Patients with histologically-confirmed HER2-positive (IHC 3+ or fluorescence in situ hybridization [FISH] amplified; by clinical assay on either primary or metastatic tumor) adenocarcinoma of the breast with unequivocal evidence of brain metastases that are refractory to standard therapy or for which no standard therapy exist or with unequivocal evidence of newly diagnosed untreated brain metastases and controlled extracranial disease which per the multi-disciplinary team decision do not require immediate radiotherapy, surgery or standard systematic chemotherapy can be included to this escalation phase as well.