Oral Vinorelbine in Combination With Trastuzumab for Metastatic Breast Cancer

Inclusion Criteria: * Woman ≥ 18 years of age. * PS 0-2. Expected lifetime of more than 12 weeks. * Histologically verified breast cancer(adenocarcinoma) * Primary tumor or metastasis is HER2 positive with IHC3+ or FISH+ (ratio ≥ 2.2). * Documented metastatic breast cancer with min. one lesion measureable according to the RECIST 1.1 criteria. All solitary lesions must be verified cytologically/histologically if representing the only evidence of malignancy. * The patient may have received (neo-) adjuvant chemotherapy (taxanes, anthracyclines and trastuzumab) and 1st line chemotherapy in combination with trastuzumab for metastatic disease. * The patient may have received previous adjuvant antihormonal treatment for metastatic breast cancer. * The patient may receive radiation therapy, however, not against lesions used for response evaluation. * Normal heart function, LVEF ≥ 50% measured by MUGA/EKKO. * Normal bone marrow function: Hemoglobin ≥ 6 mmol/l, ANC ≥ 1.5x10\^9/l. Thrombocytes ≥ 100x10\^9/l. * Normal liver function: Bilirubin ≤ 1.5 x upper normal level, ALAT ≤ 2.5 x upper normal level, BASP ≤ 2.5 x upper normal level (≤ 5 if presence of bone metastases). * Normal renal function: Creatinine ≤ upper normal level. In case of raised creatinine the measured/calculated GFR must be ≥ 50 ml/min. * Fertile women must present a negative pregnancy test and use contraceptives during and 3 months after treatment. An IUD without hormone is considered a safe contraceptive. * Written and orally informed consent prior to any study related procedure. Exclusion Criteria: * Local recurrence or counter-lateral breast cancer without other dissemination. * Pregnant or breastfeeding women. * Clinical symptoms of CNS metastases, incl. meningeal carcinomatosis. * Malabsorption syndrome or other disease affecting the gastrointestinal function. Resection of the ventriculus or the small intestine, which can affect absorption of oral vinorelbine. * Dysphagia or other conditions preventing the patient from swallowing tablets. * Mental or social conditions preventing treatment or follow-up. * Serious concurrent medical condition, such as: * AMI within 12 months or unstable angina. * Heart incompensation NYHA III or IV or uncontrolled hypertension (systolic \> 150 mm/hg and/or diastolic \>100 mm/hg). * Serious arrythmia requiring medication, excl. atrial fibrillation and paroxystic supraventricular tachycardia. * Active infection, uncontrolled diabetes or hypercalcemia. * Other concurrent experimental treatment. * Concurrent antihormonal treatment of metastatic breast cancer. * Known neuropathia ≥ grade 2. * Other previous malignant disease within the past 5 years excl. non-melanoma skin cancer and carcinoma in situ cervicis uteri. * Previous treatment with vinca alkaloid. * Previous serious allergic or unexpected reactions to trastuzumab treatment.