Phase I/II Study of Lapatinib in Combination With Paclitaxel as 1L Chemotherapy for ErbB2-positive MBC

This is an open-label, non-randomized, multi-center study of lapatinib plus paclitaxel to evaluate safety, tolerability and efficacy in Japanese patients with ErbB2 over expressing advanced or metastatic breast cancer. Lapatinib 1500mg/day will be administered in combination with paclitaxel 80mg/m2/week. Lapatinib and paclitaxel will be administered until disease progression or withdrawal from the study due to unacceptable toxicity. The study will proceed in two phases. The first phase (Phase I part) will lead to evaluate safety and tolerability of lapatinib taken together with paclitaxel in the first 6 subjects. Pharmacokinetic profile also will be evaluated as the secondary objects. Then the study will move to the next treatment phase (Phase II part) to evaluate further safety and clinical activity, if no major safety concerns are raised during Phase I part. The primary objective of the study is to evaluate overall survival (OS), and the secondary objectives are Objective tumour response rate (ORR), Duration of response, Time to response, Clinical benefit and Progression-free survival (PFS) in 12 subjects.