This is a mechanism module, not a specific disease. Disorder entries reference individual nodes via conforms_to (e.g. "vegf_inhibitor_hypertension#Vasoconstriction and Increased Peripheral Vascular Resistance"). Conforming nodes should substitute the drug-specific route to VEGF pathway blockade — ligand sequestration (bevacizumab, aflibercept), receptor-antibody blockade (ramucirumab), or intracellular VEGFR2 kinase inhibition (the VSP tyrosine kinase inhibitors) — while preserving the conserved pathway-inhibition -> endothelial NO deficit / endothelin-1 activation / rarefaction -> vasoconstriction and raised resistance -> hypertension chain. The key conformance / central-effector target is "vegf_inhibitor_hypertension#Vasoconstriction and Increased Peripheral Vascular Resistance". Two framing guardrails curators must preserve. (1) The mechanism is NOT settled: the AHA scientific statement calls the exact molecular mechanisms unclear and the vascular-toxicity literature calls them elusive, so the three arms below are curated as complementary contributors rather than as one proven sequence — see the KNOWLEDGE_GAP discussion. (2) The toxicity is on-target, so raised blood pressure on a VSP inhibitor is reported as a candidate pharmacodynamic biomarker of antitumour efficacy; that association is recorded as an OPEN_QUESTION and must not be curated as an established prognostic claim. Related modules: tumor_angiogenesis models the VEGF axis as a cancer hallmark and is the therapeutic rationale this toxicity is the price of; drug_induced_nephrotoxicity covers the separate renal arm (proteinuria, thrombotic microangiopathy) of VEGF inhibition.
Which of the three curated arms — endothelial nitric oxide deficiency with oxidative stress, endothelin-1 system activation, and microvascular rarefaction — is rate-limiting for the blood-pressure rise in patients, and in what temporal order do they act?
KNOWLEDGE GAP
OPEN
vegfi_hypertension_mechanism_unsettled
Attached to:
Endothelial Nitric Oxide Deficiency and Oxidative Stress
Endothelin-1 System Activation
Microvascular Rarefaction
Vasoconstriction and Increased Peripheral Vascular Resistance
This matters for curation discipline, not just completeness. The three upstream arms are each independently attested, but the field explicitly describes the integrated mechanism as unclear/elusive, so a conforming disorder entry must not assert one arm as "the" mechanism of its drug's hypertension. It also matters therapeutically: if endothelin-1 dominates, an endothelin receptor antagonist would be mechanism-matched therapy, whereas the two agents curated in this module's treatments block are chosen for convergence-node effect rather than for arm-specific targeting. The acute (tone) and slow (rarefaction) components also predict different blood-pressure time courses, which is testable.
Is treatment-emergent hypertension a usable pharmacodynamic biomarker of antitumour efficacy for VEGF pathway inhibitors, and if so does it warrant dose titration to a blood-pressure target?
OPEN QUESTION
OPEN
vegfi_hypertension_as_efficacy_biomarker
Attached to:
Treatment-Emergent Hypertension
Because the toxicity is on-target, a rise in blood pressure plausibly indexes the degree of VEGF pathway inhibition actually achieved in a given patient, and a growing literature associates it with better cancer outcomes. The curation risk is real in both directions: recording the association as established would license a dangerous clinical inference (tolerate or induce hypertension to improve response), while omitting it hides the main reason this toxicity is studied. Curated here as open, with the reported limitation that the supporting data are constrained by study number and by incomplete understanding of the mechanism.
Should management of VEGF-inhibitor-induced hypertension continue to follow general-population hypertension guidelines, or does the distinct mechanism and the risk of rebound hypotension after cancer-therapy withdrawal require oncology-specific targets and agent choices?
OPEN QUESTION
OPEN
vegfi_hypertension_management_evidence_gap
Attached to:
Treatment-Emergent Hypertension
The module's treatments block records angiotensin system inhibitors and calcium channel blockers as first-line, but that recommendation is extrapolated from general hypertension guidelines rather than derived from trials in this population — and the extrapolation is not obviously safe, because blood pressure falls again when the culprit drug is stopped. This is the practical knowledge gap the seed review for this module (PMID:42405920) was written to highlight.
