{"entity":{"id":"idea-bio1-rebiopsy-before-switch","kind":"idea","name":"Re-test the metastasis, not the old primary, before every change of treatment","aka":[],"tldr":"Treatment is often chosen from a biopsy taken years earlier from the original tumour. The spread disease may now look different. Test it again before switching drugs.","summary":"Receptor and biomarker discordance between primary and metastasis is well documented (oestrogen receptor, HER2, PD-L1, and actionable alterations). Yet most line changes rely on archival tissue. The proposal is a payer-backed policy that a contemporaneous biopsy or validated liquid biopsy is offered before each line change in metastatic disease, with a registry to quantify how often the result changes therapy.","asOf":"2026-09-08","links":[{"label":"Bottleneck evidence (Tumour heterogeneity and clonal evolution): Gerlinger et al., Intratumor heterogeneity and branched evolution (NEJM 2012)","url":"https://doi.org/10.1056/NEJMoa1113205"}],"tags":[],"related":[],"cancers":["breast-hr-positive","breast-her2-positive","nsclc"],"sections":[],"technologies":["liquid-biopsy","histopathology-ihc","cgp"],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":["her2-low","ihc"],"trials":[],"people":[],"bottlenecks":["b-tumor-heterogeneity","b-resistance"],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"hypothesis":"Contemporaneous re-testing changes the selected therapy in at least 15 percent of line changes and is cost-neutral or cost-saving through avoided ineffective treatment.","rationale":"Discordance rates of 10 to 30 percent for key biomarkers are consistently reported; the rate of unnecessary or missed targeted therapy is a direct cost to payers.","test":"Coverage-with-evidence pilot in one health system: fund re-testing for 1,000 line changes, record decision changes and downstream costs over 18 months.","maturity":"early-clinical","actor":"payer","cost":"medium","horizonYears":2},"route":"/ideas/idea-bio1-rebiopsy-before-switch/","neighbours":{"cancer":[{"id":"breast-her2-positive","kind":"cancer","name":"HER2-positive breast cancer","route":"/cancers/breast-her2-positive/"},{"id":"breast-hr-positive","kind":"cancer","name":"HR-positive / HER2-negative breast cancer","route":"/cancers/breast-hr-positive/"},{"id":"nsclc","kind":"cancer","name":"Non-small-cell lung cancer","route":"/cancers/nsclc/"}],"technology":[{"id":"cgp","kind":"technology","name":"Comprehensive genomic profiling","route":"/technologies/cgp/"},{"id":"histopathology-ihc","kind":"technology","name":"Histopathology & immunohistochemistry","route":"/technologies/histopathology-ihc/"},{"id":"liquid-biopsy","kind":"technology","name":"Liquid biopsy (ctDNA)","route":"/technologies/liquid-biopsy/"}],"term":[{"id":"her2-low","kind":"term","name":"HER2-low and HER2-ultralow","route":"/terms/her2-low/"},{"id":"ihc","kind":"term","name":"Immunohistochemistry (IHC)","route":"/terms/ihc/"}],"bottleneck":[{"id":"b-resistance","kind":"bottleneck","name":"Acquired resistance to every therapy","route":"/bottlenecks/b-resistance/"},{"id":"b-tumor-heterogeneity","kind":"bottleneck","name":"Tumour heterogeneity and clonal evolution","route":"/bottlenecks/b-tumor-heterogeneity/"}]}}