ERBB2 and breast cancer: In fact, the phase III randomized KATHERINE trial, which enrolled HER2+ BC who were found to have residual invasive disease (breast or axilla) after receiving neoadjuvant therapy containing at least a taxane and trastuzumab, demonstrated a clear improvement in invasive disease-free survival for patients who were switched to T-DM1 instead of continuing trastuzumab [3].