Contrary effects of the receptor tyrosine kinase inhibitor vandetanib on constitutive and flow-stimulated nitric oxide elaboration in humans

Vascularised cardiac spheroids-on-a-chip for testing the toxicity of therapeutics

Microfabricated organ-on-a-chips are rapidly becoming the gold standard for the testing of safety and efficacy of therapeutics. A broad range of designs has emerged, but recreating microvascularised tissue models remains difficult in many cases. This is particularly relevant to mimic the systemic delivery of therapeutics, to capture the complex multi-step processes associated with trans-endothelial transport or diffusion, uptake by targeted tissues and associated metabolic response. In this report, we describe the formation of microvascularised cardiac spheroids embedded in microfluidic chips. Different protocols used for embedding spheroids within vascularised multi-compartment microfluidic chips were investigated first to identify the importance of the spheroid processing, and co-culture with pericytes on the integration of the spheroid within the microvascular networks formed. The architecture of the resulting models, the expression of cardiac and endothelial markers and the perfusion of the system was then investigated. This confirmed the excellent stability of the vascular networks formed, as well as the persistent expression of cardiomyocyte markers such as cTNT and the assembly of striated F-actin, myosin and α-actinin cytoskeletal networks typically associated with contractility and beating. The ability to retain beating over prolonged periods of time was quantified, over 25 days, demonstrating not only perfusability but also functional performance of the tissue model. Finally, as a proof-of-concept of therapeutic testing, the toxicity of one therapeutic associated with cardiac disfunction was evaluated, identifying differences between direct in vitro testing on suspended spheroids and vascularised models.

Endothelial dysfunction as a complication of anti-cancer therapy

Recent strides in anti-cancer therapeutics have improved longevity and led to a growing population of cancer survivors, who are increasingly likely to die of other causes. Treatment-induced cardiotoxicity is a complication of several therapeutic agents with acute and long-term consequences for cancer patients. Vascular endothelial dysfunction is a precursor and hallmark of ischemic coronary disease and may play a role in anti-cancer therapy-induced cardiotoxicity. This review summarizes clinical evidence for endothelial dysfunction following anti-cancer therapy and extends the discussion to include the impact of therapeutic agents on conduit arteries and the microcirculation. We highlight the role of innate immune system activation and cross-talk between inflammation and oxidative stress as pathogenic mechanisms underlying anti-cancer therapy-induced vascular toxicity. Understanding the impact of anti-cancer agents on the vascular endothelium will inform therapeutic approaches to prevent or reverse treatment-induced cardiotoxicity and may serve as an important tool to predict, monitor, and prevent adverse cardiovascular outcomes in patients undergoing treatment.

Cardiotoxicity Induced by Protein Kinase Inhibitors in Patients with Cancer

Kinase inhibitors (KIs) represent a growing class of drugs directed at various protein kinases and used in the treatment of both solid tumors and hematologic malignancies. It is a heterogeneous group of compounds that are widely applied not only in different types of tumors but also in tumors that are positive for a specific predictive factor. This review summarizes common cardiotoxic effects of KIs, including hypertension, arrhythmias with bradycardia and QTc prolongation, and cardiomyopathy that can lead to heart failure, as well as less common effects such as fluid retention, ischemic heart disease, and elevated risk of thromboembolic events. The guidelines for cardiac monitoring and management of the most common cardiotoxic effects of protein KIs are discussed. Potential signaling pathways affected by KIs and likely contributing to cardiac damage are also described. Finally, the need for further research into the molecular mechanisms underlying the cardiovascular toxicity of these drugs is indicated.

Hypertension Induced by Combination Therapy of Cancer: A Systematic Review and Meta-Analysis of Global Clinical Trials

Background: Nowadays, due to the limitation of single therapy, combination therapy for cancer treatments has become important strategy. With the advancement of research on cardiotoxicities induced by anti-cancer treatment, among which cancer treatment-induced hypertension is the most frequent case. However, due to the small sample size and the absence of comparison (single-arm study alone), these studies have limitations to produce a feasible conclusion. Therefore, it is necessary to carry out a meta-analysis focusing on hypertension caused by cancer combination therapy.

Methods: We systematically searched PubMed, Embase, Cochrane Library, Web of Science, and CNKI, from database inception to November 31, 2020, with randomized controlled trials (RCTs) associated with hypertension induced by cancer combination drugs. The main endpoint of which was to assess the difference in the incidence of hypertension in cancer patients with monotherapy or combination therapy. We calculated the corresponding 95% confidence interval (95% CIs) according to the random effect model and evaluated the heterogeneity between different groups.

Results: According to the preset specific inclusion and exclusion criteria, a total of 23 eligible RCTs have been included in the present meta-analysis, including 6,241 patients (Among them, 2872 patients were the control group and 3369 patients were the experimental group). The results showed that cancer patients with combination therapy led to a higher risk of hypertension (All-grade: RR 2.85, 95% CI 2.52∼3.22; 1∼2 grade: RR 2.43, 95% CI 2.10∼2.81; 3∼4 grade: RR 4.37, 95% CI 3.33∼5.72). Furthermore, compared with the control group who received or did not receive a placebo, there was a higher risk of grade 3-4 hypertension caused by cancer combination treatment.

