Silencing or fueling metastasis with VEGF inhibitors: antiangiogenesis revisited

Epithelial-mesenchymal Transition---A Hallmark of Breast Cancer Metastasis

Epithelial-mesenchymal transition (EMT) is a highly conserved cellular program that converts polarized, immotile epithelial cells to migratory mesenchymal cells. In addition, EMT was initially recognized as a key step for morphogenesis during embryonic development. Emerging evidences indicate that this important developmental program promotes metastasis, drug resistance, and tumor recurrence, features that are associated with a poor clinical outcome for patients with breast cancer. Therefore, better understanding of regulation and signaling pathways in EMT is essential to develop novel targeted therapeutics. In this review, we present updated developments underlying EMT in tumor progression and metastasis, and discuss the challenges remaining in breast cancer research.

Role for cytotoxic chemotherapy in patients with recurrent glioblastoma progressing on bevacizumab: a retrospective case series

One hundred patients, aged 36-84 years (median 62 years) with recurrent glioblastoma (GBM), were treated previously with surgery, concurrent radiotherapy and temozolomide and postradiotherapy temozolomide followed by single-agent bevacizumab (BEV) at either first (60 patients) or second recurrence (40 patients). Patients were then treated following progression on BEV only with BEV and carboplatin (75 patients), cyclophosphamide (15 patients) or BCNU (ten patients; BEV+). Three hundred and sixteen treatment cycles (median: 2; range: 1-9) were administered of BEV+. There were 74 grade 3 adverse events in 29 patients (29%) and 20 grade 4 adverse events in ten patients (10%). Following 2 months of BEV+, 60 patients (60%) demonstrated progressive disease and discontinued therapy. Forty patients (40%) had neuroradiographic stable disease. Survival ranged from 1 to 12 months (median: 4 months). Median and 6-month progression free survival was 2.5 months and 5%, respectively. BEV plus a cytotoxic chemotherapy demonstrated limited efficacy in BEV-refractory GBM and emphasizes an unmet need in neuro-oncology in adults with BEV-refractory GBM.

Diallyl trisulfide inhibits proliferation, invasion and angiogenesis of osteosarcoma cells by switching on suppressor microRNAs and inactivating of Notch-1 signaling

Notch signaling pathway plays critical roles in human cancers, including osteosarcoma, suggesting that the discovery of specific agents targeting Notch would be extremely valuable for osteosarcoma. Our previous studies have shown that diallyl trisulfide (DATS) inhibits proliferation of osteosarcoma cells by triggering cell cycle arrest and apoptosis in vitro. However, the underlying mechanism is still unclear. In this study, we found that DATS suppressed cell survival, wound-healing capacity, invasion and angiogenesis in osteosarcoma cells. These effects were associated with decreased expression of Notch-1 and its downstream genes, such as vascular endothelial growth factor and matrix metalloproteinases, as well as increased expression of a panel of tumor-suppressive microRNAs (miRNAs), including miR-34a, miR-143, miR-145 and miR-200b/c that are typically lost in osteosarcoma. We also found that reexpression of miR-34a and miR-200b by transfection led to reduced expression of Notch-1, resulting in the inhibition of osteosarcoma cell proliferation, invasion and angiogenesis. These results clearly suggest that DATS inhibited osteosarcoma growth and aggressiveness via a novel mechanism targeting a Notch-miRNA regulatory circuit. Our data provide the first evidence that the downregulation of Notch-1 and reexpression of miRNAs by DATS may be an effective approach for the treatment of osteosarcoma.

Maintenance single-agent bevacizumab or observation after first-line chemotherapy in patients with metastatic colorectal cancer: a multicenter retrospective study

The addition of bevacizumab to standard chemotherapy has improved progression-free survival (PFS) and overall survival (OS) in patients with metastatic colorectal cancer (mCRC) in both first- and second line treatment, but the role of maintenance bevacizumab remains controversial. The association of various clinical factor and survival was examined in this retrospective cohort analysis. The clinical data from 220 previously untreated patients with mCRC, not progressive at the end of standard chemotherapy plus bevacizumab, were collected and analyzed. Patients were classified into two subgroups: those given with maintenance bevacizumab: "maintenance bevacizumab cohort (n = 118; MB)", and those discontinuing bevacizumab as a result of physician's or patient's decision: "no maintenance bevacizumab cohort (n = 102; noMB)". The baseline factors were well balanced between the study subgroups. Median PFS and OS for the general population was 10 months (range 7-15) and 22.5 months (range 18-26), respectively. Median PFS was 13 and 8 months in the BM and noBM cohorts, respectively (p < 0.0001). In the multivariate analysis, maintenance therapy resulted independently associated with improved PFS (HR 1.73; p < 0.001), but only objective response (OR) after first-line chemotherapy was associated with improved OS. Maintenance chemotherapy cannot be considered a standard of care after induction chemotherapy for mCRC, because the optimal balance between efficacy and safety of maintenance therapy remains a significant challenge. The results of our retrospective study suggest that maintenance therapy with bevacizumab is a safe and valuable option, particularly in those patients achieving an objective response after first-line chemotherapy.

Microenvironment and tumor cell plasticity: an easy way out

Cancer cells undergo genetic changes allowing their adaptation to environmental changes, thereby obtaining an advantage during the long metastatic route, disseminated of several changes in the surrounding environment. In particular, plasticity in cell motility, mainly due to epigenetic regulation of cancer cells by environmental insults, engage adaptive strategies aimed essentially to survive in hostile milieu, thereby escaping adverse sites. This review is focused on tumor microenvironment as a collection of structural and cellular elements promoting plasticity and adaptive programs. We analyze the role of extracellular matrix stiffness, hypoxia, nutrient deprivation, acidity, as well as different cell populations of tumor microenvironment.

Angiotensin-(1-7) reduces proliferation and angiogenesis of human prostate cancer xenografts with a decrease in angiogenic factors and an increase in sFlt-1

BACKGROUND

Prostate cancer is the most frequently diagnosed malignancy and the second-leading cause of cancer death in men. The purpose of this study was to determine the anti-proliferative and anti-angiogenic efficacy of angiotensin-(1-7) [Ang-(1-7)], an endogenous peptide hormone, in human prostate cancer xenografts.

METHODS

Human LNCaP prostate cancer cells were injected into the flank of athymic mice and tumors were treated with Ang-(1-7) for 54 days. Tumor growth and angiogenesis were determined by immunohistochemistry and western blot hybridization.

