface protein expressed predominantly in the tumor endothelium and in cancer cells [3, 4]. Here, we have investigated the role of TEM8 in cancer progression, angiogenesis and metastasis in invasive breast cancer, and validated the main findings and important results in colorectal cancer. We show that the loss of TEM8 in cancer cells results in inhibition of cancer progression, reduction in tumor angiogenesis and reduced metastatic burden in breast cancer mouse models. Furthermore, we show that TEM8 regulates cancer progression by affecting the expression levels of cell cycle-related genes. Taken together, our findings may have broad clinical and therapeutic potential for breast and colorectal primary tumor and metastasis treatment by targeting TEM8.

Current Status and Study Progress of Recombinant Human Endostatin in Cancer Treatment

Angiogenesis plays fundamentally critical roles in solid-tumor pathogenesis, growth, invasion and metastasis. Endostatin, one of the most potent anti-angiogenic factors, was first isolated in Folkman's lab in 1997, and was reported to dramatically shrink tumor blood formation. But its insoluble and unstable nature coupled with the high cost of synthesizing the endostatin protein doomed it for clinical cancer treatment. Intrigued by Folkman's pioneering discoveries, Chinese scientists found a way to refold the protein, making it cost-effective to manufacture a recombinant human endostatin, a soluble and stable form of endostatin. A number of clinical studies have demonstrated the significant survival benefit of rh-endostatin in treating late stage non-small-cell lung carcinoma (NSCLC) and, as a result, rh-endostatin (Endostar®) was approved by the State Food and Drug Administration of China (CFDA) in September of 2005 as a treatment option for NSCLC. Since then, increasing bodies of clinical data and experience have been obtained from a variety of other different cancers, such as small cell lung cancer, NSCLC in other settings, including malignant serous effusion, melanoma, colon cancer, gastric cancer, breast cancer, nasopharyngeal cancers, and others. This review aims at summarizing current clinical data of rh-endostatin including its survival benefits, optimized dosages, routes of administration, recommended duration and frequency of treatment, predictive biomarkers, and its safety profile in lung cancers as well as other cancers.

Successful treatment of metastatic colorectal cancer with apatinib: report of two cases and literature review

Apatinib, a novel small molecule tyrosine kinase inhibitor that inhibits vascular endothelial growth factor receptor-2, was approved for metastatic gastric adenocarcinoma in China in Oct 2014. This is the first report on its use for advanced colorectal cancer as a kind of third-line therapy to date. Here we report two Chinese patients who presented with metastatic colorectal cancer who received apatinib 850 mg daily as a third-line therapy. Both the patients achieved favorable benefits in outcomes after the administration of apatinib. Patient 1 benefited 4 months progression-free survival and 11 months overall survival, while patient 2’s progression-free survival was over 10 months. Both the patients presented hand–foot syndrome, and one of them suffered a slight impairment of liver function, mild elevated blood pressure, and proteinuria. But these adverse events were manageable with symptomatic treatment and dose reduction or a short-time drug withdrawal.

Fragments generated upon extracellular matrix remodeling: Biological regulators and potential drugs

The remodeling of the extracellular matrix (ECM) by several protease families releases a number of bioactive fragments, which regulate numerous biological processes such as autophagy, angiogenesis, adipogenesis, fibrosis, tumor growth, metastasis and wound healing. We review here the proteases which generate bioactive ECM fragments, their ECM substrates, the major bioactive ECM fragments, together with their biological properties and their receptors. The translation of ECM fragments into drugs is challenging and would take advantage of an integrative approach to optimize the design of pre-clinical and clinical studies. This could be done by building the contextualized interaction network of the ECM fragment repertoire including their parent proteins, remodeling proteinases, and their receptors, and by using mathematical disease models.

Notch4 inhibition suppresses invasion and vasculogenic mimicry formation of hepatocellular carcinoma cells

Vasculogenic mimicry (VM) is a process by which aggressive tumor cells generate non-endothelial cell-lined channels in malignant tumors including hepatocellular carcinoma (HCC). It has provided new insights into tumor behavior and has surfaced as a potential target for drug therapy. The molecular events underlying the process of VM formation are still poorly understood. In this study, we attempted to elucidate the relationship between Notch4 and VM formation in HCC. An effective siRNA lentiviral vector targeting Notch4 was constructed and transfected into Bel7402, a HCC cell line. VM networks were observed with a microscope in a 3 dimensional cell culture system. Cell migration and invasion were evaluated using wound healing and transwell assays. Matrix metalloproteinases (MMPs) activity was detected by gelatin zymography. Furthermore, the role of Notch4 inhibition in Bel7402 cells in vivo was examined in subcutaneous xenograft tumor model of mice. The results showed that downregulation of Notch4 destroyed VM network formation and inhibited migration and invasion of tumor cells in vitro (P<0.05). In vivo, tumor growth was also inhibited in subcutaneous xenograft model (P<0.05). The potential mechanisms might be related with down-regulation of MT1-MMP, MMP-2, MMP-9 expression and inhibition of the activation of MMP2 and MMP9. These results indicated that Notch4 may play an important role in VM formation and tumor invasion in HCC. Related molecular pathways may be used as novel therapeutic targets for HCC antiangiogenesis therapy.

