• Voluntarily participate and sign the informed consent form;

• Ages≥18 years;

• Histopathologically confirmed invasive breast cancer, clinical stage T2-3 (tumor diameter \> 2 cm), cN0- 3, M0;

• Invasive breast tumour tissue confirmed HER2-positive by the central laboratory, defined as HER2 protein expression of IHC 3+ by immunohistochemistry (IHC) or IHC 2+ with amplification by in situ hybridisation (ISH) (according to the HER2 Guidelines for Breast Cancer, 2019 edition); and specimens from the primary site of the tumour for HER2 testing (wax blocks, sections or fresh tissue are acceptable) can be provided for HER2 testing;

• Subjects who tolerate and are scheduled to undergo radical breast cancer surgery and have not received any prior anti-tumour systemic therapy for breast cancer, as assessed by site.

• At least one measurable lesion according to RECIST v1.1 criteria;

• Cardiac function: New York Heart Association (NYHA) class \<3; left ventricular ejection fraction ≥55%;

• Bone marrow or organ function, the following criteria should be met within 7 days prior to study dosing (normal values are based on the clinical trial centre, no transfusion of blood, haematopoietic stimulating factors, albumin or blood products within 14 days prior to the test): haemoglobin ≥ 90 g/L; absolute neutrophil count (ANC) ≥ 1.5 × 109 /L; platelets ≥ 100 × 109 /L; serum total bilirubin ≤ 1.5 times the Upper Limit of Normal (ULN); Albuminous Transaminase (AST) and Albuminous Transaminase (ALT) ≤ 2.5 × ULN; International Normalised Ratio (INR) and Activated Fractional Thromboplastin Time ≤ 1.5 × ULN; and Creatinine Clearance (CrCl) ≥ 50 mL/min according to the Cockcroft-Gault formula method;

• Subjects of childbearing potential who meet the following criteria:

∙ A serum pregnancy test (minimum sensitivity of 25 mIU/mL or equivalent units of β-human chorionic gonadotropin \[β-hCG\]) must be negative within 72 hours prior to the first dose of study intervention. Subjects with false-positive results and confirmed non-pregnancy will be eligible for participation in the study.

‣ Must agree to contraception for the duration of the study and for at least 6 months after the last dose of study drug (7 months after the last dose of patulizumab).

‣ Must agree not to breastfeed or donate eggs from the time of signing the informed consent until 6 months after the last dose of study drug (7 months after the last dose of patulizumab).

‣ If sexually active and likely to result in pregnancy, use of at least 2 acceptable contraceptive methods, at least 1 of which must be highly effective, must be continued from the time of informed consent for at least 6 months after the last dose of study drug (7 months after the last dose of patulizumab).

⁃ Subjects of childbearing potential who meet the following criteria:

• Must agree not to donate sperm from the time of signing the informed consent until at least 4 months after the last dose of study drug (7 months after the last dose of patulizumab).

∙ If sexual intercourse with a person of childbearing potential is likely to result in pregnancy, the use of at least 2 acceptable forms of contraception, at least 1 of which must be highly effective, must be continuous, beginning at the time of informed consent and continuing until at least 4 months after the last dose of study drug (7 months after the last dose of patuximab).

∙ If sex with a pregnant or breastfeeding patient, condom use must be continued from the start of informed consent and continue until at least 4 months after the last dose of study drug (7 months after the last dose of patuximab).

⁃ 12\. Be able to understand the requirements of the trial and be willing and able to comply with the trial and follow up procedural arrangements.