{"entity":{"id":"paper-mountaineer-lancet-oncol-2023","kind":"paper","name":"MOUNTAINEER: tucatinib plus trastuzumab for HER2-positive, RAS wild-type metastatic colorectal cancer","aka":[],"tldr":"The chemotherapy-free combination of tucatinib and trastuzumab shrank tumours in almost four in ten patients with previously treated HER2-positive colorectal cancer, with responses lasting about a year, and became the first approved HER2 regimen for the disease.","summary":"Phase 2 study of 117 patients with HER2-positive, RAS wild-type unresectable or metastatic colorectal cancer previously treated with chemotherapy, of whom 84 received tucatinib plus trastuzumab.\n\nObjective response was 38.1 percent with a median duration of response of 12.4 months, median progression-free survival 8.2 months and median overall survival 24.1 months; tucatinib alone was less active and patients crossed over to the combination.","asOf":"2026-09-17","links":[{"label":"Lancet Oncol 2023","url":"https://doi.org/10.1016/S1470-2045(23)00150-X"},{"label":"PubMed","url":"https://pubmed.ncbi.nlm.nih.gov/37142372/"}],"tags":[],"related":[],"cancers":["her2-amplified-colorectal"],"sections":[],"technologies":[],"targets":[],"drugs":["trastuzumab","tucatinib"],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":["mountaineer"],"people":[],"bottlenecks":[],"keyPapers":[],"journals":["lancet-oncology"],"dependsOn":[],"notes":[],"journal":"The Lancet Oncology","year":2023,"doi":"10.1016/S1470-2045(23)00150-X","pmid":"37142372","authors":"Strickler JH, Cercek A, Siena S, et al.","paperType":"observational","findings":["Objective response 38.1 percent; median duration of response 12.4 months.","Median overall survival 24.1 months."],"whatItMeans":"HER2 amplification testing is now standard in RAS wild-type metastatic colorectal cancer, and tucatinib-trastuzumab is the approved chemotherapy-free option after first-line therapy.","caveats":["Single-arm study in a RAS wild-type population; activity in RAS-mutant tumours is not expected.","Confirmatory first-line trial (MOUNTAINEER-03) ongoing."],"changedPractice":true,"participants":117},"route":"/key-papers/paper-mountaineer-lancet-oncol-2023/","neighbours":{"cancer":[{"id":"her2-amplified-colorectal","kind":"cancer","name":"HER2-amplified colorectal cancer","route":"/cancers/her2-amplified-colorectal/"}],"drug":[{"id":"trastuzumab","kind":"drug","name":"Trastuzumab","route":"/drugs/trastuzumab/"},{"id":"tucatinib","kind":"drug","name":"Tucatinib","route":"/drugs/tucatinib/"}],"trial":[{"id":"mountaineer","kind":"trial","name":"MOUNTAINEER & MOUNTAINEER-03","route":"/trials/mountaineer/"}],"journal":[{"id":"lancet-oncology","kind":"journal","name":"The Lancet Oncology","route":"/journals/lancet-oncology/"}]}}