Routine Therapy Plus Moxifloxacin in Advanced Breast Cancer

Inclusion Criteria: * Female ≥ 18 years, ≤70 years. * Has measurable metastatic MBC, with at least 1 measurable lesion per RECIST criteria. * Fail first-line or above anti-tumor treatment * Evaluation is stable disease with a trend of progression. * Minimum life expectancy 16 weeks * Histological confirmation of breast cancer on primary tumour at diagnosis/on biopsy of metastasis * ECOG Performance Status (PS) 0-2 with no deterioration over previous 2 weeks * Normal organ function. * Has signed a Patient Informed Consent Form Exclusion Criteria: * Hypersensitivity to moxifloxacin or other quinolones. * Tendon damage,peripheral neuropathy,myasthenia gravis. * Rapidly progressive visceral disease not suitable for further therapy. * Evidence of severe or uncontrolled systemic diseases, including uncontrolled hypertension, active bleeding diatheses, or active infection including hepatitis B, hepatitis C and HIV * With the exception of alopecia, any unresolved toxicities from previous therapy greater than CTCAE grade 1 before study treatment * Evidence of dementia, altered mental status or any psychiatric condition that would prohibit understanding or rendering of informed consent * Inability or unwillingness to comply with study procedures, including inability to take regular oral medication * Researchers consider it is not suitable for participation.