The signalling cascade from initial stimulus to downstream effector — and where therapeutic intervention is possible at each node.
Vascular endothelial growth factor-A (VEGF-A) is the master regulator of pathological angiogenesis, secreted by tumour cells, stromal fibroblasts, and tumour-associated macrophages in response to hypoxia via hypoxia-inducible factor-1 alpha (HIF-1alpha). VEGF-A binds its primary signalling receptor VEGFR2 (KDR) on tumour vascular endothelium, activating downstream PI3K/AKT and RAS/MAPK pathways to drive endothelial cell proliferation, migration, tube formation, and survival. This neo-vasculature provides the oxygen and nutrient supply required for tumour growth beyond 1-2mm and facilitates haematogenous metastatic spread by creating a leaky, poorly pericyte-covered vascular network.
In oncology, anti-VEGF strategies include VEGF-A neutralising monoclonal antibodies (bevacizumab, biosimilars), VEGFR-2-targeting antibodies (ramucirumab), and multi-target VEGFR tyrosine kinase inhibitors (TKIs) that additionally inhibit PDGFR, c-KIT, and other receptors (sunitinib, sorafenib, axitinib, cabozantinib, lenvatinib). Anti-VEGF therapy is integrated into first-line treatment regimens in colorectal, lung, ovarian, and hepatocellular carcinoma. In renal cell carcinoma, combined VEGFR TKI plus immune checkpoint inhibitor regimens have become standard of care across multiple risk categories.
In ophthalmology, pathological choroidal neovascularisation in age-related macular degeneration and retinal neovascularisation in diabetic macular oedema are driven by local VEGF-A overexpression. Intravitreal anti-VEGF agents (ranibizumab, aflibercept, bevacizumab off-label, faricimab — dual Ang-2/VEGF-A inhibitor, brolucizumab) suppress choroidal neovascular membrane growth and reduce retinal fluid, preserving or improving visual acuity. Faricimab uniquely targets both VEGF-A and angiopoietin-2, enabling extended dosing intervals of up to 4 months in eligible patients.
Upstream blockade vs downstream blockade — understanding the distinction is critical for treatment selection and sequencing.
Clinically actionable insights for treatment selection and sequencing
Vascular endothelial growth factor-A (VEGF-A) is the master regulator of pathological angiogenesis, secreted by tumour cells, stromal fibroblasts, and tumour-associated macrophages in response to hypoxia via hypoxia-inducible factor-1 alpha (HIF-1alpha).
VEGF-A binds its primary signalling receptor VEGFR2 (KDR) on tumour vascular endothelium, activating downstream PI3K/AKT and RAS/MAPK pathways to drive endothelial cell proliferation, migration, tube formation, and survival.
This neo-vasculature provides the oxygen and nutrient supply required for tumour growth beyond 1-2mm and facilitates haematogenous metastatic spread by creating a leaky, poorly pericyte-covered vascular network.
In oncology, anti-VEGF strategies include VEGF-A neutralising monoclonal antibodies (bevacizumab, biosimilars), VEGFR-2-targeting antibodies (ramucirumab), and multi-target VEGFR tyrosine kinase inhibitors (TKIs) that additionally inhibit PDGFR, c-KIT, and other receptors (sunitinib, sorafenib, axitinib, cabozantinib, lenvatinib).
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