Conclusion: The present meta-analysis carries out a comprehensive analysis on the risk of patients suffering from hypertension in the process of multiple cancer combination therapies. Findings in our study support that the risk of hypertension may increase significantly in cancer patients with multiple cancer combination therapies. The outcomes of this meta-analysis may provide a reference value for clinical practice and may supply insights in reducing the incidence of hypertension caused by cancer combined treatment.

Changes in blood pressure during treatment with the tyrosine kinase inhibitor lenvatinib

Background

Within the class of tyrosine kinase inhibitors (TKIs), which are used for the treatment of numerous advanced cancers, lenvatinib is associated with a higher prevalence of hypertension (HT) compared with other TKIs. In this study, we investigated the effect of lenvatinib on blood pressure (BP) and associated factors.

Methods

This single-centre, retrospective observational study included 25 consecutive patients treated with lenvatinib for unresectable hepatocellular carcinoma from April 2018 to December 2018 at the study institution. We assessed changes in BP using ambulatory BP monitoring, urinary sodium excretion, kidney function, use of antihypertensive agents and diuretics, and fluid retention following treatment initiation with lenvatinib.

Results

At 1 week after treatment initiation, the mean BP and the percentage of patients with riser pattern significantly increased compared with those at the baseline. Although there were no significant changes at 1 week, urinary sodium excretion (153.4 ± 51.7 and 112.5 ± 65.0 mEq/day at 1 and 3 weeks, respectively, P < 0.05) and estimated glomerular filtration rate significantly decreased and the number of patients with fluid retention increased at 3 weeks. Furthermore, patients with fluid retention had significantly higher BP or required more intensive BP treatment compared with those without fluid retention.

Conclusions

Lenvatinib might lead to HT without fluid retention soon after the initiation of treatment, subsequently leading to a reduction in urinary sodium excretion, thereby contributing to a rise in BP by fluid retention.

Vascular Cardio-Oncology: Vascular Endothelial Growth Factor inhibitors and hypertension

Since the formation of new blood vessels is essential for tumour growth and metastatic spread, inhibition of angiogenesis by targeting the vascular endothelial growth factor (VEGF) pathway is an effective strategy for various types of cancer, most importantly renal cell carcinoma, thyroid cancer, and hepatocellular carcinoma. However, VEGF inhibitors have serious side effects, most importantly hypertension and nephropathy. In case of fulminant hypertension, this may only be handled by lowering the dosage since the blood pressure rise is proportional to the amount of VEGF inhibition. These effects pathophysiologically and clinically resemble the most severe complication of pregnancy, preeclampsia, in which case an insufficient placenta leads to a rise in sFlt-1 levels causing a decrease in VEGF availability. Due to this overlap, studies in preeclampsia may provide important information for VEGF inhibitor-induced toxicity and vice versa. In both VEGF inhibitor-induced toxicity and preeclampsia, endothelin (ET)-1 appears to be a pivotal player. In this review, after briefly summarizing the anticancer effects, we discuss the mechanisms that potentially underlie the unwanted effects of VEGF inhibitors, focusing on ET-1, nitric oxide and oxidative stress, the renin-angiotensin-aldosterone system, and rarefaction. Given the salt sensitivity of this phenomenon, as well as the beneficial effects of aspirin in preeclampsia and cancer, we next provide novel treatment options for VEGF inhibitor-induced toxicity, including salt restriction, ET receptor blockade, and cyclo-oxygenase inhibition, in addition to classical antihypertensive and renoprotective drugs. We conclude with the recommendation of therapeutic drug monitoring to improve patient outcome.

Tyrosine Kinase Inhibitor-Induced Hypertension: Role of Hypertension as a Biomarker in Cancer Treatment

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Cancer treatment is an area of continuous improvement. Therapy is becoming more targeted and the use of anti-angiogenic agents in multiple cancers, specifically tyrosine kinase inhibitors (TKIs), has demonstrated prolonged survival outcomes compared with previous drugs. Therefore, they have become a well-established part of the treatment.

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Despite good results, there is a broad range of moderate to severe adverse effects associated with treatment. Hypertension (HTN) is one of the most frequent adverse effects and has been associated with favourable outcomes (in terms of cancer treatment) of TKI treatment.

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High blood pressure is considered a class effect of TKI treatment, although the mechanisms have not been fully described. Three current hypotheses of TKI-associated HTN are highlighted in this narrative review. These include nitric oxide decrease, a change in endothelin-1 levels and capillary rarefaction.

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Several studies have investigated HTN as a potential biomarker of TKI efficacy. HTN is easy to measure and adding this factor to prognostic models has been shown to improve specificity. HTN may become a potential biomarker in clinical practice involving treating advanced cancers. However, data are currently limited by the number of studies and knowledge of the mechanism of action.

