The goal of this clinical study is to learn if serplulimab is effective in early HR+/HER2- breast cancer. This trial serves a prospective parallel control cohort for HELEN-018 (NCT). The main questions it aims to answer are:

Does serplulimab combined with neoadjuvant chemotherapy improve the pCR rate of early HR+/HER2- breast cancer? What medical problems do participants have when receiving serplulimab? Researchers will compare the effect of serplulimab combined with chemotherapy to the effect of chemotherapy reported in literature.

Participants will: Receive serplulimab plus chemotherapy every 3 weeks for 6 cycles; All patients will receive surgery, and the primary end point is a pathological complete response at the time of definitive surgery; After definitive surgery, the participants will receive adjuvant serplulimab every 3 weeks for up to 6 months from the begining of the treatment.

In recent years, significant progress has been made in the immunotherapy of breast cancer, and PD1/PDL1 inhibitors have achieved good results in the treatment of triple-negative breast cancer. There have also been many attempts to apply them in HR+/HER2- breast cancer. In the I-SPY2 study, Pembrolizumab combined with chemotherapy increased the pCR rate of HR+/HER2- breast cancer from 13% in the chemotherapy alone group to 30%. In the KEYNOTE756 study, Pembrolizumab in combination with chemotherapy increased the pCR rate by 8.5% (24.3% vs. 15.6%) compared to the chemotherapy-only arm in HR+/HER2- breast cancer. pCR rates in the nivolizumab arm of the CheckMate 7FL study were 24.5% compared with 13.8% in the control arm. While further long-term follow-up data are still needed to confirm patient benefit, it still provides a new treatment option for HR+/HER2- breast cancer patients.

The neoadjuvant treatment options commonly used for HR+/HER2- breast cancer are mainly anthracycline sequential or combined with paclitaxel chemotherapy regimens. Several clinical studies have confirmed that albumin paclitaxel is more effective than solvent-based paclitaxel, and therefore, albumin paclitaxel in combination with epirubicin has also become a commonly used chemotherapy regimen in clinical practice.

The aim of this study was to explore the efficacy and safety of the Serplulimab combined with nab-paclitaxel and epirubicin in the neoadjuvant treatment of HR+/HER2- breast cancer

Inclusion Criteria:

1. Age>=18 years old

2. cT2 - cT4d, or cT1c with axillary lymph node metastasis confirmed clinically and pathologically；

3. Pathologically proven HR+/HER2- breast cancer:

   defined as:

   • positive for ER or PR (IHC nuclear staining >1%)
   • Her-2 negative (IHC 0, 1+ without FISH, or IHC 2+ with no amplification by FISH)；

4. Has clinically measurable lesions:Measurable lesions on ultrasound, mammography, or MR (optional) within 1 month before randomization；

5. Organ and bone marrow function tests within 1 month before chemotherapy suggest no contraindications to chemotherapy；

6. Cardiac ultrasound EF value ≧55%；

7. Females of childbearing age, with a negative serum pregnancy test 14 days before randomization;

8. ECOG score≤1 point;

9. Sign informed consent；

Exclusion Criteria:

1. The patient has evidence of metastatic breast cancer；
2. For this disease, chemotherapy, endocrine therapy, targeted therapy, radiation therapy, etc. have been received;
3. The patient has a second primary malignancy other than adequately treated skin cancer;
4. The patient has been treated with anti-programmed cell death protein 1 (anti-PD-1), anti-programmed death ligand 1 (anti-PD-L1) or anti-PD-L2 drugs, or other immunotherapy；
5. The patient has been diagnosed with immunodeficiency disease or autoimmune disease;
6. The patient has severe lung or heart disease;
7. The patient has active hepatitis B and C;
8. The patient has a history of organ transplantation or bone marrow transplantation;
9. pregnant or breastfeeding women;
10. The investigators considered chemotherapy contraindicated due to serious, uncontrolled other medical conditions.

All female breast cancer patients diagnosed and scheduled to receive neoadjuvant chemotherapy