S100A7: from mechanism to cancer therapy

Within the tumor, malignant and stromal cells support each other by secreting a wide variety of growth factors and cytokines, allowing tumor growth and disease progression. The identification and regulation of those key factors in this crosstalk has opened the opportunity to develop new therapeutic strategies that not only act on the tumor cells but also on the stroma. Among these factors, S100A7 protein has gained interest in the last years. With key roles in cell motility its expression correlates with increased tumor growth, angiogenesis and metastatic potential. This work aims to deepen in the role played by extracellular S100A7 in the tumor microenvironment, offering a new integrative insight of its mechanism of action on each cellular compartment (tumor, endothelial, immune and fibroblast). As a result, we demonstrate its implication in cell migration and invasion, and its important contribution to the formation of a proinflammatory and proangiogenic environment that favors tumor progression and metastasis. Furthermore, we define its possible role in the pre-metastatic niche formation. Considering the relevance of S100A7 in cancer progression, we have developed neutralizing monoclonal antibodies, reporting for the first time the proof of principle of this promising therapeutic strategy for cancer treatment.

Therapeutic concentrations of digitoxin inhibit endothelial focal adhesion kinase and angiogenesis induced by different growth factors

BACKGROUND AND PURPOSE

Cardiac glycosides are Na⁺ /K⁺ -ATPases inhibitors used to treat congestive heart failure and cardiac arrhythmias. Epidemiological studies indicate that patients on digitalis therapy are more protected from cancer. Evidence of a selective cytotoxicity against cancer cells has suggested their potential use as anticancer drugs. The effect on angiogenesis of clinically used cardiac glycosides has not been extensively explored.

EXPERIMENTAL APPROACH

We studied the effect of digoxin, digitoxin and ouabain on early events of the angiogenic process in HUVECs. We determined HUVEC viability, proliferation, migration and differentiation into capillary tube-like structures. We also tested drug activity using an in vivo angiogenesis model. Activation of protein tyrosine kinase 2 (FAK) and signalling proteins associated with the Na⁺ /K⁺ -ATPase signalosome was determined by Western blotting.

KEY RESULTS

Digitoxin and ouabain (1-100 nM) inhibited HUVEC migration, concentration-dependently, without affecting cell viability, while digoxin induced apoptosis at the same concentrations. Digitoxin antagonized growth factor-induced migration and tubularization at concentrations (1-25 nM) within its plasma therapeutic range. The anti-angiogenic effect of digitoxin was confirmed also by in vivo studies. Digitoxin induced Src, Akt and ERK1/2 phosphorylation but did not affect FAK autophosphorylation at Tyr³⁹⁷ . However, it significantly inhibited growth factor-induced FAK phosphorylation at Tyr^576/577 .

CONCLUSIONS AND IMPLICATIONS

Therapeutic concentrations of digitoxin inhibited angiogenesis and FAK activation by several pro-angiogenic stimuli. These novel findings suggest a potential repositioning of digitoxin as a broad-spectrum anti-angiogenic drug for diseases where pathological angiogenesis is involved.

Endostar in combination with postoperative adjuvant chemotherapy prolongs the disease free survival of stage IIIA NSCLC patients with high VEGF expression

Purpose

The aim of this study is to compare the therapeutic effect between endostar plus adjuvant chemotherapy and adjuvant chemotherapy alone in the patients with completely resected non-small cell lung cancer (NSCLC) at stage IB to IIIA.

Experimental Design

This is an open, multicenter, randomized (1:1) study with 250 NSCLC patients. Completely resected NSCLC patients at stages IB to IIIA were randomized to receive adjuvant NP plus endostar (Vinorelbine 25 mg/m² on day 1 and day 8 plus Cisplatin 75 mg/m² on day 1, and plus endostar 7.5 mg/m² per day iv for consecutive 14 days) or NP regimen alone. Every 21 days were set as one cycle for 4 cycles. The primary endpoint was disease-free survival (DFS). Secondary endpoints included tumor response rate, overall survival and safety.

Results

The two groups had no significant difference in the incidence of toxicity reaction. Endostar plus NP prolonged the DFS of patients with completely resected NSCLC at stage IIIA (19.33±3.73 vs 17.10±9.68 months) but with no statistical difference compared to NP alone. In the endostar plus NP group, those cases with high expression of vascular endothelial growth factor (VEGF) showed a significantly better DFS than those with low VEGF expression (48.45±3.52 vs 40.18±4.54 months, P<0.05).

Conclusions

Vascular targeted therapy with endostar plus NP prolongs the DFS of patients with complete resectable NSCLC in stage IIIA and significantly extends the DFS of NSCLC patients with high VEGF expression, but does not show benefits in OS for stage IB-IIIA.