RESULTS

Ang-(1-7) markedly reduced the volume and wet weight of LNCaP xenograft tumors. Histological analysis of tumor sections from saline-treated mice showed increased Ki67 immunoreactivity and enhanced phosphorylation of the MAP kinases ERK1/2 compared to tumors from Ang-(1-7)-treated mice, suggesting that the heptapeptide reduces cell proliferation. Intratumoral vessel density was decreased in Ang-(1-7)-treated mice with an associated reduction in vascular endothelial growth factor (VEGF) and placental growth factor (PlGF), suggesting that the heptapeptide attenuates vascularization by reducing angiogenic factors. Ang-(1-7) administration markedly increased the soluble fraction of VEGF receptor 1 (sFlt-1), with a concomitant reduction in VEGF receptors 1 and 2. sFlt-1 serves as a decoy receptor that traps VEGF and PlGF, making the ligands unavailable to membrane-bound VEGF receptors and preventing activation of pro-angiogenic signaling.

CONCLUSIONS

The decrease in PlGF and VEGF coupled with the increase in sFlt-1 suggests that Ang-(1-7) may serve as a novel anti-angiogenic therapy for prostate cancer. Further, the pleiotropic mechanisms of action by Ang-(1-7) may limit angiogenic resistance that occurs with VEGF inhibitors or receptor blockers.

Angiogenesis in neuroendocrine tumors: therapeutic applications

The considerable research efforts devoted to the understanding of the mechanisms of tumor angiogenesis have resulted in the development of targeted anti-angiogenic therapies and finally in their introduction in clinical practice. Neuroendocrine tumors (NETs), which are characterized by a high vascular supply and a strong expression of VEGF-A, one of the most potent pro-angiogenic factors, are an attractive indication for these new treatments. However, several lines of evidence show that the dense vascular networks associated with low-grade NETs are more likely to be a marker of differentiation than a marker of aggressiveness, as in other epithelial tumors. These observations form the basis for the so-called 'neuroendocrine paradox', according to which the most vascularized are the most differentiated and the less angiogenic NETs. This must be kept in mind when discussing the role of anti-angiogenic strategies in the treatment of NETs. Nevertheless, several targeted therapies, with direct or indirect anti-angiogenic properties, including anti-VEGF antibodies, tyrosine kinase inhibitors (sunitinib) and mTOR inhibitors (everolimus), have recently proven to be of clinical benefit. In addition, some drugs already used in NET treatment, such as somatostatin analogues and interferon-α, may also have anti-angiogenic properties. The main challenges for the next future are to validate biomarkers for the selection of patients and the prediction of their response to refine the indications of anti-angiogenic targeted therapies and to overcome the mechanisms of resistance, which explain the limited duration of action of most of these treatments.

Bevacizumab in stage II-III colon cancer: 5-year update of the National Surgical Adjuvant Breast and Bowel Project C-08 trial

PURPOSE

The National Surgical Adjuvant Breast and Bowel Project trial C-08 was designed to investigate the safety and efficacy of adding bevacizumab to fluorouracil, leucovorin, and oxaliplatin (FOLFOX6) for the adjuvant treatment of patients with stage 2-3 colon cancer. Our report summarizes the primary and secondary end points of disease-free and overall survival, respectively, with 5 years median follow-up time.

PATIENTS AND METHODS

Patients received modified FOLFOX6 once every 2 weeks for a 6-month period (control group) or modified FOLFOX6 for 6 months plus bevacizumab (5 mg/kg) once every 2 weeks for a 12-month period (experimental group). The primary end point of the study was disease-free survival (DFS) and overall survival (OS) was a secondary end point.

RESULTS

Of 2,673 analyzed patients, demographic factors were well-balanced by treatment. With a median follow-up of 5 years, the addition of bevacizumab to mFOLFOX6 did not result in an overall significant increase in DFS (hazard ratio [HR], 0.93; 95% CI, 0.81 to 1.08; P = .35). Exploratory analyses found that the effect of bevacizumab on DFS was different before and after a 1.25-year landmark (time-by-treatment interaction P value <.0001). The secondary end point of OS was no different between the two study arms for all patients (HR, 0.95; 95% CI, 0.79 to 1.13; P = .56) and for those with stage 3 disease (HR, 1.0; 95% CI, 0.83 to 1.21; P = .99).

CONCLUSION

Bevacizumab for 1 year with modified FOLFOX6 does not significantly prolong DFS or OS in stage 2-3 colon cancer. We observed no evidence of a detrimental effect of exposure to bevacizumab. A transient effect on disease-free survival was observed during bevacizumab exposure in the study's experimental arm.

Sorafenib down-regulates expression of HTATIP2 to promote invasiveness and metastasis of orthotopic hepatocellular carcinoma tumors in mice

BACKGROUND & AIMS

Antiangiogenic agents can sometimes promote tumor invasiveness and metastasis, but little is known about the effects of the antiangiogenic drug sorafenib on progression of hepatocellular carcinoma (HCC).

METHODS

Sorafenib was administered orally (30 mg · kg(-1) · day(-1)) to mice with orthotopic tumors grown from HCC-LM3, SMMC7721, or HepG2 cells. We analyzed survival times of mice, along with tumor growth, metastasis within liver and to lung, and induction of the epithelial-mesenchymal transition. Polymerase chain reaction arrays were used to determine the effects of sorafenib on gene expression patterns in HCC cells. We analyzed regulation of HIV-1 Tat interactive protein 2 (HTATIP2) by sorafenib and compared levels of this protein in tumor samples from 75 patients with HCC (21 who received sorafenib after resection and 54 who did not).

RESULTS

Sorafenib promoted invasiveness and the metastatic potential of orthotopic tumors grown from SMMC7721 and HCC-LM3 cells but not from HepG2 cells. In gene expression analysis, HTATIP2 was down-regulated by sorafenib. HCC-LM3 cells that expressed small hairpin RNAs against HTATIP2 (knockdown) formed less invasive tumors in mice following administration of sorafenib than HCC-LM3 without HTATIP2 knockdown. Alternatively, HepG2 cells that expressed transgenic HTATIP2 formed more invasive tumors in mice following administration of sorafenib. Sorafenib induced the epithelial-mesenchymal transition in HCC cell lines, which was associated with expression of HTATIP2. Sorafenib regulated expression of HTATIP2 via Jun-activated kinase (JAK) and signal transducer and activator of transcription (STAT)3 signaling. Sorafenib therapy prolonged recurrence-free survival in patients who expressed lower levels of HTATIP2 compared with higher levels.

CONCLUSIONS

Sorafenib promotes invasiveness and the metastatic potential of orthotopic tumors from HCC cells in mice, down-regulating expression of HTATIP2 via JAK-STAT3 signaling.

