VEGF-dependent plasticity of fenestrated capillaries in the normal adult microvasculature

Two-Week Aflibercept or Erlotinib Administration Does Not Induce Changes in Intestinal Morphology in Male Sprague-Dawley Rats But Aflibercept Affects Serum and Urine Metabolic Profiles

Gastrointestinal toxicity is a frequently observed adverse event during cancer treatment with traditional chemotherapeutics. Currently, traditional chemotherapeutics are often combined with targeted biologic agents. These biologics, however, possess a distinct toxicity profile, and they may also exacerbate the adverse effects of traditional chemotherapeutics. In this study, we aimed to characterize the gastrointestinal and metabolic changes after a 2-week treatment period with aflibercept, an antiangiogenic VEGFR decoy, and with erlotinib, a tyrosine-kinase inhibitor. Male rats were treated either with aflibercept or erlotinib for 2 weeks. During the 2-week treatment period, the animals in the aflibercept group received two subcutaneous doses of 25 mg/kg aflibercept. The erlotinib group got 10 mg/kg of erlotinib by oral gavage every other day. The control groups were treated similarly but received either saline injections or oral gavage of water. Intestinal toxicity was assessed by measuring intestinal permeability and by histological analyses of intestinal tissues. Metabolic changes were measured with ¹H nuclear magnetic resonance in serum and urine. Neither aflibercept nor erlotinib induced changes in intestinal permeability or intestinal tissue morphology. However, aflibercept treatment resulted in stunted body weight gain and altered choline, amino acid, and lipid metabolism. Two-week treatment with aflibercept or erlotinib alone does not induce observable changes in gastrointestinal morphology and function. However, observed aflibercept-treatment related metabolic changes suggest alterations in intestinal microbiota, nutrient intake, and adipose tissue function. The metabolic changes are also interesting in respect to the systemic effects of aflibercept and their possible associations with adverse events caused by aflibercept administration.

Renal-Limited Thrombotic Microangiopathy due to Bevacizumab Therapy for Metastatic Colorectal Cancer: A Case Report

An 88-year-old Japanese man received bevacizumab for colorectal cancer with liver and peritoneal metastasis, during which nephrotic range proteinuria occurred (7.66 g/day). Renal biopsy showed endothelial damage with subendothelial swelling and a double contour of the glomerular basement membrane, which indicated a diagnosis of thrombotic microangiopathy (TMA). After bevacizumab was stopped, proteinuria decreased to 1 g/day. During the clinical course, this patient had no extrarenal manifestations. This case suggests that renal injury induced by bevacizumab is characterized by nephrotic range proteinuria and histological TMA, and is a renal-limited condition that differs from systemic TMA related to thrombotic thrombocytopenic purpura.

Tyrosine kinase inhibitors and immune checkpoint inhibitors-induced thyroid disorders

Recently, tyrosine kinase inhibitors (TKI) and immune checkpoint inhibitors (ICPIs) have emerged as new classes of anticancer therapies. Although generally considered less toxic than cytotoxic chemotherapy, these new drugs can cause significant unanticipated side effects including thyroid dysfunction. This review provides a literature assessment of thyroid dysfunctions induced by TKI and ICPIs. We intend to define for these two classes the frequency of thyroid involvement, the potential mechanisms that result in this toxicity, the clinical-biological impact and the therapeutic management. Detection of thyroid dysfunction requires monitoring of TSH, in combination with free T4 if needed and, depending on the clinical impact and the kinetics of biological abnormalities, starting symptomatic treatment of hyperthyroidism and/or correcting hypothyroidism.

The Placental Growth Factor Pathway and Its Potential Role in Macular Degenerative Disease

There is growing evidence that placental growth factor (PlGF) is an important player in multiple pathologies, including tumorigenesis, inflammatory disorders and degenerative retinopathies. PlGF is a member of the vascular endothelial growth factor (VEGF) family and in the retina, binding of this growth factor to specific receptors is associated with pathological angiogenesis, vascular leakage, neurodegeneration and inflammation. Although they share some receptor signalling pathways, many of the actions of PlGF are distinct from VEGF and this has revealed the enticing prospect that it could be a useful therapeutic target for treating early and late stages of diabetic retinopathy (DR) and neovascular age-related macular degeneration (AMD). Recent research suggests that modulation of PlGF could also be important in the geographic atrophy (GA) form of late AMD by protecting the outer retina and the retinal pigment epithelium (RPE). This review discusses PlGF and its signalling pathways and highlights the potential of blocking the bioactivity of this growth factor to treat irreversible visual loss due to the two main forms of AMD.

Ramucirumab: the long and winding road toward being an option for mCRC treatment

INTRODUCTION

Colorectal cancer (CRC) is one of the main causes of cancer-related morbidity and mortality worldwide. Mortality is most often attributable to metastatic disease. Despite the progress achieved so far, life expectancy continues to be limited in most patients. Ramucirumab, a most recent antiangiogenic drug, is vying in the race to metastatic CRC (mCRC) treatment since its approval by the Food and Drug Administration (FDA), based on the results of the RAISE study.

AREAS COVERED

This article reviews the role of ramucirumab in mCRC, including clinical indication, safety issues, and future perspectives.

EXPERT OPINION

The use of Ramucirumab in clinical practice is still limited, probably due to economic burden and the lack of specific biomarkers. Future efforts will be addressed to improve our knowledge in the use of this drug and better guide us in patients' care.

Growth factor signaling pathways in vascular development and disease

Angiogenic blood vessel growth is essential to ensure organs receive adequate blood supply to support normal organ function and homeostasis. Angiogenesis involves a complex series of cellular events through which new vessels grow out from existing vasculature. Growth factor signaling, layered over a range of other signaling inputs, orchestrates this process. The response of endothelial cells (ECs) to growth factor signals must be carefully controlled through feedback mechanisms to prevent excessive vessel growth, remodeling or destabilization. In this article, we summarize recent findings describing how ECs respond to growth factor signals during blood vessel development and homeostasis and how perturbation of these responses can lead to disease.

Talin-Dependent Integrin Activation Regulates VE-Cadherin Localization and Endothelial Cell Barrier Function

RATIONALE

Endothelial barrier function depends on the proper localization and function of the adherens junction protein VE (vascular endothelial)-cadherin. Previous studies have suggested a functional relationship between integrin-mediated adhesion complexes and VE-cadherin yet the underlying molecular links are unclear. Binding of the cytoskeletal adaptor protein talin to the β-integrin cytoplasmic domain is a key final step in regulating the affinity of integrins for extracellular ligands (activation) but the role of integrin activation in VE-cadherin mediated endothelial barrier function is unknown.

OBJECTIVE

To test the requirement of talin-dependent activation of β1 integrin in VE-cadherin organization and endothelial cell (EC) barrier function.

METHODS AND RESULTS

EC-specific deletion of talin in adult mice resulted in impaired stability of intestinal microvascular blood vessels, hemorrhage, and death. Talin-deficient endothelium showed altered VE-cadherin organization at EC junctions in vivo. shRNA (short hairpin RNA)-mediated knockdown of talin1 expression in cultured ECs led to increased radial actin stress fibers, increased adherens junction width and increased endothelial monolayer permeability measured by electrical cell-substrate impedance sensing. Restoring β1-integrin activation in talin-deficient cells with a β1-integrin activating antibody normalized both VE-cadherin organization and EC barrier function. In addition, VE-cadherin organization was normalized by reexpression of talin or integrin activating talin head domain but not a talin head domain mutant that is selectively deficient in activating integrins.

