Efficacy of Tie2 receptor antagonism in angiosarcoma

MicroRNAs and angiosarcoma: are there promising reports?

In recent years, microRNAs (miRNAs) have garnered increasing attention for their potential implications in cancer pathogenesis, functioning either as oncogenes or tumor suppressors. Notably, angiosarcoma, along with various other cardiovascular tumors such as lipomas, rhabdomyomas, hemangiomas, and myxomas, has shown variations in the expression of specific miRNA subtypes. A substantial body of evidence underscores the pivotal involvement of miRNAs in the genesis of angiosarcoma and certain cardiovascular tumors. This review aims to delve into the current literature on miRNAs and their prospective applications in cardiovascular malignancies, with a specific focus on angiosarcoma. It comprehensively covers diagnostic methods, prognostic evaluations, and potential treatments while providing a recapitulation of angiosarcoma's risk factors and molecular pathogenesis, with an emphasis on the role of miRNAs. These insights can serve as the groundwork for designing randomized control trials, ultimately facilitating the translation of these findings into clinical applications. Moving forward, it is imperative for studies to thoroughly scrutinize the advantages and disadvantages of miRNAs compared to current diagnostic and prognostic approaches in angiosarcoma and other cardiovascular tumors. Closing these knowledge gaps will be crucial for harnessing the full potential of miRNAs in the realm of angiosarcoma and cardiovascular tumor research.

OER-073: A multicenter phase 2 study evaluating the role of pazopanib in angiosarcoma

BACKGROUND

Angiosarcomas are rare mesenchymal sarcomas that can present as primary cutaneous or noncutaneous disease. They express a variety of vascular endothelial growth factor receptors. The authors hypothesized that the treatment of angiosarcoma with pazopanib, a multikinase inhibitor with activity against vascular endothelial growth factor receptors, would result in disease response and prolonged disease stabilization.

METHODS

This was an open-label, phase 2 trial of pazopanib in patients who had incurable angiosarcoma. The co-primary end points were response according to the Response Evaluation Criteria in Solid Tumors and progression-free survival (PFS) at 3 months. The starting dose of pazopanib was 800 mg daily.

RESULTS

Twenty-nine patients were accrued between 2011 and 2018, and 22 patients were evaluable for response. Toxicities were similar to those identified in prior reports. There was one partial response (3%), and the clinical benefit rate (including complete responses, partial responses, and stable disease) was 48%, which was observed more frequently in patients who had cutaneous disease. The median PFS was 14.4 weeks, and the 3-month PFS rate determined by Kaplan-Meier estimate was 54.6% (95% CI, 36.0%-82.9%), meeting the primary study objective. The Kaplan-Meier overall survival estimate was 16.1 months.

CONCLUSIONS

Pazopanib therapy in patients who had incurable angiosarcoma was associated with meaningful disease control, especially in those who had cutaneous disease with limited objective responses.

LAY SUMMARY

Angiosarcoma is a rare cancer that can be found on the skin or in internal organs. This study tested pazopanib, an oral targeted medication, to determine its benefit in patients with angiosarcoma who could not undergo the removal of their tumors by surgery. Pazopanib treatment was safe, and no new side effects were reported. The study showed that pazopanib controlled tumor growth in one half of patients at 3 months and was more common in angiosarcomas of the skin; it led to tumor shrinkage in a minority of patients (1 of 29).

Kutane Angiosarkome: molekulare Pathogenese und neue therapeutische Ansätze

Das kutane Angiosarkom (CAS) ist ein hochaggressiver maligner Tumor mit schlechter Prognose. Das primäre, spontane CAS (pCAS) und das sekundäre, mit einer Bestrahlung oder einem Lymphödem assoziierte CAS (sCAS) unterscheiden sich klinisch sowie molekular. Die Amplifikation/Überexpression von Myc ist ein charakteristisches, wenn auch nicht ausschließliches Merkmal von sCAS, während der Verlust von TP53 selektiv bei pCAS vorkommt. Detaillierte molekulare Analysen mit modernen Multi-Omics-Ansätzen haben gezeigt, dass sowohl pCAS als auch sCAS eine erhebliche molekulare Heterogenität aufweisen. Die betroffenen Gene und ihre molekularen Regulatoren sind mögliche therapeutische Zielstrukturen. Darüber hinaus kann das pCAS in Cluster mit hoher Mutationsrate und/oder ausgeprägten Entzündungssignaturen eingeteilt werden, die als Grundlage für die künftige Stratifizierung von pCAS-Patienten in immuntherapeutischen klinischen Studien dienen können. Während die Aufklärung der der Erkrankung zugrunde liegenden molekularen Veränderungen zügig voranschreitet, verläuft die Entwicklung daraus abgeleiteter neuer Therapien für das CAS jedoch bisher eher langsam. Dennoch wurden einige über die Standardtherapien wie Operation und Radiochemotherapie hinausgehende klinische Studien zu neuen Behandlungsmöglichkeiten initiiert. Dazu gehören zielgerichtete Therapien gegen VEGF und VEGFR1-3 wie Bevacizumab und Pazopanib, sowie β-Adrenozeptorenblocker wie Propranolol. Derzeit werden auch Immuntherapien entwickelt, unter anderem unter Verwendung der Immuncheckpoint-Inhibitoren Pembrolizumab und Nivolumab sowie des Anti-RANKL-Antikörper Denosumab.