Antiangiogenesis therapy in the treatment of metastatic colorectal cancer

The process of new blood vessel formation, or angiogenesis, has become an important target for therapeutic intervention in many cancers, including metastatic colorectal cancer (mCRC). The growth and metastasis of primary tumors is dependent upon their ability to acquire and maintain an adequate blood supply; however, angiogenesis in tumors is an irregular process leading to chaotic and hyperpermeable vessels that may result in increased intratumoral pressure and poor exchange of macromolecules and oxygen. It has been hypothesized that inhibition of angiogenesis in tumors can both impair the formation of new tumor blood vessels and possibly 'normalize' the existing tumor vasculature, causing a more efficient delivery of cytotoxic chemotherapies (CTs). Over the last decade, therapies that target vascular endothelial growth factor (VEGF) have become a component of treatment for several cancers. In particular, the combination of bevacizumab with established chemotherapeutic regimens for mCRC has been shown to improve overall and progression-free survival, as well as response rates, over CT alone. Agents that target various members of the VEGF family, as well as signaling by the VEGF receptors and their tyrosine kinase components, are currently under development and evaluation in clinical trials. Integration of these new therapies into the treatment of mCRC will ultimately increase the available therapeutic options for patients. Still, many challenges remain, including identifying and validating relevant biomarkers to guide the optimal use of antiangiogenesis agents.

A possible role for microRNA-141 down-regulation in sunitinib resistant metastatic clear cell renal cell carcinoma through induction of epithelial-to-mesenchymal transition and hypoxia resistance

PURPOSE

We identified microRNA driven mechanisms in clear cell renal cell carcinoma associated with the tumor response to the multitargeted receptor tyrosine kinase inhibitor sunitinib.

MATERIALS AND METHODS

We performed screening genome-wide microRNA real-time quantitative polymerase chain reaction on 20 freshly frozen clear cell renal cell carcinoma tissue samples of patients who received sunitinib as first line targeted therapy. Nine patients with progressive disease within 6 months after initiating therapy were considered poor responders and 11 with at least 1-year progression-free survival were considered good responders. We studied microRNA-141 function in vitro by stable up-regulation of microRNA-141, quantification of target gene expression and cell viability in normoxic and hypoxic conditions. Relative expression in clinical and cell line samples was determined by real-time quantitative polymerase chain reaction. Localization of microRNA-141 and its targets was assessed by microRNA in situ hybridization and immunohistochemistry. Hypoxia induced cytotoxicity was assessed by a luminescence adenosine triphosphate detection assay.

RESULTS

Compared to good responders, microRNA-141 was significantly down-regulated in tumors of poor responders to sunitinib. This seemed spatially linked to epithelial-to-mesenchymal transition in vivo. Reintroduction of microRNA-141 in vitro reversed epithelial-to-mesenchymal transition and decreased cell viability in hypoxic conditions.

CONCLUSIONS

In our study microRNA-141 down-regulation driven epithelial-to-mesenchymal transition in clear cell renal cell carcinoma was linked to an unfavorable response to sunitinib therapy. Reintroduction of microRNA-141 in vitro led to epithelial-to-mesenchymal transition reversal and increased sensibility to a hypoxic environment. Future experiments should be done in vivo to see whether microRNA-141 driven reversal of epithelial-to-mesenchymal transition could affect the efficacy of sunitinib treatment.

The "Sharp" blade against HIF-mediated metastasis

Hypoxia-inducible factors (HIFs) control cellular adaptation to oxygen deprivation. Cancer cells engage HIFs to sustain their growth in adverse conditions, thus promoting a cellular reprograming that includes metabolism, proliferation, survival and mobility. HIFs overexpression in human cancer biopsies correlates with high metastasis and mortality. A recent report has elucidated a novel mechanism for HIFs regulation in triple-negative breast cancer. Specifically, the basic helix-loop-helix (bHLH), Sharp-1, serves HIF1α to the proteasome and promotes its O₂-indendpendet degradation, counteracting HIF-mediated metastasis. These findings shed light on how HIFs are manipulated during cancer pathogenesis.

ARTEMIN promotes de novo angiogenesis in ER negative mammary carcinoma through activation of TWIST1-VEGF-A signalling

The neurotrophic factor ARTEMIN (ARTN) has been reported to possess a role in mammary carcinoma progression and metastasis. Herein, we report that ARTN modulates endothelial cell behaviour and promotes angiogenesis in ER-mammary carcinoma (ER-MC). Human microvascular endothelial cells (HMEC-1) do not express ARTN but respond to exogenously added, and paracrine ARTN secreted by ER-MC cells. ARTN promoted endothelial cell proliferation, migration, invasion and 3D matrigel tube formation. Angiogenic behaviour promoted by ARTN secreted by ER-MC cells was mediated by AKT with resultant increased TWIST1 and subsequently VEGF-A expression. In a patient cohort of ER-MC, ARTN positively correlated with VEGF-A expression as measured by Spearman’s rank correlation analysis. In xenograft experiments, ER-MC cells with forced expression of ARTN produced tumors with increased VEGF-A expression and increased microvessel density (CD31 and CD34) compared to tumors formed by control cells. Functional inhibition of ARTN by siRNA decreased the angiogenic effects of ER-MC cells. Bevacizumab (a humanized monoclonal anti-VEGF-A antibody) partially inhibited the ARTN mediated angiogenic effects of ER-MC cells and combined inhibition of ARTN and VEGF-A by the same resulted in further significant decrease in the angiogenic effects of ER-MC cells. Thus, ARTN stimulates de novo tumor angiogenesis mediated in part by VEGF-A. ARTN therefore co-ordinately regulates multiple aspects of tumor growth and metastasis.

Mechanisms of tumor resistance to small-molecule vascular disrupting agents: treatment and rationale of combination therapy

Small-molecule vascular disrupting agents (VDAs) target the established tumor blood vessels, resulting in rapidly and selectively widespread ischemia and necrosis of central tumor; meanwhile, blood flow in normal tissues is relatively unaffected. Although VDAs therapy is considered an important option for treatment, its use is still limited. The tumor cells at the periphery are less sensitive to vascular shutdown than those at the center, and subsequently avoid a nutrient-deprived environment. This phenomenon is referred to as tumor resistance to VDAs treatment. The viable periphery rim of tumor cells contributes to tumor regeneration, metastasis, and ongoing progression. However, there is no systematic review of the plausible mechanisms of repopulation of the viable tumor cells following VDAs therapy. The purpose of this review is to provide insights into mechanisms of tumor surviving small-molecule VDAs therapy, and the synergetic treatment to the remaining viable tumor cells at the periphery.

