{"entity":{"id":"irecist","kind":"term","name":"iRECIST (response criteria for immunotherapy trials)","aka":["iRECIST","iUPD","iCPD","unconfirmed progressive disease","confirmed progressive disease"],"tldr":"iRECIST is the version of the scan-measuring rules used in immunotherapy trials, where a tumour can look bigger before it shrinks, so apparent growth must be confirmed on a later scan before it counts as progression.","summary":"Tumours respond to immunotherapy differently from chemotherapy. The RECIST working group wrote iRECIST (Seymour and colleagues, Lancet Oncology 2017) as a consensus guideline for using a modified RECIST 1.1 in trials of immunotherapy, to make the design, data collection and analysis of those trials consistent and to build a data warehouse for validating it later. Responses carry an i prefix (iCR, iPR, iSD). Growth that meets RECIST 1.1 progression is recorded as unconfirmed progression (iUPD) and becomes confirmed progression (iCPD) only when the next assessment shows further growth, more new lesions, or progression in another lesion category; if the tumour shrinks instead, the bar resets. Clinical stability is considered when deciding whether to continue treatment after iUPD.","asOf":"2026-11-04","links":[{"label":"Seymour et al., iRECIST: guidelines for response criteria for use in trials testing immunotherapeutics (Lancet Oncol 2017)","url":"https://doi.org/10.1016/S1470-2045(17)30074-8"},{"label":"iRECIST full text (PubMed Central PMC5648544)","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC5648544/"}],"tags":[],"related":["recist","progressive-disease","irrc","imrecist","itrecist"],"cancers":[],"sections":[],"technologies":["ct","mri","checkpoint-inhibitor"],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"category":"Endpoints"},"route":"/terms/irecist/","neighbours":{"term":[{"id":"irrc","kind":"term","name":"Immune-related response criteria (irRC)","route":"/terms/irrc/"},{"id":"imrecist","kind":"term","name":"imRECIST (immune-modified RECIST)","route":"/terms/imrecist/"},{"id":"irano","kind":"term","name":"iRANO (immunotherapy response in neuro-oncology)","route":"/terms/irano/"},{"id":"itrecist","kind":"term","name":"itRECIST (response criteria for injected immunotherapy)","route":"/terms/itrecist/"},{"id":"lyric","kind":"term","name":"LYRIC (lymphoma response to immunomodulatory therapy criteria)","route":"/terms/lyric/"},{"id":"progressive-disease","kind":"term","name":"Progressive disease and radiographic progression","route":"/terms/progressive-disease/"},{"id":"recist","kind":"term","name":"RECIST","route":"/terms/recist/"}],"technology":[{"id":"ct","kind":"technology","name":"CT (computed tomography)","route":"/technologies/ct/"},{"id":"checkpoint-inhibitor","kind":"technology","name":"Immune checkpoint inhibitors","route":"/technologies/checkpoint-inhibitor/"},{"id":"mri","kind":"technology","name":"MRI","route":"/technologies/mri/"}]}}