About this trial

This is an international multi-center, open label study where patients with HER2+ metastatic colorectal cancer will be randomly assigned to the tucatinib arm or standard of care arm of the study. Patients in the tucatinib group will be treated with tucatinib, trastuzumab and mFOLFOX6. The standard of care group will be treated with mFOLFOX6 with or without either Cetuximab or Bevacizumab.

Patient Profile

Adults with Histologically and/or cytologically confirmed HER2 positive adenocarcinoma of the colon or rectum which is locally advanced unresectable or metastatic. Note that participants may have received a maximum of 2 doses of mFOLFOX6 in the locally advanced/unresectable or metastatic setting prior to randomization.

Where’s this trial being run?

Beaumont Hospital, Bon Secours Cork, University Hospital Waterford, Mater Misericordiae University Hospital, and Mater Private Hospital

Can I join this study / trial?

The first thing you do is to talk to your doctor and/or the cancer trials research team in your hospital. The contact details for the cancer trials research units in Ireland is here.

Why not Print this page and bring it with you. It will help your doctor and research team advise you.

For more detailed information


Here’s a list of questions you may have for your doctor or local cancer research team.

Summary Data

Name: Mountaineer-03
Number: 23-25
Full Title:

An Open-label Randomized Phase 3 Study of Tucatinib in Combination With Trastuzumab and mFOLFOX6 Versus mFOLFOX6 Given With or Without Either Cetuximab or Bevacizumab as First-line Treatment for Subjects With HER2+ Metastatic Colorectal Cancer

Principal Investigator: John McCaffrey (MMUH & MPH), Adrian Murphy (Beaumont), Anne Horgan (UHW)
Type: Industry Sponsored

Seagen Inc.

Recruitment Started: Global: October 2022
Ireland: October 2023
Global Recruitment Target: 400
Ireland Recruitment Target: TBC