Cells throughout the body make proteins called human epidermal growth factor receptor (also known as HER family receptors). These receptors live on the surface of cells and act like antennas, receiving messages about how to help the cells grow, divide, and survive. The receptors are numbered and talk to one another. For example, there is HER1 (also called EGFR), HER2, HER3, and HER4.
When these receptors are working together and at healthy levels, the whole body stays healthy. But sometimes errors and defects happen as cells grow and divide.
All of the genes that create HER receptors can encounter errors, but problems with HER2 (in the gene ERBB2) are found in several GI cancers. Some cancer cells have too many copies of the ERBB2 gene, this is called “gene amplification.” Too many copies of a gene can lead to too many receptors, which is called “overexpression.” An overexpression of HER2 causes cancer cells to grow and spread quickly.
Biomarker testing is typically run on tumor samples to determine if a patient has an overexpression of HER2. Researchers have developed several drugs to fight this overexpression.
A set of drugs called “monoclonal antibodies” serve as a plug on the HER2 receptors on a cancer cell’s surface. Drugs called "inhibitors" get inside cancer cells and block the signals telling the cancer to grow. Immunotherapy activates the body’s immune system to fight cancer.
The following drugs may be recommended for patients with HER2 overexpression, also called HER2-positive. Many times these drugs will be combined with other drugs. Each treatment plan depends on your stage, line of treatment, surgical or additional treatment options, and your overall health.
Gastric/GEJ cancers (in advanced, specific situations)
Colon and rectal cancers (in advanced, specific situations. Must be RAS-wild type)
All GI cancers (in advanced, specific situations)
Ask your doctor how your biomarker test results are informing your treatment plan and if you qualify for any clinical trials.
