A Prospective, Open-label, Randomized Trial Comparing Switch to A1811 Versus Continued THP Neoadjuvant Therapy After THP Induction in HER2-Positive Breast Cancer

This is a multicenter, open-label, randomized controlled trial. A total of 432 eligible patients with HER2-positive breast cancer will be enrolled after screening. All patients will receive THP-based neoadjuvant therapy (THP) for 2 cycles. After 2 cycles, imaging-based response will be assessed according to RECIST v1.1. Patients with a response or stable disease (PR or SD) will be randomized 1:1 into the experimental group or the control group. Randomization occurs after the 2-cycle assessment. Experimental group: Switch to A1811 therapy for 4 cycles. Control group: Continue the THP regimen for 4 cycles. After completing a total of 6 cycles of neoadjuvant therapy, all patients will undergo definitive surgical treatment for pathological assessment. Primary endpoint: Pathologic complete response (pCR).