The goal of this clinical trial is to evaluate the efficacy and safety of SHR-A1811 plus pertuzumab in combination with or without albumin-paclitaxel neoadjuvant therapy for early or locally advanced HER2-positive breast cancer. The main questions it aims to answer are:

• Does the pCR of SHR-A1811 plus pertuzumab with or without albumin-paclitaxel improve compared to the current standard of treatment?
• Is the safety of SHR-A1811 plus pertuzumab with or without albumin-paclitaxel better compared to the current standard of treatment? Researchers will compare SHR-A1811+pertuzumab or SHR-A1811+pertuzumab+albumin-paclitaxel to TCbHP to see if SHR-A1811 plus pertuzumab with or without albumin-paclitaxel works to treat early or locally advanced HER2-positive breast cancer.

Subjects will be randomly assigned 1:1:1 to：

• cohort 1：SHR-A1811 combined with pertuzumab for 6 cycles;
• cohort 2：SHR-A1811 combined with pertuzumab and albumin-paclitaxel for 6 cycles;
• cohort 3：TCbHP (docetaxel, carboplatin, trastuzumab and pertuzumab) for 6 cycles.

There may be higher treatment burden for participants in this trial compared to their standard of care. Participants will attend regular visits during the study at a hospital or clinic and may require frequent medical assessments, blood tests, questionnaires, and scans.

Inclusion Criteria:

• Age: 18-70 years old, ECOG 0-1 point.
• Clinical T2-T4, with any LN, M0.
• HER2+, invasive breast cancer confirmed by histopathology;(HER2 positive expression means that there is at least one case of tumor cell immunohistochemical staining intensity of 3+or positive confirmed by fluorescence in situ hybridization [FISH] in the pathological test/review of the primary focus conducted by the Pathology Department of the Research Center Hospital).
• Having clinically measurable lesions: measurable lesions displayed on ultrasound, mammography, or MR (optional) within the first month of randomization.
• Organ and bone marrow function tests within one month before chemotherapy indicate no contraindications to chemotherapy：Absolute value of neutrophil count ≥ 1.5 × 10^9/L; Hemoglobin ≥ 90g/L; Platelet count ≥ 100 × 10^9/L; Total bilirubin≤1.5 ULN (upper limit of normal value); Creatinine≤1.5 × ULN; AST/ALT ≤ 2.5 × ULN.
• Cardiac ultrasound: Left ventricular ejection fraction (LVEF ≥ 50%).
• Women of childbearing age tested negative for serum pregnancy test 7 days before randomization.
• Sign an informed consent form.

Exclusion Criteria:

• Stage IV (metastatic) breast cancer.
• Has received chemotherapy, endocrine therapy, targeted therapy, reflex therapy, etc. for this disease.
• The patient has a second primary malignant tumor, except for fully treated skin cancer.
• The patient had undergone major surgical procedures unrelated to breast cancer within 4 weeks before enrollment, or the patient has not fully recovered from such surgical procedures.
• The presence of uncontrolled cardiovascular and cerebrovascular disease, including (but not limited to) any of the following within the 6 months prior to the first dose: congestive heart failure (NYHA III or IV), myocardial infarction or cerebral infarction, pulmonary embolism, unstable angina, or arrhythmia requiring treatment at the time of screening; Primary cardiomyopathy (e.g., dilated cardiomyopathy, hypertrophic cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, restricted cardiomyopathy, undefined cardiomyopathy); A clinically significant history of prolonged QTc, grade II type II atrioventricular block or grade III atrioventricular block or QTc interphase (F method) > 470 msec (female); Atrial fibrillation (EHRA grade ≥2b); Unmanageable hypertension, which the investigators judged unsuitable for study participation.
• Due to serious and uncontrollable other medical diseases, researchers believe that there are contraindications to chemotherapy.
• Individuals with a known history of allergies to the drug components of this protocol;
• Having a history of immunodeficiency, including HIV testing positive, or suffering from other acquired or congenital immunodeficiency diseases, or having a history of organ transplantation.

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