Dose Finding Study for Combination of Capecitabine, Lapatinib and Vinorelbine in Metastatic Breast Cancer

Key Inclusion Criteria: * Written informed consent * Able to comply with the protocol * ECOG performance status 0-1 * Adequate contraception * Confirmed Her2/neu-positive, adenocarcinoma of the breast * At least one measurable lesion according to RECIST 1.1 criteria * First or second chemotherapy after diagnosis of metastasis * Lapatinib treatment indicated (adjuvant trastuzumab treatment \<12 months ago or progressive disease with trastuzumab treatment) * No signs and symptoms of CHF (chronic heart failure), LVEF (left ventricular ejection fraction) at study start at least 55% * Adequate hepatic and renal function value * Adequate hematologic function values Exclusion Criteria: * Pregnant or lactating women * Concurrent participation in another clinical trial. Prior participation is allowed if the last study medication was administered more than 4 weeks prior to randomization * Asymptomatic with regards to tumor illness * Previous treatment with lapatinib, capecitabine or vinorelbine * Necessity of planned treatment with other chemotherapeutics oder anti-hormone therapy * Major surgical procedure, open biopsy or significant traumatic injury within 28 days prior to randomization, or anticipation of the need for major surgery during the course of the study * Evidence of cardiovascular disease, e.g. myocardial infection, unstable angina pectoris or arrhythmia * History of vascular or cardiovascular disease within the past 6 months * All illnesses that result in malabsorption of oral medication or inability to take oral medication * Concurrent treatment with anti-viral drugs based on sorivudine or with aminoglycosides * Concurrent treatment with any drug interfering with study medication, especially, those that induce CYP3A * Concurrent treatment with allopurinol * Other malignancies (except for basal cell carcinoma of the skin and cervical carcinoma in situ); patient can be included in the study if no recurrent disease has been observed for at least 5 years * Concurrent illnesses or other circumstances that could interfere with trial participation, efficacy or safety of the patient