Abstract P1-14-05: Phase I/II Trial of primary chemotherapy with non-pegylated liposomal doxorubicin, paclitaxel and lapatinib in patients with HER2-positive, early stage breast cancer

Abstract Background: Several studies showed that pathologic complete response (pCR) is a surrogate for disease free survival (DFS) and overall survival (OS). Combinations of trastuzumab and anthracyclines in HER2-positive breast cancer are highly active but associated with a high incidence of cardiotoxicity. The risk of cardiac damage can be significantly reduced through liposomal encapsulation of anthracyclines. This phase I/II study was initiated to evaluate the combination of non-pegylated liposomal doxorubicin (NPLD), paclitaxel and lapatinib as primary treatment for patients with early stage, HER2-positive primary breast cancer. Patients and Methods: Patients with newly diagnosed HER2-positive (IHC 3+ or FISH+) early stage (T1c N1-2 or T2 N0-2) breast cancer were treated with NPLD (60mg/m2; day 1), paclitaxel (175mg/m2, day 1) and lapatinib (750–1500 mg orally daily) in 3-week intervals for up to 6 cycles. The primary endpoints were dose-limiting toxicities (DLT) and pathological complete response (pCR). Secondary endpoints include safety, incidence of cardiac events, and clinical response. Exploratory endpoints include molecular markers for sensitivity or resistance to chemotherapy and/or lapatinib evaluated. Results: A total of 84 patients have been included. No dose-limiting toxicity were observed and the maximum tolerated doses were NPLD 60mg/m2, paclitaxel 175mg/m2 and lapatinib 1500mg. Recommended phase 2 doses (P2D) were NPLD 60mg/m2, paclitaxel 175mg/m2 and lapatinib 1250mg. The treatment was generally well tolerated and associated with toxicities that were consistent with the known side-effects of the individual agents. No cardiac event has been observed to date. Preliminary efficacy data confirm a pCR breast rate of 41.7% and pCR rate in breast and lymph nodes of 37.5%, in 32 evaluable patients treated at ≥P2D. Conclusions: The combination of NPLD, paclitaxel and lapatinib is well tolerated and has high antitumor activity in patients with HER2-positive primary breast cancer. Updated results of all 84 patients will be presented. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P1-14-05.