CONCLUSIONS

Talin-dependent activation of EC β1-integrin stabilizes VE-cadherin at endothelial junctions and promotes endothelial barrier function.

Primary Adrenal Insufficiency During Lenvatinib or Vandetanib and Improvement of Fatigue After Cortisone Acetate Therapy

CONTEXT

Two tyrosine kinase inhibitors (TKIs), lenvatinib and vandetanib, are often used to treat advanced radioiodine-refractory differentiated thyroid cancer (RAI-R DTC) and medullary thyroid cancer (MTC), respectively. Fatigue is a common adverse event during treatment with these and other TKIs and a common cause of drug discontinuation or dosage reduction.

CASES DESCRIPTION

We evaluated the basal and stimulated adrenal function in 12 patients with advanced RAI-R DTC and MTC treated with lenvatinib or vandetanib, respectively. Ten patients complaining of fatigue showed a progressive ACTH increase with normal cortisol levels. Moreover, six of 10 patients had a blunted cortisol response after ACTH stimulation, thus confirming the diagnosis of primary adrenal insufficiency (PAI). The causal relationship between TKIs and PAI onset was also demonstrated by the repeated testing of adrenal function before and during treatment. Patients with PAI received cortisone acetate replacement therapy, with a substantial and prompt improvement in the degree of fatigue, as assessed by the Common Terminology Criteria for Adverse Events version 4.03, thus supporting the major impact of impaired adrenal function in the genesis of this adverse event.

CONCLUSIONS

We show that the occurrence of PAI may be a common cause of fatigue during lenvatinib and vandetanib treatment, and we therefore recommend testing adrenal function for a prompt start of replacement therapy to avoid treatment discontinuation, dosage reduction, and potentially severe PAI complications.

Therapeutic Inhibition of VEGF Signaling and Associated Nephrotoxicities

Inhibition of vascular endothelial growth factor A (VEGFA)/vascular endothelial growth factor receptor 2 (VEGFR2) signaling is a common therapeutic strategy in oncology, with new drugs continuously in development. In this review, we consider the experimental and clinical evidence behind the diverse nephrotoxicities associated with the inhibition of this pathway. We also review the renal effects of VEGF inhibition's mediation of key downstream signaling pathways, specifically MAPK/ERK1/2, endothelial nitric oxide synthase, and mammalian target of rapamycin (mTOR). Direct VEGFA inhibition via antibody binding or VEGF trap (a soluble decoy receptor) is associated with renal-specific thrombotic microangiopathy (TMA). Reports also indicate that tyrosine kinase inhibition of the VEGF receptors is preferentially associated with glomerulopathies such as minimal change disease and FSGS. Inhibition of the downstream pathway RAF/MAPK/ERK has largely been associated with tubulointerstitial injury. Inhibition of mTOR is most commonly associated with albuminuria and podocyte injury, but has also been linked to renal-specific TMA. In all, we review the experimentally validated mechanisms by which VEGFA-VEGFR2 inhibitors contribute to nephrotoxicity, as well as the wide range of clinical manifestations that have been reported with their use. We also highlight potential avenues for future research to elucidate mechanisms for minimizing nephrotoxicity while maintaining therapeutic efficacy.

Hormonal Changes Associated With Intra-Uterine Growth Restriction: Impact on the Developing Brain and Future Neurodevelopment

The environment in which a fetus develops is not only important for its growth and maturation but also for its long-term postnatal health and neurodevelopment. Several hormones including glucocorticosteroids, estrogens and progesterone, insulin growth factor and thyroid hormones, carefully regulate the growth of the fetus and its metabolism during pregnancy by controlling the supply of nutrients crossing the placenta. In addition to fetal synthesis, hormones regulating fetal growth are also expressed and regulated in the placenta, and they play a key role in the vulnerability of the developing brain and its maturation. This review summarizes the current understanding and evidence regarding the involvement of hormonal dysregulation associated with intra-uterine growth restriction and its consequences on brain development.

Identification and characterization of agnuside, a natural proangiogenic small molecule

Due to its important role in regulating angiogenesis, vascular homeostasis and remodeling, and arteriogenesis in blood vascular and lymphatic endothelial cells, VEGFR2 stimulation has demonstrated promise in preclinical studies as an endovascular treatment for ischemic myocardial and peripheral disease. However, the short half-life of protein- and cytokine-based strategies and transduction inefficiency of vector-based modalities have hindered its clinical therapeutic applications. In the present study, we used a streamlined bioinformatics strategy combining ligand-based pharmacophore development and validation, virtual screening, and molecular docking to identify agnuside, a non-toxic, natural small molecule extract of Vitex agnus-castus possessing strong binding affinity, druggable physiochemical properties, and conformationally stable hydrogen bond and hydrophobic interactions with catalytically important residues within VEGFR2's active and allosteric sites. In-vitro proliferation, tube formation, and scratch wound migration assays provide evidence that agnuside promotes endothelial cell angiogenesis. Agnuside increases HUVEC proliferation with an EC50 of 1.376 μg/mL, stimulates tubulogenesis dose-dependently, and increases scratch wound migration rate. An additional angiogenesis assay suggests that agnuside may actively compete with a VEGFR2 inhibitor for VEGFR2 binding site occupancy to increase total length and branching length of HUVEC tubular networks. Chemometric analysis of molecular interaction fields (MIFs) by partial least squares (PLS)-derived quantitative structure activity relationship (QSAR) analysis and MIF contours provides the framework for the formulation of agnuside analogues possessing greater potency. Our research supports that agnuside may be a lead molecule for therapeutic angiogenesis.

Phorbol esters induce PLVAP expression via VEGF and additional secreted molecules in MEK1-dependent and p38, JNK and PI3K/Akt-independent manner

Endothelial diaphragms are subcellular structures critical for mammalian survival with poorly understood biogenesis. Plasmalemma vesicle associated protein (PLVAP) is the only known diaphragm component and is necessary for diaphragm formation. Very little is known about PLVAP regulation. Phorbol esters (PMA) are known to induce de novo PLVAP expression and diaphragm formation. We show that this induction relies on the de novo production of soluble factors that will act in an autocrine manner to induce PLVAP transcription and protein expression. We identified vascular endothelial growth factor-A (VEGF-A) signalling through VEGFR2 as a necessary but not sufficient downstream event as VEGF-A inhibition with antibodies and siRNA or pharmacological inhibition of VEGFR2 only partially inhibit PLVAP upregulation. In terms of downstream pathways, inhibition of MEK1/Erk1/2 MAP kinase blocked PLVAP upregulation, whereas inhibition of p38 and JNK MAP kinases or PI3K and Akt had no effect on PMA-induced PLVAP expression. In conclusion, we show that VEGF-A along with other secreted proteins act synergistically to up-regulate PLVAP in MEK1/Erk1/2 dependent manner, bringing us one step further into understanding the genesis of the essential structures that are endothelial diaphragms.

