{"entity":{"id":"horizon-breast01","kind":"trial","name":"HORIZON-Breast01","aka":[],"tldr":"A Chinese HER2 ADC cut the risk of progression by nearly 80% versus a pill-plus-chemotherapy standard, matching the scale of Enhertu's results.","summary":"HORIZON-Breast01, trial NCT05424835 sponsored by Jiangsu Hengrui and reported at ESMO 2025 and in Lancet Oncology in 2026, showed that the Chinese HER2 antibody-drug conjugate trastuzumab rezetecan cut the risk of progression by nearly eighty percent compared with pyrotinib plus capecitabine in HER2-positive metastatic breast cancer after trastuzumab and a taxane, matching the scale of trastuzumab deruxtecan's results. It randomised 366 patients in China and met its primary progression-free survival endpoint by blinded review at an interim analysis with a very large effect. OnCo links it to trastuzumab rezetecan and pyrotinib. The effect is comparable in magnitude to DESTINY-Breast03, but there is no head-to-head comparison with trastuzumab deruxtecan, which is the open question.","status":"positive","asOf":"2026-09-07","links":[{"label":"ClinicalTrials.gov NCT05424835","url":"https://clinicaltrials.gov/study/NCT05424835"}],"tags":[],"related":[],"cancers":["breast-her2-positive"],"sections":[],"technologies":["adc","topoisomerase-inhibitors"],"targets":[],"drugs":["trastuzumab-rezetecan","pyrotinib"],"companies":["hengrui"],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":["paper-horizon-breast01-lancet-oncol-2026"],"journals":[],"dependsOn":[],"notes":[],"nct":"NCT05424835","phase":"3","setting":"HER2+ metastatic breast cancer after trastuzumab and taxane (China): trastuzumab rezetecan (SHR-A1811) vs pyrotinib + capecitabine","sponsor":"Jiangsu Hengrui","result":"PFS 30.6 vs 8.3 months, HR 0.22.","started":"2022-08-04","startedType":"actual","yearReported":2025,"enrolled":381,"enrolledBasis":"registry","outcomes":[{"endpoint":"Progression-free survival (BICR)","primary":true,"unit":"months","arms":[{"name":"Trastuzumab rezetecan","value":30.6},{"name":"Pyrotinib + capecitabine","value":8.3}],"hr":0.22,"source":"https://www.thelancet.com/journals/lanonc/article/PIIS1470-2045(26)00193-2/abstract"}],"replication":"Comparable in magnitude to DESTINY-Breast03; no head-to-head with T-DXd."},"route":"/trials/horizon-breast01/","neighbours":{"cancer":[{"id":"breast-her2-positive","kind":"cancer","name":"HER2-positive breast cancer","route":"/cancers/breast-her2-positive/"}],"technology":[{"id":"adc","kind":"technology","name":"Antibody-drug conjugate (ADC)","route":"/technologies/adc/"},{"id":"topoisomerase-inhibitors","kind":"technology","name":"Topoisomerase-I inhibitors (and ADC payloads)","route":"/technologies/topoisomerase-inhibitors/"}],"drug":[{"id":"pyrotinib","kind":"drug","name":"Pyrotinib","route":"/drugs/pyrotinib/"},{"id":"trastuzumab-rezetecan","kind":"drug","name":"Trastuzumab rezetecan","route":"/drugs/trastuzumab-rezetecan/"}],"company":[{"id":"hengrui","kind":"company","name":"Jiangsu Hengrui Pharmaceuticals","route":"/companies/hengrui/"}],"paper":[{"id":"paper-horizon-breast01-lancet-oncol-2026","kind":"paper","name":"Trastuzumab rezetecan versus pyrotinib plus capecitabine for patients with HER2-positive metastatic breast cancer (HORIZON-Breast01): interim analysis of a multicentre, open-label, randomised, controlled, phase 3 trial","route":"/key-papers/paper-horizon-breast01-lancet-oncol-2026/"}]}}