Tumor angiogenesis revisited: Regulators and clinical implications

Since Judah Folkman hypothesized in 1971 that angiogenesis is required for solid tumor growth, numerous studies have been conducted to unravel the angiogenesis process, analyze its role in primary tumor growth, metastasis and angiogenic diseases, and to develop inhibitors of proangiogenic factors. These studies have led in 2004 to the approval of the first antiangiogenic agent (bevacizumab, a humanized antibody targeting vascular endothelial growth factor) for the treatment of patients with metastatic colorectal cancer. This approval launched great expectations for the use of antiangiogenic therapy for malignant diseases. However, these expectations have not been met and, as knowledge of blood vessel formation accumulates, many of the original paradigms no longer hold. Therefore, the regulators and clinical implications of angiogenesis need to be revisited. In this review, we discuss recently identified angiogenesis mediators and pathways, new concepts that have emerged over the past 10 years, tumor resistance and toxicity associated with the use of currently available antiangiogenic treatment and potentially new targets and/or approaches for malignant and nonmalignant neovascular diseases.

Sialyllactose suppresses angiogenesis by inhibiting VEGFR-2 activation, and tumor progression

The oligosaccharides in human milk have various biological functions. However, the molecular mechanism(s) underlying the anti-angiogenic action of sialylated human milk oligosaccharides (HMOs) are still unclear. Here, we show that siallylactose (SL) found in human milk can inhibit the activation of vascular endothelial growth factor (VEGF)-mediated VEGF receptor-2 (VEGFR-2) by binding to its VEGF binding site (second and third IgG-like domains), thus blocking downstream signal activation. SL also inhibits growth of VEGF-stimulated endothelial cells. In endothelial cells treated with VEGF, SL diminished tube formation, migration, and the arrangement of actin filament. In addition, SL clearly suppressed VEGF-induced neovascularization in an in vivo Matrigel plug assay. Notably, SL prevented the growth of tumor cells, and angiogenesis on tumor tissues in in vivo mice models allotransplanted with Lewis lung carcinoma, melanoma, and colon carcinoma cells. Taken together, we have demonstrated that the sialylated milk oligosaccharide sialyllactose functions as an inhibitor of angiogenesis through suppression of VEGF-mediated VEGFR-2 activation in endothelial cells, Accordingly, it could be a novel candidate for the development of anti-angiogenic drugs without any side effects.

The Role of the Tumor Vasculature in the Host Immune Response: Implications for Therapeutic Strategies Targeting the Tumor Microenvironment

Recently developed cancer immunotherapy approaches including immune checkpoint inhibitors and chimeric antigen receptor T cell transfer are showing promising results both in trials and in clinical practice. These approaches reflect increasing recognition of the crucial role of the tumor microenvironment in cancer development and progression. Cancer cells do not act alone, but develop a complex relationship with the environment in which they reside. The host immune response to tumors is critical to the success of immunotherapy; however, the determinants of this response are incompletely understood. The immune cell infiltrate in tumors varies widely in density, composition, and clinical significance. The tumor vasculature is a key component of the microenvironment that can influence tumor behavior and treatment response and can be targeted through the use of antiangiogenic drugs. Blood vascular and lymphatic endothelial cells have important roles in the trafficking of immune cells, controlling the microenvironment, and modulating the immune response. Improving access to the tumor through vascular alteration with antiangiogenic drugs may prove an effective combinatorial strategy with immunotherapy approaches and might be applicable to many tumor types. In this review, we briefly discuss the host's immune response to cancer and the treatment strategies utilizing this response, before focusing on the pathological features of tumor blood and lymphatic vessels and the contribution these might make to tumor immune evasion.

Hypoxia induced CCL28 promotes angiogenesis in lung adenocarcinoma by targeting CCR3 on endothelial cells

Tumor hypoxia is one of the important features of lung adenocarcinoma. Chemokines might mediate the effects caused by tumor hypoxia. As confirmed in tumor tissue and serum of patients, CC chemokine 28 (CCL28) was the only hypoxia induced chemokine in lung adenocarcinoma cells. CCL28 could promote tube formation, migration and proliferation of endothelial cells. In addition, angiogenesis was promoted by CCL28 in the chick chorioallantoic membrane and matrigel implanted in dorsal back of athymic nude mice (CByJ.Cg-Foxn1^nu/J). Tumors formed by lung adenocarcinoma cells with high expression of CCL28 grew faster and had a higher vascular density, whereas tumor formation rate of lung adenocarcinoma cells with CCL28 expression knockdown was quite low and had a lower vascular density. CCR3, receptor of CCL28, was highly expressed in vascular endothelial cells in lung adenocarcinoma when examining by immunohistochemistry. Further signaling pathways in endothelial cells, modulated by CCL28, were analyzed by Phosphorylation Antibody Array. CCL28/CCR3 signaling pathway could bypass that of VEGF/VEGFR on the levels of PI3K-Akt, p38 MAPK and PLC gamma. The effects could be neutralized by antibody against CCR3. In conclusion, CCL28, as a chemokine induced by tumor hypoxia, could promote angiogenesis in lung adenocarcinoma through targeting CCR3 on microvascular endothelial cells.