VEGF Signaling Pathway Inhibition
trigger
The conserved initiating lesion is pharmacological removal of tonic VEGFA-VEGFR2 signalling from the vascular endothelium. The route varies by agent — ligand sequestration by an anti-VEGF antibody or VEGF trap, receptor blockade by an anti-VEGFR2 antibody, or intracellular inhibition of the VEGFR2 kinase by a small-molecule tyrosine kinase inhibitor — but each silences the same receptor. Hypertension is the most common vascular toxicity of this drug class and is dose dependent, consistent with an on-target class effect rather than an idiosyncratic reaction.
Downstream
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Endothelial Nitric Oxide Deficiency and Oxidative Stress
Loss of VEGFR2 drive withdraws the PI3K/Akt-eNOS stimulus that maintains endothelial nitric oxide production.
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Endothelin-1 System Activation
VEGF pathway blockade is accompanied by increased endothelin production and activation of the endothelin system.
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Microvascular Rarefaction
Withdrawal of the VEGF survival/angiogenic signal reduces microvessel density in peripheral vascular beds.
Show evidence (2 references)
"One of the most common side effects of these drugs is hypertension, especially in patients treated with vascular endothelial growth factor inhibitors, as well as tyrosine kinase inhibitors and proteasome inhibitors."
Establishes VEGF inhibition as the leading anticancer-drug route to hypertension, the trigger this node captures. Evidence source is OTHER because this is a scientific statement / review.
"The incidence of TKI-induced HTN among the VEGF inhibitors ranges from 5 to 80% and is dose dependent."
Dose dependence across the VEGF-inhibitor class supports an on-target pathway-inhibition trigger rather than an agent-specific idiosyncrasy. Evidence source is OTHER because this is a review article.
Endothelial Nitric Oxide Deficiency and Oxidative Stress
amplifier
VEGFR2 signalling normally sustains endothelial nitric oxide synthase activity through PI3K/Akt and MAPK, so pathway blockade lowers endothelial nitric oxide production. The resulting loss of the dominant endothelium-derived vasodilator is compounded by oxidative stress, which further consumes available nitric oxide. This is the best-characterised of the module's three parallel amplifier arms.
Downstream
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Vasoconstriction and Increased Peripheral Vascular Resistance
Loss of nitric-oxide-mediated vasodilator tone shifts the vessel wall toward constriction and raises resistance.
Show evidence (2 references)
"inhibition of endothelial NO synthase (eNOS), reduced nitric oxide (NO) production, oxidative stress, activation of the endothelin system, and rarefaction have been implicated"
Names eNOS inhibition, reduced nitric oxide and oxidative stress among the implicated mechanisms of VEGF-inhibitor vascular toxicity, the amplifier captured here. Evidence source is OTHER because this is a review article.
"VEGF, mediated by PI3K/Akt and MAPK pathway, upregulates the endothelial nitric oxide synthase enzyme leading to up-regulation of NO production. So inhibition of signaling through the VEGF pathway would lead to a decrease in NO production, resulting in an increase in vascular resistance and..."
Gives the molecular link from VEGFR2 signalling through PI3K/Akt to eNOS, and states that removing it lowers nitric oxide and raises vascular resistance — the mechanistic content of this node and its downstream edge. Evidence source is OTHER because this is a review article.
Endothelin-1 System Activation
amplifier
VEGF pathway blockade is accompanied by increased endothelin production and activation of the endothelin system. Endothelin-1 acting on smooth-muscle endothelin receptors is a potent vasoconstrictor, so this arm pushes the vessel wall toward constriction from the opposite direction to the nitric oxide deficit — a loss of vasodilator tone paired with a gain of vasoconstrictor tone.
Downstream
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Vasoconstriction and Increased Peripheral Vascular Resistance
Endothelin-1 acting on vascular smooth muscle is a direct vasoconstrictor stimulus.
Show evidence (2 references)
"The mechanism of action involves VSP inhibition, leading to decreased nitric oxide and increased endothelin production, which causes vasoconstriction, capillary rarefaction, and hypertension."
States the increased-endothelin arm explicitly and places it, alongside the nitric oxide deficit, upstream of vasoconstriction and hypertension. Evidence source is OTHER because this is a review article.
"recent discoveries indicate an important role for reduced nitric oxide generation, oxidative stress, endothelin-1, prostaglandins, endothelial dysfunction, increased sympathetic outflow, and microvascular rarefaction"
Independently lists endothelin-1 among the mediators of cancer therapy-related hypertension. Evidence source is OTHER because this is a scientific statement / review.
