Second Line ERIbulin Followed by CApecitabine or the Reverse Sequence in HER2-negative Metastatic Breast Cancer Patients

Inclusion Criteria: Written informed consent (both for clinical and blood biomarker study) Histological diagnosis of HER2 negative MBC Females ≥ 18 years Measurable disease (according RECIST criteria version 1.1) Prior Anthracyclines and Taxanes in either (neo-) adjuvant or metastatic setting, unless the patient was not suitable for one of these treatments 1 prior cytotoxic regimen for advanced or MBC (not including adjuvant or neo-adjuvant therapy). Patients with no prior cytotoxic regimens for advanced or metastatic disease will only be allowed if they relapsed during or within 6 months of (neo-) adjuvant cytotoxic therapy that included anathracyclines and/or taxanes (see prior criteria); Prior hormonotherapy and Cyclines inhibitors are allowed, so as indicated in the international guidelines for the management of hormone positive breast cancer (ER and/or PR positive); ECOG Performance Status ≤ 2 Absence of angina or heart failure or infarction within 12 months from inclusion Adequate bone marrow and organ function as follows (haemoglobin ≥9.0 g/dl; absolute neutrophil count ≥ 1.5x103/mm3; plateled count ≥ 100x103/mm3; bilirubin levels ≤ 1.5 times Upper Limits of Normal biliary stenting is allowed to resolve obstruction - Serum Transaminase level ≤ 2.5 times ULN; serum creatinine ≤ 1.5 times ULN; Life expectancy of at least 12 weeks; If women of childbearing potential (WOCBP) age: effective contraceptive measures must be used during the study treatment period and up to 3 months after the last dose of study drug. Exclusion Criteria: Unability to give informed consent Absence of measurable disease Concurrent active malignancies (except of in situ carcinoma of the cervix and inactive non-melanoma skin cancer) Current active infection; Serious pre-existing medical conditions or serious concomitant diseases; systemic disorders that would compromise the safety of the patient or her ability to complete the study, at the discretion of the investigator (for example, unstable angina pectoris, or a clinically significant history of cardiac disease or uncontrolled diabetes mellitus); Known immunodeficiency virus infection; Pregnant or breastfeeding women Unable to undergo medical test for geographical, social or psychological reason; Active or symptomatic brain metastases; Known complete Dihydropyrimidine dehydrogenase (DPD) deficiency (phenotype and/or genotype testing, according to applicable national guidelines, prior to the initiation of treatment with Capecitabine is recommended) Recent or concomitant treatment with brivudine (there must be at least a 4-week waiting period between end of treatment with brivudine and start of capecitabine therapy).