Antiangiogenesis and vascular disrupting agents in cancer: circumventing resistance and augmenting their therapeutic utility

Angiogenesis is a process essential for tumor growth and metastasis. Inhibition of angiogenesis as an anticancer strategy has shown only moderately improved results and is beset with practical limitations, despite theoretical therapeutic advantages. Inevitably resistance develops, through redundancy of signaling pathways and selection for subclonal populations adapted for hypoxic conditions, with more invasive phenotypes. Antiangiogenic-targeted therapies may find improved efficacy in combination therapies; with others in this class, that directly or indirectly target separate pathways or different components of the same pathway, or with a separate class of tumor vasculature-disrupting agents. This review discusses the challenges and strategies for optimization of combination therapies including metronomic administration of drugs and the need for suitable prognostic and surrogate response biomarkers.

Lebein, a snake venom disintegrin, suppresses human colon cancer cells proliferation and tumor-induced angiogenesis through cell cycle arrest, apoptosis induction and inhibition of VEGF expression

Lebein, is an heterodimeric disintegrin isolated from Macrovipera lebetina snake venom that was previously characterized as an inhibitor of ADP-induced platelet aggregation. In this study, we investigated the effect of Lebein on the p53-dependent growth of human colon adenocarcinoma cell lines. We found that Lebein significantly inhibited LS174 (p53wt), HCT116 (p53wt), and HT29 (p53mut) colon cancer cell viability by inducing cell cycle arrest through the modulation of expression levels of the tumor suppression factor p53, cell cycle regulating proteins cyclin D1, CDK2, CDK4, retinoblastoma (Rb), CDK1, and cyclin-dependent kinase inhibitors p21 and p27. Interestingly, Lebein-induced apoptosis of colon cancer cells was dependent on their p53 status. Thus, in LS174 cells, cell death was associated with PARP cleavage and the activation of caspases 3 and 8 while in HCT116 cells, Lebein induced caspase-independent apoptosis through increased expression of apoptosis inducing factor (AIF). In LS174 cells, Lebein triggers the activation of the MAPK ERK1/2 pathway through induction of reactive oxygen species (ROS). It also decreased cell adhesion and migration to fibronectin through down regulation of α5β1 integrin. Moreover, Lebein significantly reduced the expression of two angiogenesis stimulators, Vascular Endothelial Growth Factor (VEGF) and Neuropilin 1 (NRP1). It inhibited the VEGF-induced neovascularization process in the quail embryonic CAM system and blocked the development of human colon adenocarcinoma in nude mice. Overall, our work indicates that Lebein may be useful to design a new therapy against colon cancer. © 2016 Wiley Periodicals, Inc.

Changes in plasma biomarkers following treatment with cabozantinib in metastatic castration-resistant prostate cancer: a post hoc analysis of an extension cohort of a phase II trial

Background

Cabozantinib is an orally available inhibitor of tyrosine kinases including VEGFR2 and c-MET. We performed a post hoc analysis to find associations between select plasma biomarkers and treatment response in patients (pts) with metastatic castration resistant prostate cancer (mCRPC) who received cabozantinib 100 mg daily as part of a phase 2 non-randomized expansion cohort (NCT00940225).

Methods

Plasma samples were collected at baseline, 6 weeks and at time of maximal response from 81 mCRPC pts with bone metastases, of which 33 also had measurable soft-tissue disease. Levels of 27 biomarkers were measured in duplicate using enzyme-linked immunosorbent assay. Spearman correlation coefficients were calculated for the association between biomarker levels or their change on treatment and either bone scan response (BSR) or soft tissue response according to RECIST.

Results

A BSR and RECIST response were seen in 66/81 pts (81 %) and 6/33 pts (18 %) respectively. No significant associations were found between any biomarker at any time point and either type of response. Plasma concentrations of VEGFA, FLT3L, c-MET, AXL, Gas6A, bone-specific alkaline phosphatase, interleukin-8 and the hypoxia markers CA9 and clusterin significantly increased during treatment with cabozantinib irrespective of response. The plasma concentrations of VEGFR2, Trap5b, Angiopoietin-2, TIMP-2 and TIE-2 significantly decreased during treatment with caboznatinib.

Conclusions

Our data did not reveal plasma biomarkers associated with response to cabozantinib. The observed alterations in several biomarkers during treatment with cabozantinib may provide insights on the effects of cabozantinib on tumor cells and on tumor micro-environment and may help point to potential co-targeting approaches.

