ERBB2 and breast cancer: The efficacy of trastuzumab duocarmazine in locally advanced or metastatic HER2-positive BC in patients with ≥ 2 prior metastatic BC treatments or previous treatment with T-DM1 in a 2:1 randomization compared to physician’s treatment of choice was evaluated in 437 patients (median age 56 years, median number of 4 prior treatments).