• Sign the informed consent form voluntarily and follow the protocol requirements;

• Women aged ≥18 years and ≤75 years at the time of written informed consent;

• Expected survival time ≥6 months;

• Patients with histologically confirmed HER2-positive invasive breast cancer;

• Before neoadjuvant therapy, the clinical TNM staging was T1-4, N0-3, M0 (excluding T1N0) based on the 8th edition of the American Joint Committee on Cancer (AJCC) staging system;

• The presence of residual invasive cancer confirmed by postoperative pathological examination must meet one of the conditions specified in the protocol;

• Previous neoadjuvant therapy should meet the prescribed treatment conditions;

• Had received radical mastectomy;

• Determine hormone receptor (HR) status;

⁃ The interval between radical surgery and randomization was at least 3 weeks and at most 12 weeks;

⁃ ECOG score 0 or 1;

⁃ The toxicity of previous antineoplastic therapy has returned to ≤ grade 1 as defined by NCI-CTCAE v5.0;

⁃ No blood transfusion within 14 days before the first use of the study drug and no use of colony-stimulating factors were allowed;

⁃ For premenopausal women with childbearing potential, a pregnancy test must be performed within 7 days before starting treatment, serum pregnancy must be negative, and the patient must not be lactating; All enrolled patients should use adequate and highly effective contraception during the entire treatment cycle and for 7 months after the end of treatment.