Temozolomide as a Prophylaxis Against Brain Recurrence in Participants With Metastatic Breast Cancer (P05225 AM2)

Inclusion Criteria: * Diagnosis of metastatic breast cancer. * Participants must have completed first line of metastatic chemotherapy and have achieved complete or partial response or disease stability for at least 6 months from the first confirmation of disease stabilization. * No clinical sign of brain progression. * At least one of the following 3 conditions: HER2 +++, Young age (\< 50 years), and/or estrogen receptor (ER)-/progesterone receptor (PgR)- * Eastern Cooperative Oncology Group (ECOG) performance status ≤2. * Life expectancy ≥3 months. * Neutrophils ≥1.5 x 10\^9/L, platelets ≥100 x 10\^9/L, hemoglobin ≥9 g/dL, lymphocytes ≥1 x 10\^9/L. * Bilirubin level either normal or \<1.5 x ULN (upper limit of normal). * AST (aspartate aminotransferase) and ALT (alanine aminotransferase) ≤2.5 x ULN (≤5 x ULN if liver metastases are present). * Serum creatine \<1.5 x ULN. * Effective contraception if the risk of conception exists. Exclusion Criteria: * Concurrent chronic systemic immune therapy not indicated in the study protocol. * Any investigational agent(s) within 4 weeks prior to entry. * Participants that have completed 2nd, 3rd, or 4th line metastatic chemotherapy or participant in active chemotherapy treatment. * Clinically relevant coronary artery disease or a history of a myocardial infarction within the last 12 months. * Acute or sub acute intestinal occlusion or history of inflammatory bowel disease. * Known Grade 3 or Grade 4 allergic reaction to any of the components of the treatment. * Known drug abuse/alcohol abuse. * Legal incapacity or limited legal capacity. * Medical or psychological condition which in the opinion of the investigator would not permit the participant to complete the study or sign meaningful informed consent. * Women who are pregnant or breastfeeding. * Any concurrent malignancy other than non-melanoma skin cancer, or carcinoma in situ of the cervix (participants with a previous malignancy but without evidence of disease for ≥5 years will be allowed to enter the trial).