Cutaneous Angiosarcomas: Molecular Pathogenesis Guides Novel Therapeutic Approaches

Cutaneous angiosarcoma (CAS) is a highly aggressive cancer with a poor prognosis. Primary, spontaneous CAS (pCAS) and secondary, post-irradiation- or lymphedema-associated CAS (sCAS) are clinically, but also molecularly distinct. Myc amplification/overexpression is a characteristic, although not exclusive feature of sCAS, while loss of TP53 selectively occurs in pCAS. Detailed molecular analyses with modern multi-omics approaches have revealed that both pCAS and sCAS exhibit considerable molecular heterogeneity. Affected genes and their molecular regulators including a plethora of microRNAs may serve as future drug targets. Furthermore, pCAS could be subdivided into clusters with high tumor mutational burden and/or high tumor inflammation signatures providing a rationale for the stratification of pCAS patients in future immunotherapeutic clinical studies. Development of novel treatment regimens guided by these molecular alterations, however, cannot fully keep up with the pace of their discovery due to the low incidence of the disease. Nevertheless, beyond conventional surgery and chemoradiotherapy, clinical trials investigating novel treatment options have been initiated including targeted therapies against VEGF and VEGFR1-3 such as bevacizumab and pazopanib, and β-adrenoreceptor blockers such as propranolol. Finally, immunotherapies are being developed including immune checkpoint inhibitors pembrolizumab and nivolumab as well as anti-RANKL antibody denosumab.

Targeting the Angiopoietin/Tie Pathway: Prospects for Treatment of Retinal and Respiratory Disorders

Anti-angiogenic approaches have significantly advanced the treatment of vascular-related pathologies. The ephemeral outcome and known side effects of the current vascular endothelial growth factor (VEGF)-based anti-angiogenic treatments have intensified research on other growth factors. The angiopoietin/Tie (Ang/Tie) family has an established role in vascular physiology and regulates angiogenesis, vascular permeability, and inflammatory responses. The Ang/Tie family consists of angiopoietins 1-4, their receptors, tie1 and 2 and the vascular endothelial-protein tyrosine phosphatase (VE-PTP). Modulation of Tie2 activation has provided a promising outcome in preclinical models and has led to clinical trials of Ang/Tie-targeting drug candidates for retinal disorders. Although less is known about the role of Ang/Tie in pulmonary disorders, several studies have revealed great potential of the Ang/Tie family members as drug targets for pulmonary vascular disorders as well. In this review, we summarize the functions of the Ang/Tie pathway in retinal and pulmonary vascular physiology and relevant disorders and highlight promising drug candidates targeting this pathway currently being or expected to be under clinical evaluation for retinal and pulmonary vascular disorders.

The efficacy of eribulin mesylate for patients with cutaneous angiosarcoma previously treated with taxane: a multicentre prospective observational study

BACKGROUND

Taxanes are the current first-line treatment for advanced cutaneous angiosarcoma (CAS) for patients who are considered difficult to treat with doxorubicin owing to advanced age or comorbidity. However, no effective second-line therapy for such patients has been established.

METHODS

We designed a single-arm prospective observational study of eribulin mesylate (ERB) administered at a dose of 1·4 mg m^-2 on days 1 and 8 in a 21-day cycle. Patients with advanced CAS who were previously treated with a taxane and were scheduled to begin ERB treatment were enrolled. The primary endpoint was overall survival (OS) and the secondary endpoints were response rate (RR), progression-free survival (PFS) and toxicity assessment.

RESULTS

We enrolled a total of 25 patients. The median OS and PFS were 8·6 months and 3·0 months, respectively. The best overall RR was 20% (five of 25). In total, 16 grade 3/4 severe adverse events (SAEs) occurred; however, all patients recovered. Patients who achieved partial response or stable disease as best response had longer OS than those with progressive disease (median OS not reached and 3·3 months, respectively; P < 0·001). Patients who did not experience SAEs showed longer OS than those who did (median OS 18·8 months and 7·5 months, respectively; P < 0·05). Patients with distant metastasis had shorter median OS than those with locoregional disease, but without statistically significant difference.

CONCLUSIONS

ERB showed a promising RR and is a potential candidate for second-line treatment for patients with CAS, after treatment with taxanes. However, owing to the occurrence of SAEs in over half of the participants, caution should be exercised regarding ERB use in elderly patients. What is already known about this topic? Taxanes are the current first-line treatment for patients with advanced cutaneous angiosarcoma (CAS) who are considered difficult to treat with doxorubicin owing to advanced age or comorbidity. No effective therapy for taxane-resistant CAS has been established thus far. Eribulin suppresses microtubule polymerization and elicits an antitumour effect similar to that of taxanes. What does this study add? In our single-arm prospective observational study to evaluate the efficacy of eribulin for treating patients with advanced CAS who previously received taxanes, the median overall survival and progression-free survival were 8·6 and 3·0 months, respectively. Response rates at weeks 7, 13 and 25 were 20%, 17% and 14%, respectively. Although 16 grade 3/4 severe adverse events occurred, all patients recovered. Eribulin showed a promising response rate and is a potential candidate for second-line treatment in CAS after taxane treatment. Linked Comment: Smrke and Benson. Br J Dermatol 2020; 183:797-798.

Treatment with a Combination of Metformin and 2-Deoxyglucose Upregulates Thrombospondin-1 in Microvascular Endothelial Cells: Implications in Anti-Angiogenic Cancer Therapy