Preeclampsia: A close look at renal dysfunction

Preeclampsia (PE) is a unique pathophysiologic situation that physiologic interests of mother, fetus, and placenta diverge. PE is related to the increased circulating antiangiogenic factors originated from hypoxic placenta. It is simply defined by the new onset of hypertension (≥140/90 mmHg) and proteinuria (≥0.3 g/day) after 20 weeks of gestation. PE is associated with kidney dysfunction due to deficiency in podocyte specific vascular endothelial growth factor (VEGF). Hypoxic placenta in PE patients produces increased levels of fms-like tyrosine kinase 1(sFlt-1), a soluble receptor of VEGF. sFlt-1 abrogates binding of VEGF to its receptor on endothelial cells and podocytes, and ultimately damages the filtration barrier. Glomerular endotheliosis and thrombotic microangiopathy (TMA) are the main features of kidney involvement in PE and can induce clotting and vessel occlusion. This complex pathophysiology is ameliorated after delivery; however, permanent kidney damages may remain and is intensified thereafter. This review aims to highlight the biochemical, genetic, and immunological-involved factors in the initiation of PE and explores the relationship between the kidney and PE. This work mainly discusses the pathologic mechanisms of kidney involvement in PE through the lens of the imbalanced VEGF-VEGF receptor signaling pathway.

Focal segmental glomerulosclerosis lesion associated with inhibition of tyrosine kinases by lenvatinib: a case report

Background

Lenvatinib is a tyrosine kinase inhibitor with novel binding ability. It is considered the standard of care for metastatic thyroid cancer; moreover, whether it is indicated for other malignant tumors has been examined. Lenvatinib increases the risk of kidney injury in some patients. In comparison with sorafenib, which is a conventional tyrosine kinase inhibitor (TKI), lenvatinib results in more side effects, including hypertension and proteinuria. We describe a case of secondary focal segmental glomerulosclerosis (FSGS) that developed following treatment of metastatic thyroid cancer with lenvatinib and reviewed the mechanisms of renal impairment.

Case presentation

We describe a patient with metastatic thyroid cancer who developed hypertension, nephrotic syndrome, and acute kidney injury after 3 months of lenvatinib treatment. Renal biopsy results revealed that 7 of 16 glomeruli indicated complete hyalinization, and that the glomeruli with incomplete hyalinization showed FSGS due to a vascular endothelial disorder and podocyte damage, which seemed to have been induced by lenvatinib treatment. These findings were similar to those of renal impairment treated with conventional TKIs. Although lenvatinib treatment was discontinued, up to 15 months were required to achieve remission of proteinuria, thus leading to chronic kidney disease with hyalinized lesions.

Conclusions

To the best of our knowledge, this is the first reported case of secondary FSGS by lenvatinib treatment. Renal impairment treated with TKIs is commonly associated with minimal change nephrotic syndrome/FSGS findings, and it is suggested that renal involvement with TKI is different from that with the vascular endothelial growth factor ligand. Overexpression of c-mip due to TKI causes disorders such as podocyte dysregulation and promotion of apoptosis, which cause FSGS. Lenvatinib may result in FSGS by a similar mechanism with another TKI and could cause irreversible renal impairment; therefore caution must be used. It is essential to monitor blood pressure, urinary findings, and the renal function.

Prethreshold retinopathy of prematurity: VEGF inhibition without VEGF inhibitors

The risk of developing treatment-warranted Type 1 retinopathy of prematurity (ROP) might be reduced in preterm infants by modifying certain systemic factors. There are steps that can be taken both early and late in the course of retinal vascular maturation that may potentially reduce an infant's risk of developing Type 1 ROP. In prethreshold stage 2-3 ROP without plus disease, a combination of supplemental oxygen, correction of severe anemia, and light adaptation to reduce rod photoreceptor oxygen consumption helped us to reduce ROP severity, and encouraged a return to a more physiologic retinal vascular maturation pattern. Thus, it may be possible to reduce the risk of developing Type 1 ROP by making adjustments in certain systemic parameters aimed at reducing retinal hypoxia, thereby gently lowering pathologically elevated levels of vascular endothelial growth factor (VEGF) within the eye.

Life-threatening Hyperkalemia Associated with Axitinib Treatment in Patients with Recurrent Renal Carcinoma

Axitinib has emerged as a promising antineoplastic agent for the treatment of advanced renal cell carcinoma. Although the administration of axitinib was well-tolerated in clinical trials, the real-world safety and tolerability remain unverified. We herein report a patient with metastatic renal cell carcinoma who suddenly developed life-threatening hyperkalemia following the initiation of axitinib treatment. Although hyperkalemia has been reported with an incidence of <10%, acute severe hyperkalemia may be a considerably critical adverse event of axitinib therapy, especially in patients with risk factors for hyperkalemia. An abundance of caution for unusual and unpredictable toxicities is warranted when using axitinib.

Cell-specific gene therapy driven by an optimized hypoxia-regulated vector reduces choroidal neovascularization

Aberrant growth of blood vessels in the choroid layer of the eye, termed choroidal neovascularization (CNV), is the pathological hallmark of exudative age-related macular degeneration (AMD), causing irreversible blindness among the elderly. Co-localization of proangiogenic factors and hypoxia inducible factors (HIF) in neovascular membranes from AMD eyes suggests the role of hypoxia in pathogenesis of CNV. In order to utilize hypoxic conditions in RPE for therapeutic purposes, we developed an optimized hypoxia regulated, RPE cell-specific gene therapy to inhibit choroidal neovascularization. An adeno-associated virus (AAV2) vector comprising a RPE-specific promoter and HIF-1 response elements (HRE) was designed to regulate production of human endostatin (a powerful angiostatic protein) in RPE. The vector was tested in a mouse model of laser-induced CNV using subretinal delivery. Spectral domain optical coherence tomography (SD-OCT) images from live mice and confocal images from lectin stained RPE flat mount sections demonstrated reduction in CNV areas by 80% compared to untreated eyes. Quantitative real-time polymerase chain reaction (qPCR) confirmed exogenous endostatin mRNA expression from the regulated vector that was significantly elevated 3, 7, and 14 days following laser treatment, but its expression was completely shut off after 45 days. Thus, RPE-specific, hypoxia-regulated delivery of anti-angiogenic proteins could be a valuable therapeutic approach to treat neovascular AMD at the time and in the ocular space where it arises.

KEY POINTS

An optimized gene therapy vector targeting hypoxia and tissue-specific expression has been designed. The inhibitory role of gene therapy vector was tested in a mouse model of laser-induced CNV. An 80% reduction in choroidal neovascularization was achieved by the optimized vector. The expression of endostatin was limited to retinal pigment epithelium and regulated by hypoxia.

Bevacizumab-associated Bowel Microperforation in a Patient With Neuroblastoma

The antivascular endothelial growth factor antibody, bevacizumab, is effective against several malignancies in adults but unproven in pediatric oncology. In early phase pediatric studies toxicities were similar to those in adults. Bowel perforation in adults is a rare but serious toxicity, but has not been hitherto reported in children. A 5-year-old boy with chemoresistant neuroblastoma treated with bevacizumab plus radioimmunotherapy developed acute abdominal pain. Computed tomography scan showed free abdominal air and pneumatosis coli. Emergency laparotomy and bowel diversion were performed leading to complete recovery and timely continuation of antineuroblastoma therapy. Early recognition and rapid intervention can prevent a catastrophic outcome in bevacizumab-related bowel perforation.

