A Phase Ⅰb/Ⅱ Clinical Study of SHR-A1811 Combined With Other Therapies in Patients With HER2 Low Advanced or Metastatic Breast Cancer.

Inclusion Criteria: 1. Ability to give informed consent, signed and dated IRB/EC approved informed consent, willing and able to comply with treatment planning visits, tests and other procedural requirements 2. When signing the informed consent, the age is 18-75 years old (including both ends), female patients who have pathologically documented HER2 low breast cancer 3. ECOG Performance Status of 0 or 1 4. Patient must have adequate tumor sample for biomarker assessment 5. At least one measurable lesion 6. Adequate organ function Exclusion Criteria: 1. There are untreated or active central nervous system (CNS) tumor metastases 2. There was a third space effusion that could not be controlled by drainage (such as a large number of ascites, pleural effusion and pericardial effusion) 3. Major surgery within 4 weeks prior to enrollment 4. Has multiple primary malignancies within 5 years, excluding cured basal cell carcinoma of skin, cervical carcinoma in situ, papillary thyroid carcinoma, etc 5. Has current ILD/pneumonitis, or where suspected ILD/pneumonitis cannot be ruled out at screening 6. Uncontrolled intercurrent illness 7. Uncontrolled or significant cardiovascular disease 8. Has known human immunodeficiency virus (HIV) infection, or active hepatitis B or C infection. 9. According to NCI-CTCAE v5.0 classification, those who have not recovered to grade Ⅰ toxicity caused by previous anti-tumour treatment