Metformin, the most widely used anti-diabetic drug, also exhibits anti-cancer properties; however, the true potential of metformin as an anticancer drug remains largely unknown. In this study using mouse microvascular endothelial cells (MMECs), we investigated the effects of metformin alone or in combination with the glycolytic inhibitor, 2-deoxyglucose (2DG), on angiogenesis-a process known to be an integral part of tumor growth, cancer cell survival and metastasis. MMECs were exposed to 2DG (1–10 mM) for 48 h in the absence or presence of metformin (2 mM). The status of angiogenic and anti-angiogenic marker proteins, proteins of the mTOR pathway and cell-cycle-related proteins were quantified by Western blot analysis. Assays for cell proliferation, migration and tubulogenesis were also performed. We observed robust up-regulation of anti-angiogenic thrombospondin-1 (TSP1) and increased TSP1-CD36 co-localization with a marked decrease in the levels of phosphorylated vascular endothelial growth factor receptor-2 (pVEGFR2; Y1175) in 2DG (5 mM) exposed cells treated with metformin (2 mM). Additionally, treatment with metformin and 2DG (5 mM) inhibited the Akt/mTOR pathway and down-regulated the cell-cycle-related proteins such as p-cyclin B1 (S147) and cyclins D1 and D2 when compared to cells that were treated with either 2DG or metformin alone. Treatment with a combination of 2DG (5 mM) and metformin (2 mM) also significantly decreased cell proliferation, migration and tubulogenic capacity when compared to cells that were treated with either 2DG or metformin alone. The up-regulation of TSP1, inhibition of cell proliferation, migration and tubulogenesis provides support to the argument that the combination of metformin and 2DG may prove to be an appropriate anti-proliferative and anti-angiogenic therapeutic strategy for the treatment of some cancers.

miR-15a/-16 Inhibit Angiogenesis by Targeting the Tie2 Coding Sequence: Therapeutic Potential of a miR-15a/16 Decoy System in Limb Ischemia

MicroRNA-15a (miR-15a) and miR-16, which are transcribed from the miR-15a/miR-16-1 cluster, inhibit post-ischemic angiogenesis. MicroRNA (miRNA) binding to mRNA coding sequences (CDSs) is a newly emerging mechanism of gene expression regulation. We aimed to (1) identify new mediators of the anti-angiogenic action of miR-15a and -16, (2) develop an adenovirus (Ad)-based miR-15a/16 decoy system carrying a luciferase reporter (Luc) to both sense and inhibit miR-15a/16 activity, and (3) investigate Ad.Luc-Decoy-15a/16 therapeutic potential in a mouse limb ischemia (LI) model. LI increased miR-15a and -16 expression in mouse muscular endothelial cells (ECs). The miRNAs also increased in cultured human umbilical vein ECs (HUVECs) exposed to serum starvation, but not hypoxia. Using bioinformatic tools and luciferase activity assays, we characterized miR-15a and -16 binding to Tie2 CDS. In HUVECs, miR-15a or -16 overexpression reduced Tie2 at the protein, but not the mRNA, level. Conversely, miR-15a or -16 inhibition improved angiogenesis in a Tie2-dependent manner. Local Ad.Luc-Decoy-15a/16 delivery increased Tie2 levels in ischemic skeletal muscle and improved post-LI angiogenesis and perfusion recovery, with reduced toe necrosis. Bioluminescent imaging (in vivo imaging system [IVIS]) provided evidence that the Ad.Luc-Decoy-15a/16 system responds to miR-15a/16 increases. In conclusion, we have provided novel mechanistic evidence of the therapeutic potential of local miR-15a/16 inhibition in LI.

Potent and PPARα-independent anti-proliferative action of the hypolipidemic drug fenofibrate in VEGF-dependent angiosarcomas in vitro

Angiosarcomas are highly aggressive tumors of endothelial origin, which carry a poor prognosis. Fenofibrate is a hypolipidemic drug, which acts by activating the transcription factor PPARα. It has also been widely reported to have ‘anti-cancer’ activity. The current study investigated its effect in a murine VEGF-dependent angiosarcoma cell-line, MS1 VEGF. The study utilised assays to monitor cell proliferation and viability, apoptosis, cell cycle progression, mitochondrial membrane potential, changes in protein expression, and changes in miRNA expression using microarrays. Fenofibrate showed potent anti-proliferative action in MS1 VEGF angiosarcoma cells, without inducing apoptosis. It enriched cells in G2/M cell cycle phase and hyperpolarised mitochondria. Other PPARα activators failed to mimic fenofibrate action. Inhibitors of PPARα and NFκB failed to reverse the inhibitory effect of fenofibrate and their combination with fenofibrate was cytotoxic. Fenofibrate downregulated the expression of key VEGF-effector proteins, including Akt, ERK, Bcl-2 and survivin, and a chemical inhibitor screen discovered relevance of these proteins to cell proliferation. A miRNA microarray revealed that fenofibrate differentially regulated cellular miRNAs with known roles in cancer and angiogenesis. The data raise the possibility that fenofibrate could be useful in angiosarcoma therapy, especially considering its well-established clinical safety and tolerability profile.

Phosphorylation of serine/arginine-rich splicing factor 1 at tyrosine 19 promotes cell proliferation in pediatric acute lymphoblastic leukemia

Serine/arginine‐rich splicing factor 1 (SRSF1) has been linked to various human cancers including pediatric acute lymphoblastic leukemia (ALL). Our previous study has shown that SRSF1 potentially contributes to leukemogenesis; however, its underlying mechanism remains unclear. In this study, leukemic cells were isolated from pediatric ALL bone marrow samples, followed by immunoprecipitation assays and mass spectrometry analysis specific to SRSF1. Subcellular localization of the SRSF1 protein and its mutants were analyzed by immunofluorescence staining. Cell growth, colony formation, cell apoptosis, and the cell cycle were investigated using stable leukemic cell lines generated with lentivirus‐mediated overexpressed WT or mutant plasmids. Cytotoxicity of the Tie2 kinase inhibitor was also evaluated. Our results showed the phosphorylation of SRSF1 at tyrosine 19 (Tyr‐19) was identified in newly diagnosed ALL samples, but not in complete remission or normal control samples. Compared to the SRSF1 WT cells, the missense mutants of the Tyr‐19 phosphorylation affected the subcellular localization of SRSF1. In addition, the Tyr‐19 phosphorylation of SRSF1 also led to increased cell proliferation and enhanced colony‐forming properties by promoting the cell cycle. Remarkably, we further identified the kinase Tie2 as a potential therapeutic target in leukemia cells. In conclusion, we identify for the first time that the phosphorylation state of SRSF1 is linked to different phases in pediatric ALL. The Tyr‐19 phosphorylation of SRSF1 disrupts its subcellular localization and promotes proliferation in leukemia cells by driving cell‐cycle progression. Inhibitors targeting Tie2 kinase that could catalyze Tyr‐19 phosphorylation of SRSF1 offer a promising therapeutic target for treatment of pediatric ALL.

