Abstract P4 10 22: Loss of androgen receptor after neoadjuvant anti HER2 therapy in patients with locally advanced HER2 positive breast cancer

Background.Androgen receptor (AR) is widely expressed in different breast cancer subtypes. AR plays an important role in promoting the growth of HER2 +  breast cancer through cross-talk with HER2 signaling, including WNT7B upregulation, beta-catenin activation, stimulation of HER3 gene transcription, and promotion of HER2/HER3 heterodimerization. Preclinical data have shown that inhibiting AR with enzalutamide results in decreased HER2 phosphorylation and activation of ERK and AKT, without affecting HER2 and HER3 expression; however, the role that inhibiting HER2 with anti-HER2 therapy plays in AR expression and regulation is still unknown. In this study, we sought to identify the influence of anti-HER2 therapy on AR and estrogen receptor (ER) expression after neoadjuvant treatment in patients with locally advanced HER2+ breast cancer. Methods.We retrospectively collected data from 68 …