This study is for people with advanced breast or stomach cancer, where the cancer has spread or can't be removed. It focuses on tumors with a protein called HER2, which helps cancer grow faster. The study uses a new drug called disitamab vedotin (DV), which aims to attach to and kill cancer cells. Another drug in the study is tucatinib, known as TUKYSA®, which is already used to treat cancer.

The trial will test how safe these drugs are when used together and how well they work against tumors. It will also check for side effects, which are unwanted effects of the drugs.

• The study involves multiple phases to find the best dose and test safety.
• Participants must have cancer that cannot be surgically removed or has spread.
• People who join may not have had certain other treatments before.

If you're interested, discuss with your doctor to see if you qualify and to understand the risks and benefits.