ERBB2 and breast cancer: However, in another 3-arm, phase III study (MARIANNE) that compared T-DM1 with or without Pertuzumab versus Trastuzumab and Taxane therapy showed unsatisfied outcomes in consideration of taking T-DM1 as a first-line treatment solution of HER2-positive, advanced breast cancer [overall survival (OS): 50.86 months with trastuzumab plus taxane, 53.68 months with T-DM1, and 51.78 months with T-DM1 plus pertuzumab] (Perez et al., 2017).