Efficacy of intravitreal conbercept injection in the treatment of retinopathy of prematurity

BACKGROUND

To evaluate the safety and efficacy of intravitreal conbercept (IVC) injection in the treatment of retinopathy of prematurity (ROP).

METHODS

Patients with ROP who underwent IVC injection in Zhujiang Hospital from June 2015 to July 2016 were studied retrospectively. The primary outcome was defined as the regression of plus disease. The secondary outcomes were defined as the presence of recurrence, number of injections and the final regression of disease.

RESULTS

A total of 48 eyes of 24 patients with ROP were included. Among them, 9 eyes of 5 patients had zone I ROP, 35 eyes of 18 patients had zone II ROP and 4 eyes of 2 patients had aggressive posterior ROP. The mean gestational age was 28.5±1.6 weeks, the mean birth weight was 1209.6±228.6 g, the mean postmenstrual age of first injection was 34.2±1.9 weeks and the mean follow-up period was 31.0±4.7 weeks. Forty of 48 eyes (83.3%) received IVC only once, and the regression of plus disease occurred at an average of 3.5±1.5 weeks after the first injection of conbercept. For eight recurrent eyes (16.7%), four eyes received a second IVC and the remaining four eyes received laser photocoagulation, and the regression of plus disease occurred in 3 weeks. No lens opacity, vitreous haemorrhage, entophthalmia or retinal detachment was observed during follow-up.

CONCLUSION

IVC injection is an effective treatment for ROP.

Cancer Lipid Metabolism Confers Antiangiogenic Drug Resistance

Intrinsic and evasive antiangiogenic drug (AAD) resistance is frequently developed in cancer patients, and molecular mechanisms underlying AAD resistance remain largely unknown. Here we describe AAD-triggered, lipid-dependent metabolic reprogramming as an alternative mechanism of AAD resistance. Unexpectedly, tumor angiogenesis in adipose and non-adipose environments is equally sensitive to AAD treatment. AAD-treated tumors in adipose environment show accelerated growth rates in the presence of a minimal number of microvessels. Mechanistically, AAD-induced tumor hypoxia initiates the fatty acid oxidation metabolic reprogramming and increases uptake of free fatty acid (FFA) that stimulates cancer cell proliferation. Inhibition of carnitine palmitoyl transferase 1A (CPT1) significantly compromises the FFA-induced cell proliferation. Genetic and pharmacological loss of CPT1 function sensitizes AAD therapeutic efficacy and enhances its anti-tumor effects. Together, we propose an effective cancer therapy concept by combining drugs that target angiogenesis and lipid metabolism.

Biology of Bone: The Vasculature of the Skeletal System

Blood vessels are essential for the distribution of oxygen, nutrients, and immune cells, as well as the removal of waste products. In addition to this conventional role as a versatile conduit system, the endothelial cells forming the innermost layer of the vessel wall also possess important signaling capabilities and can control growth, patterning, homeostasis, and regeneration of the surrounding organ. In the skeletal system, blood vessels regulate developmental and regenerative bone formation as well as hematopoiesis by providing vascular niches for hematopoietic stem cells. Here we provide an overview of blood vessel architecture, growth and properties in the healthy, aging, and diseased skeletal system.

The Versatile Tanycyte: A Hypothalamic Integrator of Reproduction and Energy Metabolism

The fertility and survival of an individual rely on the ability of the periphery to promptly, effectively, and reproducibly communicate with brain neural networks that control reproduction, food intake, and energy homeostasis. Tanycytes, a specialized glial cell type lining the wall of the third ventricle in the median eminence of the hypothalamus, appear to act as the linchpin of these processes by dynamically controlling the secretion of neuropeptides into the portal vasculature by hypothalamic neurons and regulating blood-brain and blood-cerebrospinal fluid exchanges, both processes that depend on the ability of these cells to adapt their morphology to the physiological state of the individual. In addition to their barrier properties, tanycytes possess the ability to sense blood glucose levels, and play a fundamental and active role in shuttling circulating metabolic signals to hypothalamic neurons that control food intake. Moreover, accumulating data suggest that, in keeping with their putative descent from radial glial cells, tanycytes are endowed with neural stem cell properties and may respond to dietary or reproductive cues by modulating hypothalamic neurogenesis. Tanycytes could thus constitute the missing link in the loop connecting behavior, hormonal changes, signal transduction, central neuronal activation and, finally, behavior again. In this article, we will examine these recent advances in the understanding of tanycytic plasticity and function in the hypothalamus and the underlying molecular mechanisms. We will also discuss the putative involvement and therapeutic potential of hypothalamic tanycytes in metabolic and fertility disorders.

VEGF/VEGFR2 blockade does not cause retinal atrophy in AMD-relevant models

Intraocular injections of VEGF-neutralizing proteins provide tremendous benefits in patients with choroidal neovascularization (NV) due to age-related macular degeneration (AMD), but during treatment some patients develop retinal atrophy. Suggesting that VEGF is a survival factor for retinal neurons, a clinical trial group attributed retinal atrophy to VEGF suppression and cautioned against frequent anti-VEGF injections. This recommendation may contribute to poor outcomes in clinical practice from insufficient treatment. Patients with type 3 choroidal NV have particularly high risk of retinal atrophy, an unexplained observation. Herein we show in mouse models that VEGF signaling does not contribute to photoreceptor survival and functioning: (a) neutralization of VEGFR2 strongly suppresses choroidal NV without compromising photoreceptor function or survival; (b) VEGF does not slow loss of photoreceptor function or death in mice with inherited retinal degeneration, and there is no exacerbation by VEGF suppression; and (c) mice with type 3 choroidal NV develop retinal atrophy due to oxidative damage with no contribution from VEGF suppression. Intraocular injections of VEGF-neutralizing proteins, a highly effective treatment in patients with neovascular AMD, should not be withheld or reduced due to concern that they may contribute to long-term visual loss from retinal atrophy.

Cardiotoxicity with vascular endothelial growth factor inhibitor therapy

Angiogenesis inhibitors targeting the vascular endothelial growth factor (VEGF) signaling pathway (VSP) have been important additions in the therapy of various cancers, especially renal cell carcinoma and colorectal cancer. Bevazicumab, the first VSP to receive FDA approval in 2004 targeting all circulating isoforms of VEGF-A, has become one of the best-selling drugs of all times. The second wave of tyrosine kinase inhibitors (TKIs), which target the intracellular site of VEGF receptor kinases, began with the approval of sorafenib in 2005 and sunitinib in 2006. Heart failure was subsequently noted, in 2-4% of patients on bevacizumab and in 3-8% of patients on VSP-TKIs. The very fact that the single-targeted monoclonal antibody bevacizumab can induce cardiotoxicity supports a pathomechanistic role for the VSP and the postulate of the "vascular" nature of VSP inhibitor cardiotoxicity. In this review we will outline this scenario in greater detail, reflecting on hypertension and coronary artery disease as risk factors for VSP inhibitor cardiotoxicity, but also similarities with peripartum and diabetic cardiomyopathy. This leads to the concept that any preexisting or coexisting condition that reduces the vascular reserve or utilizes the vascular reserve for compensatory purposes may pose a risk factor for cardiotoxicity with VSP inhibitors. These conditions need to be carefully considered in cancer patients who are to undergo VSP inhibitor therapy. Such vigilance is not to exclude patients from such prognostically extremely important therapy but to understand the continuum and to recognize and react to any cardiotoxicity dynamics early on for superior overall outcomes.

