{"entity":{"id":"integrin-avb3","kind":"target","name":"Integrin αvβ3","aka":["Integrin alpha-v beta-3","vitronectin receptor"],"tldr":"A docking protein on the surface of cells that are building new blood vessels, including the blood vessels a growing tumour needs. Peptides that mimic the docking sequence (RGD) can be radiolabelled to see where this new blood-vessel growth, or the tumour cells themselves, are most active.","summary":"Integrin αvβ3 is a heterodimeric transmembrane adhesion receptor that binds extracellular matrix proteins - vitronectin, fibronectin, fibrinogen - through their exposed arginine-glycine-aspartate (RGD) amino acid motif. It is minimally expressed on quiescent, resting blood vessel endothelium but becomes strongly upregulated on activated endothelial cells during angiogenesis, where it is required for the migration, survival and maturation of newly forming vessels, and it is also directly overexpressed on the tumour cells themselves in a range of solid cancers (including glioma, melanoma and some carcinomas), where it promotes invasion and metastasis.\n\nRadiolabelled cyclic RGD peptides (starting with 18F-Galacto-RGD, the first tracer used in patients, and followed by 68Ga-, 64Cu- and 99mTc-labelled RGD monomers, dimers and tetramers) bind αvβ3 and have been used in PET and SPECT imaging as a non-invasive biomarker of tumour angiogenesis, for patient selection ahead of anti-angiogenic therapy and for monitoring treatment response. Multimeric RGD constructs improve binding avidity through a polyvalency effect and show higher, more persistent tumour uptake than monomeric RGD.\n\nAs a target, αvβ3's strength is its sharp induction on angiogenic endothelium, giving genuine biological contrast between growing and quiescent vasculature. Its central weakness for imaging purposes is that αvβ3 is not exclusively expressed on new tumour vessels - it is also present on the tumour cells, on macrophages, and in non-malignant angiogenic settings such as atherosclerotic plaque and post-infarction myocardium - so a static PET signal cannot on its own distinguish tumour-cell expression from vascular expression, and genetic knockout studies suggest angiogenesis can still proceed without αvβ3, which has limited the target's use as a stand-alone therapeutic target despite active imaging interest.","asOf":"2026-09-22","links":[{"label":"PMC: PET imaging of integrin αvβ3 expression","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC3086612/"},{"label":"PMC: clinical application of radiolabeled RGD peptides for PET imaging of angiogenesis","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC4679356/"},{"label":"PMC: RGD-binding integrins revisited - review of imaging targets including αvβ3","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC8038522/"},{"label":"PMC: PET radiopharmaceuticals for imaging integrin expression","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC4072020/"}],"tags":["angiogenesis","integrin","RGD peptide"],"related":["f-18","ga-68","tc-99m","cu-64"],"indications":[],"sections":[],"technologies":[],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"biology":"A heterodimeric transmembrane adhesion receptor that binds RGD-motif extracellular matrix proteins such as vitronectin and fibronectin. It is minimally expressed on quiescent blood vessels but strongly upregulated on activated endothelial cells during tumour angiogenesis, and is also directly overexpressed on some tumour cells, where it promotes invasion and migration.","whereFound":["Tumour neovasculature (activated endothelial cells during angiogenesis): strongly upregulated versus quiescent vessels","Tumour cells directly in glioma, melanoma and some carcinomas: overexpression linked to invasion and metastasis","Atherosclerotic plaque and post-myocardial-infarction myocardium: upregulated on macrophages and activated endothelium, a non-oncological imaging application","Quiescent normal vasculature: low or absent expression"],"targetClass":"surface-antigen","prevalence":[]},"route":"/targets/integrin-avb3/","neighbours":{"isotope":[{"id":"cu-64","kind":"isotope","name":"Copper-64","route":"/isotopes/cu-64/"},{"id":"f-18","kind":"isotope","name":"Fluorine-18","route":"/isotopes/f-18/"},{"id":"ga-68","kind":"isotope","name":"Gallium-68","route":"/isotopes/ga-68/"},{"id":"tc-99m","kind":"isotope","name":"Technetium-99m","route":"/isotopes/tc-99m/"}],"drug":[{"id":"pexiretide-tc99m","kind":"drug","name":"Technetium (99mTc) pexiretide","route":"/drugs/pexiretide-tc99m/"}],"indication":[{"id":"nsclc","kind":"indication","name":"Non-small cell lung cancer","route":"/indications/nsclc/"}]}}