• Female patients aged between 18 and 75 years old.

• With an Eastern Cooperative Oncology Group (ECOG) performance status score of 0 to 1.

• Patients with histologically or pathologically confirmed invasive ductal carcinoma of the breast, and simultaneously meeting the following conditions:

• T1c (≥1 cm) - 4c N0-2; Histologically confirmed as grade 3 by the research center; Immunohistochemical staining results confirm ER+ (≥1%), HER2 negative (Her2/neu fluorescence in situ hybridization (FISH) ratio ≤ 1.8 or IHC 0 or 1+); and the combined positive score (CPS) is greater than or equal to 10 points. The PD-L1 antibody site detected in our center is 22C3.

• Have not received any previous treatment.

• The functional levels of the major organs must meet the following requirements (no blood transfusion, and no use of drugs for increasing white blood cells or platelets within 2 weeks before screening):

‣ Blood routine: Absolute neutrophil count (ANC) \> 1.5×10⁹/L; platelet count (PLT) \> 75× 10⁹/L; hemoglobin (Hb) \> 90 g/L; lymphocyte count ≥ 1.5×10⁹/L.

⁃ Blood biochemistry: Total bilirubin (TBIL) \< 1.5× the upper limit of normal (ULN); alanine aminotransferase (ALT) and aspartate aminotransferase (AST) \< 1.5×ULN; alkaline phosphatase \< 2.5×ULN; blood urea nitrogen/urea (BUN/UREA) and creatinine (Cr) \< 1.5×ULN.

⁃ Echocardiogram: Left ventricular ejection fraction (LVEF) \> 55%.

⁃ 12-lead electrocardiogram: The corrected QT interval using the Fridericia method (QTcF) \< 470 msec.

• For premenopausal female patients or those who have not undergone surgical sterilization: Use an effective contraceptive method during the treatment period and for at least 6 months after the last administration of the study treatment.

• Voluntarily participate in this study, sign the informed consent form, have good compliance, and be willing to cooperate with the follow-up.