Requisite endothelial reactivation and effective siRNA nanoparticle targeting of Etv2/Er71 in tumor angiogenesis

Angiogenesis, new blood vessel formation from preexisting vessels, is critical for solid tumor growth. As such, there have been efforts to inhibit angiogenesis as a means to obstruct tumor growth. However, antiangiogenic therapy faces major challenges to the selective targeting of tumor-associated-vessels, as current antiangiogenic targets also disrupt steady-state vessels. Here, we demonstrate that the developmentally critical transcription factor Etv2 is selectively upregulated in both human and mouse tumor-associated endothelial cells (TAECs) and is required for tumor angiogenesis. Two-photon imaging revealed that Etv2-deficient tumor-associated vasculature remained similar to that of steady-state vessels. Etv2-deficient TAECs displayed decreased Flk1 (also known as Vegfr2) expression, FLK1 activation, and proliferation. Endothelial tube formation, proliferation, and sprouting response to VEGF, but not to FGF2, was reduced in Etv2-deficient ECs. ROS activated Etv2 expression in ECs, and ROS blockade inhibited Etv2 expression in TAECs in vivo. Systemic administration of Etv2 siRNA nanoparticles potently inhibited tumor growth and angiogenesis without cardiovascular side effects. These studies highlight a link among vascular oxidative stress, Etv2 expression, and VEGF response that is critical for tumor angiogenesis. Targeting the ETV2 pathway might offer a unique opportunity for more selective antiangiogenic therapies.

Risk Factors for New Hypothyroidism During Tyrosine Kinase Inhibitor Therapy in Advanced Nonthyroidal Cancer Patients

BACKGROUND

Thyroid dysfunction during tyrosine kinase inhibitor (TKI) cancer treatment is common, but predisposing risk factors have not been determined. Recommendations for monitoring patients treated with one or multiple TKI and in conjunction with other relevant cancer therapies could be improved. The study objective was to assess the risk factors for new thyroid dysfunction in TKI-treated previously euthyroid cancer patients.

METHODS

A retrospective cohort study of patients with advanced nonthyroidal cancer treated with TKI from 2000 to 2017, having available thyroid function tests showing initial euthyroid status, excluding patients with preexisting thyroid disease or lack of follow-up thyroid function tests. During TKI treatment, patients were classified as euthyroid (thyrotropin [TSH] normal), subclinical hypothyroidism (TSH 5-10 mIU/L, or higher TSH if free thyroxine normal), or overt hypothyroidism (TSH >10 mIU/L, low free thyroxine, or requiring thyroid hormone replacement). The timing of thyroid dysfunction and TKI used were assessed. Risk factors for incident hypothyroidism were evaluated using multivariate models.

RESULTS

In 538 adult patients included, subclinical hypothyroidism occurred in 71 (13.2%) and overt hypothyroidism occurred in 144 (26.8%) patients with TKI therapy, following a median cumulative TKI exposure of 196 days (interquartile range [IQR] 63.5-518.5 days). The odds of hypothyroidism were greatest during the first six months on a TKI. Median exposure time on the TKI concurrent with thyroid dysfunction in patients treated with only one TKI was 85 days (IQR 38-293.5 days) and was similar to the 74 days (IQR 38-133.3 days) in patients treated previously with other TKI (p = 0.41). Patients who developed hypothyroidism compared to those who remained euthyroid had greater odds of being female (odds ratio = 1.99 [confidence interval 1.35-2.93], p < 0.01), but greater cumulative TKI exposure and greater number of TKI received were not associated with thyroid dysfunction.

CONCLUSIONS

Thyroid dysfunction occurred in 40% of euthyroid patients. Monitoring thyroid function in TKI-treated patients is recommended, with particular attention to female patients and within the first six months of exposure to a new TKI.

Pazopanib-induced Endothelial Injury with Podocyte Changes

Pazopanib has been reported to induce proteinuria; however, no pathological findings have been reported. We herein report the case of a 31-year-old man with rhabdomyosarcoma treated with pazopanib who developed nephrotic syndrome. A renal biopsy revealed endothelial injury with podocyte changes. Based on the biopsy findings, we diagnosed the patient with nephrotic syndrome caused by pazopanib. Following the discontinuation of pazopanib, the patient's proteinuria gradually decreased without any specific treatment. We should be careful when encountering drug-induced proteinuria in patients taking pazopanib.

Clinical predictors of bevacizumab-associated intestinal perforation in non-small cell lung cancer

Background Bevacizumab (Bev) is generally well-tolerated, and Bev-associated intestinal perforation (BAP) is a rare albeit serious side effect in cases of non-small cell lung cancer (NSCLC). Therefore, the present study aimed to identify clinical predictors of BAP to help predict and manage the development of life-threatening intestinal complications among patients receiving Bev. Methods This retrospective study evaluated demographic, clinical, and treatment factors for patients with NSCLC who were treated with Bev between February 2010 and August 2015 at our center. Results We identified 314 regimens (208 patients; median age: 65 years; 115 women) for analysis, which included 119 first-line regimens, 74 s-line regimens, and 121 third-line or later regimens. BAP occurred in 7 cases (2.23% among all regimens and 3.37% among all patients), which generally occurred during first- or second-line treatment and was caused by ulcerative colitis (1 case), colon diverticulitis (1 case), and idiopathic perforations (5 cases). Univariate analyses revealed that BAP was significantly associated with deteriorating PS during the first cycle of chemotherapy (odd ratio [OR]: 11.07, 95% confidence interval [CI]: 2.37-51.63, p = 0.0022), grade ≥ 3 diarrhea (OR: 11.37, 95% CI: 2.37-54.50, p = 0.0024), febrile neutropenia (OR: 9.16, 95% CI: 1.98-42.49, p = 0.0047), and stomatitis (OR: 4.60, 95% CI: 1.01-21.04, p = 0.0492). Conclusions Among patients with NSCLC, BAP was associated with deteriorating PS during the first cycle of chemotherapy, grade ≥ 3 diarrhea, febrile neutropenia, and stomatitis. Therefore, careful observation is needed for patients with NSCLC who receive Bev in any line of treatment, especially if they develop serious side effects that affect their PS or mucous membrane.

