• Aged ≥ 18 and ≤ 75 years at the time of signing the ICF, male or female;

• Histologically and/or cytologically confirmed HR+/HER2- BC based on pathological reports from the most recent biopsy or other pathological specimens;

• Subjects must have radiologically documented disease progression during or after the most recent treatment prior to enrollment;

• No prior systemic chemotherapy for locally advanced, relapsed, or metastatic stages. Subjects who previously received adjuvant/neoadjuvant chemotherapy and progressed \>6 months after completion of the last chemotherapy treatment will be allowed for study inclusion;

• The investigator assessed that the patient could not continue to benefit from endocrine therapy and was suitable for receiving first-line chemotherapy;

• Able to provide recently newly obtained or archival tumor tissue sections at or after diagnosis of relapsed or metastatic tumor within the recent prior to randomization;

• At least one measurable lesion per RECIST v1.1；

• Eastern Cooperative Oncology Group (ECOG) performance status of 0 to 1 with no worsening within 2 weeks prior to randomization;

• Life expectancy of ≥ 12 weeks;

⁃ Suitable to receive one of the chemotherapy regimens listed in the investigator's choice of chemotherapy (paclitaxel, nab-paclitaxel, capecitabine) as assessed by the investigator;

⁃ Adequate organ and bone marrow function;

⁃ Having recovered from all toxicities due to prior treatment;

⁃ Use of effective medical contraception during study treatment and for 6 months after the end of dosing for female subjects of childbearing potential and male subjects with partners of childbearing potential;

⁃ Willingness to participate in the study, sign the ICF, and comply with the protocol-specified visits and relevant procedures.