In Vitro Assays for Endothelial Cell Functions Required for Angiogenesis: Proliferation, Motility, Tubular Differentiation, and Matrix Proteolysis

This chapter deconstructs the process of angiogenesis into its component parts in order to provide simple assays to measure discrete endothelial cell functions. The techniques described will be suitable for studying stimulators and/or inhibitors of angiogenesis and determining which aspect of the process is modulated. The assays are designed to be robust and straightforward, using human umbilical vein endothelial cells, but with an option to use other sources such as microvascular endothelial cells from various tissues or lymphatic endothelial cells. It must be appreciated that such reductionist approaches cannot cover the complexity of the angiogenic process as a whole, incorporating as it does a myriad of positive and negative signals, three-dimensional interactions with host tissues and many accessory cells including fibroblasts, macrophages, pericytes and platelets. The extent to which in vitro assays predict physiological or pathological processes in vivo (e.g., wound healing, tumor angiogenesis) or surrogate techniques such as the use of Matrigel™ plugs, sponge implants, corneal assays etc remains to be determined.

Vascular Complications of Cancer Chemotherapy

Development of new anticancer drugs has resulted in improved mortality rates and 5-year survival rates in patients with cancer. However, many of the modern chemotherapies are associated with cardiovascular toxicities that increase cardiovascular risk in cancer patients, including hypertension, thrombosis, heart failure, cardiomyopathy, and arrhythmias. These limitations restrict treatment options and might negatively affect the management of cancer. The cardiotoxic effects of older chemotherapeutic drugs such as alkylating agents, antimetabolites, and anticancer antibiotics have been known for a while. The newer agents, such as the antiangiogenic drugs that inhibit vascular endothelial growth factor signalling are also associated with cardiovascular pathology, especially hypertension, thromboembolism, myocardial infarction, and proteinuria. Exact mechanisms by which vascular endothelial growth factor inhibitors cause these complications are unclear but impaired endothelial function, vascular and renal damage, oxidative stress, and thrombosis might be important. With increasing use of modern chemotherapies and prolonged survival of cancer patients, the incidence of cardiovascular disease in this patient population will continue to increase. Accordingly, careful assessment and management of cardiovascular risk factors in cancer patients by oncologists and cardiologists working together is essential for optimal care so that prolonged cancer survival is not at the expense of increased cardiovascular events.

Monitoring vascular normalization induced by antiangiogenic treatment with (18)F-fluoromisonidazole-PET

Background: Rationalization of antiangiogenics requires biomarkers. Vascular re‐normalization is one widely accepted mechanism of action for this drug class. The interstitium of tumors with abnormal vasculature is hypoxic. We sought to track vascular normalization with 18F‐misonidazole ([18F]‐FMISO, a probe that detects hypoxia) PET, in response to window‐of‐opportunity (WoO) treatment with the antiangiogenic dovitinib.

Methods: Two patient‐derived pancreas xenografts (PDXs; Panc215 and Panc286) and the spontaneous breast cancer model MMTV‐PyMT were used. Animals were treated during 1 week of WoO treatment with vehicle or dovitinib, preceded and followed by [18F]‐FMISO‐PET, [18F]‐FDG‐PET, and histologic assessment (dextran extravasation, hypoxia and microvessel staining, and necrosis, cleaved caspase‐3 and Ki67 measurements). After WoO treatment, gemcitabine (pancreas)/adriamycin (breast) or vehicle was added and animals were treated until the humane endpoint. Tumor growth inhibition (TGI) and survival were the parameters studied.

Results: [18F]‐FMISO SUV did not change after dovitinib‐WoO treatment compared to vehicle‐WoO (0.54 vs. 0.6) treatment in Panc215, but it decreased significantly in Panc286 (0.58 vs. 1.18; P < 0.05). In parallel, 10‐KDa perivascular dextran extravasation was not reduced with dovitinib or vehicle‐WoO treatment in Panc215, but it was reduced in Panc286. Whereas the addition of dovitinib to gemcitabine was indifferent in Panc215, it increased TGI in Panc286 (TGI switched from −59% to +49%). [18F]‐FMISO SUV changes were accompanied by an almost 100% increase in interstitial gemcitabine delivery (665–1260 ng/mL). The results were validated in the PyMT model.

Conclusions: [18F]‐FMISO accurately monitored vascular re‐normalization and improved interstitial chemotherapy delivery.

We describe a new technique to monitor the efficacy of antiangiogenics.

This drug class currently lacks biomarkers.

Antiangiogenics exert their positive effect by inducing stromal normalization.

18F‐fluoromisonidazole PET is able to monitor stromal normalization.

Tumors showing stromal normalization by PET experience benefit from antiangiogenics.