Acute blood pressure elevation associated with biological therapies for cancer: a focus on VEGF signaling pathway inhibitors

INTRODUCTION

Treatment with biological agents interfering with mechanisms of angiogenesis, such as vascular endothelial growth factor (VEGF) signaling pathway (VSP) inhibitors, was associated with an enhanced risk of acute and severe blood pressure (BP) increase and development of hypertensive emergencies. Areas covered: The present article will review the scientific literature reporting hypertensive emergencies as a complication of biological treatment with VSP inhibitors. Hypertensive emergency is a life-threatening condition characterized by very high BP values (>180/110 mmHg) associated with acute organ damage. The exact mechanism of action is still incompletely clarified. Endothelial dysfunction following reduced bioavailability of nitric oxide has been hypothesized to play an important role in promoting hypertension and the occurrence of acute organ damage. Expert opinion: Prevention, prompt recognition and treatment of hypertensive emergencies associated with treatment with VSP-inhibitors are essential to reduce the risk of adverse events. Not infrequently, the occurrence of hypertensive emergency led to VSP treatment discontinuation, with potential negative consequences on patient overall survival. The present review aims at providing detailed knowledge for the clinician regarding this specific issue, which could be of high impact in usual clinical practice, given the increasing burden of indications to treatment with biological agents targeted to the VEGF pathway.

Vascular toxicities with VEGF inhibitor therapies-focus on hypertension and arterial thrombotic events

The vascular endothelial growth factor (VEGF) signaling pathway (VSP) fulfills a cardinal role in endothelial cells and its inhibition has profound cardiovascular impact. This is true not only for the normal vasculature but also for the tumor vasculature when VSP inhibitors are used as anti-angiogenic therapies. Generalized endothelial dysfunction predisposes to vasoconstriction, atherosclerosis, platelet activation, and thrombosis (arterial more than venous). All of these have been reported with VSP inhibitors and collectively give rise to vascular toxicities, the most concerning of which are arterial thromboembolic events (ATE). VSP inhibitors include antibodies, acting extracelluarly on VEGF, such as bevacizumab and tyrosine kinases inhibitors, acting intracellularly on the kinase domain of VEGF receptors, such as sunintib and sorafenib. The addition of bevacizumab and VSP tyrosine kinase inhibitor therapy to the cancer treatment regimen is associated with a 1.5-2.5-fold and 2.3-4.6-fold increase risk of ATEs, respectively. Risk factors for ATEs while on VSP inhibitor therapy include age older than 65 years, previous thromboembolic events, history of atherosclerotic disease, and duration of VSP inhibitor therapy. In clinical practice, hypertension remains the most commonly noted vascular manifestation of VSP inhibition. Optimal blood pressure goals and preferred therapeutic strategies toward reaching these goals are not defined at present. This review summarizes current data on this topic and proposes a more intensive management approach to patients undergoing VSP inhibitor therapy including Systolic Blood PRessure Intervention Trial (SPRINT) blood pressure goals, pleiotropic vasoprotective agents such as angiotensin converting enzyme inhibitors, amlodipine, and carvedilol, high-dose statin therapy, and aspirin.

Cardio-Oncology: mechanisms of cardiovascular toxicity

The therapeutic options available to treat a wide range of malignancies are rapidly increasing. At the same time, the population being treated is aging with more cardiovascular risk factors, comorbid conditions, and associated poor cardiac reserve. Both traditional chemotherapeutic agents (for example, anthracyclines) and newer therapies (for example, targeted tyrosine kinase inhibitors and immune checkpoint inhibitors) have demonstrated profound cardiovascular toxicities. It is important to understand the mechanisms of these toxicities to establish strategies for the prevention and management of complications—arrhythmias, heart failure, and even death. In the first of this two-part review series, we focus on what is known and hypothesized about the mechanisms of cardiovascular toxicity from anthracyclines, HER2/ErbB2 inhibitors, immune checkpoint inhibitors, and vascular endothelial growth factor inhibitors.

