This is a phase I/II clinical trial. In phase I part, the primary objective is To determine the recommended dose of the combination of lapatinib with oral vinorelbine in patients with ErbB2 positive metastatic breast cancer. In phase II part, the primary objective is progression free survival of the combination of lapatinib with oral vinorelbine as first line chemotherapy in patients with ErbB2 positive metastatic breast cancer. The secondary objectives are safety profile and the response rate~Lapatinib, an oral inhibitor of EGFR and HER2, have been shown to be an effective treatment in HER2/neu overexpressing metastatic breast cancer patient who refractory herceptin, taxane, and anthracycline treatment. In pre-clinical studies, the highest synergism between anti-Her2 treatment (trastuzumab) and cytotoxics was seen with the platinum compounds and with vinorelbine. The oral vinorelbine has similar efficacy to that of the injection formulation and has demonstrated generally favorable tolerability. We are interested in lapatinib plus oral vinorelbine as 1st line treatment in Her2+ MBC, to which we believe this convenience treatment offer a good response rate with satisfactory life quality.~For phase I part, we plan to use the standard phase I 3-patient cohort (''3 + 3'') design. Up to 18 patients may be enrolled. For phase II part, the expected progression-free survival of the protocol treatment in first line treatment of ErbB2 positive metastatic breast cancer is more than 6 months. With type 1 and type 2 errors of 0.05 and 0.1, respectively, this design calls for 29 patients at the first stage. If 20 or more progression disease is observed after 6 months of treatment, then the study will be terminated. Otherwise, additional 25 patients will be entered at the second stage. The treatment will be rejected if a total of 37 or more progression disease are observed out of 54 patients after 6 months of treatment. With the estimated dropout rate of 10%, 32 patients will be accrued in the first stage and 28 in the second stage.
Phase I part: to determine the recommended dose, and observe the preliminary response and safety profile of the combination of oral lapatinib with vinorelbine in patients with ErbB2 positive metastatic breast cancer.~Phase II part: to determine the progression free survival, response rate, and to evaluate the safety profile of the combination of oral lapatinib with vinorelbine in patients with ErbB2 positive metastatic breast cancer.~Phase I part has been completed. Phase II part is underway.