{"entity":{"id":"paper-turner-serena-6-extended-lancet-oncol-2026","kind":"paper","name":"Switching to camizestrant at ESR1 mutation emergence before disease progression during first-line treatment of hormone receptor-positive advanced breast cancer (SERENA-6): extended analysis of a double-blind, placebo-controlled, randomised, phase 3 trial","aka":[],"tldr":"With longer follow-up, switching to camizestrant when an ESR1 mutation appeared in the blood kept its benefit and also lengthened control on the next treatment.","summary":"SERENA-6 tested ctDNA for ESR1 mutation every two to three months with Guardant360 CDx in patients on first-line aromatase inhibitor plus CDK4/6 inhibitor at 264 centres in 23 countries. From June 2021 to June 2024, 3,325 patients were screened, 3,256 had at least one test and 548 had a positive ESR1 test by screening closure; 315 were randomised to switch to camizestrant with the CDK4/6 inhibitor (157) or continue the aromatase inhibitor (158). At a median follow-up of 23.5 months, median progression-free survival was 16.8 months (95% CI 14.7 to 19.4) against 9.2 months (7.2 to 9.7), hazard ratio 0.45 (0.34 to 0.59), descriptive and consistent with the interim analysis. Median second progression-free survival was 25.7 months (20.4 to 30.3) against 19.1 months (16.8 to 21.0), hazard ratio 0.63 (0.46 to 0.86), p = 0.0037.","asOf":"2026-11-04","links":[{"label":"Turner et al., Lancet Oncol 2026 (SERENA-6 extended analysis)","url":"https://doi.org/10.1016/S1470-2045(26)00287-1"},{"label":"PubMed","url":"https://pubmed.ncbi.nlm.nih.gov/42442380/"}],"tags":[],"related":[],"cancers":["breast-hr-positive"],"sections":["diagnostics"],"technologies":["liquid-biopsy"],"targets":["estrogen-receptor"],"drugs":["camizestrant","guardant360-cdx"],"companies":["astrazeneca"],"institutions":[],"pathways":[],"terms":["esr1-mutation","ctdna"],"trials":["serena-6"],"people":[],"bottlenecks":[],"keyPapers":[],"journals":["lancet-oncology"],"dependsOn":[],"notes":[],"journal":"The Lancet Oncology","year":2026,"doi":"10.1016/S1470-2045(26)00287-1","pmid":"42442380","authors":"Turner NC, Mayer EL, Park YH, et al.","paperType":"rct","findings":["3,256 tested; 548 ESR1-positive; 315 randomised.","Updated PFS 16.8 vs 9.2 months, HR 0.45 (0.34 to 0.59).","Second PFS 25.7 vs 19.1 months, HR 0.63 (0.46 to 0.86), p = 0.0037."],"whatItMeans":"Acting on a resistant subclone found in blood keeps its benefit into the next line of treatment. It works where the clone carries a mutation that both marks it and chooses the drug.","caveats":["Advanced disease, hotspot genotyping rather than residual disease testing.","Overall survival not reported in this analysis."],"participants":315},"route":"/key-papers/paper-turner-serena-6-extended-lancet-oncol-2026/","neighbours":{"cancer":[{"id":"breast-hr-positive","kind":"cancer","name":"HR-positive / HER2-negative breast cancer","route":"/cancers/breast-hr-positive/"}],"section":[{"id":"diagnostics","kind":"section","name":"Diagnostics & Biomarkers","route":"/fronts/diagnostics/"}],"technology":[{"id":"liquid-biopsy","kind":"technology","name":"Liquid biopsy (ctDNA)","route":"/technologies/liquid-biopsy/"}],"target":[{"id":"estrogen-receptor","kind":"target","name":"Estrogen receptor (ERα)","route":"/targets/estrogen-receptor/"}],"drug":[{"id":"camizestrant","kind":"drug","name":"Camizestrant","route":"/drugs/camizestrant/"},{"id":"guardant360-cdx","kind":"drug","name":"Guardant360 CDx","route":"/drugs/guardant360-cdx/"}],"company":[{"id":"astrazeneca","kind":"company","name":"AstraZeneca","route":"/companies/astrazeneca/"}],"term":[{"id":"ctdna","kind":"term","name":"Circulating tumour DNA (ctDNA)","route":"/terms/ctdna/"},{"id":"esr1-mutation","kind":"term","name":"ESR1 mutation","route":"/terms/esr1-mutation/"}],"trial":[{"id":"serena-6","kind":"trial","name":"SERENA-6","route":"/trials/serena-6/"}],"journal":[{"id":"lancet-oncology","kind":"journal","name":"The Lancet Oncology","route":"/journals/lancet-oncology/"}],"biomarker":[{"id":"esr1-mutation-ctdna","kind":"biomarker","name":"ESR1 mutation (ligand-binding domain, usually in ctDNA)","route":"/biomarkers/esr1-mutation-ctdna/"}]}}