Endothelial dysfunction and vascular disease - a 30th anniversary update

The endothelium can evoke relaxations of the underlying vascular smooth muscle, by releasing vasodilator substances. The best-characterized endothelium-derived relaxing factor (EDRF) is nitric oxide (NO) which activates soluble guanylyl cyclase in the vascular smooth muscle cells, with the production of cyclic guanosine monophosphate (cGMP) initiating relaxation. The endothelial cells also evoke hyperpolarization of the cell membrane of vascular smooth muscle (endothelium-dependent hyperpolarizations, EDH-mediated responses). As regards the latter, hydrogen peroxide (H₂ O₂ ) now appears to play a dominant role. Endothelium-dependent relaxations involve both pertussis toxin-sensitive G_i (e.g. responses to α₂ -adrenergic agonists, serotonin, and thrombin) and pertussis toxin-insensitive G_q (e.g. adenosine diphosphate and bradykinin) coupling proteins. New stimulators (e.g. insulin, adiponectin) of the release of EDRFs have emerged. In recent years, evidence has also accumulated, confirming that the release of NO by the endothelial cell can chronically be upregulated (e.g. by oestrogens, exercise and dietary factors) and downregulated (e.g. oxidative stress, smoking, pollution and oxidized low-density lipoproteins) and that it is reduced with ageing and in the course of vascular disease (e.g. diabetes and hypertension). Arteries covered with regenerated endothelium (e.g. following angioplasty) selectively lose the pertussis toxin-sensitive pathway for NO release which favours vasospasm, thrombosis, penetration of macrophages, cellular growth and the inflammatory reaction leading to atherosclerosis. In addition to the release of NO (and EDH, in particular those due to H₂ O₂ ), endothelial cells also can evoke contraction of the underlying vascular smooth muscle cells by releasing endothelium-derived contracting factors. Recent evidence confirms that most endothelium-dependent acute increases in contractile force are due to the formation of vasoconstrictor prostanoids (endoperoxides and prostacyclin) which activate TP receptors of the vascular smooth muscle cells and that prostacyclin plays a key role in such responses. Endothelium-dependent contractions are exacerbated when the production of nitric oxide is impaired (e.g. by oxidative stress, ageing, spontaneous hypertension and diabetes). They contribute to the blunting of endothelium-dependent vasodilatations in aged subjects and essential hypertensive and diabetic patients. In addition, recent data confirm that the release of endothelin-1 can contribute to endothelial dysfunction and that the peptide appears to be an important contributor to vascular dysfunction. Finally, it has become clear that nitric oxide itself, under certain conditions (e.g. hypoxia), can cause biased activation of soluble guanylyl cyclase leading to the production of cyclic inosine monophosphate (cIMP) rather than cGMP and hence causes contraction rather than relaxation of the underlying vascular smooth muscle.

Ebselen does not improve oxidative stress and vascular function in patients with diabetes: a randomized, crossover trial

Oxidative stress is a key driver of vascular dysfunction in diabetes mellitus. Ebselen is a glutathione peroxidase mimetic. A single-site, randomized, double-masked, placebo-controlled, crossover trial was carried out in 26 patients with type 1 or type 2 diabetes to evaluate effects of high-dose ebselen (150 mg po twice daily) administration on oxidative stress and endothelium-dependent vasodilation. Treatment periods were in random order of 4 wk duration, with a 4-wk washout between treatments. Measures of oxidative stress included nitrotyrosine, plasma 8-isoprostanes, and the ratio of reduced to oxidized glutathione. Vascular ultrasound of the brachial artery and plethysmographic measurement of blood flow were used to assess flow-mediated and methacholine-induced endothelium-dependent vasodilation of conduit and resistance vessels, respectively. Ebselen administration did not affect parameters of oxidative stress or conduit artery or forearm arteriolar vascular function compared with placebo treatment. There was no difference in outcome by diabetes type. Ebselen, at the dose and duration evaluated, does not improve the oxidative stress profile, nor does it affect endothelium-dependent vasodilation in patients with diabetes mellitus.

Hypertension in cancer patients treated with anti-angiogenic based regimens

New anti-cancer drugs that inhibit the vascular endothelial growth factor (VEGF) signaling pathway are highly effective in the treatment of solid tumors, however concerns remain regarding their cardiovascular safety. The most common side effect of VEGF signaling pathway (VSP) inhibition is the development of systemic hypertension. We review the incidence, possible mechanisms, significance and management of hypertension in patients treated with VSP inhibitors.

In vitro pharmacological profiling of R406 identifies molecular targets underlying the clinical effects of fostamatinib

Off-target pharmacology may contribute to both adverse and beneficial effects of a new drug. In vitro pharmacological profiling is often applied early in drug discovery; there are fewer reports addressing the relevance of broad profiles to clinical adverse effects. Here, we have characterized the pharmacological profile of the active metabolite of fostamatinib, R406, linking an understanding of drug selectivity to the increase in blood pressure observed in clinical studies. R406 was profiled in a broad range of in vitro assays to generate a comprehensive pharmacological profile and key targets were further investigated using functional and cellular assay systems. A combination of traditional literature searches and text-mining approaches established potential mechanistic links between the profile of R406 and clinical side effects. R406 was selective outside the kinase domain, with only antagonist activity at the adenosine A3 receptor in the range relevant to clinical effects. R406 was less selective in the kinase domain, having activity at many protein kinases at therapeutically relevant concentrations when tested in multiple in vitro systems. Systematic literature analyses identified KDR as the probable target underlying the blood pressure increase observed in patients. While the in vitro pharmacological profile of R406 suggests a lack of selectivity among kinases, a combination of classical searching and text-mining approaches rationalized the complex profile establishing linkage between off-target pharmacology and clinically observed effects. These results demonstrate the utility of in vitro pharmacological profiling for a compound in late-stage clinical development.

Anti-angiogenic-specific adverse events in patients with non-small cell lung cancer treated with nintedanib and docetaxel

OBJECTIVES

LUME-Lung 1 was a randomized, placebo-controlled, Phase III trial investigating nintedanib+docetaxel versus placebo+docetaxel in patients with advanced NSCLC progressing after first-line chemotherapy. Progression-free survival was significantly improved with nintedanib+docetaxel in the overall population and overall survival was significantly improved in the pre-specified analysis of patients with adenocarcinoma. We evaluated the frequency of characteristic adverse events (AEs) commonly seen with existing anti-angiogenic agents.

