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

This study is testing whether adding serplulimab (an immunotherapy drug that helps the immune system attack cancer cells) to standard chemotherapy before surgery improves outcomes for patients with high-risk hormone receptor-positive, HER2-negative early breast cancer. **You may be eligible if...** - You are 18 or older with histologically confirmed HR+/HER2-negative invasive breast cancer - Your tumor is at least cT2 size, or cT1c with lymph node involvement - Your tumor has a Ki67 value of 20% or higher (indicating fast-growing cancer) - Your blood counts and organ function meet required thresholds - There is a measurable tumor on imaging (ultrasound, mammography, or MRI) within 1 month before treatment **You may NOT be eligible if...** - You have metastatic (stage 4) breast cancer - You have active autoimmune disease or have required systemic steroids recently - You have received prior chemotherapy or radiation for this cancer - You have serious cardiovascular, liver, kidney, or lung problems - You are pregnant or breastfeeding Talk to your doctor to see if this trial is right for you.