Bone marrow-derived mesenchymal stem cell-secreted IL-8 promotes the angiogenesis and growth of colorectal cancer

Mesenchymal stem cells (MSCs) have recently been shown to home to tumors and contribute to the formation of the tumor-associated stroma. In addition, MSCs can secrete paracrine factors to facilitate tumor progression. However, the involvement of MSC-derived cytokines in colorectal cancer (CRC) angiogenesis and growth has not been clearly addressed. In this study, we report that interleukin-8 (IL-8) was the most highly upregulated pro-angiogenic factor in MSCs co-cultured with CRC cells and was expressed at substantially higher levels in MSCs than CRC cells. To evaluate the effect of MSC-derived IL-8 on CRC angiogenesis and growth, we used MSCs that expressed small hairpin (interfering) RNAs (shRNA) targeting IL-8 (shIL-8-MSCs). We found that MSC-secreted IL-8 promoted human umbilical vein endothelial cell (HUVEC) proliferation and migration, tube-formation ability and CRC cell proliferation. Additionally, in vivo studies showed that MSCs promoted tumor angiogenesis partially through IL-8. Taken together, these findings suggest that IL-8 secreted by MSCs promotes CRC angiogenesis and growth and can therefore serve as a potential novel therapeutic target.

Pathologic response during chemo-radiotherapy and variation of serum VEGF levels could predict effects of chemo-radiotherapy in patients with esophageal cancer

BACKGROUND

To investigate the relationship between pathologic tumor response to concurrent chemo- radiotherapy and variation of serum VEGF in patients with esophageal cancer.

MATERIALS AND METHODS

Forty six patients with esophageal cancer who were treated with concurrent chemo-radiotherapy were enrolled. Endoscopic and pathologic examination was conducted before and four weeks afterwards. Serum level of VEGF was documented before, four weeks later and after chemo-radiotherapy. The relationship between pathologic response and the variation of serum level of VEGF and its influence on the prognosis were investigated.

RESULTS

Serum level of VEGF decreased remarkably during and after chemo-radiotherapy in patients whose pathologic response was severe (F=5.393, 4.587, P(0.05). There were no statistical differences of serum VEGF level before, during and after chemo-radiotherapy for patients whose pathologic response was moderate or mild. There were 18 (85.7%), 7 (53.8%) and 6 patients (50.0%) whose serum VEGF level dropped in the severe, moderate and mild group, respectively, with significant differences among these groups (p=0.046). Two year survival rates of patients with severe, moderate and mild pathologic response were 61.9%, 53.8% and 33.3% respectively, and no statistically difference between severe and mild group regarding OS (p=0.245) was tested.

CONCLUSIONS

Tumor pathologic response during chemo-radiotherapy and the changes of serum VEGF lever could predict curative effects of chemo-radiotherapy in patients with esophageal cancer.

Cancer prevention and therapy through the modulation of the tumor microenvironment

Cancer arises in the context of an in vivo tumor microenvironment. This microenvironment is both a cause and consequence of tumorigenesis. Tumor and host cells co-evolve dynamically through indirect and direct cellular interactions, eliciting multiscale effects on many biological programs, including cellular proliferation, growth, and metabolism, as well as angiogenesis and hypoxia and innate and adaptive immunity. Here we highlight specific biological processes that could be exploited as targets for the prevention and therapy of cancer. Specifically, we describe how inhibition of targets such as cholesterol synthesis and metabolites, reactive oxygen species and hypoxia, macrophage activation and conversion, indoleamine 2,3-dioxygenase regulation of dendritic cells, vascular endothelial growth factor regulation of angiogenesis, fibrosis inhibition, endoglin, and Janus kinase signaling emerge as examples of important potential nexuses in the regulation of tumorigenesis and the tumor microenvironment that can be targeted. We have also identified therapeutic agents as approaches, in particular natural products such as berberine, resveratrol, onionin A, epigallocatechin gallate, genistein, curcumin, naringenin, desoxyrhapontigenin, piperine, and zerumbone, that may warrant further investigation to target the tumor microenvironment for the treatment and/or prevention of cancer.

Radio-Immunotherapy-Induced Immunogenic Cancer Cells as Basis for Induction of Systemic Anti-Tumor Immune Responses - Pre-Clinical Evidence and Ongoing Clinical Applications

Radiotherapy (RT) primarily aims to locally destroy the tumor via the induction of DNA damage in the tumor cells. However, the so-called abscopal, namely systemic and immune–mediated, effects of RT move over more and more in the focus of scientists and clinicians since combinations of local irradiation with immune therapy have been demonstrated to induce anti-tumor immunity. We here summarize changes of the phenotype and microenvironment of tumor cells after exposure to irradiation, chemotherapeutic agents, and immune modulating agents rendering the tumor more immunogenic. The impact of therapy-modified tumor cells and damage-associated molecular patterns on local and systemic control of the primary tumor, recurrent tumors, and metastases will be outlined. Finally, clinical studies affirming the bench-side findings of interactions and synergies of radiation therapy and immunotherapy will be discussed. Focus is set on combination of radio(chemo)therapy (RCT) with immune checkpoint inhibitors, growth factor inhibitors, and chimeric antigen receptor T-cell therapy. Well-deliberated combination of RCT with selected immune therapies and growth factor inhibitors bear the great potential to further improve anti-cancer therapies.

