A review of treatment options in HER2‐low breast cancer and proposed treatment sequencing algorithm

Abstract

AbstractThe expansion of the spectrum of human epidermal growth factor receptor 2 (HER2)‐status to HER2‐low, defined as HER2 expression of 1+ by immunohistochemistry (IHC) or 2+ by IHC without gene amplification, has made a major impact in the field of oncology. The HER2‐low expression has emerged as a targetable biomarker, and anti‐HER2 antibody‐drug conjugate trastuzumab deruxtecan has shown significant survival benefit in pretreated metastatic HER2‐low breast cancer (BC). With these recent data, the treatment algorithm for hormone receptor–positive and triple‐negative BC needs to be reconsidered, as approximately half of these BCs are HER2‐low. Although there are different therapeutic agents for hormone receptor–positive and hormone receptor–negative HER2‐low BCs, there is no consensus regarding the sequencing of these agents. In this article, the treatment options for HER2‐low BC are enumerated and a treatment sequencing algorithm based on the current clinical evidence proposed.