Immune microenvironment dynamics of HER2 overexpressing breast cancer under dual anti-HER2 blockade.

Introduction: The clinical prognosis of the HER2-overexpressing (HER2-OE) subtype of breast cancer (BC) is influenced by the immune infiltrate of the tumor. Specifically, monocytic cells, which are promoters of pro-tumoral immunosuppression, and NK cells, whose basal cytotoxic function may be enhanced with therapeutic antibodies. One of the standards of care for HER2 BC patients includes the combination of the anti-HER2 antibodies trastuzumab and pertuzumab.