Structure-Activity Relationship of Indole-Tethered Pyrimidine Derivatives that Concurrently Inhibit Epidermal Growth Factor Receptor and Other Angiokinases

Antiangiogenic agents have been widely investigated in combination with standard chemotherapy or targeted cancer agents for better management of advanced cancers. Therapeutic agents that concurrently inhibit epidermal growth factor receptor and other angiokinases could be useful alternatives to combination therapies for epidermal growth factor receptor-dependent cancers. Here, we report the synthesis of an indole derivative of pazopanib using a bioisosteric replacement strategy, which was designated MKP101. MKP101 inhibited not only the epidermal growth factor receptor with an IC50 value of 43 nM but also inhibited angiokinases as potently as pazopanib. In addition, MKP101 effectively inhibited vascular endothelial growth factor-induced endothelial proliferation, tube formation, migration of human umbilical vein endothelial cells and proliferation of HCC827, an epidermal growth factor receptor-addicted cancer cell line. A docking model of MKP101 and the kinase domain of the epidermal growth factor receptor was generated to predict its binding mode, and validated by synthesizing and evaluating MKP101 derivatives. Additionally, a study of structure-activity relationships of indolylamino or indolyloxy pyrimidine analogues derived from MKP101 demonstrated that selectivity for epidermal growth factor receptor and other angiokinases, especially vascular endothelial growth factor receptor 2 depends on the position of substituents on pyrimidine and the type of link between pyrimidine and the indole moiety. We believe that this study could provide a basis for developing angiokinase inhibitors having high affinity for the epidermal growth factor receptor, from the pyrimidine scaffold.

Activin Receptor-like Kinase 1 Ligand Trap Reduces Microvascular Density and Improves Chemotherapy Efficiency to Various Solid Tumors

PURPOSE

Antiangiogenic therapy, mostly targeting VEGF, has been applied in cancer patients for the last decade. However, resistance to anti-VEGF therapy and/or no significant benefit as monotherapeutic agent is often observed. Therefore, new antiangiogenic strategies are needed. In the current study, we investigated the therapeutic effect of interfering with the bone morphogenetic protein (BMP)9/activin receptor-like kinase (ALK)1 signaling pathway by using an ALK1-Fc ligand trap.

EXPERIMENTAL DESIGN

We analyzed the potential antiangiogenic and antitumor effects of ALK1-Fc protein as monotherapy and in combination with chemotherapy in vivo in mouse models of melanoma, head and neck cancer, and invasive lobular breast carcinomas. ALK1-Fc sequesters BMP9 and 10 and prevents binding of these ligands to endothelial ALK1, which regulates angiogenesis.

RESULTS

Treatment of mice with ALK1-Fc strongly decreased the tumors' microvascular density in the three different mouse cancer models. However, this effect was not accompanied by a reduction in tumor volume. An immunohistochemical analysis of the tumor samples revealed that ALK1-Fc treatment increased the pericyte coverage of the remaining tumor vessels and decreased the hypoxia within the tumor. Next, we observed that combining ALK1-Fc with cisplatin inhibited tumor growth in the breast and head and neck cancer models more efficiently than chemotherapy alone.

CONCLUSIONS

The addition of ALK1-Fc to the cisplatin treatment was able to enhance the cytotoxic effect of the chemotherapy. Our results provide strong rationale to explore combined targeting of ALK1 with chemotherapy in a clinical setting, especially in the ongoing phase II clinical trials with ALK1-Fc.

The coming of ramucirumab in the landscape of anti-angiogenic drugs: potential clinical and translational perspectives

INTRODUCTION

Angiogenesis plays a pivotal role in the development and progression of tumors and it represents a crucial target for therapeutic strategies. Until now, regulatory agencies approved antiangiogenic agents targeting the VEGF and multi-target agents carrying antiangiogenic and anti-proliferative effects. They often provide only a modest survival benefit and their role in clinical practice is debated. The limited efficacy may be partially explained by the complexity of the molecular background of angiogenic processes, composed of several pathways interacting with both tumor cells and the microenvironment.

AREAS COVERED

Ramucirumab is a fully human monoclonal antibody selectively binding and inhibiting the VEGF receptor 2 (VEGFR-2), a crucial molecule involved in angiogenesis. A series of Phase I-II trials conducted in a wide spectrum of malignancies reported promising antitumor activity. In 2014, data from large Phase III clinical trials in gastrointestinal, lung and breast malignancies were released.

EXPERT OPINION

Considering the evidences of efficacy emerging from the available Phase III trials, the antiangiogenic approach emerged as a promising strategy particularly for the treatment of gastric cancer. Nevertheless, the identification and validation of potentially predictive biomarkers are necessary to improve the selection of patients and the globally awaited clinical benefit.