Prognostic and predictive factors for angiosarcoma patients receiving paclitaxel once weekly plus or minus bevacizumab: an ancillary study derived from a randomized clinical trial

BACKGROUND

We report here a correlation analysis conducted along with a phase II trial assessing bevacizumab in combination with weekly paclitaxel.

METHODS

Circulating pro/anti-angiogenic factors were assessed on day 1 (D1) and day 8 (D8). The prognostic value for progression-free survival (PFS) was evaluated using a Cox model with biomarkers as continuous variables.

RESULTS

Among the 51 patients enrolled and treated in this trial, biomarker analysis was performed for 42: 18 in Arm A (single-agent) and 24 in Arm B (combination). With a median follow-up of 46 months, PFS was 5.5 versus 5.7 months, respectively (p = 0.75). According to univariate analysis, factors associated with a poor PFS were as follows: visceral angiosarcoma, de novo angiosarcoma, and high PlGF and low VEGF-C baseline values. In multivariate analysis, de novo angiosarcoma (HR = 2.5; p = 0.024) and baseline VEGF-C value (HR = 0.7; p = 0.003) were significant prognostic factors. We observed a significant increase in circulating PlGF (< 0.001) and a decrease in VEGF (< 0.001) during bevacizumab treatment. An increase in FGF was associated with a poor outcome.

CONCLUSIONS

De novo angiosarcoma and a low baseline level of VEGF-C were found to be associated with a poor prognosis. Addition of bevacizumab induces major changes in circulating biomarkers (VEGF and PlGF) in a short timeframe without impacting PFS.

TRIAL REGISTRATION

Retrospectively registered on EudraCT N° 2009-017020-59 and NCT01303497 (February 24, 2011).

Targeting the Tie2-αvβ3 integrin axis with bi-specific reagents for the inhibition of angiogenesis

BACKGROUND

Increased activity of the receptor tyrosine kinase Tie2 has been implicated in the promotion of pathological angiogenesis. This activity is mainly mediated through angiopoietin (Ang)1- and Ang2-dependent activation of integrins by Tie2, rendering the Ang/Tie2/integrin axis an attractive putative target for cancer therapeutics.

RESULTS

To target this axis, we developed single domain, non-immunoglobulin high-affinity bi-specific protein inhibitors against both Tie2 and αvβ3 integrin. We have previously engineered the Ang2-binding domain of Tie2 (Ang2-BD) as a Tie2 inhibitor. Here, we engineered an exposed loop in Ang2-BD to generate variants that include an integrin-binding Arg-Gly-Asp (RGD) motif and used flow cytometry screening of a yeast-displayed Ang2-BD RGD loop library to identify the integrin antagonists. The bi-specific antagonists targeting both Tie2 and αvβ3 integrin inhibited adhesion and proliferation of endothelial cells cultured together with the αvβ3 integrin ligand vitronectin, as well as endothelial cell invasion and tube formation. The bi-specific reagents inhibited downstream signaling by Tie2 intracellularly in response to its agonist Ang1 more effectively than the wild-type Ang2 BD that binds Tie2 alone.

CONCLUSIONS

Collectively, this study-the first to describe inhibitors targeting all the known functions resulting from Tie2/integrin αvβ3 cross-talk-has created new tools for studying Tie2- and integrin αvβ3-dependent molecular pathways and provides the basis for the rational and combinatorial engineering of ligand-Tie2 and ligand-integrin αvβ3 receptor interactions. Given the roles of these pathways in cancer angiogenesis and metastasis, this proof of principle study paves the route to create novel Tie2/integrin αvβ3-targeting proteins for clinical use as imaging and therapeutic agents.

Primary Colonic Angiosarcoma Seen in a Patient on Calcium Channel Blocker: A Case Report with Summary Analysis of 32 Other Cases from the Literature

Patient: Female, 54

Final Diagnosis: Primary colonic angiosarcoma

Symptoms: Rectal bleeding

Medication: Levamlodipine Besylate

Clinical Procedure: Hemicolectomy

Specialty: Gastroenterology and Hepatology

Cutaneous Angiosarcoma: The Possibility of New Treatment Options Especially for Patients with Large Primary Tumor

The most widely accepted treatment for cutaneous angiosarcoma (CAS) is wide local excision and postoperative radiation to decrease the risk of recurrence. Positive surgical margins and large tumors (T2, >5 cm) are known to be associated with poor prognosis. Moreover, T2 tumors are known to be associated with positive surgical margins. According to previous reports, the majority of CAS patients in Japan had T2 tumors, whereas less than half of the patients in the studies from western countries did so. Consequently, the reported 5-year overall survival of Japanese CAS patients without distant metastasis was only 9%, lower than that for stage-IV melanoma. For patients with T2 tumors, management of subclinical metastasis should be considered when planning the initial treatment. Several attempts to control subclinical metastasis have been reported, such as using adjuvant/neoadjuvant chemotherapy in addition to conventional surgery plus radiation. Unfortunately, those attempts did not show any clinical benefit. Besides surgery, new chemotherapeutic approaches for advanced CAS have been introduced in the past couple of decades, such as paclitaxel and docetaxel. We proposed the use of chemoradiotherapy (CRT) using taxanes instead of surgery plus radiation for patients with T2 tumors without distant metastasis and showed a high response ratio with prolonged survival. However, this prolonged survival was seen only in patients who received maintenance chemotherapy after CRT, indicating that continuous chemotherapy is mandatory to control subclinical residual tumors. With the recent development of targeted drugs for cancer, many potential drugs for CAS are now available. Given that CAS expresses a high level of vascular endothelial growth factor (VEGF) receptor, drugs that target VEGF signaling pathways such as anti-VEGF monoclonal antibody and tyrosine kinase inhibitors are also promising, and several successful treatments have been reported. Besides targeted drugs, several new cytotoxic anticancer drugs such as eribulin or trabectedin have also been shown to be effective for advanced sarcoma. However, most of the clinical trials did not include a sufficient number of CAS patients. Therefore, clinical trials focusing only on CAS should be performed to evaluate the effectiveness of these new drugs.