Microvascular Rarefaction
effector
VEGF is a survival and maintenance signal for the microvasculature, so sustained pathway blockade reduces the density of functional capillaries and small vessels in peripheral beds. Rarefaction raises resistance structurally rather than by acute tone, which is consistent with the slower, sustained component of the blood-pressure rise and with its reversal after drug withdrawal.
Downstream
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Vasoconstriction and Increased Peripheral Vascular Resistance
Loss of parallel microvascular conduits raises total peripheral resistance independently of vasomotor tone.
Show evidence (2 references)
"the potential role of microparticles, vascular smooth muscle cells, vascular stiffness, and microvessel rarefaction"
Identifies microvessel rarefaction among the mechanisms connecting endothelial dysfunction to VEGFR-inhibitor-induced hypertension, the effector captured here. Evidence source is OTHER because this is a review article.
"These include nitric oxide decrease, a change in endothelin-1 levels and capillary rarefaction."
Names capillary rarefaction as one of the three standing hypotheses for tyrosine-kinase-inhibitor-associated hypertension, corroborating this arm. Evidence source is OTHER because this is a narrative review.
Vasoconstriction and Increased Peripheral Vascular Resistance
central effector
The three upstream arms — nitric oxide deficiency with oxidative stress, endothelin-1 system activation, and microvascular rarefaction — converge on a net shift of the peripheral circulation toward constriction and a rise in total peripheral vascular resistance. This is the central effector lesion and the key conformance target; conforming disorder nodes substitute the drug-specific route to VEGF blockade upstream but funnel through this step.
Downstream
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Treatment-Emergent Hypertension
Sustained elevation of peripheral vascular resistance raises systemic arterial blood pressure.
Show evidence (2 references)
"The mechanism of action involves VSP inhibition, leading to decreased nitric oxide and increased endothelin production, which causes vasoconstriction, capillary rarefaction, and hypertension."
Places vasoconstriction as the step between the upstream mediator changes and the clinical hypertension, which is what this central-effector node asserts. Evidence source is OTHER because this is a review article.
"inhibition of signaling through the VEGF pathway would lead to a decrease in NO production, resulting in an increase in vascular resistance and blood pressure"
States the rise in vascular resistance as the proximate cause of the blood pressure rise, the convergence point this node models. Evidence source is OTHER because this is a review article.
Treatment-Emergent Hypertension
consequence
The defining clinical consequence: a new or worsened elevation of systemic arterial blood pressure emerging on therapy. It is frequently dose limiting, it increases cardiovascular mortality in cancer survivors, and it is usually reversible after interruption or discontinuation of the culprit drug — the reversibility being a strong argument that the mechanism is on-target pharmacology rather than structural vascular damage.
Show evidence (2 references)
"these drugs cause hypertension in a majority of patients. This side effect is often dose limiting and increases cardiovascular mortality in cancer survivors."
Establishes hypertension as the majority-incidence, dose-limiting consequence of VEGF receptor inhibition, the endpoint of this module. Evidence source is OTHER because this is a review article.
"Cancer therapy-induced hypertension is often dose limiting, increases cardiovascular mortality in cancer survivors, and is usually reversible after interruption or discontinuation of treatment."
Documents the dose-limiting nature, the mortality consequence, and the reversibility on drug withdrawal asserted by this node. Evidence source is OTHER because this is a scientific statement / review.
Renin-Angiotensin System Inhibition (ACE Inhibitor or ARB)
Platform:
Small molecule
Angiotensin system inhibitors are a first-line antihypertensive choice in this setting. They act on the same central-effector node the module converges on — reducing angiotensin-II-driven vasoconstriction and so lowering peripheral vascular resistance — rather than restoring the upstream VEGF signal, which would antagonise the antitumour effect of the culprit drug. This is the drug-target design pattern conforming entries should copy: the antihypertensive targets the convergence node, not the trigger.
Evidence: 1
Calcium Channel Blocker
Platform:
Small molecule
Dihydropyridine calcium channel blockers are the other first-line option, acting directly on vascular smooth muscle to oppose the vasoconstriction the module converges on. Note the practical caveat carried in the oncology literature but not modelled as a node here: non-dihydropyridine agents inhibit CYP3A4 and can raise exposure to several VSP tyrosine kinase inhibitors, so agent choice within the class is not mechanism-neutral.
Evidence: 1