Study of Neoadjuvant Endocrine Therapy in HR Positive and HER2 Negative Premenopausal Breast Cancer Patients

Inclusion Criteria: * All patients were operable estrogen receptor (ER) positive (\>1%), regardless of PR expression level, HER2 receptor negative invasive breast cancer. Follow the 2018 ASCO-CAP HER2 negative interpretation guideline standard. Confirmed by the pathological laboratory that the immunohistochemical (IHC) score is 0 or 1-2+and the in situ hybridization (ISH) test is negative (ISH amplification rate\<2.0); * Stage II-III initial treatment patients whose tumor staging meets the AJCC 8th edition standards; * At least one measurable breast and/or axillary disease; * ECOG 0-1, with an estimated lifespan of at least 12 months; * The functional level of the main organs must meet the following requirements: Blood routine: ANC ≥ 1.5 × ten9/L; PLT ≥ 90 × ten9/L; Hb ≥ 90 g/L;Blood biochemistry: TBIL ≤ 2.5 × ULN; ALT and AST ≤ 2.5 × ULN; BUN and Cr≤ 1.5 × ULN; * Lead ECG: QT interval (QTcF) corrected by Fridericia method\<470 ms for women; * Able to accept all puncture biopsies required by the protocol; * Volunteer to join this study, sign informed consent, have good compliance, and be willing to cooperate with follow-up; * Women with fertility potential must have a negative Pregnancy test (urine or serum) within 7 days after administration, And agree to use acceptable birth control methods during the study period to avoid pregnancy. Exclusion Criteria: * Received any form of anti-tumor treatment within 28 days prior to the start of the study; * Simultaneously receivi…