Plexin structures are coming: opportunities for multilevel investigations of semaphorin guidance receptors, their cell signaling mechanisms, and functions

Plexin transmembrane receptors and their semaphorin ligands, as well as their co-receptors (Neuropilin, Integrin, VEGFR2, ErbB2, and Met kinase) are emerging as key regulatory proteins in a wide variety of developmental, regenerative, but also pathological processes. The diverse arenas of plexin function are surveyed, including roles in the nervous, cardiovascular, bone and skeletal, and immune systems. Such different settings require considerable specificity among the plexin and semaphorin family members which in turn are accompanied by a variety of cell signaling networks. Underlying the latter are the mechanistic details of the interactions and catalytic events at the molecular level. Very recently, dramatic progress has been made in solving the structures of plexins and of their complexes with associated proteins. This molecular level information is now suggesting detailed mechanisms for the function of both the extracellular as well as the intracellular plexin regions. Specifically, several groups have solved structures for extracellular domains for plexin-A2, -B1, and -C1, many in complex with semaphorin ligands. On the intracellular side, the role of small Rho GTPases has been of particular interest. These directly associate with plexin and stimulate a GTPase activating (GAP) function in the plexin catalytic domain to downregulate Ras GTPases. Structures for the Rho GTPase binding domains have been presented for several plexins, some with Rnd1 bound. The entire intracellular domain structure of plexin-A1, -A3, and -B1 have also been solved alone and in complex with Rac1. However, key aspects of the interplay between GTPases and plexins remain far from clear. The structural information is helping the plexin field to focus on key questions at the protein structural, cellular, as well as organism level that collaboratoria of investigations are likely to answer.

Long-term exposure to sorafenib of liver cancer cells induces resistance with epithelial-to-mesenchymal transition, increased invasion and risk of rebound growth

Sorafenib leads to a survival benefit in patients with advanced hepatocellular carcinoma but its use is hampered by the occurrence of drug resistance. To investigate the molecular mechanisms involved we developed five resistant human liver cell lines in which we studied morphology, gene expression and invasive potential. The cells changed their appearance, lost E-cadherin and KRT19 and showed high expression of vimentin, indicating epithelial-to-mesenchymal transition. Resistant cells showed reduced adherent growth, became more invasive and lost liver-specific gene expression. Furthermore, following withdrawal of sorafenib, the resistant cells showed rebound growth, a phenomenon also found in patients. This cell model was further used to investigate strategies for restoration of sensitivity to sorafenib.

Increasing the oxygen load by treatment with myo-inositol trispyrophosphate reduces growth of colon cancer and modulates the intestine homeobox gene Cdx2

Preventing tumor neovascularisation is one of the strategies recently developed to limit the dissemination of cancer cells and apparition of metastases. Although these approaches could improve the existing treatments, a number of unexpected negative effects have been reported, mainly linked to the hypoxic condition and the subsequent induction of the pro-oncogenic hypoxia inducible factor(s) resulting from cancer cells' oxygen starvation. Here, we checked in vivo on colon cancer cells an alternative approach. It is based on treatment with myo-inositol trispyrophosphate (ITPP), a molecule that leads to increased oxygenation of tumors. We provide evidence that ITPP increases the survival of mice in a model of carcinomatosis of human colon cancer cells implanted into the peritoneal cavity. ITPP also reduced the growth of subcutaneous colon cancer cells xenografted in nu/nu mice. In the subcutaneous tumors, ITPP stimulated the expression of the homeobox gene Cdx2 that is crucial for intestinal differentiation and that also has an anti-tumoral function. On this basis, human colon cancer cells were cultured in vitro in hypoxic conditions. Hypoxia was shown to decrease the level of Cdx2 protein, mRNA and the activity of the Cdx2 promoter. This decline was unrelated to the activation of HIF1α and HIF2α by hypoxia. However, it resulted from the activation of a phosphatidylinositol 3-kinases-like mitogen-activated protein kinase pathway, as assessed by the fact that LY294002 and U0126 restored high Cdx2 expression in hypoxia. Corroborating these results, U0126 recapitulated the increase of Cdx2 triggered by ITPP in subcutaneous colon tumor xenografts. The present study provides evidence that a chemical compound that increases oxygen pressure can antagonize the hypoxic setting and reduce the growth of human colon tumors implanted in nu/nu mice.

Molecular targeted therapies in hepatocellular carcinoma

In vivo tumor progression requires the supply of oxygen and nutrition by neovasculature. Hepatocellular carcinoma (HCC) is one of the typical tumors with neovascularization, and the dramatic alteration in the arterial vascularity may lead to acquisition of the potential for vascular invasiveness and metastasis. In 2008, phase III clinical trials revealed anti-angiogenic agent "sorafenib" as the first drug that demonstrated an improved overall survival in patients with advanced HCC. A new era of HCC treatment had arrived, but there has been limited further improvement in survival benefits. This review summarizes molecular targeted therapy with a focus on angiogenesis, growth signals, and mitotic abnormalities, as well as the promising concepts of "cancer stemness" and "synthetic lethality" for the strategy of targeted therapy.

Endothelial cell-to-cell junctions: adhesion and signaling in physiology and pathology

Besides intercellular recognition and adhesion, which are primarily performed by the transmembrane components, many of the molecules associated in endothelial cell-to-cell junctions initiate or regulate signal transmission. Clustering of molecules at junctions has the consequence of allowing new local interactions to direct specific cellular responses with crucial effects on the physiology and pathology of the endothelium and, more generally, of the vascular system. The implication is that cell-to-cell junctions could be envisaged as molecular targets for different types of therapeutic intervention. These could be directed to "cure" the defects of endothelial junctions that accompany several pathologies or to reversibly open them in a controlled way for the efficient delivery of drugs to the tissues. These aims can become more and more approachable as the knowledge of the molecular organization and function of endothelial junctions increases and their organ and tissue specificities become understood.

Synergy between a collagen IV mimetic peptide and a somatotropin-domain derived peptide as angiogenesis and lymphangiogenesis inhibitors

Angiogenesis is central to many physiological and pathological processes. Here we show two potent bioinformatically-identified peptides, one derived from collagen IV and translationally optimized, and one from a somatotropin domain-containing protein, synergize in angiogenesis and lymphangiogenesis assays including cell adhesion, migration and in vivo Matrigel plugs. Peptide-peptide combination therapies have recently been applied to diseases such as human immunodeficiency virus (HIV), but remain uncommon thus far in cancer, age-related macular degeneration and other angiogenesis-dependent diseases. Previous work from our group has shown that the collagen IV-derived peptide primarily binds β1 integrins, while the receptor for the somatotropin-derived peptide remains unknown. We investigate these peptides' mechanisms of action and find both peptides affect the vascular endothelial growth factor (VEGF) pathway as well as focal adhesion kinase (FAK) by changes in phosphorylation level and total protein content. Blocking of FAK both through binding of β1 integrins and through inhibition of VEGFR2 accounts for the synergy we observe. Since resistance through activation of multiple signaling pathways is a central problem of anti-angiogenic therapies in diseases such as cancer, we suggest that peptide combinations such as these are an approach that should be considered as a means to sustain anti-angiogenic and anti-lymphangiogenic therapy and improve efficacy of treatment.

Phase I study of the antiangiogenic antibody bevacizumab and the mTOR/hypoxia-inducible factor inhibitor temsirolimus combined with liposomal doxorubicin: tolerance and biological activity

PURPOSE

Preclinical data suggest that combining the mTOR/hypoxia-inducible factor (HIF) inhibitor temsirolimus and the antiangiogenesis antibody bevacizumab may augment antitumor activity as well as resensitize cells to anthracyclines.

