{"entity":{"id":"amyloid-beta","kind":"target","name":"Amyloid beta plaques","aka":["Aβ","beta-amyloid neuritic plaques"],"tldr":"Sticky clumps of protein that build up in the brain in Alzheimer's disease. PET scans using tracers that bind these clumps can show a doctor how much amyloid is present, well before it would show up on a brain biopsy.","summary":"Amyloid beta is a peptide, cleaved from the amyloid precursor protein, that misfolds and aggregates into extracellular neuritic plaques, one of the two neuropathological hallmarks of Alzheimer's disease (the other being tau neurofibrillary tangles). PET tracers such as 18F-florbetapir bind fibrillar amyloid aggregates with nanomolar affinity (Kd approximately 3.7 nM for florbetapir) and do not appreciably bind tau, so they read out plaque burden rather than tangle burden.\n\nFlorbetapir (Amyvid) was FDA-approved in 2012 for PET imaging to estimate beta-amyloid neuritic plaque density in adults with cognitive impairment being evaluated for Alzheimer's disease; its label was updated in June 2025 to add selection of patients for amyloid-targeting therapy, reflecting the arrival of anti-amyloid antibody drugs whose eligibility and monitoring depend on amyloid PET or blood biomarkers. Other approved 18F amyloid tracers include florbetaben (Neuraceq) and flutemetamol (Vizamyl); all three are stilbene or benzothiazole derivatives related to the original 11C-Pittsburgh compound B.\n\nAs an imaging target, amyloid's strength is that a negative scan has high negative predictive value (sparse or no plaque makes an Alzheimer's diagnosis unlikely), which is clinically decisive. Its main limitation is specificity for a diagnosis: a positive scan indicates plaque is present but this can also occur in cognitively normal older adults and in other neurodegenerative conditions, so a positive result does not by itself confirm Alzheimer's disease, and none of the approved tracers is validated to monitor treatment response or to predict conversion to dementia.","asOf":"2026-09-22","links":[{"label":"FDA label: Amyvid (florbetapir F 18 injection)","url":"https://www.accessdata.fda.gov/drugsatfda_docs/label/2012/202008s000lbl.pdf"},{"label":"Eli Lilly: FDA approves updated Amyvid label for amyloid-targeting therapy selection (25 June 2025)","url":"https://investor.lilly.com/news-releases/news-release-details/fda-approves-updated-label-lillys-amyvid-florbetapir-f-18"},{"label":"PMC: the role of amyloid PET in imaging neurodegenerative disorders","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC9165727/"},{"label":"CMS national coverage determination memo: beta-amyloid PET in dementia","url":"https://www.cms.gov/medicare-coverage-database/view/ncacal-decision-memo.aspx?proposed=N&NCAId=265"}],"tags":["neurology","Alzheimer's disease","protein aggregate"],"related":["tau-protein","f-18","c-11"],"indications":[],"sections":[],"technologies":[],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"biology":"A peptide cleaved from the amyloid precursor protein that misfolds and aggregates into extracellular neuritic plaques, one of the two defining pathologies of Alzheimer's disease. PET tracers bind fibrillar amyloid aggregates with high affinity, giving an in-vivo readout of plaque burden that was previously only obtainable at autopsy.","whereFound":["Alzheimer's disease: neuritic plaques throughout association cortex; presence and density scored on amyloid PET","Cognitively normal older adults: a minority show plaque on amyloid PET without dementia","Cerebral amyloid angiopathy and some other neurodegenerative conditions: variable vascular and parenchymal amyloid"],"targetClass":"other","prevalence":[]},"route":"/targets/amyloid-beta/","neighbours":{"target":[{"id":"alpha-synuclein","kind":"target","name":"Alpha-synuclein","route":"/targets/alpha-synuclein/"},{"id":"dlg4-psd95","kind":"target","name":"DLG4 (PSD-95)","route":"/targets/dlg4-psd95/"},{"id":"tau-protein","kind":"target","name":"Tau protein (neurofibrillary tangles)","route":"/targets/tau-protein/"}],"isotope":[{"id":"c-11","kind":"isotope","name":"Carbon-11","route":"/isotopes/c-11/"},{"id":"f-18","kind":"isotope","name":"Fluorine-18","route":"/isotopes/f-18/"}],"opportunity":[{"id":"opp-alpha-synuclein-pet-parkinsons","kind":"opportunity","name":"Alpha-synuclein PET: works for MSA, not for Parkinson's","route":"/opportunities/opp-alpha-synuclein-pet-parkinsons/"}]}}