Radiotherapy Plus CAPOX, and Iparomlimab and Tuvonralimab (QL1706) as Neoadjuvant Therapy for LARC

This study is a single-center, prospective, randomized, double-arm, Phase II clinical trial designed to evaluate the efficacy of radiotherapy combined with CAPOX, and Iparomlimab and Tuvonralimab (QL1706) as neoadjuvant therapy for locally advanced rectal cancer. Additionally, the study seeks to explore the relationship between biomarkers in blood and tumor tissue and treatment efficacy. Eligible participants (locally advanced rectal cancer) were randomly assigned in a 1:1 ratio to two groups. Participants will: Group A patients received radiotherapy, chemotherapy, and immunotherapy. During the first week of radiotherapy, they received one cycle of CAPOX concurrent chemoradiotherapy. Two weeks after the completion of radiotherapy, they continued with four cycles of CAPOX combined with QL1706 immunotherapy. Group B patients received radiotherapy and chemotherapy. After completing the concurrent radiotherapy and chemotherapy, they rested for 2-3 weeks before completing 3 cycles of CAPOX consolidation chemotherapy. Two to three weeks after the completion of neoadjuvant therapy in groups A and B, the efficacy was evaluated, and a decision was made on whether to proceed with surgery or watchful waiting based on the efficacy.

Improving the tumor downstaging rate and complete response rate of neoadjuvant therapy remains a key focus and hot topic in clinical research. Neoadjuvant immunotherapy has been recommended by clinical guidelines for locally advanced rectal cancer (LARC) with DNA mismatch repair deficiency/high microsatellite instability (dMMR/MSI-H), achieving a pCR rate as high as 60-70%. However, the efficacy of immunotherapy in locally advanced rectal cancer with microsatellite stable disease (pMMR/MSS), which accounts for the vast majority, remains controversial. Recent phase II studies have shown that combining chemotherapy and immunotherapy with long-course or short-course radiotherapy may further improve the pCR rate to 30-40% compared to traditional concurrent chemoradiotherapy. In a study by Professor Zhang Zhen's team at Fudan University, short-course radiotherapy combined with consolidation or induction chemotherapy and immunotherapy even achieved a cCR rate exceeding 50%. A meta-analysis published in 2025 also showed that in pMM locally advanced rectal cancer patients receiving neoadjuvant radiotherapy combined with immunotherapy, patients receiving short-course radiotherapy combined with PD-1 inhibitors or concurrent immunoradiotherapy showed better treatment outcomes, while the toxic side effects were tolerable. However, these studies have small sample sizes, lack consistency in drug use and study design, and have insufficient levels of evidence, requiring further exploration and verification. This study will explore the efficacy and safety of neoadjuvant chemoradiotherapy combined with erato combination antibody for the treatment of locally advanced pMMR rectal cancer through a prospective phase II randomized controlled clinical trial, aiming to provide a reference for achieving higher cCR/pCR rates and preservation of anal function in patients with locally advanced rectal cancer. Specifically, the study will assess the pathological complete response (pCR) rate two weeks after neoadjuvant therapy, the clinical complete response (cCR) rate under the "watch-and-wait" strategy, R0 resection rate, tumor regression grade (TRG), and sphincter preservation rate. Additionally, the study will evaluate the 3-year disease-free survival (DFS) and overall survival (OS) following dual-inhibitor combined neoadjuvant chemoradiotherapy. The safety and tolerability of this combination therapy will also be comprehensively assessed based on NCI-CTCAE 4.03 criteria.