EXPERIMENTAL DESIGN

We initiated a phase I study of bevacizumab and temsirolimus plus liposomal doxorubicin in patients with advanced malignancies. Patients (N = 136) were enrolled according to a modified 3 + 3 design plus dose expansion in responsive tumor types.

RESULTS

The most common cancers were breast (n = 29), epithelial ovarian (n = 23), and colorectal cancer (n = 17). The median number of prior chemotherapy regimens was four (range: 0-16). Grade 3 or higher adverse events (> 5%) included pancytopenia, mucositis, hand-foot syndrome, hypertension, and fistula. This regimen led to a 21% (n = 28) stable disease (SD) ≥ 6 months and 21% (n = 29) rate of partial or complete remission [PR/CR; (total SD ≥ 6 months/PR/CR = 42% (n = 57)]. PR/CR was most common in parotid gland adenocarcinoma (4/6, 67%), metaplastic breast cancer (5/12, 42%), endometrial endometrioid carcinoma (6/15, 40%), and in patients with a PIK3CA mutation and/or a PTEN mutation/loss (11/28, 39%). The maximum tolerated dose was liposomal doxorubicin 30 mg/m(2) and bevacizumab 15 mg/kg every three weeks with temsirolimus 25 mg weekly.

CONCLUSIONS

Patients tolerated bevacizumab and temsirolimus together with liposomal doxorubicin. Further evaluation, especially in patients with parotid, metaplastic breast, and endometrial endometrioid cancer, and in patients with PIK3CA and/or PTEN aberrations is warranted.

Beta-adrenergic blocking drugs in breast cancer: a perspective review

The purpose of this review is to present the preclinical, epidemiological and clinical data relevant to the association between β-blockers and breast cancer progression. Preclinical studies have shown that β-adrenergic receptor (β-AR) signalling can inhibit multiple cellular processes involved in breast cancer progression and metastasis, including extracellular matrix invasion, expression of inflammatory and chemotactic cytokines, angiogenesis and tumour immune responses. This has led to the hypothesis that the commonly prescribed class of β-AR antagonist drugs (β-blockers) may favourably impact cancer progression. A number of recent pharmacoepidemiological studies have examined the association between β-blocker exposure and breast cancer progression. The results from these studies have suggested a potential role for targeting the β-AR pathway in breast cancer patients. Larger observational studies are, however, required to confirm these results. Questions regarding the type of β-blocker, predictive biomarkers or tumour characteristics, appropriate treatment paradigms and, most importantly, efficacy must also be answered in randomized clinical studies before β-blockers can be considered a therapeutic option for patients with breast cancer.

Gene-targeting of Phd2 improves tumor response to chemotherapy and prevents side-toxicity

The success of chemotherapy in cancer treatment is limited by scarce drug delivery to the tumor and severe side-toxicity. Prolyl hydroxylase domain protein 2 (PHD2) is an oxygen/redox-sensitive enzyme that induces cellular adaptations to stress conditions. Reduced activity of PHD2 in endothelial cells normalizes tumor vessels and enhances perfusion. Here, we show that tumor vessel normalization by genetic inactivation of Phd2 increases the delivery of chemotherapeutics to the tumor and, hence, their antitumor and antimetastatic effect, regardless of combined inhibition of Phd2 in cancer cells. In response to chemotherapy-induced oxidative stress, pharmacological inhibition or genetic inactivation of Phd2 enhances a hypoxia-inducible transcription factor (HIF)-mediated detoxification program in healthy organs, which prevents oxidative damage, organ failure, and tissue demise. Altogether, our study discloses alternative strategies for chemotherapy optimization.

Molecular mechanisms of sorafenib action in liver cancer cells

Sorafenib, a multikinase inhibitor, recently received FDA approval for the treatment of advanced hepatocellular carcinoma (HCC). However, as the clinical application of sorafenib evolves, there is increasing interest in defining the mechanisms underlying its anti-tumor activity. Considering that this specific inhibitor could target unexpected molecules depending on the biologic context, a precise understanding of its mechanism of action could be critical to maximize its treatment efficacy, while minimizing adverse effects. Two human HCC cell lines (HepG2 and Huh7), carrying different biological and genetic characteristics, were used in this study to examine the intracellular events leading to sorafenib-induced HCC cell-growth inhibition. Sorafenib inhibited cell growth in both cell lines in a dose- and time-dependent manner and significantly altered expression levels of 826 and 2011 transcripts in HepG2 and Huh7 cells, respectively. Genes functionally involved in angiogenesis, apoptosis, transcription regulation, signal transduction, protein biosynthesis and modification were predominantly upregulated, while genes implicated in cell cycle control, DNA replication recombination and repair, cell adhesion, metabolism and transport were mainly downregulated upon treatment. However, each sorafenib-treated HCC cell line displayed specificity in the expression and activity of crucial factors involved in hepatocarcinogenesis. The altered expression of some of these genes was confirmed by semiquantitative and quantitative RT-PCR and by western blotting. Many novel genes emerged from our transcriptomics analysis that had not previously been reported to be effected by sorafenib. Further functional analyses may determine whether these genes can serve as potential molecular targets for more effective anti-HCC strategies.

Contrasting effects of sunitinib within in vivo models of metastasis

Sunitinib is a potent and clinically approved tyrosine kinase inhibitor that can suppress tumour growth by inhibiting angiogenesis. However, conflicting data exist regarding the effects of this drug on the growth of metastases in preclinical models. Here we use 4T1 and RENCA tumour cells, which both form lung metastases in Balb/c mice, to re-address the effects of sunitinib on the progression of metastatic disease in mice. We show that treatment of mice with sunitinib prior to intravenous injection of tumour cells can promote the seeding and growth of 4T1 lung metastases, but not RENCA lung metastases, showing that this effect is cell line dependent. However, increased metastasis occurred only upon administration of a very high sunitinib dose, but not when lower, clinically relevant doses were used. Mechanistically, high dose sunitinib led to a pericyte depletion effect in the lung vasculature that correlated with increased seeding of metastasis. By administering sunitinib to mice after intravenous injection of tumour cells, we demonstrate that while sunitinib does not inhibit the growth of 4T1 lung tumour nodules, it does block the growth of RENCA lung tumour nodules. This contrasting response was correlated with increased myeloid cell recruitment and persistent vascularisation in 4T1 tumours, whereas RENCA tumours recruited less myeloid cells and were more profoundly devascularised upon sunitinib treatment. Finally, we show that progression of 4T1 tumours in sunitinib treated mice results in increased hypoxia and increased glucose metabolism in these tumours and that this is associated with a poor outcome. Taken together, these data suggest that the effects of sunitinib on tumour progression are dose-dependent and tumour model-dependent. These findings have relevance for understanding how anti-angiogenic agents may influence disease progression when used in the adjuvant or metastatic setting in cancer patients.

