Tucatinib plus trastuzumab for chemotherapy-refractory, HER2 +, RAS wild-type metastatic colorectal cancer (MOUNTAINEER): final analysis
Later report from the MOUNTAINEER trial registered as NCT03043313, in Nature Communications (2026); its title describes an updated or longer-term analysis.
Overview
MOUNTAINEER was a multicenter, open-label, phase 2 trial (NCT03043313) that evaluated the efficacy and safety of tucatinib plus trastuzumab, a dual HER2-targeted chemotherapy-free regimen. Patients were included if they had chemotherapy-refractory, HER2+, RAS wild-type unresectable or metastatic colorectal cancer. This final analysis reports updated efficacy and safety after a median follow-up of 32.4 months. Of the 84 patients who received tucatinib plus trastuzumab, the confirmed objective response rate was 39.3%; median duration of response was 15.2 months. Median progression-free survival was 8.1 months and overall survival was 23.9 months. Efficacy was relatively similar across central HER2+ testing methods. No clear association of treatment response with co-occurring biomarker alterations was seen. Few patients discontinued treatment due to adverse events; no treatment-emergent deaths occurred. Tucatinib plus trastuzumab showed clinically meaningful efficacy and favorable safety. Efficacy was observed irrespective of central HER2+ testing methods and in patients with heterogeneous tumor biomarker profiles.
Indexed on Europe PMC as PubMed record 41526345 (DOI 10.1038/s41467-025-67824-z). Its abstract cites the registry id NCT03043313, which is how it was matched to this trial; no figure has been checked by an editor.
A second publication from the MOUNTAINEER trial, later than the first and described in its title as an update or longer-term analysis. Read it with the primary publication linked from the trial page; the record was linked automatically and its figures have not been checked by hand.
- Matched to the trial by the registry id cited in the Europe PMC record; the summary reproduces the record's abstract and no figure has been verified against the full paper.
- Chosen as a later report by words in its title (updated, long-term, final, overall survival or a year count), not by reading the paper.