A Study of SHR-A1811 as Neoadjuvant Treatment for Patients With HR-Positive, Low HER2 Expression Breast Cancer

Inclusion Criteria: 1. Patients aged 18 to 70 years old (inclusive); 2. Treatment-naive patients with clinically confirmed T2-T3, any nodal status and M0; 3. HR-positive, HER2 low expression, the expression of Ki-67 exceed 14% invasive breast cancer confirmed by histology or cytology; 4. ECOG performance status of 0-1; 5. Normal organ and bone marrow function; 6. Patients of childbearing age must consent to use highly effective contraception for 7 months from the start of study screening until the last study medication and agree not to breastfeeding; 7. Patients voluntarily joined the study and signed informed consent; Exclusion Criteria: 1. Patients have evidence of metastatic breast cancer, or inflammatory breast cancer; 2. Patients previously received antineoplastic therapy or radiotherapy for any malignancy, excluding cured malignancies such as cervical carcinoma in situ, basal cell carcinoma, or squamous carcinoma; 3. Patients received any other anti-tumor therapy at the same time, including endocrine therapy, bisphosphonates or immunotherapy; 4. Patients have major surgical procedures unrelated to breast cancer within 4 weeks before the first medication, or not fully recovered from surgical procedures; 5. Clinically significant pulmonary or cardiovascular disease; 6. Failure to swallow, chronic diarrhea, intestinal obstruction, or presence of other factors affecting drug administration and absorption; 7. Known to be allergic to any study drug or any of its excipients; 8. History of immunodeficiency, including HIV-positive, or other acquired or congenital immunodeficiency diseases, or history of organ transplantation; 9. Pregnant and lactating women; 10. Patients with serious concomitant diseases or other comorbidities that will interfere with the planned treatment, or any other condition that is not suitable for participation assessed by investigator.