Negative pressure wound therapy: Regulating blood flow perfusion and microvessel maturation through microvascular pericytes

Negative pressure wound therapy (NPWT) has been demonstrated to accelerate wound healing by promoting angiogenesis. However, whether blood flow perfusion is regulated by microvessel maturation and pericytes following NPWT remains unclear, as well as the exact association between pericytes and collagen type IV. The aim of this study was to investigate the relevant association between blood flow perfusion and microvessel maturation and pericytes following NPWT, and to further explore the underlying molecular mechanisms. We also aimed to investigate the association between pericytes and collagen type IV. For this purpose, we created a rat model of diabetic wounds and microvascular blood flow perfusion was detected using a laser Doppler blood perfusion imager. The expression levels of angiogenin-1, tyrosine phosphorylation of tyrosine kinase receptor-2 (Tie-2), α-smooth muscle actin (α-SMA) and collagen type IV were detected and analyzed through immunohistochemistry, immunofluorescence, RT-qPCR and western blot analysis. The results revealed that NPWT promoted the overexpression of angiogenin-1, Tie-2, α-SMA and collagen type IV, and significantly increased blood flow perfusion coupled with microvessel maturation in the NPWT group at the later stages (7–10 days) of wound healing. Our results suggested that NPWT can preferentially enhance vessel maturation and increase the number of pericytes, thus regulating blood flow perfusion. On the other hand, pericytes and collagen type IV had a mutual interaction, promoting microvessel maturation.

Nitric-oxide synthase trafficking inducer is a pleiotropic regulator of endothelial cell function and signaling

Endothelial nitric-oxide synthase (eNOS) and its bioactive product, nitric oxide (NO), mediate many endothelial cell functions, including angiogenesis and vascular permeability. For example, vascular endothelial growth factor (VEGF)-mediated angiogenesis is inhibited upon reduction of NO bioactivity both in vitro and in vivo Moreover, genetic disruption or pharmacological inhibition of eNOS attenuates angiogenesis during tissue repair, resulting in delayed wound closure. These observations emphasize that eNOS-derived NO can promote angiogenesis. Intriguingly, eNOS activity is regulated by nitric-oxide synthase trafficking inducer (NOSTRIN), which sequesters eNOS, thereby attenuating NO production. This has prompted significant interest in NOSTRIN's function in endothelial cells. We show here that NOSTRIN affects the functional transcriptome of endothelial cells by down-regulating several genes important for invasion and angiogenesis. Interestingly, the effects of NOSTRIN on endothelial gene expression were independent of eNOS activity. NOSTRIN also affected the expression of secreted cytokines involved in inflammatory responses, and ectopic NOSTRIN overexpression functionally restricted endothelial cell proliferation, invasion, adhesion, and VEGF-induced capillary tube formation. Furthermore, NOSTRIN interacted directly with TNF receptor-associated factor 6 (TRAF6), leading to the suppression of NFκB activity and inhibition of AKT activation via phosphorylation. Interestingly, TNF-α-induced NFκB pathway activation was reversed by NOSTRIN. We found that the SH3 domain of NOSTRIN is involved in the NOSTRIN-TRAF6 interaction and is required for NOSTRIN-induced down-regulation of endothelial cell proteins. These results have broad biological implications, as aberrant NOSTRIN expression leading to deactivation of the NFκB pathway, in turn triggering an anti-angiogenic cascade, might inhibit tumorigenesis and cancer progression.

Angiopoetin-2 Signals Do Not Mediate the Hypervascularization of Islets in Type 2 Diabetes

AIMS

Changes in the islet vasculature have been implicated in the regulation of β-cell survival and function during the progression to type 2 diabetes (T2D). Failure of the β-cell to compensate for the increased insulin demand in obesity eventually leads to diabetes; as a result of the complex interplay of genetic and environmental factors (e.g. ongoing inflammation within the islets) and impaired vascular function. The Angiopoietin/Tie (Ang/Tie) angiogenic system maintains vasculature and is closely related to organ inflammation and angiogenesis. In this study we aimed to identify whether the vessel area within the islets changes in diabetes and whether such changes would be triggered by the Tie-antagonist Ang-2.

METHODS

Immunohistochemical and qPCR analyses to follow islet vascularization and Ang/Tie levels were performed in human pancreatic autopsies and isolated human and mouse islets. The effect of Ang-2 was assessed in β-cell-specific Ang-2 overexpressing mice during high fat diet (HFD) feeding.

