A Study to Evaluate the Pharmacokinetics, Efficacy, and Safety of HLX319 vs. EU-Phesgo® in the Neoadjuvant Therapy of HER2-Positive Early or Locally Advanced Breast Cancer

Inclusion Criteria: * Voluntary participation in the clinical study and signed the Informed Consent Form (ICF). * Male or female aged ≥ 18 years old at the time of signing the ICF; * Histologically confirmed invasive breast cancer, stage II-IIIC, Human Epidermal Growth Factor Receptor 2 (HER2) positive confirmed by central laboratory. * Participants agree to undergo surgery while meeting the criteria for surgery after neoadjuvant therapy. * Left ventricular ejection fraction (LVEF) at baseline ≥ 55%. * An Eastern Cooperative Oncology Group (ECOG) performance status (PS) score of 0-1. * Adequate major organ functions. * Women with child-bearing potential have a negative result of serum pregnancy test at screening period (within 7 days prior to the first dose) or if they are infertile, non- lactating, reproduction-age men and women following highly effective contraceptive measures until 7 months after last dose. Exclusion Criteria: * Stage IV breast cancer, bilateral breast cancer, or multicentric breast cancer. * History of other malignancy within 5 years. * Prior systemic therapy for breast cancer treatment or radiotherapy. * Patients with a history of ductal carcinoma in situ (DCIS) or lobular carcinoma in situ (LCIS) who have received systemic therapy or radiotherapy to the ipsilateral breast. * Patients who have undergone excision biopsy of the primary tumor and/or axillary lymph nodes or lymph node dissection. * Have severe heart disease or medical conditions. * Partic…