• Signed the informed consent form;

• Women aged ≥ 18 years;

• Patients with locally advanced or metastatic, histologically or cytologically documented breast cancer;

• The primary tumor and metastases (if re-biopsy was performed) were both HER2-negative;

• Eastern Cooperative Oncology Group (ECOG) score \[0-1\] points;

• Patients must have metastatic disease that is evaluable on imaging: including at least one measurable lesion (assessed according to Response Evaluation Criteria in Solid Tumors (RECIST 1.1)); or only non-measurable disease as defined by RECIST 1.1 , especially in patients with bone metastases only, while the disease could be documented/assessed by bone scan, PET or MRI;

• Previous chemotherapy with taxane for early breast cancer (eBC; neoadjuvant or adjuvant setting) is permitted if completed ≥12 months before randomization;

• No previous chemotherapy for advanced breast cancer ;

• For HR+ breast cancer patients shall meet one of the two criteria below: a) radiographically confirmed recurrence or progression within 2 years of adjuvant endocrine therapy; b) received at least one line of endocrine therapy in the recurrence or metastasis stage;

• Patients must have recovered to ≤ Grade 1 (CTCAE v5.0) from all toxicities related to prior antineoplastic therapy. However, patients with any grade of alopecia were allowed ;

• Patients with asymptomatic CNS metastases may be enrolled, if:

‣ Intracranial lesions are evaluable and eligible for systemic therapy only in the absence of extracranial evaluable lesions, or

⁃ Patients with stable intracranial lesions after local treatment while there are extracranial evaluable lesions ;

• Adequate hematological, hepatic and renal function;

• Women of childbearing potential must agree to use a contraceptive method during the treatment period and for at least 90 days after the last dose of experiment treatment;

• Life expectancy of at least 12 weeks;

• Patients must be able to participate and comply with treatment and follow up.