Taselisib, GDC-0032 (Genentech, South San Francisco, CA), a novel, oral, selective inhibitor of PI3KCA, has been shown to be active in uterine serous carcinoma (USC) mouse xenografts harboring PI3KCA mutations and overexpressing HER2/neu (Lopez et al., 2014). Here, ERBB2 is linked to endometrial serous adenocarcinoma.