Incorporating Agents that Target HER2 in the Neoadjuvant Setting

Neoadjuvant treatment of patients with HER2-positive breast cancer has shown a tremendous success during the last decade since anti-HER2-targeted agents were added to conventional chemotherapy regimen. Efficacy determined by pathological complete response (pCR) increased from approximately 17% with chemotherapy alone to 40% with the addition of trastuzumab, and up to 75% when a dual blockage of the HER2 receptor was achieved by combining chemotherapy with trastuzumab and lapatinib or pertuzumab. pCR rates are higher in hormone receptor–negative tumors. No other predictor for the effect of neoadjuvant anti-HER2 agents on a pCR is validated. In general, patients with a pCR after chemotherapy and trastuzumab showed a highly favorable outcome, whereas patients without a pCR are at high need for additional treatment options. Similar observations for the addition of lapatinib or pertuzumab are awaited. However, recent data suggest that pCR might not be a surrogate for long-term outcome for patients with HER2-positive/hormone receptor–positive tumors.