The study is being conducted to evaluate the safety and tolerability of HRS-1358 monotherapy or combination with Dalpiciclib Isethionate Tablets in patients with metastatic or locally advanced breast cancer in order to estimate the Dose-Limiting Toxicity (DLT), Maximum Tolerated Dose (MTD) and select the Recommended Phase 2 Dose (RP2D).

Inclusion Criteria:

1. Histologically diagnosis of local advanced or metastatic breast cancer
2. Women must be postmenopausal, or pre-/peri-menopausal women must be on ovarian suppression
3. At least 1 line of endocrine therapy in the metastatic or advanced setting
4. ECOG performance status score: 0-1;
5. Adequate organ functions as defined
6. Ability to understand and voluntarily agrees to participate by giving written informed consent for the study.

Exclusion Criteria:

1. the investigators judged that it was not suitable to endocrine therapy
2. patients with active brain metastasis (without medical control or with clinical symptoms),
3. History of clinically significant cardiovascular or cerebrovascular diseases
4. The subject has one of many factors affecting oral 、absorption, distribution, metabolism and excretion of drugs
5. Active autoimmune diseases, History of immunodeficiency, including positive HIV serum test result and other acquired or congenital immunodeficiency diseases, or history of organ transplantation
6. Have received other similar drugs in the past;
7. Known history of allergy to HRS-1358 ingredients