HER2-low advanced breast cancer treatment

Breast cancer cells can express HER2 receptors on their membranes to varying degrees. HER2 signalling pathway is important for tumor growth and metastasis. Patients with HER2-positive disease had worse treatment outcomes until the implementation of trastuzumab started, followed by other anti-HER2 drugs. So far, they have been used exclusively for strong HER2 expression. The development of new drugs, primarily antibody-drug conjugates, has proven their efficacy on tumor cells that have lower levels of the HER2 receptors, today referred to as HER2-low tumors. Since the results of the DESTINY breast04 study showed a prolongation of progression free survival and overall survival in HER2-low pretreated patients, a new perspective opens up in the treatment, as well as in HER2 testing.