Evaluation Of Lapatinib As A Component Of Neoadjuvant Therapy For Her2+Operable Breast Cancer: 5-Year Outcomes Of Nsabp Protocol B-41.

501Background: The primary aim of this randomized trial of neoadjuvant therapy in operable, HER2-positive breast cancer (BC) was to determine the effect on pathologic complete response (pCR) rates of substituting lapatinib (L) for trastuzumab (T) in combination with weekly paclitaxel (WP) following AC as well as adding L to T with WP following AC. Previously reported results showed pCR breast 52.5% for AC→WP+T, 53.2% for AC→WP+L, and 62% for AC→WP+TL. Planned secondary endpoints included 5-year recurrence-free interval (RFI) and overall survival (OS) and are reported here. Methods: All patients received standard AC q3wks x 4 cycles followed by WP (80 mg/m2) on days 1, 8, and 15 q28 days x 4 cycles. Concurrently with WP, patients received either T (4 mg/kg load, then 2 mg/kg) weekly until surgery, L (1250 mg) daily until surgery, or weekly T plus L (750 mg) daily until surgery. Following surgery, all patients received T to complete 52 wks of HER2-targeted therapy. 529 pts were randomized and 522 had follow...