DETECT IV - A Study in Patients With HER2-negative Metastatic Breast Cancer and Persisting HER2-negative Circulating Tumor Cells (CTCs).

Exclusion criteria

• ✕. Treatment with other investigational agents of any type or anticancer therapy during the trial, within 2 weeks prior to the start of treatment.
• ✕. Adverse events due to prior anticancer therapy which are \> Grade 1 (NCI CTCAE) and therapeutically relevant at time of treatment start.
• ✕. Known HIV infection.
• ✕. Current active hepatitis B or C, cliniclally relevant known liver dysfunction, e.g. according to Child Pugh Classifica-tion class B and C, or biliary disease (with exception of patients with Gilbert's syndrome, asymptomatic gall-stones, liver metastases or stable chronic non-viral liver disease per investigator assessment).
• ✕. Concurrent disease or condition that might interfere with adequate assessment or evaluation of study data, or any medical disorder that would make the patient's participation unreasonably hazardous.
• ✕. Other malignant diseases within the last 3 years (apart from carcinoma in situ of the cervix or non-melanoma skin cancer)
• ✕. Dementia, altered mental status, or any psychiatric or social condition which would prohibit the understanding or rendering of informed consent or which might interfere with the patient's adherence to the protocol.
• ✕. Life expectancy \< 3 months.