SKB264 Combined With KL-A167 Neoadjuvant Therapy for Early-stage, High-risk ER+/HER2- Breast Cancer

This is a single-arm, multi-center, phase II clinical trial to evaluate the efficacy and safety of SKB264 combined with KL-A167 as neoadjuvant treatment for early-stage high-risk ER+HER2- breast cancer. Eligible patients receive intravenous injections of 5mg/kg SKB264 and 900mg KL-167 every 2 weeks, with a total duration of 18 weeks for neoadjuvant therapy. During neoadjuvant therapy, tumor assessments will be conducted every 6 weeks, followed by surgery after neoadjuvant therapy is completed. Following surgery, participants have the option to receive additional adjuvant therapy at the discretion of the treating physician. Participants will be followed at least every 6 months initially as per standard clinical practice. The primary endpoint is to determine the pCR rate of SKB264 combined with KL-A167. Secondary endpoints include ORR, EFS, OS, and safety profile. Safety was evaluated by measuring the occurrence and severity of adverse effects by National Cancer Institute Common Terminology Criteria for Adverse Events, Version 5.0.