A Single-center, Phase II Study on Efficacy & Safety of SCRT+CAPOX+Serplulimab+Bevacizumab for MSS Rectal Cancer

In a single-center, prospective, phase II study (ClinicalTrials registration number: \[to be filled in\]) initiated by our center to evaluate the safety and preliminary efficacy of short-course radiotherapy followed by sequential CAPOX chemotherapy combined with serplulimab and bevacizumab as total neoadjuvant therapy for MSS-type mid-low locally advanced rectal cancer, patients with mid-low MSS-type locally advanced rectal adenocarcinoma were enrolled. They received short-course radiotherapy combined with CAPEOX, serplulimab, and bevacizumab as preoperative total neoadjuvant therapy. It is anticipated that 30 subjects with locally advanced rectal cancer will be enrolled between September 2025 and September 2027. This phase II exploratory study targets patients with locally advanced mid-low MSS/pMMR rectal cancer. It employs short-course radiotherapy combined with CAPEOX, serplulimab, and bevacizumab as preoperative total neoadjuvant therapy, aiming to clarify the efficacy and safety of this new combined radiotherapy, chemotherapy, targeted therapy, and immunotherapy approach, while also assessing the rectal/anal preservation rate and quality of life of patients. After neoadjuvant therapy, patients will undergo imaging and endoscopic evaluations to determine subsequent treatment strategies. Radical surgical resection will be performed on patients after neoadjuvant immunotherapy, followed by further analysis of the pathological complete response (pCR) rate. The primary study endpoint is the pCR rate, and secondary study endpoints include the objective response rate, organ preservation rate, 3-year disease-free survival (DFS), 3-year overall survival (OS), incidence of adverse events, and quality of life scores (EORTC QLQ-C30, EORTC QLQ-CR29, Wexner).