Dr. Marshall on HER2 Amplification in Colorectal Cancer

John L. Marshall, MD, chief, Division of Hematology/Oncology, Medstar Georgetown University Hospital director, Otto J. Ruesch Center for the Cure of Gastrointestinal Cancer, Georgetown-Lombardi Comprehensive Cancer Center, discusses HER2 amplification in colorectal cancer (CRC).

Approximately, 3% to 5% of patients with CRC have HER2 expression. Although rare, the marker should be accounted for on molecular panels; otherwise, these alterations might never be detected. The most commonly used method of testing is done by immunohistochemistry, says Marshall. The higher the gene amplification, the more responsive the patient will be to HER2-targeted therapy.

Although HER2 is not as potent of a target in colorectal cancer as it is in breast cancer or gastric cancer, it helps inform the patient’s potential treatment course in the refractory setting. As it stands, this target has no impact on first- or second-line therapy. However, some of the data seen with trastuzumab (Herceptin) and lapatinib (Tykerb) look promising, says Marshall.