Jonathan Strickler, MD, Duke Cancer Institute, Durham, NC, gives an update on the Phase II MOUNTAINEER trial (NCT03043313), which investigated the safety and efficacy of tucatinib plus trastuzumab in patients with HER2+ metastatic colorectal cancer. Patients were randomised to receive either tucatinib plus trastuzumab or tucatinib alone. Blinded independent central review reported a 38% confirmed objective response rate (ORR) among patients receiving tucatinib plus trastuzumab, with promising data reported for progression-free survival and overall survival. The regimen was also reported to be well-tolerated. This interview took place at the European Society for Medical Oncology World Congress on Gastrointestinal Cancer (ESMO WCGIC) 2022 in Barcelona, Spain.