Opportunities and challenges in tumor angiogenesis research: back and forth between bench and bed

Angiogenesis is essential for tumor growth and metastasis. Many signaling pathways are involved in regulating tumor angiogenesis, with the vascular endothelial growth factor pathway being of particular interest. The recognition of the heterogeneity in tumor vasculature has led to better predictions of prognosis through differential analyses of the vasculature. However, the clinical benefits from antiangiogenic therapy are limited, because many antiangiogenic agents cannot provide long-term survival benefits, suggesting the development of drug resistance. Activation of the hypoxia and c-Met pathways, as well as other proangiogenic factors, has been shown to be responsible for such resistance. Vessel co-option could be another important mechanism. For future development, research to improve the efficacy of antiangiogenic therapy includes (a) using tumor-derived endothelial cells for drug screening; (b) developing the drugs focusing on specific tumor types; (c) developing a better preclinical model for drug study; (d) developing more accurate biomarkers for patient selection; (e) targeting the c-Met pathway or other pathways; and (f) optimizing the dose and schedule of antiangiogenic therapy. In summary, the future of antiangiogenic therapy for cancer patients depends on our efforts to develop the right drugs, select the right patients, and optimize the treatment conditions.

The urokinase receptor (CD87) represents a central mediator of growth factor-induced endothelial cell migration

Angiogenesis, the sprouting of blood vessels form pre-existing vasculature after injury or in neoplastic diseases, is initiated by growth factor-induced endothelial cell migration. Recently, the major angiogenic growth factor VEGF165 has become the target of therapeutic interventions. However, this approach has been clinically proven to be of limited efficacy, which might be due to the fact that tumour angiogenesis is not only induced by VEGF, but also by a variety of other growth factors. Thus, the identification of a common downstream mediator of growth-factor-induced endothelial cell migration is mandatory to effectively interfere with (tumour-) angiogenesis. We found that the urokinase-type plasminogen activator (uPA)-system, which affects proteolytic as well as adhesive capacities, represents an essential regulatory mechanism in growth factor-induced endothelial cell migration and invasion. This mechanism was not limited to VEGF165, but mediated pro-angiogenic endothelial cell behaviour induced by various growth factors. Thus, VEGF165, VEGF-E, FGF-2, EGF as well as HGF induced a PI3k-dependent activation of pro-uPA when bound to uPAR, which led to an increase in cell surface fibrinolytic activity. As a consequence, uPAR became internalised and redistributed via LDLR-proteins. Interference with these events led to a reduced migratory response of endothelial cells towards VEGF in vitro as well as endothelial cell invasion in vivo. These data give first evidence that the uPA-system, which represents the only level-of-evidence-1 cancer biomarker system for prognosis and/or prediction in node negative breast cancer, might directly affect (tumour-) angiogenesis.

Differential drug class-specific metastatic effects following treatment with a panel of angiogenesis inhibitors

Inhibiting angiogenesis has become an important therapeutic strategy for cancer treatment but, like other current targeted therapies, benefits experienced for late-stage cancers can be curtailed by inherent refractoriness or by acquired drug resistance, requiring a need for better mechanistic understanding of such effects. Numerous preclinical studies have demonstrated that VEGF pathway inhibitors suppress primary tumour growth and metastasis. However, it has been recently reported that short-term VEGF and VEGFR inhibition can paradoxically accelerate tumour invasiveness and metastasis in certain models. Here we comprehensively compare the effects of both antibody and small molecule receptor tyrosine kinase (RTK) inhibitors targeting the VEGF-VEGFR pathway, using short-term therapy in various mouse models of metastasis. Our findings demonstrate that antibody inhibition of VEGF pathway molecules does not promote metastasis, in contrast to selected small molecule RTK inhibitors at elevated-therapeutic drug dosages. In particular, a multi-targeted RTK inhibitor, sunitinib, which most profoundly potentiated metastasis, also increased lung vascular permeability and promoted tumour cell extravasation. Mechanistically, sunitinib, but not anti-VEGF treatment, attenuated endothelial barrier function in culture and caused a global inhibition of protein tyrosine phosphorylation, including molecules important for maintaining endothelial cell-cell junctions. Together these findings indicate that, rather than a specific consequence of inhibiting the VEGF signalling pathway, pharmacological inhibitors of the VEGF pathway can have dose- and drug class-dependent side-effects on the host vasculature. These findings also advocate for the continued identification of mechanisms of resistance to anti-angiogenics and for therapy development to overcome it.

Neutrophil-mediated experimental metastasis is enhanced by VEGFR inhibition in a zebrafish xenograft model

Inhibition of VEGF signalling effectively suppresses localized tumour growth but accelerates tumour invasiveness and micrometastasis by unknown mechanisms. To study the dynamic and reciprocal interactions between tumour cells and their microenvironment during these processes, we established a xenograft model by injecting tumour cells into the blood circulation of transparent zebrafish embryos. This reproducibly results in rapid simultaneous formation of a localized tumour and experimental micrometastasis, allowing time-resolved imaging of both processes at single-cell resolution within 1 week. The tumour vasculature was initiated de novo by remodelling of primitive endothelial cells into a functional network. Roles of myeloid cells in critical tumourigenesis steps such as vascularization and invasion were revealed by genetic and pharmaceutical approaches. We discovered that the physiological migration of neutrophils controlled tumour invasion by conditioning the collagen matrix and forming the metastatic niche, as detected by two-photon confocal microscopy and second harmonic generation. Administration of VEGFR inhibitors blocked tumour vascularization and a localized tumour growth but enhanced migration of neutrophils, which in turn promoted tumour invasion and formation of micrometastasis. This demonstrates the in vivo cooperation between VEGF signalling and myeloid cells in metastasis and provides a new mechanism underlying the recent findings that VEGFR targeting can promote tumour invasiveness. Copyright © 2012 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Live imaging in zebrafish reveals neu(trophil) insight into the metastatic niche

Non-cancerous immune cells can significantly contribute to tumour progression and metastases. Neutrophils associated with tumours can both promote and inhibit tumour progression, but less is known about how non-associated immune cells contribute to cancer biology. In a recent issue of the Journal of Pathology, He and colleagues use non-invasive, high-resolution imaging of the whole living animal to provide a compelling glimpse at how physiological migration of neutrophils can prepare a metastatic niche and how their activities can be altered by the unintended consequences of targeted therapeutics.

