This study is looking at how well a drug called *zanidatamab* works when given before surgery to treat people with certain types of colon and rectal cancer. These cancers have a special feature called HER2 (Human Epidermal Growth Factor Receptor 2), which makes them grow faster. Zanidatamab is a special type of medicine called a monoclonal antibody. It is designed to stop cancer cells from growing and spreading.

In this study, patients are divided into two groups based on whether they have colon or rectal cancer. They will receive zanidatamab through an IV (a needle in the vein) every two weeks. The treatment can last for up to 4 cycles (about 2 months) for colon cancer and up to 12 cycles (about 6 months) for rectal cancer. After treatment, patients may have surgery or further observation, depending on their needs. Additionally, various tests and scans will be done to check the cancer's progress and the patient's health.

• The study involves regular visits for treatment every 14 days.
• Participants may have surgery after treatment.
• Follow-up checks continue for up to 2 years.