Small-molecule BH3 mimetic and pan-Bcl-2 inhibitor AT-101 enhances the antitumor efficacy of cisplatin through inhibition of APE1 repair and redox activity in non-small-cell lung cancer

AT-101 is a BH3 mimetic and pan-Bcl-2 inhibitor that has shown potent anticancer activity in non-small-cell lung cancer (NSCLC) in murine models, but failed to show clinical efficacy when used in combination with docetaxel in NSCLC patients. Our recent study has demonstrated that AT-101 enhanced the antitumor effect of cisplatin (CDDP) in a murine model of NSCLC via inhibition of the interleukin-6/signal transducer and activator of transcription 3 (STAT3) pathway. This study explored the underlying mechanisms for the enhanced anticancer activity of CDDP by AT-101. Our results show that, when compared with monotherapy, AT-101 significantly enhanced the inhibitory effects of CDDP on proliferation and migration of A549 cells and on tube formation and migration in human umbilical vein endothelial cells. AT-101 promoted the proapoptotic activity of CDDP in A549 cells. AT-101 also enhanced the inhibitory effect of CDDP on DNA repair and redox activities of apurinic/apyrimidinic endonuclease 1 (APE1) in A549 cells. In tumor tissues from nude mice treated with AT-101 plus CDDP or monotherapy, the combination therapy resulted in greater inhibition of angiogenesis and tumor cell proliferation than the monotherapy. These results suggest that AT-101 can enhance the antitumor activity of CDDP in NSCLC via inhibition of APE1 DNA repair and redox activities and by angiogenesis and induction of apoptosis, but other mechanisms cannot be excluded. We are now conducting a Phase II trial to examine the clinical efficacy and safety profile of combined use of AT-101 plus CDDP in advanced NSCLC patients.

Anti-angiogenic activity of gecko aqueous extracts and its macromolecular components in CAM and HUVE-12 cells

Gecko is a kind of traditional Chinese medicine with remarkable antineoplastic activity. However, undefined mechanisms and ambiguity regarding active ingredients limit new drug development from gecko. This study was conducted to assess anti-angiogenic properties of the aqueous extracts of fresh gecko (AG) or macromolecular components separated from AG (M-AG). An enzyme-linked immunosorbent assay (ELISA) approach was applied to detect the vascular endothelial growth factor (VEGF) secretion of the tumor cells treated with AG or M-AG. The effect of AG or M-AG on vascular endothelial cell proliferation and migratory ability was analyzed by tetrazolium dye colorimetric method, transwell and wound-healing assays. Chick embryo chorioallantoic membrane (CAM) assays were used to ensure the anti-angiogenic activity of M-AG in vivo. The results showed that AG or M-AG inhibited the VEGF secretion of tumor cells, the relative inhibition rates of AG and M-AG being 27.2% and 53.2% respectively at a concentration of 20 μL/mL. AG and M-AG inhibited the vascular endothelial (VE) cell proliferation with IC50 values of 11.5 ± 0.5 μL/mL and 12.9 ± 0.4 μL/mL respectively. The VE cell migration potential was inhibited significantly (p<0.01) by the AG (≥ 24 μL/mL) or M-AG (≥ 12 μL/ mL) treatment. In vivo, neovascularization of CAM treated with M-AG was inhibited significantly (p<0.05) at a concentration of 0.4 μL/mL. This study provided evidence that anti-angiogenesis is one of the anti-tumor mechanisms of AG and M-AG, with the latter as a promising active component.

FKBPL is a critical antiangiogenic regulator of developmental and pathological angiogenesis

OBJECTIVE

The antitumor effects of FK506-binding protein like (FKBPL) and its extracellular role in angiogenesis are well characterized; however, its role in physiological/developmental angiogenesis and the effect of FKBPL ablation has not been evaluated. This is important as effects of some angiogenic proteins are dosage dependent. Here we evaluate the regulation of FKBPL secretion under angiogenic stimuli, as well as the effect of FKBPL ablation in angiogenesis using mouse and zebrafish models.

APPROACH AND RESULTS

FKBPL is secreted maximally by human microvascular endothelial cells and fibroblasts, and this was specifically downregulated by proangiogenic hypoxic signals, but not by the angiogenic cytokines, VEGF or IL8. FKBPL's critical role in angiogenesis was supported by our inability to generate an Fkbpl knockout mouse, with embryonic lethality occurring before E8.5. However, whilst Fkbpl heterozygotic embryos showed some vasculature irregularities, the mice developed normally. In murine angiogenesis models, including the ex vivo aortic ring assay, in vivo sponge assay, and tumor growth assay, Fkbpl(+/-) mice exhibited increased sprouting, enhanced vessel recruitment, and faster tumor growth, respectively, supporting the antiangiogenic function of FKBPL. In zebrafish, knockdown of zFkbpl using morpholinos disrupted the vasculature, and the phenotype was rescued with hFKBPL. Interestingly, this vessel disruption was ineffective when zcd44 was knocked-down, supporting the dependency of zFkbpl on zCd44 in zebrafish.

CONCLUSIONS

FKBPL is an important regulator of angiogenesis, having an essential role in murine and zebrafish blood vessel development. Mouse models of angiogenesis demonstrated a proangiogenic phenotype in Fkbpl heterozygotes.