RESULTS

Islet vessel area was increased in autopsy pancreases from patients with T2D. The vessel markers Tie-1, Tie-2 and CD31 were upregulated in mouse islets upon HFD feeding from 8 to 24 weeks. Ang-2 was transiently upregulated in mouse islets at 8 weeks of HFD and under glucolipotoxic conditions (22.2 mM glucose/ 0.5 mM palmitate) in vitro in human and mouse islets, in contrast to its downregulation by cytokines (IL-1β, IFN-ɣ and TNF-α). Ang-1 on the other hand was oppositely regulated, with a significant loss under glucolipotoxic condition, a trend to reduce in islets from patients with T2D and an upregulation by cytokines. Modulation of such changes in Ang-2 by its overexpression or the inhibition of its receptor Tie-2 impaired β-cell function at basal conditions but protected islets from cytokine induced apoptosis. In vivo, β-cell-specific Ang-2 overexpression in mice induced hypervascularization under normal diet but contrastingly led to hypovascularized islets in response to HFD together with increased apoptosis and reduced β-cell mass.

CONCLUSIONS

Islet hypervascularization occurs in T2D. A balanced expression of the Ang1/Ang2 system is important for islet physiology. Ang-2 prevents β-cell mass and islet vascular adaptation in response to HFD feeding with no major influence on glucose homeostasis.

Paclitaxel Given Once Per Week With or Without Bevacizumab in Patients With Advanced Angiosarcoma: A Randomized Phase II Trial

Purpose

The aim of this randomized, phase II trial was to explore the activity and safety of adding bevacizumab to paclitaxel once per week in treatment of angiosarcomas (AS).

Methods

Patients were treated with paclitaxel alone (90 mg/m2 per week for six cycles of 28 days each; arm A) or with paclitaxel combined with bevacizumab (10 mg/kg once every 2 weeks; arm B). In the combination treatment arm, bevacizumab was administered after the six cycles of chemotherapy as maintenance therapy (15 mg/kg once every 3 weeks) until intolerance or progression occurred. Stratification factors were superficial versus visceral AS and de novo versus radiation-induced AS. The primary end point was the 6-month progression-free survival (PFS) rate, which was based on RECIST, version 1.1. Statistical assumptions were P0 = 20%, P1 = 40%, a = 10%, and b = 20%. P0 was the PFS rate at 6 months defining inactive drug, and P1 was the PFS rate at 6 months defining promising drug.

Results

A total of 52 patients were enrolled, and 50 were randomly assigned in 14 centers. The most common primary sites were the breast (49%) and skin (12%). There were 17 (34%) visceral and 24 (49%) radiation-induced AS. The performance status was 0 in 24 patients (49%) and 1 in the remaining 25 patients (51%). The median follow-up time was 14.5 months. Both treatment regimens were considered active, with 6-month PFS rates of 54% (14 of 26) in arm A and 57% (14 of 24) in arm B. The median overall survival rates were 19.5 months in arm A and 15.9 months in arm B. Toxicity was higher with the combination arm and included one fatal drug-related toxicity (intestinal occlusion).

Conclusion

The primary objective was met in both treatment arms. However, the present data do not support additional clinical investigation of combined paclitaxel/bevacizumab for the treatment of advanced AS.

Generation of a murine hepatic angiosarcoma cell line and reproducible mouse tumor model

Hepatic angiosarcoma (AS) is a rare and highly aggressive tumor of endothelial origin with dismal prognosis. Studies of the molecular biology of AS and treatment options are limited as animal models are rare. We have previously shown that inducible knockout of Notch1 in mice leads to spontaneous formation of hepatic AS. The aims of this study were to: (1) establish and characterize a cell line derived from this murine AS, (2) identify molecular pathways involved in the pathogenesis and potential therapeutic targets, and (3) generate a tumor transplantation model. AS cells retained specific endothelial properties such as tube formation activity, as well as expression of CD31 and Von Willebrand factor. However, electron microscopy analysis revealed signs of dedifferentiation with loss of fenestrae and loss of contact inhibition. Microarray and pathway analysis showed substantial changes in gene expression and revealed activation of the Myc pathway. Exposing the AS cells to sorafenib reduced migration, filopodia dynamics, and cell proliferation but did not induce apoptosis. In addition, sorafenib suppressed ERK phosphorylation and expression of cyclin D2. Injection of AS cells into NOD/SCID mice resulted in formation of undifferentiated tumors, confirming the tumorigenic potential of these cells. In summary, we established and characterized a murine model of spontaneous AS formation and hepatic AS cell lines as a useful in vitro tool. Our data demonstrate antitumor activity of sorafenib in AS cells with potent inhibition of migration, filopodia formation, and cell proliferation, supporting further evaluation of sorafenib as a novel treatment strategy. In addition, AS cell transplantation provides a subcutaneous tumor model useful for in vivo preclinical drug testing.

Angiosarcoma outcomes and prognostic factors: a 25-year single institution experience

OBJECTIVE

Angiosarcoma is an aggressive malignancy with endothelial differentiation and notoriously poor prognosis despite aggressive therapy. Limited data are available to guide management decisions. To address this limitation, we present a large retrospective analysis of angiosarcoma patients treated at a single institution over a 25-year period.

METHODS

To identify factors that impact angiosarcoma outcomes, we reviewed demographic, tumor, and treatment characteristics of angiosarcoma patients evaluated at the University of Wisconsin Hospital between 1987 and 2012.

RESULTS

The cohort included 81 patients diagnosed at ages 19 to 90 years (median, 67 y). Fifty-five (68%) patients presented with localized disease, whereas 26 (32%) presented with metastases. The primary sites were visceral/deep soft tissue (42%), head and neck/cutaneous (37%), breast (16%), and limbs in the setting of Stewart-Treves (5%). The 5-year overall survival was 40% with a median of 16 months. By univariate analysis, significant adverse predictors of survival included metastases at presentation, visceral/deep soft tissue tumor location, tumor size > 5 cm, tumor necrosis, and the absence of surgical excision. A trend toward prolonged survival was observed with radiation therapy and for chemotherapy in patients with metastases. Age, sex, and prior radiation showed no correlation with survival.

