This is a prospective, randomized, 2-arm, multicenter study to compare the safety and efficiency of T-DM1 + Afatinib versus T-DM1 in HER2-positive breast cancer patients with active refractory brain metastases. This study will be divided into two phases. The purpose of Phase I is to find out the highest dose of Afatinib that can be given safely with T-DM1. 3 ~ 24 eligible subjects will be enrolled in the study. The purpose of Phase II is to find out whether the dose of Afatinib with T-DM1 determined in Phase I will keep subjects from getting worse for a period of time. The estimated ORR is 17.9 percent in the control group, hypothesis Afatinib can improve the prognosis of subjects, so objective respond rate (ORR) of experimental group is increased by 30 percent, with alpha = 0.025 (unilateral), beta = 0.1. The ratio of the experimental group and control group is 1:1, assuming a 5 percent loss rate. As a result, calculating by PASS 11 software, approximately 106 subjects will be enrolled, with 53 cases in the experimental group, and 53 cases in the control group.
This study is being done for the following reasons:~The study has two parts. The purpose of the first part (Phase I) of the study is to find out the highest dose of Afatinib that can be given safely with T-DM1.~The purpose of the second part of the study (Phase II) is to find out whether the dose of Afatinib with T-DM1 determined in Phase I will keep breast cancer from getting worse for a period of time.