RecruitingPhase 2Drug trialATEMPT 2.0: Adjuvant T-DM1 vs THThis research study is studying how well newly diagnosed breast cancer that has tested positive for a protein called HER2 responds using one of two different combination of HER2-directed therapies as a treatment after surgery. The name of the study drugs involved are: * Trastuzumab-emtansine (T-DM1, Kadcyla) * Trastuzumab SC (Herceptin Hylecta) * Paclitaxel