This study is testing new cancer drugs for people with a special type of colorectal cancer called HER2 positive that has spread (metastatic) or can't be removed by surgery (unresectable). The study compares a drug called tucatinib, along with trastuzumab and mFOLFOX6, against the usual treatment. HER2 positive means the cancer cells have more of a protein that helps them grow. mFOLFOX6 is a mix of drugs often used for this cancer. The study checks if tucatinib works better and what side effects, or extra problems caused by the drugs, might happen.

Participants are randomly placed in one of two groups: one gets tucatinib with other drugs, and the other gets standard treatments like mFOLFOX6 alone or with bevacizumab or cetuximab. To join, participants must have a type of colorectal cancer confirmed by tests, have the HER2+ disease, and have measurable disease areas.

• The study involves taking new drugs, which might help more than current treatments.
• Participants are randomly assigned to either the new drug group or the usual treatment group.
• Participants need to meet specific health criteria to join the study.