• 529 patients received preoperative AC followed by paclitaxel with lapatinib (L) or trastuzumab (T) or both.
• pCR rates in breast: T + L: 62%; L: 53.2%; T: 52.5% (not statistically significant). Findings were similar regardless of ER status.

Another important trial from a research perspective, this data set, although it did not reach statistical significance, adds to multiple prior studies demonstrating improved outcomes when lapatinib (L) is added to trastuzumab (T)/chemotherapy in the neoadjuvant setting. While chemo combined with TL is generally not used in clinical practice, the TL doublet is commonly used without chemo in metastatic disease. Although combined anti-HER2 neoadjuvant treatment continues to be evaluated, great interest also exists in trials of treatment after surgery for patients at substantial risk of disease progression, particularly with T-DM1.