{"entity":{"id":"antigen","kind":"term","name":"Antigen","aka":["antigens","tumour antigen","tumour antigens","tumor antigen","tumor antigens","target antigen","target antigens","antigenic","tumour-associated antigen","tumour-associated antigens","tumor-associated antigen","tumor-associated antigens","antigen-negative","antigen loss"],"tldr":"Anything an antibody or immune cell can recognise, typically a protein on a cell's surface. In cancer, an antigen is the flag that tells a drug or an immune cell 'this is the cell to attack'.","summary":"Most cancer antigens are ordinary human proteins that a tumour makes in unusual amounts (HER2, TROP2, CD19, PSMA), so drugs targeting them also touch normal cells that carry a little; truly tumour-specific antigens arise from mutations (neoantigens) or from viral proteins. A good drug antigen is abundant on tumour cells, scarce on essential normal tissue, and stable over time. Tumours escape by losing the antigen, which is how CD19-negative relapse defeats CAR-T, and by hiding the pieces of antigen they would normally display to T cells.","asOf":"2026-09-09","wikipedia":"https://en.wikipedia.org/wiki/Antigen","links":[{"label":"Wikipedia","url":"https://en.wikipedia.org/wiki/Antigen"}],"tags":[],"related":[],"indications":[],"sections":[],"technologies":[],"targets":["her2","trop2","psma"],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"category":"Biology basics"},"route":"/terms/antigen/","neighbours":{"target":[{"id":"her2","kind":"target","name":"HER2","route":"/targets/her2/"},{"id":"psma","kind":"target","name":"PSMA","route":"/targets/psma/"},{"id":"trop2","kind":"target","name":"TROP2","route":"/targets/trop2/"}]}}