• The age at the time of signing the informed consent form is ≥ 18 years old and ≤ 75 years old, for menopausal/premenopausal women (premenopausal women need to receive ovarian function suppression treatment at the same time).

• Breast cancer patients with HR positive (ER expression ≥ 10%, PR positive or negative) and HER2 negative (Immunohistochemical(IHC)0,1+; 2+, Fluorescence in situ hybridization(FISH) not expanded) confirmed by histology.

• Histologically confirmed locally advanced breast cancer (no radical local treatment) or recurrent and metastatic breast cancer.

• The patients who had previously progressed after the treatment of first-line or second-line cyclin-dependent kinases 4 and 6 inhibitors（CDK4/6 inhibitors）of endocrine and whose chemotherapy was ≤ second-line (relapse during the period of new adjuvant/adjuvant treatment or within 12 months after the end of treatment was regarded as first-line chemotherapy), the PIK3CA gene mutation detection was performed a. PIK3CA Mutant subjects were enrolled in queue A; b. PIK3CA wild-type subjects were included in queue B.

• At least one measurable primary lesion (according to RECIST v1.1 standard) before enrollment.

• The Eastern Oncology Collaborative Group (ECOG) physical fitness score is 0-2.

• The toxic and side effects caused by previous anti-tumor therapy were relieved to 0-1 levels before the screening period (judged according to The NCI Common Terminology Criteria for Adverse Events version5.0 (NCICTCAE5.0); except for toxicity that researchers believe does not pose a safety risk to the subjects due to hair loss).

• The functional level of organs must meet the following requirements: 1) Blood routine:

⁃ Absolute neutrophil count(ANC)≥1.5 × 109/L (growth factor not used within 14 days); Platelet(PLT) ≥100 × 109/L (no corrective treatment used within 7 days); Hb ≥ 100 g/L (without corrective treatment within 7 days); 2) Blood biochemistry: Total bilirubin(TBIL) ≤1.5 × upper limits of normal(ULN); Glutamine aminotransferase(ALT),Glutamic transaminase(AST)≤3 × ULN; Glutamine transpeptidase(GGT) ≤2.5 × ULN; If there is liver metastasis, then ALT and/or AST ≤ 5 × ULN; Glutamine transpeptidase GGT ≤5 × ULN; Urea, Blood urea nitrogen (BUN), creatinine (Cr) ≤1.5 × ULN; 3) Cardiac ultrasound: Left ventricular ejection fraction（LVEF）≥ 50%; 4) 12 lead ECG: QT interval (QTcF) corrected by Fridericia method, male\<450ms, female.

• Expected survival time ≥ 3 months.

• Voluntarily participate in this clinical trial and sign a written informed consent form.