Combining Bevacizumab with Radiation or Chemoradiation for Solid Tumors: A Review of the Scientific Rationale, and Clinical Trials

Radiation therapy or the combination of radiation and chemotherapy is an important component in the local control of many tumor types including glioblastoma, rectal cancer, and pancreatic cancer. The addition of anti-angiogenic agents to chemotherapy is now standard treatment for a variety of metastatic cancers including colorectal cancer and non-squamous cell lung cancer. Anti-angiogenic agents can increase the efficacy of radiation or chemoradiation for primary tumors through mechanisms such as vascular normalization and augmentation of endothelial cell injury. The most commonly used anti-angiogenic drug, bevacizumab, is a humanized monoclonal antibody that binds and neutralizes vascular endothelial growth factor A (VEGF-A). Dozens of preclinical studies nearly uniformly demonstrate that inhibition of VEGF-A or its receptors potentiates the effects of radiation therapy against solid tumors, and this potentiation is generally independent of the type or schedule of radiation and timing of VEGF-A inhibitor delivery. There are now several clinical trials combining bevacizumab with radiation or chemoradiation for the local control of various primary, recurrent, and metastatic tumors, and many of these early trials show encouraging results. Some added toxicities occur with the delivery of bevacizumab but common toxicities such as hypertension and proteinuria are generally easily managed while severe toxicities are rare. In the future, bevacizumab and other anti-angiogenic agents may become common additions to radiation and chemoradiation regimens for tumors that are difficult to locally control.

Anti-VEGF antibody therapy does not promote metastasis in genetically engineered mouse tumour models

Resistance to anti-angiogenic therapy can occur via several potential mechanisms. Unexpectedly, recent studies showed that short-term inhibition of either VEGF or VEGFR enhanced tumour invasiveness and metastatic spread in preclinical models. In an effort to evaluate the translational relevance of these findings, we examined the consequences of long-term anti-VEGF monoclonal antibody therapy in several well-validated genetically engineered mouse tumour models of either neuroendocrine or epithelial origin. Anti-VEGF therapy decreased tumour burden and increased overall survival, either as a single agent or in combination with chemotherapy, in all four models examined. Importantly, neither short- nor long-term exposure to anti-VEGF therapy altered the incidence of metastasis in any of these autochthonous models, consistent with retrospective analyses of clinical trials. In contrast, we observed that sunitinib treatment recapitulated previously reported effects on tumour invasiveness and metastasis in a pancreatic neuroendocrine tumour (PNET) model. Consistent with these results, sunitinib treatment resulted in an up-regulation of the hypoxia marker GLUT1 in PNETs, whereas anti-VEGF did not. These results indicate that anti-VEGF mediates anti-tumour effects and therapeutic benefits without a paradoxical increase in metastasis. Moreover, these data underscore the concept that drugs targeting VEGF ligands and receptors may affect tumour metastasis in a context-dependent manner and are mechanistically distinct from one another.

Overcoming evasive resistance from vascular endothelial growth factor a inhibition in sarcomas by genetic or pharmacologic targeting of hypoxia-inducible factor 1α

Increased levels of hypoxia and hypoxia-inducible factor 1α (HIF-1α) in human sarcomas correlate with tumor progression and radiation resistance. Prolonged antiangiogenic therapy of tumors not only delays tumor growth but may also increase hypoxia and HIF-1α activity. In our recent clinical trial, treatment with the vascular endothelial growth factor A (VEGF-A) antibody, bevacizumab, followed by a combination of bevacizumab and radiation led to near complete necrosis in nearly half of sarcomas. Gene Set Enrichment Analysis of microarrays from pretreatment biopsies found that the Gene Ontology category “Response to hypoxia” was upregulated in poor responders and that the hierarchical clustering based on 140 hypoxia-responsive genes reliably separated poor responders from good responders. The most commonly used chemotherapeutic drug for sarcomas, doxorubicin (Dox), was recently found to block HIF-1α binding to DNA at low metronomic doses. In four sarcoma cell lines, HIF-1α shRNA or Dox at low concentrations blocked HIF-1α induction of VEGF-A by 84–97% and carbonic anhydrase 9 by 83–93%. HT1080 sarcoma xenografts had increased hypoxia and/or HIF-1α activity with increasing tumor size and with anti-VEGF receptor antibody (DC101) treatment. Combining DC101 with HIF-1α shRNA or metronomic Dox had a synergistic effect in suppressing growth of HT1080 xenografts, at least in part via induction of tumor endothelial cell apoptosis. In conclusion, sarcomas respond to increased hypoxia by expressing HIF-1α target genes that may promote resistance to antiangiogenic and other therapies. HIF-1α inhibition blocks this evasive resistance and augments destruction of the tumor vasculature.

Angiogenesis inhibitors increase tumor stem cells

The clinical efficacy of angiogenesis inhibitors targeting the vascular endothelial growth factor pathway has recently been met with numerous phase III failures that showed modest survival benefits. Understanding the resistance mechanisms of antiangiogenic therapy is essential to overcoming the limited effectiveness of VEGF-pathway inhibitors. A recent study published in the Proceedings of the National Academy of Sciences provides a novel explanation to the treatment limitations of angiogenesis inhibitors and suggests a potential strategy to improve the clinical utility of these agents.

Strategies for the discovery and development of therapies for metastatic breast cancer

Nearly all deaths caused by solid cancers occur as a result of metastasis--the formation of secondary tumours in distant organs such as the lungs, liver, brain and bone. A major obstruction to the development of drugs with anti-metastatic efficacy is our fragmented understanding of how tumours 'evolve' and metastasize, at both the biological and genetic levels. Furthermore, although there is significant overlap in the metastatic process among different types of cancer, there are also marked differences in the propensity to metastasize, the extent of metastasis, the sites to which the tumour metastasizes, the kinetics of the process and the mechanisms involved. Here, we consider the case of breast cancer, which has some marked distinguishing features compared with other types of cancer. Considerable progress has been made in the development of preclinical models and in the identification of relevant signalling pathways and genetic regulators of metastatic breast cancer, and we discuss how these might facilitate the development of novel targeted anti-metastatic drugs.

Beta-adrenergic blocking drugs in breast cancer: a perspective review

The purpose of this review is to present the preclinical, epidemiological and clinical data relevant to the association between β-blockers and breast cancer progression. Preclinical studies have shown that β-adrenergic receptor (β-AR) signalling can inhibit multiple cellular processes involved in breast cancer progression and metastasis, including extracellular matrix invasion, expression of inflammatory and chemotactic cytokines, angiogenesis and tumour immune responses. This has led to the hypothesis that the commonly prescribed class of β-AR antagonist drugs (β-blockers) may favourably impact cancer progression. A number of recent pharmacoepidemiological studies have examined the association between β-blocker exposure and breast cancer progression. The results from these studies have suggested a potential role for targeting the β-AR pathway in breast cancer patients. Larger observational studies are, however, required to confirm these results. Questions regarding the type of β-blocker, predictive biomarkers or tumour characteristics, appropriate treatment paradigms and, most importantly, efficacy must also be answered in randomized clinical studies before β-blockers can be considered a therapeutic option for patients with breast cancer.

