This is a single-arm exploratory study to explore the effect of RC48 in HER2-positive neoadjuvant therapy and evaluate the non-inferiority of RC48 by comparing the latest reported data of T-DM1 in neoadjuvant therapy.

A single-arm exploratory study was conducted in 20 patients with HER2-positive breast cancer to explore the effect of RC48 in HER2-positive neoadjuvant therapy (treatment regimen: RC482.0 mg/kg, intravenous drip, once every 2 weeks). After 4-6 cycles, surgery was performed to evaluate the effect of neoadjuvant chemotherapy. The latest reported data of T-DM1 in neoadjuvant therapy were compared to evaluate the non-inferiority of RC48.

Inclusion Criteria:

1. Enrolled were ≥ 18 years of age and < 80 years of age
2. Female or male breast cancer
3. Patients with early or locally advanced breast cancer who are HER2-positive, have a tumor larger than 2 cm and/or have lymph node metastasis: HER2-positive is defined as 3 + by immunohistochemistry, or 2 + by immunohistochemistry, with a positive FISH test.
4. Left ventricular score ≥ 55%
5. ECOGPS score 0 or 1
6. Able to understand the test requirements, willing and able to comply with the test and follow-up procedures
7. Adequate organ function

Exclusion Criteria:

1. cardiac, hepatic, renal, or psychiatric disease history
2. History of other malignancy within the last 5 years, with the exception of adequately treated basal or squamous cell carcinoma of the skin or carcinoma in situ of the cervix.