MATERIALS AND METHODS

The incidence and intensity of AEs were evaluated in all patients who received at least one dose of study medication (N=1307) and for the two main histologies: adenocarcinoma (n=653) and squamous cell carcinoma (SCC; n=553). AEs of special interest were analyzed by category, preferred term, and worst CTCAE grade and included perforation, hypertension, bleeding, thromboembolic events, and skin disorders.

RESULTS AND CONCLUSION

The incidence of patients with all-grade gastrointestinal (GI) perforations was low and balanced between arms (0.5% in both) and across histologies; the incidence of non-GI perforations was 1.2% with nintedanib+docetaxel versus 0.2% with placebo+docetaxel. The incidence of some events was higher with nintedanib+docetaxel versus placebo+docetaxel; hypertension (3.5% vs 0.9%), rash (11.0% vs 8.1%), and cutaneous adverse reactions (13.0% vs 10.7%). Rash and cutaneous adverse reactions were predominantly Grade 1-2 with both treatments. The incidence of all-grade bleeding was also slightly higher in nintedanib+docetaxel-treated patients (14.1% vs 11.6%) driven by between-treatment differences in the SCC subpopulation; most events were Grade 1-2. The proportion of patients with a thromboembolic event was low and comparable between arms for all grades (5.1% vs 4.6%) and Grade ≥3 (2.1% vs 3.1%). Safety evaluation of the LUME-Lung 1 study showed that the frequency of AEs commonly associated with other anti-angiogenic agents was lower with nintedanib+docetaxel. Survival benefits from addition of nintedanib to docetaxel in patients with adenocarcinoma after first-line therapy can be achieved alongside a manageable safety profile.

Etiology of angiogenesis inhibition-related hypertension

Angiogenesis inhibition, targeting vascular endothelial growth factor (VEGF) or its receptors, is an established treatment for solid tumors. A common side effect of this treatment is the development of sometimes severe hypertension. This hypertension is associated with a decrease in nitric oxide production, activation of the endothelin-signaling pathway and renin suppression. The mechanism underlying activation of the endothelin-signaling pathway is not fully understood. Both activation of endothelial cells and disinhibition of the VEGF-induced suppression of endothelin production by endothelial cells may be involved. The development of hypertension can be a reason to discontinue the angiogenesis inhibitor, thereby compromising anticancer treatment, but possibly is also a biomarker for a favorable antitumor response.

The contribution of VEGF signalling to fostamatinib-induced blood pressure elevation

BACKGROUND AND PURPOSE

Fostamatinib is an inhibitor of spleen tyrosine kinase (TK). In patients, fostamatinib treatment was associated with increased BP. Some TK inhibitors cause BP elevation, by inhibiting the VEGF receptor 2 (VEGFR2). Here, we have assessed the mechanistic link between fostamatinib-induced BP elevation and inhibition of VEGF signalling.

EXPERIMENTAL APPROACH

We used conscious rats with automated blood sampling and radio telemetry and anaesthetized rats to measure cardiovascular changes. Rat isolated aorta and isolated hearts, and human resistance vessels in vitro were also used. NO production by human microvascular endothelial cells was measured with the NO-dependent probe, DAF-FM and VEGFR2 phosphorylation was determined in mouse lung, ex vivo.

KEY RESULTS

In conscious rats, fostamatinib dose-dependently increased BP. The time course of the BP effect correlated closely with the plasma concentrations of R406 (the active metabolite of fostamatinib). In anaesthetized rats, infusion of R406 increased BP and decreased femoral arterial conductance. Endothelial function was unaffected, as infusion of R406 did not inhibit hyperaemia- or ACh-induced vasodilatation in rats. R406 did not affect contraction of isolated blood vessels. R406 inhibited VEGF-stimulated NO production from human endothelial cells in vitro, and treatment with R406 inhibited VEGFR2 phosphorylation in vivo. R406 inhibited VEGF-induced hypotension in anaesthetized rats.

CONCLUSIONS AND IMPLICATIONS

Increased vascular resistance, secondary to reduced VEGF-induced NO release from endothelium, may contribute to BP increases observed with fostamatanib. This is consistent with the elevated BP induced by other drugs inhibiting VEGF signalling, although the contribution of other mechanisms cannot be excluded.

