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 receiving any anti-tumor treatment beyond the provisions of other protocols;
* Bilateral breast cancer, inflammatory breast cancer or occult breast;
* Stage IV breast cancer;
* Severe dysfunction of important organs such as heart, liver, and kidney;
* Unable to swallow, chronic diarrhea and Bowel obstruction, there are many factors that affect drug taking and absorption;
* Participated in other drug clinical trials within 4 weeks prior to enrollment;
* Those with a known history of allergies to the drug components of this protocol; Have a history of immunodeficiency, including positive Diagnosis of HIV/AIDS test Sex, HCV, active hepatitis B, or other acquired or congenital immunodeficiency diseases Illness or a history of organ transplantation;
* Have ever suffered from any heart disease, including: (1) arrhythmia that requires medication or has clinical significance