ESR1 and breast cancer: The role of autophagy as a pro-survival mechanism is supported further by other studies in which this pathway was shown to confer resistance to chemotherapy, immunotherapy, and HER2- and ER-targeted therapies in breast cancer (Martin et al., 2009; Robainas et al., 2017; Samaddar et al., 2008; Schoenlein et al., 2009; Sui et al., 2013; Tracey et al., 2020; Vazquez-Martin et al., 2009; Zambrano and Yeh, 2016).