• Premenopausal/perimenopausal or postmenopausal women aged ≥18 years and ≤75 years;

• Histologically confirmed HR+/HER2- invasive breast cancer (specific definition: ER \>10% tumor cell positive is defined as ER positive, PR \>10% tumor cell positive is defined as PR positive, ER and/or PR positive is defined as HR positive; HER2 0-1+ or HER2 ++ but negative by FISH test, no amplification, defined as HER2 negative);

• Locally advanced breast cancer (radical local treatment is not possible) or recurrent metastatic breast cancer;

• Did not receive any systemic anti-cancer therapy at the stage of recurrence and metastasis or failed to receive first-line endocrine therapy at the advanced stage;

• Allowed to receive ≤1 line of chemotherapy

• Have at least one measurable lesion according to RECIST version 1.1

• Adequate hematology and organ function, including:

• hemoglobin \> 9 g/dL without blood transfusion or erythropoietin in the past 14 days.

• ANC ≥ 1.5×109/L without using granulocyte colony stimulating factor in the past 14 days.

• PLT ≥ 75×109/L without blood transfusion in the past 14 days. TBIL ≤ 1.5 ×ULN (Gilbert syndrome allows ≤ 3 × ULN). ALT and AST ≤ 3 × ULN (if there is liver metastasis, ALT and AST ≤ 5 × ULN). Serum Cr ≤ 1.5 × ULN or endogenous creatinine clearance ≥ 50 mL/min (Cockcroft-Gault formula)

• ECOG score 0 or 1, and life expectancy ≥3 months;

• Fertile female subjects are required to use a medically approved contraceptive during the study treatment period and for at least 3 months after the last use of the study drug;

⁃ Subjects voluntarily joined the study, signed informed consent, had good compliance, and cooperated with follow-up.