Hypertension due to antiangiogenic cancer therapy with vascular endothelial growth factor inhibitors: understanding and managing a new syndrome

Novel antiangiogenic cancer therapies, particularly agents that block vascular endothelial growth factor (VEGF) signalling, have improved outcomes in patients with cancers and are now used as first-line therapies for some tumours. However, with VEGF inhibitors (VEGFIs) are new complications, particularly hypertension. VEGFI-induced hypertension is a dose-dependent phenomenon due to on-target effects rather than off-target effects. Increased blood pressure occurs in almost 100% of patients who take VEGFIs, with a subset who develop severe hypertension. Molecular mechanisms underlying VEGFI-induced hypertension are unclear, but endothelial dysfunction and increased vascular resistance, due to impaired nitric oxide signalling, reduced prostacyclin production, endothelin-1 (ET-1) upregulation, oxidative stress, and rarefaction have been implicated. Treatment of hypertension should be aimed at reducing the risk of short-term morbidity associated with hypertension while maintaining effective dosing of antiangiogenic therapy for optimal cancer treatment. Although specific guidelines are not yet available for the management of VEGFI-induced hypertension, angiotensin-converting enzyme inhibitors and dihydropyridine calcium channel blockers are commonly used. Severe hypertension might require reduction of VEGFI dosing, or in some cases, interruption of treatment. As more potent VEGFIs are developed and as more cancer patients are treated with VEGFIs, the burden of hypertension toxicity will increase. This will be further compounded as the use of antiangiogenic drugs broadens to include older patients and those with pre-existing cardiovascular disease. Here we focus on VEGF as a target for antiangiogenesis and how this affects increased blood pressure. Putative mechanisms underlying VEGFI-induced hypertension are highlighted and therapeutic strategies to manage such hypertension are discussed.

The effect of salsalate therapy on endothelial function in a broad range of subjects

Background

Inflammation is fundamental to the development of atherosclerosis. We examined the effect of anti‐inflammatory doses of salicylate on endothelium‐dependent vasodilation, a biomarker of cardiovascular risk, in a broad range of subjects.

Methods and Results

We performed a randomized, double‐blind, placebo‐controlled crossover trial evaluating the effects of 4 weeks of high‐dose salsalate (disalicylate) therapy on endothelium‐dependent flow‐mediated and endothelium‐independent vasodilation. Fifty‐eight subjects, including 17 with metabolic syndrome, 13 with atherosclerosis, and 28 healthy controls, were studied. Among all subjects, endothelium‐dependent flow‐mediated vasodilation decreased after salsalate compared with placebo therapy (P=0.01), whereas nitroglycerin‐mediated, endothelium‐independent vasodilation was unchanged (P=0.97). Endothelium‐dependent flow‐mediated vasodilation after salsalate therapy was impaired compared with placebo therapy in subjects with therapeutic salicylate levels (n=31, P<0.02) but not in subjects with subtherapeutic levels (P>0.2).

Conclusions

Salsalate therapy, particularly when therapeutic salicylate levels are achieved, impairs endothelium‐dependent vasodilation in a broad range of subjects. These data raise concern about the possible deleterious effects of anti‐inflammatory doses of salsalate on cardiovascular risk.

Clinical Trial Registration

URL: www.clinicaltrials.gov. Unique Identifiers: NCT00760019 and NCT00762827.

Hypertension during vascular endothelial growth factor inhibition: focus on nitric oxide, endothelin-1, and oxidative stress

SIGNIFICANCE

Angiogenesis inhibition with humanized antibodies targeting vascular endothelial growth factor (VEGF) or orally active small tyrosine kinase inhibitors targeting VEGF receptors has become an established treatment modality for various forms of cancer. A common side effect of angiogenesis inhibition is the development of sometimes severe hypertension, which simultaneously appears to be predictive for a favorable antitumor response.

RECENT ADVANCES

Since VEGF increases the expression and activity of endothelial nitric oxide synthase, it has been assumed that the mean blood pressure (MAP) rise during angiogenesis inhibition is caused by a decrease in nitric oxide bioavailability. Yet, the results from experimental and clinical studies exploring this possibility are conflicting. Recent studies provided evidence that the MAP rise during angiogenesis inhibition rather is mediated by activation of the endothelin-1 (ET-1) axis, which, among others, induces oxidative stress. Nevertheless, conclusive evidence for the involvement of reactive oxygen species in the MAP rise could not be obtained so far.

CRITICAL ISSUES

The mechanism underlying activation of the ET-1 axis during angiogenesis inhibition is unclear, and this activation was not anticipated in view of studies showing that VEGF stimulates both the expression and production of ET-1 by endothelial cells.

FUTURE DIRECTIONS

In fact, this activation of the ET-1 axis may support the use of ET receptor antagonists for the treatment of angiogenesis inhibition-induced hypertension, especially because ET receptor stimulation in vascular smooth muscle cells results in VEGF production and mitogenesis in a mitogen-activated protein kinase pathway-dependent manner.