CONCLUSIONS

Our large single institution series confirms the poor prognosis of angiosarcoma, supports a central role for surgical excision in management, and highlights the need for novel therapies particularly in patients who present with metastatic disease.

Cancer subclonal genetic architecture as a key to personalized medicine

The future of personalized oncological therapy will likely rely on evidence-based medicine to integrate all of the available evidence to delineate the most efficacious treatment option for the patient. To undertake evidence-based medicine through use of targeted therapy regimens, identification of the specific underlying causative mutation(s) driving growth and progression of a patient's tumor is imperative. Although molecular subtyping is important for planning and treatment, intraclonal genetic diversity has been recently highlighted as having significant implications for biopsy-based prognosis. Overall, delineation of the clonal architecture of a patient's cancer and how this will impact on the selection of the most efficacious therapy remain a topic of intense interest.

Irradiation-induced angiosarcoma and anti-angiogenic therapy: a therapeutic hope?

Angiosarcomas are rare soft-tissue sarcomas of endothelial cell origin. They can be sporadic or caused by therapeutic radiation, hence secondary breast angiosarcomas are an important subgroup of patients. Assessing the molecular biology of angiosarcomas and identify specific targets for treatment is challenging. There is currently great interest in the role of angiogenesis and of angiogenic factors associated with tumor pathogenesis and as targets for treatment of angiosarcomas. A primary cell line derived from a skin fragment of a irradiation-induced angiosarcoma patient was obtained and utilized to evaluate cell biomarkers CD31, CD34, HIF-1 alpha and VEGFRs expression by immunocytochemistry and immunofluorescence, drugs cytotoxicity by cell counting and VEGF release by ELISA immunoassay. In addition to previous biomarkers, FVIII and VEGF were also evaluated on tumor specimens by immunohistochemistry to further confirm the diagnosis. We targeted the VEGF-VEGFR-2 axis of tumor angiogenesis with two different class of vascular targeted drugs; caprelsa, the VEGFR-2/EGFR/RET inhibitor and bevacizumab the anti-VEGF monoclonal antibody. We found the same biomarkers expression either in tumor specimens and in the cell line derived from tumor. In vitro experiments demonstrated that angiogenesis plays a pivotal role in the progression of this tumor as cells displayed high level of VEGFR-2, HIF-1 alpha strongly accumulated into the nucleus and the pro-angiogenic factor VEGF was released by cells in culture medium. The evaluation of caprelsa and bevacizumab cytotoxicity demonstrated that both drugs were effective in inhibiting tumor proliferation. Due to these results, we started to treat the patient with pazopanib, which was the unique tyrosine kinase inhibitor available in Italy through a compassionate supply program, obtaining a long lasting partial response. Our data suggest that the study of the primary cell line could help physicians in choosing a therapeutic approach for patient that almost in vitro shows chances of success and that the anti-angiogenetic agents are a reliable therapeutic opportunity for angiosarcomas patients.

Vascular tumors have increased p70 S6-kinase activation and are inhibited by topical rapamycin

Vascular tumors are endothelial cell neoplasms whose cellular and molecular mechanisms, leading to tumor formation, are poorly understood, and current therapies have limited efficacy with significant side effects. We have investigated mechanistic (mammalian) target of rapamycin (mTOR) signaling in benign and malignant vascular tumors, and the effects of mTOR kinase inhibitor as a potential therapy for these lesions. Human vascular tumors (infantile hemangioma and angiosarcoma) were analyzed by immunohistochemical stains and western blot for the phosphorylation of p70 S6-kinase (S6K) and S6 ribosomal protein (S6), which are activated downstream of mTOR complex-1 (mTORC1). To assess the function of S6K, tumor cells with genetic knockdown of S6K were analyzed for cell proliferation and migration. The effects of topical rapamycin, an mTOR inhibitor, on mTORC1 and mTOR complex-2 (mTORC2) activities, as well as on tumor growth and migration, were determined. Vascular tumors showed increased activation of S6K and S6. Genetic knockdown of S6K resulted in reduced tumor cell proliferation and migration. Rapamycin fully inhibited mTORC1 and partially inhibited mTORC2 activities, including the phosphorylation of Akt (serine 473) and PKCα, in vascular tumor cells. Rapamycin significantly reduced vascular tumor growth in vitro and in vivo. As a potential localized therapy for cutaneous vascular tumors, topically applied rapamycin effectively reduced tumor growth with limited systemic drug absorption. These findings reveal the importance of mTOR signaling pathways in benign and malignant vascular tumors. The mTOR pathway is an important therapeutic target in vascular tumors, and topical mTOR inhibitors may provide an alternative and well-tolerated therapy for the treatment of cutaneous vascular lesions.

Clinical and endoscopic features of angiosarcoma of the colon: two case reports and a review of the literature

BACKGROUND

Angiosarcoma of the gastrointestinal tract is an extremely rare tumor. We present two cases of angiosarcoma of the colon. One patient developed syncope and anemia and the other had rectal bleeding.

DISCUSSION

Endoscopic findings of the colon were different; the first case demonstrated a reddened colonic fold without an obvious mass and the other had an ulcerated friable mass. Both of the tumors had positive immunohistochemical stains for CD31 and CD34 (one was also positive for CD117). Surgery was not performed in either case. Treatment included chemotherapy with imatinib for the first patient and paclitaxel for the second. Prognosis for this tumor is generally poor; in our cases, one patient was still alive after 5 months of follow-up and the other died within 2 months of diagnosis. After presenting our cases, we reviewed the current literature on angiosarcoma of the colon.

