Study of ASLAN001 in Combination With Capecitabine in MBC That Has Failed on Prior Trastuzumab

Inclusion Criteria: * Patients with documented histological confirmation of breast cancer with HER 2 overexpression or gene amplification prior to study entry. * Patients with HER 2-positive metastatic breast cancer that have failed on prior first line treatment with trastuzumab or who have progressed within 1 year of treatment with trastuzumab in adjuvant setting. * Presence of at least one radiographically measurable disease (bone metastases and ascites are not considered measurable lesions). * Patients of the respective country's legal age or older at the time of written informed consent. * Patients with acceptable organ and hematological function Exclusion Criteria: * Patients with radiation treatment or major surgical procedures within 21 days prior to study entry. * Patients with malabsorption syndrome, diseases significantly affecting gastrointestinal function, resection of the stomach or small bowel, or difficulty in swallowing and retaining oral medications. * Patients with an uncontrolled intercurrent illness including, but not limited to, ongoing or active infection, unstable angina pectoris, cardiac arrhythmia, diabetes, hypertension, or psychiatric illness/social situations that would limit compliance with study requirements. * Patients with any history of other malignancy unless in remission for more than 1 year. (Nonmelanoma skin carcinoma and carcinoma-in-situ of uterine cervix treated with curative intent is not exclusionary). * Patients with symptomatic central nervous system metastasis and/or on systemic steroids or anticonvulsants within 3 months before the first dose of randomized therapy. * Patients who are pregnant or breast-feeding. * Patients who were previously treated with ASLAN001 and/or with lapatinib. * Patients who have received more than 2 lines of any therapies in metastatic stage. * Patients who have received any investigational drug (or have used an investigational device) within 21 days or received any antineoplastic monoclonal antibodies within a period of 5 half-lives before receiving the first dose of randomized therapy. * Patients with unresolved or unstable serious toxicity from prior administration of another investigational drug and/or prior cancer treatment.