* Patients need to meet all of the following conditions
+ Patients must be ≥18 and ≤ 75 years of age;
+ Pathologically confirmed breast cancer is HR+/HER2- breast cancer (IHC ER >10%, or/and PR>10%, HER 0 OR +, if HER2++, FISH negative);
+ SNF1 subtype definition: SNF1 subtype confirmed by digital pathology of H&E sections;
+ Locally advanced breast cancer (radical local therapy is not possible) or metastatic breast cancer (without using adjuvant CDK4/6 inhibitors in the past, or one year after adjuvant CDK4/6 inhibitor therapy has ended);
+ No prior therapy (chemotherapy, targeted therapy, etc.) for advanced or metastatic breast cancer;
+ Patients with at least one measurable lesion that has not previously received radiation therapy and can be evaluated repeatedly according to RECIST 1.1;
+ The functions of the main organs are basically normal, and the following conditions are met:
1. Blood routine examination standards should meet: HB≥90g/L (no blood transfusion within 14 days); ANC≥1.5×109/L; PLT≥75×109/L;
2. Biochemical examination shall meet the following standards: TBIL≤1.5×ULN (upper limit of normal value); ALT and AST≤3 x ULN; In case of liver metastasis, ALT and AST≤5×ULN; Serum Cr ≤1.5×ULN, endogenous creatinine clearance > 50ml/min (Cockcroft-Gault formula);
+ ECOG performance status 0 or 1; The expected survival is more than 3 months;
+ Fertile female is required to use a medically approved contraceptive during study treatment and for at least 3 months after the last use of the study drug;
+ Patients voluntarily join the study, sign the informed consent, have good compliance, and cooperate with follow-up.