Expression of angiopoietin-TIE system components in angiosarcoma

Angiosarcoma is an aggressive malignancy of endothelial differentiation. Potential roles of the endothelial angiopoietin-tunica interna endothelial cell kinase (ANGPT-TIE) system in angiosarcoma diagnosis, pathogenesis, prognosis and treatment are undefined. To examine the expression and prognostic significance of angiopoietin-1, angiopoietin-2, TIE1 and TEK (TIE2) proteins in angiosarcoma, we immunohistochemically evaluated clinically annotated human angiosarcoma samples. Correlations of protein expression with overall survival and pathological features were explored. The cohort included 51 patients diagnosed with angiosarcoma at the age of 30-86 years (median 67). The 5-year overall survival was 45% with a median of 26 months. Moderate to strong expression of angiopoietin-1, TIE1 and TEK (TIE2) was identified in the majority of angiosarcomas and moderate to strong expression of angiopoietin-2 was observed in 42% of angiosarcomas. Increased angiopoietin-1 expression correlated with improved survival. Non-significant trends toward longer survival were also observed with increased TIE1 and TEK (TIE2) expression. Increased expression of angiopoietin-2, TIE1 and TEK (TIE2) was associated with vasoformative architecture. No differences in expression of these proteins were observed when patients were segregated by age, gender, presence or absence of metastases at diagnosis, primary tumor location, radiation association or the presence of necrosis. We conclude that components of the ANGPT-TIE system are commonly expressed in angiosarcomas. Reduced expression of these proteins is associated with non-vasoformative and clinically more aggressive lesions.

Overcoming intratumor heterogeneity of polygenic cancer drug resistance with improved biomarker integration

Improvements in technology and resources are helping to advance our understanding of cancer-initiating events as well as factors involved with tumor progression, adaptation, and evasion of therapy. Tumors are well known to contain diverse cell populations and intratumor heterogeneity affords neoplasms with a diverse set of biologic characteristics that can be used to evolve and adapt. Intratumor heterogeneity has emerged as a major hindrance to improving cancer patient care. Polygenic cancer drug resistance necessitates reconsidering drug designs to include polypharmacology in pursuit of novel combinatorial agents having multitarget activity to overcome the diverse and compensatory signaling pathways in which cancer cells use to survive and evade therapy. Advances will require integration of different biomarkers such as genomics and imaging to provide for more adequate elucidation of the spatially varying location, type, and extent of diverse intratumor signaling molecules to provide for a rationale-based personalized cancer medicine strategy.

Plasma Fibronectin Promotes Tumor Cell Survival and Invasion through Regulation of Tie2

Our previous research has shown that plasma fibronectin promotes lung metastasis by facilitating tumor cell invasion in clotted plasma. To evaluate the role of clotted plasma for tumor cell survival, we treated B16F1 cells embedded in a 3-dimensional matrix of fibrin with tumor necrosis factor α (TNFα), a cytokine with anti-tumor activity. Under these conditions, TNFα caused significant cytotoxicity, which was prevented when we added plasma fibronectin to the fibrin clot. Fibronectin-mediated TNFα resistance was dependent on PI3-kinase, which also mediated the pro-adhesive and pro-invasive effects of plasma fibronectin on tumor cells. To further investigate the role of plasma fibronectin in tumor cell signaling, we performed a gene array that showed specific upregulation of Tie2 in B16F1 cells embedded in fibrin-fibronectin compared to fibrin. Importantly, inhibition of Tie2 resulted in decreased tumor cell invasion, reduced colony formation and increased tumor cell death in response to TNFα. Together, our findings indicate that plasma fibronectin induces tumor cell invasion and protects tumor cells from the cytotoxic effects of inflammatory mediators through up-regulation of Tie2.

Regorafenib inhibits growth, angiogenesis, and metastasis in a highly aggressive, orthotopic colon cancer model

The combination of target-specific drugs like bevacizumab with chemotherapeutics has improved treatment efficacy in advanced colorectal cancer (CRC). However, the clinical prognosis of metastatic CRCs is still poor, and novel drugs are currently assessed with respect to their efficacies in patients with CRCs. In a phase III study, the multikinase inhibitor regorafenib (BAY 73-4506) has recently been shown to prolong survival of patients with CRCs after standard therapies failed. In the present study, the activity of regorafenib was investigated in comparison with the angiogenesis inhibitor DC101 in the highly aggressive, murine CT26 metastatic colon cancer model. While a treatment for 10 days with DC101 given at a dose of 34 mg/kg every third day significantly delayed tumor growth compared with vehicle-treated animals, regorafenib completely suppressed tumor growth at a daily oral dose of 30 mg/kg. Regorafenib also induced a stronger reduction in tumor vascularization, as longitudinally assessed in vivo by dynamic contrast-enhanced MRI (DCE-MRI) and confirmed by immunohistochemistry. In addition, regorafenib inhibited the angiogenic activity more strongly and induced a three times higher apoptosis rate than DC101. Even more important, regorafenib completely prevented the formation of liver metastases, whereas in DC101-treated animals, the metastatic rate was only reduced by 33% compared with the vehicle group. In addition, regorafenib significantly reduced the amount of infiltrating macrophages. These data show that the multikinase inhibitor regorafenib exerts strong antiangiogenic, antitumorigenic, and even antimetastatic effects on highly aggressive colon carcinomas indicative for its high potential in the treatment of advanced CRCs.

Aberrations in Angiogenic Signaling and MYC Amplifications are Distinguishing Features of Angiosarcoma

Angiosarcomas are very aggressive, rare malignant tumors that originate from vascular or lymphatic vessels and primarily occur following chemical exposure or radiation therapy. Tumor response to either chemotherapy, radiation, or novel anti-angiogenic therapeutics is very low, and because little is known regarding the aberrant signaling that controls these tumors, personalized treatment options for many of these patients are lacking. In this review, we summarize several recent findings regarding the genomics of angiosarcomas, including new discoveries regarding aberrant angiogenic signaling and Myc amplification as key features of this tumor type.