Management of Adverse Events Associated with Cabozantinib Therapy in Renal Cell Carcinoma

Cabozantinib was recently approved for the treatment of advanced renal cell carcinoma (RCC) after treatment with vascular endothelial growth factor (VEGF)-targeted therapy. Cabozantinib is a multikinase inhibitor targeting VEGF receptor (VEGFR) 2, mesenchymal-epithelial transition receptor, and "anexelekto" receptor tyrosine kinase. A 60-mg daily dose led to improved overall survival and progression-free survival (PFS) versus everolimus in advanced RCC patients as a second- or later-line treatment in the METEOR trial. Improved PFS with cabozantinib versus sunitinib has also been demonstrated in the first-line setting in CABOSUN. However, cabozantinib, like other VEGFR inhibitors, is associated with toxicity that may affect the patient's quality of life. The most frequent adverse events (AEs) are diarrhea, fatigue, hypertension, hand-foot syndrome, weight loss, nausea, and stomatitis. This article summarizes the safety profile of cabozantinib in RCC patients and offers guidance for the management of these AEs. We discuss the underlying mechanisms of these AEs and, based on our experiences with cabozantinib and other multikinase inhibitors, we present approaches to manage toxicity. Prophylactic and therapeutic solutions are available to help with the management of toxicity associated with cabozantinib, and adequate interventions can ensure optimum adherence and maximize patient outcomes.

IMPLICATIONS FOR PRACTICE

Cabozantinib leads to improved survival outcomes in renal cell carcinoma patients compared with everolimus. However, management of the adverse event profile is crucial to achieve optimum adherence and outcomes with the use of cabozantinib. This review aims to provide appropriate guidance that will minimize the impact of adverse events and help to maximize the utility of this agent in patients with advanced renal cell carcinoma.

Co-option of pre-existing vascular beds in adipose tissue controls tumor growth rates and angiogenesis

Many types of cancer develop in close association with highly vascularized adipose tissues. However, the role of adipose pre-existing vascular beds on tumor growth and angiogenesis is unknown. Here we report that pre-existing microvascular density in tissues where tumors originate is a crucial determinant for tumor growth and neovascularization. In three independent tumor types including breast cancer, melanoma, and fibrosarcoma, inoculation of tumor cells in the subcutaneous tissue, white adipose tissue (WAT), and brown adipose tissue (BAT) resulted in markedly differential tumor growth rates and angiogenesis, which were in concordance with the degree of pre-existing vascularization in these tissues. Relative to subcutaneous tumors, WAT and BAT tumors grew at accelerated rates along with improved neovascularization, blood perfusion, and decreased hypoxia. Tumor cells implanted in adipose tissues contained leaky microvessel with poor perivascular cell coverage. Thus, adipose vasculature predetermines the tumor microenvironment that eventually supports tumor growth.

VEGFR2 but not VEGFR3 governs integrity and remodeling of thyroid angiofollicular unit in normal state and during goitrogenesis

Thyroid gland vasculature has a distinguishable characteristic of endothelial fenestrae, a critical component for proper molecular transport. However, the signaling pathway that critically governs the maintenance of thyroid vascular integrity, including endothelial fenestrae, is poorly understood. Here, we found profound and distinct expression of follicular epithelial VEGF‐A and vascular VEGFR2 that were precisely regulated by circulating thyrotropin, while there were no meaningful expression of angiopoietin–Tie2 system in the thyroid gland. Our genetic depletion experiments revealed that VEGFR2, but not VEGFR3, is indispensable for maintenance of thyroid vascular integrity. Notably, blockade of VEGF‐A or VEGFR2 not only abrogated vascular remodeling but also inhibited follicular hypertrophy, which led to the reduction of thyroid weights during goitrogenesis. Importantly, VEGFR2 blockade alone was sufficient to cause a reduction of endothelial fenestrae with decreases in thyrotropin‐responsive genes in goitrogen‐fed thyroids. Collectively, these findings establish follicular VEGF‐A–vascular VEGFR2 axis as a main regulator for thyrotropin‐dependent thyroid angiofollicular remodeling and goitrogenesis.

Tumor refractoriness to anti-VEGF therapy

Vascular endothelial growth factor (VEGF) has been identified as the most potent cytokine involved in tumor angiogenesis and metastasis formation. Clinical results of anti-angiogenic therapies targeting VEGF and its receptors are very modest, resulting in a moderate improvement of overall survival. The clinical outcome is associated with the development of resistance and the increased risk of invasion and metastasis. In this article, I have analyzed the principal mechanisms of resistance to VEGF pathway inhibitors, including normalization of tumor blood vessels, hypoxia, recruitment of inflammatory cells and immature myeloid cells, alternative mechanisms of tumor vessel formation, genomic instability of tumor endothelial cells. In this context, the concept and strategies of anti-angiogenic therapies should be extensively re-considered and re-evaluated. In particular, rational combinations of anti-angiogenic agents based on pharmacokinetic and pharmacodynamics data are needed to overcome resistance and it is extremely important to determine the optimal duration and scheduling of anti-VEGF agents.

Diffusion kurtosis imaging in identifying the malignancy of lymph nodes during the primary staging of rectal cancer

AIM

The aim was to assess the diagnostic value of diffusion kurtosis imaging (DKI) for discriminating between benign and malignant lymph nodes in patients with rectal carcinoma.

METHOD

ighty-five patients with rectal adenocarcinoma who underwent total mesorectal excision of the rectum were studied. A total of 273 lymph nodes were harvested and subjected to histological analysis. Quantitative parameters [apparent diffusion parameter D_app of the Gaussian distribution, apparent kurtosis coefficient K_app and apparent diffusion coefficient (ADC)] of lymph nodes were derived from DKI. Differences and the diagnostic performance of these parameters were calculated by using the independent-samples t test and receiver operating characteristic curve analyses.

RESULTS

The median D_app and ADC values of metastatic lymph nodes were significantly greater than those of benign lymph nodes, whereas the median K_app of metastatic lymph nodes was statistically less than that of normal lymph nodes. D_app had the relatively highest area under the curve of 0.774. When 1126.15 × 10^-6  mm² /s was used as a D_app threshold value, the sensitivity and specificity were 96.97% and 41.82%, respectively.

CONCLUSION

DKI can help differentiate metastatic vs benign lymph nodes during the primary staging of rectal cancer.

Colon Perforation during Sorafenib Therapy for Advanced Hepatocelluar Carcinoma. A Case Report

There are no effective conventional systemic cytotoxic therapies for patients with unresectable or advanced hepatocellar carcinoma (HCC). Sorafenib, an oral multi-targeted tyrosine kinase inhibitor, was recently approved for the treatment of patients with HCC. Sorafenib is generally well tolerated and has an acceptable toxicity profile. Gastrointestinal perforation is a rare adverse event. We present a case of transverse colon perforation during sorafenib therapy for advanced HCC. A 68-year-old woman with advanced HCC was treated with sorafenib. Eight weeks later the patient presented with the sudden onset of sharp abdominal pain. Emergency surgery was performed for panperitonitis and a perforation involving the transverse colon.

Control of Blood Vessel Formation by Notch Signaling

Blood vessels span throughout the body to nourish tissue cells and to provide gateways for immune surveillance. Endothelial cells that line capillaries have the remarkable capacity to be quiescent for years but to switch rapidly into the activated state once new blood vessels need to be formed. In addition, endothelial cells generate niches for progenitor and tumor cells and provide organ-specific paracrine (angiocrine) factors that control organ development and regeneration, maintenance of homeostasis and tumor progression. Recent data indicate a pivotal role for blood vessels in responding to metabolic changes and that endothelial cell metabolism is a novel regulator of angiogenesis. The Notch pathway is the central signaling mode that cooperates with VEGF, WNT, BMP, TGF-β, angiopoietin signaling and cell metabolism to orchestrate angiogenesis, tip/stalk cell selection and arteriovenous specification. Here, we summarize the current knowledge and implications regarding the complex roles of Notch signaling during physiological and tumor angiogenesis, the dynamic nature of tip/stalk cell selection in the nascent vessel sprout and arteriovenous differentiation. Furthermore, we shed light on recent work on endothelial cell metabolism, perfusion-independent angiocrine functions of endothelial cells in organ-specific vascular beds and how manipulation of Notch signaling may be used to target the tumor vasculature.

