This study aims to evaluate the efficacy and safety of neoadjuvant short-course radiotherapy combined with Retlirafusp alfa and CAPOX chemotherapy in the treatment of locally advanced rectal cancer. This is a prospective, single-arm, phase II clinical trial planned to enroll 44 patients with locally advanced rectal cancer. The primary endpoint is the complete response rate, and secondary endpoints include objective response rate, pathological complete response rate, event-free survival, and overall survival, with the goal of providing evidence to optimize clinical treatment decisions.