Buparlisib with trastuzumab demonstrated limited efficacy in patients with heavily pretreated trastuzumab-resistant HER2-positive breast cancer, whereas the phase II NeoPHOEBE trial showed that the combination of neoadjuvant buparlisib plus trastuzumab and paclitaxel for HER2-positive primary breast cancer was not feasible due to significant liver toxicity [110,111]. Here, ERBB2 is linked to breast cancer.