Estrogen receptor and Human epidermal growth factor receptor 2 (ER/HER2)

The Estrogen Receptor (ER) and Human Epidermal Growth Factor Receptor 2 (HER2) are pivotal therapeutic targets}

Other names

ER/HER2 axisESR1/ERBB2Hormone receptor and HER2HR+/HER2+ signaling axis

Fulvestrant acts as a selective estrogen receptor degrader (SERD) that binds to the estrogen receptor (ER), inhibiting its transcriptional activity and promoting its degradation [12]. Trastuzumab is a monoclonal antibody that targets the extracellular domain of the human epidermal growth factor receptor 2 (HER2), blocking its homodimerization and heterodimerization, inhibiting downstream PI3K/AKT and MAPK signaling pathways, and mediating antibody-dependent cellular cytotoxicity (ADCC) [3, 4]. The combination of these agents simultaneously blocks the ER and HER2 signaling pathways, which frequently exhibit crosstalk leading to therapeutic resistance [1, 2].