Historical Perspectives and Current Challenges in Cell Microencapsulation

The principle of immunoisolation of cells is based on encapsulation of cells in immunoprotective but semipermeable membranes that protect cells from hazardous effects of the host immune system but allows ingress of nutrients and outgress of therapeutic molecules. The technology was introduced in 1933 but has only received its deserved attention for its therapeutic application for three decades now.In the past decade important advances have been made in creating capsules that provoke minimal or no inflammatory responses. There are however new emerging challenges. These challenges relate to optimal nutrition and oxygen supply as well as standardization and documentation of capsule properties.It is concluded that the proof of principle of applicability of encapsulated grafts for treatment of human disease has been demonstrated and merits optimism about its clinical potential. Further innovation requires a much more systematic approach in identifying crucial properties of capsules and cellular grafts to allow sound interpretations of the results.

Development and plasticity of meningeal lymphatic vessels

The recent discovery of meningeal lymphatic vessels (LVs) has raised interest in their possible involvement in neuropathological processes, yet little is known about their development or maintenance. We show here that meningeal LVs develop postnatally, appearing first around the foramina in the basal parts of the skull and spinal canal, sprouting along the blood vessels and cranial and spinal nerves to various parts of the meninges surrounding the central nervous system (CNS). VEGF-C, expressed mainly in vascular smooth muscle cells, and VEGFR3 in lymphatic endothelial cells were essential for their development, whereas VEGF-D deletion had no effect. Surprisingly, in adult mice, the LVs showed regression after VEGF-C or VEGFR3 deletion, administration of the tyrosine kinase inhibitor sunitinib, or expression of VEGF-C/D trap, which also compromised the lymphatic drainage function. Conversely, an excess of VEGF-C induced meningeal lymphangiogenesis. The plasticity and regenerative potential of meningeal LVs should allow manipulation of cerebrospinal fluid drainage and neuropathological processes in the CNS.

Endothelial cell apoptosis in angiogenesis and vessel regression

Blood vessel regression is an essential process for ensuring blood vessel networks function at optimal efficiency and for matching blood supply to the metabolic needs of tissues as they change over time. Angiogenesis is the major mechanism by which new blood vessels are produced, but the vessel growth associated with angiogenesis must be complemented by remodeling and maturation events including the removal of redundant vessel segments and cells to fashion the newly forming vasculature into an efficient, hierarchical network. This review will summarize recent findings on the role that endothelial cell apoptosis plays in vascular remodeling during angiogenesis and in vessel regression more generally.

Systemic effects of angiogenesis inhibition alter pharmacokinetics and intratumoral delivery of nab-paclitaxel

Angiogenesis is critical to the growth of tumors. Vascularization-targeting agents, with or without cytotoxic drugs, are widely used for the treatment of several solid tumors including esophagogastric adenocarcinoma. However, little is known about the systemic effects of anti-angiogenic therapies and how this affects the pharmacokinetics and intratumoral delivery of cytotoxic agents. In this study, patient-derived xenograft mouse models of esophageal adenocarcinoma were used to identify the effects of DC101, a murine vascular endothelial growth factor receptor 2 (VEGFR2) inhibitor, on the pharmacokinetics and the intratumoral uptake of nab-paclitaxel (NPTX). We showed that DC101 had large systemic effects resulting in decreased vasculature of intraperitoneally located organs. As a consequence, after intraperitoneal administration of NPTX, plasma uptake (5.029 ± 4.35 vs. 25.85 ± 2.27 µM) and intratumoral delivery (5.48 ± 5.32 vs. 38.49 ± 2.805 pmol/mg) of NPTX were greatly impaired in DC101-treated animals compared to control animals. Additionally, routes of NPTX elimination were altered upon angiogenesis inhibition; unchanged renal clearance and intraperitoneal accumulation of NPTX were observed, but NPTX levels were significantly lower in the liver. Histological examination of the intestine revealed a reduced thickness of the intestinal wall following DC101 therapy and suggested seepage of intraperitoneally injected NTPX through the intestinal wall to explain its reduced uptake in liver, plasma, and tumor tissue. These data explain several adverse effects observed in the clinic when using anti-angiogenic therapies and also imply that the combined use of anti-angiogenesis and cytotoxic agents in both preclinical and clinical setting is still suboptimal.

Anaplastic thyroid carcinoma: from clinicopathology to genetics and advanced therapies

Anaplastic thyroid carcinoma (ATC) is a rare malignancy, accounting for 1-2% of all thyroid cancers. Although rare, ATC accounts for the majority of deaths from thyroid carcinoma. ATC often originates in a pre-existing thyroid cancer lesion, as suggested by the simultaneous presence of areas of differentiated or poorly differentiated thyroid carcinoma. ATC is characterized by the accumulation of several oncogenic alterations, and studies have shown that an increased number of oncogenic alterations equates to an increased level of dedifferentiation and aggressiveness. The clinical management of ATC requires a multidisciplinary approach; according to recent American Thyroid Association guidelines, surgery, radiotherapy and/or chemotherapy should be considered. In addition to conventional therapies, novel molecular targeted therapies are the most promising emerging treatment modalities. These drugs are often multiple receptor tyrosine kinase inhibitors, several of which have been tested in clinical trials with encouraging results so far. Accordingly, clinical trials are ongoing to evaluate the safety, efficacy and effectiveness of these new agents. This Review describes the updated clinical and pathological features of ATC and provides insight into the molecular biology of this disease. The most recent literature regarding conventional, newly available and future therapies for ATC is also discussed.

Impact of Diabetes on Outcomes of Sorafenib Therapy for Hepatocellular Carcinoma

BACKGROUND

Patients with diabetes are at increased risk of developing hepatocellular carcinoma (HCC) and have a poorer prognosis as compared to non-diabetics when HCC occurs. Diabetics with non-HCC cancers are at higher risk of toxicity related to systemic therapy, but data on HCC are lacking.

OBJECTIVE

The aim of this study was to evaluate safety and effectiveness of sorafenib in HCC patients according to the presence/absence of diabetes.

PATIENTS AND METHODS

From October 2008 to June 2014, 313 patients with HCC treated with sorafenib were enrolled. The patients were staged according to the BCLC system. Treatment response was evaluated according to the mRECIST criteria. The main evaluated outcomes were the overall survival and the safety in the two groups.

RESULTS

Patients were divided in two groups: 80 diabetics (DIAB) and 233 nondiabetics (nDIAB). The median treatment duration was 4 months in DIAB and 3 months in nDIAB. Main adverse events occurred with comparable frequency in both groups, with the exception of rash, that was more frequent among DIAB than in nDIAB: 27.5 % vs 17.6 % (P = .047). The median overall survival was 9 months in nDIAB and 10 months in DIAB group (P = .535). Median time-to-progression (TTP) was longer the in DIAB than the nDIAB group (P = .038).

