{"entity":{"id":"antigen-escape","kind":"term","name":"Antigen escape (antigen loss, lineage switch)","aka":["antigen escape","antigen loss","antigen-negative relapse","CD19-negative relapse","CD19-negative","BCMA-negative","BCMA loss","target loss","target downregulation","antigen downregulation","antigen-low","lineage switch","lineage plasticity","trogocytosis","antigen heterogeneity","antigen-negative"],"tldr":"When a cancer treated with a therapy aimed at one surface marker (CD19, BCMA, HER2) survives by shedding that marker, so the drug has nothing to grab. About a third of relapses after CD19 CAR-T are antigen-negative.","summary":"Mechanisms include mutations or splice variants that remove the epitope, deletion of the gene (TNFRSF17/BCMA biallelic loss in myeloma), lineage switch (B-ALL relapsing as myeloid leukaemia under CD19 pressure), trogocytosis (CAR-T cells stripping antigen off tumour cells), and pre-existing antigen-low subclones. Responses are dual-targeting CARs (CD19/CD22, BCMA/GPRC5D), sequencing to a different antigen (GPRC5D or FcRH5 after BCMA), logic-gated CARs and antigen-independent strategies. It is distinct from T-cell-intrinsic failure (exhaustion, poor persistence), which is the other main cause of relapse, and flow cytometry at relapse distinguishes the two.","asOf":"2026-09-09","wikipedia":"https://en.wikipedia.org/wiki/Chimeric_antigen_receptor_T_cell","links":[{"label":"Wikipedia","url":"https://en.wikipedia.org/wiki/Chimeric_antigen_receptor_T_cell"}],"tags":[],"related":["t-cell-exhaustion-term","resistance","flow-cytometry"],"cancers":[],"sections":["cell-therapy"],"technologies":["car-t","t-cell-engager","logic-gated-therapeutics"],"targets":["cd19","bcma"],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"category":"Treatment jargon"},"route":"/terms/antigen-escape/","neighbours":{"term":[{"id":"resistance","kind":"term","name":"Drug resistance (primary and acquired)","route":"/terms/resistance/"},{"id":"flow-cytometry","kind":"term","name":"Flow cytometry (immunophenotyping)","route":"/terms/flow-cytometry/"},{"id":"t-cell-exhaustion-term","kind":"term","name":"T-cell exhaustion and CAR-T persistence","route":"/terms/t-cell-exhaustion-term/"}],"section":[{"id":"cell-therapy","kind":"section","name":"Cell Therapy","route":"/fronts/cell-therapy/"}],"technology":[{"id":"car-t","kind":"technology","name":"CAR-T cell therapy","route":"/technologies/car-t/"},{"id":"logic-gated-therapeutics","kind":"technology","name":"Logic-gated therapeutics (AND, NOT gates)","route":"/technologies/logic-gated-therapeutics/"},{"id":"t-cell-engager","kind":"technology","name":"T-cell engagers (bispecific)","route":"/technologies/t-cell-engager/"}],"target":[{"id":"bcma","kind":"target","name":"BCMA","route":"/targets/bcma/"},{"id":"cd19","kind":"target","name":"CD19","route":"/targets/cd19/"}],"biomarker":[{"id":"bcma-expression","kind":"biomarker","name":"BCMA expression","route":"/biomarkers/bcma-expression/"},{"id":"cd19-expression","kind":"biomarker","name":"CD19 expression (CD19-positive)","route":"/biomarkers/cd19-expression/"},{"id":"cd20-expression","kind":"biomarker","name":"CD20 expression (CD20-positive)","route":"/biomarkers/cd20-expression/"},{"id":"cd22-expression","kind":"biomarker","name":"CD22 expression (CD22-positive)","route":"/biomarkers/cd22-expression/"},{"id":"gprc5d-expression","kind":"biomarker","name":"GPRC5D expression","route":"/biomarkers/gprc5d-expression/"}]}}