Dr. Hamilton on Tests to Identify HER2-Low and HER2+ Breast Cancer

Erika P. Hamilton, MD, director, Breast Cancer and Gynecologic Cancer Research Program, principal investigator, Sarah Cannon Research Institute, discusses testing used to identify patients with HER2-positive and HER2-low breast cancer.

Though immunohistochemistry (IHC) has traditionally been used to identify patients with HER2-positive breast cancer, IHC has not routinely been utilized to pinpoint patients with HER2-low disease, Hamilton says. With HER2-low breast cancer now considered a separate subgroup, IHC scores of 1+ and 2+ are now actionable, Hamilton continues, adding that since IHC was not initially designed to distinguish between 0 and 1+, there may be a need to refine how HER2 testing is conducted. It is important to educate pathologists and refine testing with this new knowledge of HER2-low patients, Hamilton explains.

By being able to better define and identify patients with HER2-low breast cancer, other antibody-drug conjugates and bispecific antibodies that have produced positive data in HER2-positive breast cancer can be explored in the HER2-low population, Hamilton concludes.