CONCLUSIONS

Sorafenib was as safe as effective in DIAB and in nDIAB patients. The longer TTP observed among DIAB than in nDIAB patients might suggest a better anticancer effect of sorafenib in patients with diabetes.

Off-tumor targets compromise antiangiogenic drug sensitivity by inducing kidney erythropoietin production

Anti-VEGF drugs are commonly used for treatment of a variety of cancers in human patients, and they often develop resistance. The mechanisms underlying anti-VEGF resistance in human cancer patients are largely unknown. Here, we show that in mouse tumor models and in human cancer patients, the anti-VEGF drug-induced kidney hypoxia augments circulating levels of erythropoietin (EPO). Gain-of-function studies show that EPO protects tumor vessels from anti-VEGF treatment and compromises its antitumor effects. Loss of function by blocking EPO function using a pharmacological approach markedly increases antitumor activity of anti-VEGF drugs through inhibition of tumor angiogenesis. Similarly, genetic loss-of-function data shows that deletion of EpoR in nonerythroid cells significantly increases antiangiogenic and antitumor effects of anti-VEGF therapy. Finally, in a relatively large cohort study, we show that treatment of human colorectal cancer patients with bevacizumab augments circulating EPO levels. These findings uncover a mechanism of desensitizing antiangiogenic and anticancer effects by kidney-produced EPO. Our work presents conceptual advances of our understanding of mechanisms underlying antiangiogenic drug resistance.

Thyroid disease in pregnancy: new insights in diagnosis and clinical management

Adequate thyroid hormone availability is important for an uncomplicated pregnancy and optimal fetal growth and development. Overt thyroid disease is associated with a wide range of adverse obstetric and child development outcomes. An increasing number of studies now indicate that milder forms of thyroid dysfunction are also associated with these adverse pregnancy outcomes. The definitions of both overt and subclinical thyroid dysfunction have changed considerably over the past few years, as new data indicate that the commonly used fixed upper limits of 2.5 mU/l or 3.0 mU/l for thyroid-stimulating hormone (TSH) are too low to define an abnormal thyroid function. Furthermore, some studies now show that the reference ranges are not necessarily the best cut-off for identifying pregnancies at high risk of adverse outcomes. In addition, data suggest that thyroid peroxidase autoantibody positivity and high or low concentrations of human chorionic gonadotropin seem to have a more prominent role in the interpretation of thyroid dysfunction than previously thought. Data on the effects of thyroid disease treatment are lacking, but some studies indicate that clinicians should be aware of the potential for overtreatment with levothyroxine. Here, we put studies from the past decade on reference ranges for TSH, determinants of thyroid dysfunction, risks of adverse outcomes and options for treatment into perspective. In addition, we provide an overview of the current views on thyroid physiology during pregnancy and discuss strategies to identify high-risk individuals who might benefit from levothyroxine treatment.

FLT1 and transcriptome-wide polyadenylation site (PAS) analysis in preeclampsia

Maternal symptoms of preeclampsia (PE) are primarily driven by excess anti-angiogenic factors originating from the placenta. Chief among these are soluble Flt1 proteins (sFlt1s) produced from alternatively polyadenylated mRNA isoforms. Here we used polyadenylation site sequencing (PAS-Seq) of RNA from normal and PE human placentae to interrogate transcriptome-wide gene expression and alternative polyadenylation signatures associated with early-onset PE (EO-PE; symptom onset < 34 weeks) and late-onset PE (LO-PE; symptom onset > 34 weeks) cohorts. While we observed no general shift in alternative polyadenylation associated with PE, the EO-PE and LO-PE cohorts do exhibit gene expression profiles distinct from both each other and from normal placentae. The only two genes upregulated across all transcriptome-wide PE analyses to date (microarray, RNA-Seq and PAS-Seq) are NRIP1 (RIP140), a transcriptional co-regulator linked to metabolic syndromes associated with obesity, and Flt1. Consistent with sFlt1 overproduction being a significant driver of clinical symptoms, placental Flt1 mRNA levels strongly correlate with maternal blood pressure. For Flt1, just three mRNA isoforms account for > 94% of all transcripts, with increased transcription of the entire locus driving Flt1 upregulation in both EO-PE and LO-PE. These three isoforms thus represent potential targets for therapeutic RNA interference (RNAi) in both early and late presentations.

Bevacizumab-induced hypertension: Clinical presentation and molecular understanding

Bevacizumab is a vascular endothelial growth factor-A-specific angiogenesis inhibitor indicated as an adjunct to chemotherapy for the treatment of several types of cancer. Hypertension is commonly observed during bevacizumab treatment, and high-grade toxicity can limit therapy and lead to other cardiovascular complications. The factors that contribute to interindividual variability in blood pressure response to bevacizumab treatment are not well understood. In this review, we outline research efforts to understand the mechanisms and pathophysiology of hypertension resulting from bevacizumab treatment. Moreover, we highlight current knowledge of the pharmacogenetics of bevacizumab-induced hypertension, which may be used to develop strategies to prevent or minimize this toxicity.

SAVE-AMD: Safety of VEGF Inhibitors in Age-Related Macular Degeneration

OBJECTIVE

To determine whether intraocular treatment with vascular endothelial growth factor (VEGF) inhibitors change systemic endothelial function (EF) in patients with neovascular age-related macular degeneration (AMD).

METHODS

In this prospective, randomized, 2-center, double-masked controlled interventional trial, patients with neovascular and dry AMD were enrolled. Eligible neovascular AMD patients received 2 intravitreal loading doses of either ranibizumab 0.5 mg or bevacizumab 1.25 mg at 4-week intervals and were subsequently followed every 4 weeks and treated according to a pro re nata regime for up to 1 year. Patients with dry AMD served as controls. The primary endpoint was the change in EF assessed by flow-mediated dilatation (FMD) after 2 months of treatment with VEGF inhibitors in patients with AMD compared to patients with dry AMD. FMD was assessed with B-mode high-resolution ultrasonography of the left brachial artery.

RESULTS

24 patients with neovascular AMD and 26 patients with dry ADM were included in the trial. Treatment with VEGF inhibitors did not significantly change FMD (from 4.7 ± 2.4 to 3.9 ± 1.9% after 8 weeks, p = 0.07, and to 5.1 ± 2.0% after 1 year; p = 0.93 vs. baseline, respectively).

CONCLUSIONS

EF did not significantly differ between patients with neovascular AMD treated with intravitreal VEGF inhibition and patients with dry AMD.

Intestinal lymphatic vasculature: structure, mechanisms and functions

The mammalian intestine is richly supplied with lymphatic vasculature, which has functions ranging from maintenance of interstitial fluid balance to transport of antigens, antigen-presenting cells, dietary lipids and fat-soluble vitamins. In this Review, we provide in-depth information concerning the organization and structure of intestinal lymphatics, the current view of their developmental origins, as well as molecular mechanisms of intestinal lymphatic patterning and maintenance. We will also discuss physiological aspects of intestinal lymph flow regulation and the known and emerging roles of intestinal lymphatic vessels in human diseases, such as IBD, infection and cancer.