ERBB2 and breast cancer: Moreover, based on the positive results from the phase 3 study (KATHERINE), the FDA extended the approval to Kadcyla® for adjuvant treatment of patients with HER2-positive early breast cancer (EBC) who have residual invasive disease after neoadjuvant taxane and trastuzumab-based treatment in May 2019.197,198 A total of 1486 patients met criteria were enrolled in the study and randomly assigned to treat with T-DM1 or trastuzumab.