ADC Based Therapy Accroding to HER2 Heterogeneous

• 1.18 years or older and be treatment-naïve breast cancer patients 2.histology confirmed invasive breast carcinoma.HER2-positive defined by our pathology department, defined as IHC 3+ or IHC 2+ with fluorescence/chromogenic in situ hybridization (FISH/CISH) confirming HER2 gene amplification; 3.Clinically staged as Stage II or III according to AJCC 8th edition 4.Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1 5.Adequate function of major organs to meet study safety and tolerability requirements 6.Agree to provide tissue biopsies and/or blood samples at specified study timepoints (baseline, after cycle 4, after cycle 8, and at surgical resection) for translational research purposes 7.No contraindication to breast-enhanced MRI (no contraindications to breast MRI enhancement 8.Reproductive-age women must have a negative serum pregnancy test within 7 days prior to enrollment and agree to use an effective form of contraception recognized clinically during the study and for 3 months after the last study drug administration 9.agrees to participate in this study and signs the informed consent form

Exclusion Criteria:

• 1.bilateral breast cancer or presenting as recurrent or metastatic disease 2.Within the preceding 5 years prior to written informed consent, any history of malignant neoplasm other than treated cervical in situ carcinoma, skin basal cell carcinoma, or skin squamous cell carcinoma will exclude the subject 3.Within 4 weeks prior to enrollment, subjects who have undergone major surgery unrelated to breast cancer, or who have not fully recovered from such surgery, are excluded; procedures necessary for diagnostic tissue biopsy or peripheral venous catheter placement are allowed 4.History of interstitial lung disease (ILD) or non-infectious pneumonia, or current active ILD/pneumonia, or radiologic findings during screening that cannot exclude suspected ILD/pneumonia 5.Presence of significant cardiac disease or other conditions that would make participation unsafe or unsuitable 6.Severe infection within 4 weeks prior to the first dose 7.Known HIV infection or known acquired immunodeficiency syndrome (AIDS); active hepatitis B (HBV-DNA ≥ 500 IU/mL) or hepatitis C (HCV-RNA above the assay's lower limit) or co-infection with HBV and HCV; autoimmune hepatitis 8.Known hypersensitivity to the study drug or any of its excipients 9.Pregnant or lactating women; women of childbearing potential with a positive baseline pregnancy test; or women unwilling to use an effective contraception method throughout the study 10.History of definite neurologic or psychiatric disorders including epilepsy or dementia, or known history of psychiatric drug abuse, alcoholism, or substance misuse 11.Any other condition that, in the opinion of the investigator, would make participation unsuitable for this study.