Exercise modulation of the host-tumor interaction in an orthotopic model of murine prostate cancer

The purpose of this study is to investigate the effects of exercise on cancer progression, metastasis, and underlying mechanisms in an orthotopic model of murine prostate cancer. C57BL/6 male mice (6-8 wk of age) were orthotopically injected with transgenic adenocarcinoma of mouse prostate C-1 cells (5 × 10(5)) and randomly assigned to exercise (n = 28) or a non-intervention control (n = 31) groups. The exercise group was given voluntary access to a wheel 24 h/day for the duration of the study. Four mice per group were serially killed on days 14, 31, and 36; the remaining 38 mice (exercise, n = 18; control, n = 20) were killed on day 53. Before death, MRI was performed to assess tumor blood perfusion. Primary tumor growth rate was comparable between groups, but expression of prometastatic genes was significantly modulated in exercising animals with a shift toward reduced metastasis. Exercise was associated with increased activity of protein kinases within the MEK/MAPK and PI3K/mTOR signaling cascades with subsequent increased intratumoral protein levels of HIF-1α and VEGF. This was associated with improved tumor vascularization. Multiplex ELISAs revealed distinct reductions in plasma concentrations of several angiogenic cytokines in the exercise group, which was associated with increased expression of angiogenic and metabolic genes in the skeletal muscle. Exercise-induced stabilization of HIF-1α and subsequent upregulation of VEGF was associated with "productive" tumor vascularization with a shift toward suppressed metastasis in an orthotopic model of prostate cancer.

Peritoneal carcinomatosis: cytoreductive surgery and HIPEC--overview and basics

Tumor involvement of the peritoneum-peritoneal carcinomatosis-is a heterogeneous form of cancer that had been generally regarded as a sign of systemic tumor disease and as a terminal condition. The multimodal treatment approach for patients with peritoneal carcinomatosis, which had been conceived and developed, consists of what is known as cytoreductive surgery, followed by hyperthermic intraperitoneal chemotherapy (HIPEC). Depending on the tumor mass as assessed intraoperatively and the histopathological differentiation, patients who undergo cytoreductive surgery and HIPEC have a significant survival benefit. Mean increases in the survival period ranging from six months to up to four years have now been reported. In view of the substantial logistic effort and the extent of the surgery involved, this treatment approach represents a major challenge both for patients and for surgical oncologists, as well as for the members of the overall interdisciplinary structure required, which includes oncology, anesthesiology and intensive care, psycho-oncology, and patient management. The surgical procedures alone may take 8-14 hr. The present paper provides an overview of the basis for the approach and the use of specialized classifications and quantitative prognostic indicators.

The evolution of adjuvant therapy in the treatment of early-stage colon cancer

Adjuvant treatment of colon cancer, one of the most common malignancies, is an important issue in oncology. This article describes the development of adjuvant therapy and how the 2 major evolution steps, the successes of fluoropyrimidines, and then of oxaliplatin, have been achieved, Problems and failures, such as those of targeted therapies, also are addressed to help us to overcome their limitations. Special situations, such as stage II disease and an elderly population in which adjuvant chemotherapy is still controversial, are reviewed from the clinician perspective. The synthesis of these data allows us to conceive a future development focused on translational research.

Hypoxia-inducible factors: mediators of cancer progression and targets for cancer therapy

Hypoxia-inducible factors (HIFs) mediate adaptive physiological responses to hypoxia. In human cancers that are accessible for O(2) electrode measurements, intratumoral hypoxia is common and severe hypoxia is associated with increased risk of mortality. HIF activity in regions of intratumoral hypoxia mediates angiogenesis, epithelial-mesenchymal transition, stem-cell maintenance, invasion, metastasis, and resistance to radiation therapy and chemotherapy. A growing number of drugs have been identified that inhibit HIF activity by a variety of molecular mechanisms. Because many of these drugs are already FDA-approved for other indications, clinical trials can (and should) be initiated to test the hypothesis that incorporation of HIF inhibitors into current standard-of-care therapy will increase the survival of cancer patients.

Vascular normalization by loss of Siah2 results in increased chemotherapeutic efficacy

Tumor hypoxia is associated with resistance to antiangiogenic therapy and poor prognosis. The Siah E3 ubiquitin ligases regulate the hypoxic response pathway by modulating the turnover of the master proangiogenic transcription factor hypoxia-inducible factor-1α (Hif-1α). In this study, we show that genetic deficiency in the Siah family member Siah2 results in vascular normalization and delayed tumor growth in an established transgenic model of aggressive breast cancer. Tumors arising in a Siah2(-/-) genetic background showed increased perfusion and pericyte-associated vasculature, similar to that occurring with antiangiogenic therapy. In support of the role of Siah2 in regulating levels of Hif-1α, expression of angiogenic factors was decreased in Siah2(-/-) tumors. Blood vessel normalization in Siah2(-/-) tumors resulted in an increased response to chemotherapy and prolonged survival. Together, our findings offer a preclinical proof of concept that targeting Siah2 is sufficient to attenuate Hif-1α-mediated angiogenesis and hypoxia signaling, thereby improving responses to chemotherapy.

First-line treatment of advanced breast cancer with sunitinib in combination with docetaxel versus docetaxel alone: results of a prospective, randomized phase III study

PURPOSE

To investigate whether sunitinib plus docetaxel improves clinical outcomes for patients with human epidermal growth factor receptor 2 (HER2)/neu-negative advanced breast cancer (ABC) versus docetaxel alone.

PATIENTS AND METHODS

In this phase III study, patients were randomly assigned to open-label combination therapy (sunitinib 37.5 mg/d, days 2 to 15 every 3 weeks; and docetaxel 75 mg/m(2), day 1 every 3 weeks) or monotherapy (docetaxel 100 mg/m(2) every 3 weeks). Progression-free survival (PFS) was the primary end point.

RESULTS

Two hundred ninety-six patients were randomly assigned to combination therapy, and 297 patients were assigned to monotherapy. Median PFS times were 8.6 and 8.3 months with combination therapy and monotherapy, respectively (hazard ratio, 0.92; one-sided P = .265). The objective response rate (ORR) was significantly higher with the combination (55%) than with monotherapy (42%; one-sided P = .001). Duration of response was similar in both arms (7.5 months with the combination v 7.2 months with monotherapy). Median overall survival (OS) times were 24.8 and 25.5 months with combination therapy and monotherapy, respectively (one-sided P = .904). There were 107 deaths with the combination and 91 deaths with monotherapy. The frequency of common adverse events (AEs) was higher with the combination, as were treatment discontinuations caused by AEs.

CONCLUSION

The combination of sunitinib plus docetaxel improved ORR but did not prolong either PFS or OS compared with docetaxel alone when given to an unselected HER2/neu-negative cohort as first-line treatment for ABC. Sunitinib combination therapy may also have resulted in AEs that yield an unfavorable risk-benefit ratio. The sunitinib-docetaxel regimen evaluated in this study is not recommended for further use in ABC.