Serplulimab Combined With Chemotherapy for Early-stage HR+/HER2- Breast Cancer

3.1 Inclusion Criteria

Patients must meet all of the following criteria to be eligible:

Age: ≥18 years old.

Clinical-pathological confirmation:

cT2-cT4 breast cancer, or cT1c with axillary lymph node metastasis.

Histopathologically confirmed HR+/HER2- invasive breast cancer:

ER and/or PR positive (IHC nuclear staining ≥1%).

HER2-negative (IHC 0 or 1+ without FISH testing, or IHC 2+ with FISH-negative amplification).

Ki67 ≥20%.

Clinically measurable lesions:

Measurable lesions confirmed by ultrasound, mammography, or MRI (optional) within 1 month prior to randomization.

Adequate organ and bone marrow function (within 1 month prior to chemotherapy):

Absolute neutrophil count (ANC) ≥2.0 × 10\^9/L.

Hemoglobin ≥90 g/L.

Platelet count ≥100 × 10\^9/L.

Total bilirubin \<1.5 × ULN (upper limit of normal).

Creatinine \<1.5 × ULN.

AST/ALT \<1.5 × ULN.

Cardiac function: Left ventricular ejection fraction (LVEF) ≥55% by echocardiography.

Reproductive status: Women of childbearing potential must have a negative serum pregnancy test within 14 days prior to randomization.

ECOG performance status: ≤1.

Informed consent: Signed written informed consent.

3.2 Exclusion Criteria

Patients meeting any of the following criteria will be excluded:

Evidence of metastatic breast cancer:

Chest/abdominal CT and bone scan required at any time from diagnosis to randomization to exclude metastasis.

PET/CT may substitute for other imaging modalities.

Prior systemic therapy: Chemotherapy, endocrine therapy, targeted therapy, or radiotherapy for the current breast cancer.

Second primary malignancy, except:

Adequately treated non-melanoma skin cancer.

Prior immunotherapy: Treatment with anti-PD-1, anti-PD-L1, anti-PD-L2, or other immune checkpoint inhibitors.

Immune-related conditions:

Diagnosed immunodeficiency or active autoimmune disease.

Severe cardiopulmonary disease: Uncontrolled or clinically significant.

Active hepatitis: Hepatitis B or C with detectable viral load.

Transplant history: Prior organ or bone marrow transplantation.

Pregnancy or lactation: Pregnant or breastfeeding women.

Other contraindications: Severe uncontrolled comorbidities deemed by investigators to contraindicate chemotherapy or PD-1 inhibitor therapy.