A Phase I dose-escalation study of the VEGFR inhibitor tivozanib hydrochloride with weekly paclitaxel in metastatic breast cancer

Tivozanib is a potent selective tyrosine kinase inhibitor (TKI) of vascular endothelial growth factor receptors (VEGFRs) 1, 2, and 3. This Phase Ib study investigated the safety/tolerability, pharmacokinetics (PK), and activity of tivozanib with weekly paclitaxel in metastatic breast cancer (MBC). MBC patients with no prior VEGFR TKI treatment received daily oral tivozanib (3 weeks on, 1 week off) with weekly paclitaxel 90 mg/m(2). Standard 3 + 3 dose escalation was used; tivozanib cohorts (C) included C1 0.5 mg, C2 1.0 mg, and C3 1.5 mg. Assessments included Response Evaluation Criteria in Solid Tumors response, PK, and vascular function. Eighteen patients enrolled. Toxicities in >20 % of patients included fatigue, alopecia, nausea, diarrhea, peripheral sensory neuropathy, and hypertension. Grade 3/4 toxicities in >15 % of patients included fatigue and neutropenia. Maximum tolerated dose was tivozanib 1.5 mg with paclitaxel 90 mg/m(2). Four patients withdrew because of toxicity and one due to progressive disease. Thirteen patients were evaluable for response: four (30.8 %) had confirmed partial response; four had stable disease ≥6 months (30.8 %). PK data suggest no influence of paclitaxel on tivozanib concentrations. Tivozanib plus weekly paclitaxel was tolerable at all dose levels, supporting their combination at full dose. Activity in this small population was encouraging.

Role of Endogenous Vascular Endothelial Growth Factor in Endothelium-Dependent Vasodilation in Humans

Angiogenesis inhibitors have remarkably improved the outcome of patients with several types of cancer. Hypertension is the most reported side effect of angiogenesis inhibitors interfering with vascular endothelial growth factor signaling. In this study, we test the hypothesis that circulating vascular endothelial growth factor at physiological concentrations is essential to preserve normal endothelial control of vasomotor tone. In 7 healthy male volunteers, infusion of bevacizumab (monoclonal vascular endothelial growth factor antibody) into the brachial artery for 15 minutes (144 μg/dL forearm volume per minute) did not affect forearm vasodilator tone as measured with venous occlusion strain gauge plethysmography. In a separate group of 12 male volunteers, a similar bevacizumab infusion reduced the vasodilator response to 2 dosages of acetylcholine from (mean±SE) 440±157% and 926±252% to 169±40% and 612±154% ( P <0.05). Finally, in a third group of 12 volunteers, bevacizumab did not alter the percentage increase in forearm blood flow during infusion of sodium nitroprusside at dosages equipotent to acetylcholine. Bevacizumab acutely and specifically reduced endothelium-mediated vasodilation at local concentrations that resemble plasma concentrations after systemic exposure to bevacizumab. This observation suggests a physiological role for vascular endothelial growth factor in maintaining normal endothelial control of vasomotor tone. The role of the endothelium in the mechanism of bevacizumab-induced hypertension deserves further exploration.

Cardiovascular toxicity of tyrosine kinase inhibitors

INTRODUCTION

Small-molecule tyrosine kinase inhibitors (TKIs) have revolutionized the management of many malignancies. However, they also have been shown to be associated with a certain degree of cardiovascular side effects that are often reversible.

AREAS COVERED

As the number of new TKIs continues to grow, it is expected that clinicians will be facing the challenge of early detection and 10 management of these side effects while balancing the risk-benefit ratios of continuing with life-saving cancer therapy medications. This review will present the current knowledge related to incidence and proposed mechanisms of cardiovascular side effects of TKIs and also discuss treatment recommendations when available

EXPERT OPINION

We will present and discuss available data and suggest recommendations related to patient monitoring and early identification of TKIs related cardiovascular toxities.

Cardiovascular complications associated with novel angiogenesis inhibitors: emerging evidence and evolving perspectives

Novel cancer therapies targeting tumor angiogenesis have revolutionized treatment options in a variety of tumors. Specifically, VEGF signaling pathway (VSP) inhibitors have been introduced into clinical practice at a rapid pace over the last decade. It is becoming increasingly clear that VSP inhibitors can cause cardiovascular toxicities including hypertension, thrombosis, and heart failure. This review highlights these toxicities and proposes several strategies in their prevention and treatment. However, we recognize the dearth of data in this area and advocate a multi-disciplinary approach involving cardiologists and oncologists, as well as clinical and translational studies, in understanding and treating VSP-inhibitor associated toxicities.

Combination antiangiogenic therapy in advanced breast cancer: a phase 1 trial of vandetanib, a VEGFR inhibitor, and metronomic chemotherapy, with correlative platelet proteomics

This phase 1 study evaluated the safety and tolerability of antiangiogenic therapy using vandetanib and metronomic cyclophosphamide and methotrexate in metastatic breast cancer. Eligible patients had metastatic breast cancer with 0-4 prior chemotherapy regimens. All received cyclophosphamide 50 mg daily, methotrexate 2.5 mg days 1-2 weekly, and vandetanib daily in 3 dose-escalation cohorts: 100 mg (C1), 200 mg (C2), and 300 mg (C3). The primary endpoint was safety and tolerability; secondary endpoints included response rate and evaluation of platelet-associated proteins. Twenty three patients were treated and evaluable for toxicity. Common mild toxicities included nausea, vomiting, LFTs abnormalities, fatigue, and rash. Three episodes of dose-limiting toxicity occurred in C3. In all cohorts, 1/3 of patients required vandetanib dose reduction, and 22 % ended therapy for toxicity. Of the 20 response-evaluable patients, 10 % demonstrated partial response and 15 % stable disease ≥24 weeks. Proteomic analyses demonstrated changes in platelet content of angiogenesis regulators, including vascular endothelial growth factor and platelet factor 4, with exposure to therapy. This regimen was tolerable at a maximum vandetanib dose of 200 mg; modest clinical activity was observed in this heavily pretreated population. Changes in the platelet proteome may serve as pharmacodynamic markers of angiogenesis inhibition. Metronomic chemotherapy is an attractive partner with biologics and deserves further study in metastatic breast cancer.

Regorafenib induces rapid and reversible changes in plasma nitric oxide and endothelin-1

BACKGROUND

Hypertension is a toxicity of antiangiogenic therapies and a possible biomarker that identifies patients with superior cancer outcomes. Understanding its mechanism will aid in treatment and could lead to the development of other biomarkers for predicting toxicity and anticancer efficacy. Recent evidence implicates nitric oxide (NO) suppression and endothelin-1 (ET-1) stimulation as potential mechanisms leading to antiangiogenic therapy-induced hypertension. The aim of this study was to evaluate the effects of regorafenib, a novel broad-spectrum kinase inhibitor with activity against multiple targets, including vascular endothelial growth factor receptor 2 inhibition, on NO and ET-1 levels.

METHODS

Regorafenib was administered to 32 subjects with gastrointestinal stromal tumor on a 3-week-on, 1-week-off basis. Plasma levels of NO and ET-1 were measured at baseline, 2, 4, and 6 weeks of therapy. Data analysis was by Wilcoxon rank-sum and paired t-tests.

RESULTS

Twenty subjects (63%) developed regorafenib-induced hypertension. Two weeks after starting regorafenib therapy, plasma ET-1 levels increased (25% increase, P < 0.05) and NO was suppressed (20% decrease, P < 0.05). These normalized after 1-week washout but ET-1 rose again by 30% (P < 0.05) and NO fell by 50% (P < 0.05) after restarting regorafenib.

CONCLUSIONS

These findings indicate that regorafenib induces a coordinated and reversible suppression of NO and stimulation of ET-1. Whether NO and ET-1 might predict therapeutic efficacy in these patients requires further study.

Novel tyrosine kinase signaling pathways: implications in vascular remodeling

PURPOSE OF REVIEW

This review summarizes the recent advances in molecular mechanisms by which five classes of receptor tyrosine kinases (RTKs) contribute to vascular remodeling.

RECENT FINDINGS

Recent findings have expanded our knowledge regarding RTK regulation. In particular, G-protein-coupled receptors, mineralocorticoid receptors, mechanical and oxidative stresses transactivate RTKs. These receptors are highly interactive with many downstream targets (including tyrosine kinases and other RTKs) and function as key regulatory nodes in a dynamic signaling network. Interactions between vascular and nonvascular (immune and neuronal) cells are controlled by RTKs in vascular remodeling. Inhibition of RTKs could be an advantageous therapeutic strategy for vascular disorders.

SUMMARY

RTK-dependent signaling is important for regulation of key functions during vascular remodeling. However, current challenges are related to integration of the data on multiple RTKs in vascular pathology.

Sunitinib-Induced Systemic Vasoconstriction in Swine Is Endothelin Mediated and Does Not Involve Nitric Oxide or Oxidative Stress

Angiogenesis inhibition with agents targeting tyrosine kinases of vascular endothelial growth factor receptors is an established anticancer treatment, but is, unfortunately, frequently accompanied by systemic hypertension and cardiac toxicity. Whether vascular endothelial growth factor receptor antagonism also has adverse effects on the pulmonary and coronary circulations is presently unknown. In chronically instrumented awake swine, the effects of the vascular endothelial growth factor receptor antagonist sunitinib on the systemic, pulmonary, and coronary circulation were studied. One week after sunitinib (50 mg PO daily), mean aortic blood pressure (MABP) had increased from 83±5 mm Hg at baseline to 97±6 mm Hg ( P <0.05) because of a 57±20% increase in systemic vascular resistance as cardiac output decreased. In contrast, sunitinib had no discernible effects on pulmonary and coronary hemodynamics or cardiac function. We subsequently investigated the mechanisms underlying the sunitinib-induced systemic hypertension. Intravenous administration of NO synthase inhibitor N G -nitro- l -arginine increased MABP by 24±1 mm Hg under baseline conditions, whereas it increased MABP even further after sunitinib administration (32±3 mm Hg; P <0.05). Reactive oxygen species scavenging with a mixture of antioxidants lowered MABP by 13±2 mm Hg before but only by 5±2 mm Hg ( P <0.05) after sunitinib administration. However, intravenous administration of the dual endothelin A/endothelin B receptor blocker tezosentan, which did not lower MABP at baseline, completely reversed MABP to presunitinib values. These findings indicate that sunitinib produces vasoconstriction selectively in the systemic vascular bed, without affecting pulmonary or coronary circulations. The sunitinib-mediated systemic hypertension is principally attributed to an increased vasoconstrictor influence of endothelin, with no apparent contributions of a loss of NO bioavailability or increased oxidative stress.