Different-Dose Short-Course Radiotherapy Plus CAPOX, Anti-PD-1 Antibody and Interleukin-2 for Locally Advanced Rectal Cancer: A Single-Centre, Prospective, Randomised Phase II Trial
This prospective, randomized phase II trial is designed to evaluate whether low-dose short-course radiotherapy differs from common-dose short-course radiotherapy in terms of efficacy when both regimens are sequentially combined with CAPOX, a PD-1 monoclonal antibody, and interleukin-2 (IL-2) in patients with locally advanced rectal cancer. The study is based on findings from our previous single-center, single-arm PRIDE01 study, in which neoadjuvant short-course radiotherapy followed by systemic chemoimmunotherapy and IL-2 demonstrated encouraging antitumor activity relative to historical short-course radiotherapy-based approaches. The current trial aims to provide more robust clinical evidence regarding the potential role of low-dose radiotherapy combined with IL-2 as a sensitization strategy in multimodal neoadjuvant therapy. By comparing complete response rates between the two radiotherapy dose levels, this study may help define an optimized neoadjuvant approach and support future organ-preservation strategies for patients with locally advanced rectal cancer.
• Male and female patients aged 18 to 70 years.
• Histologically confirmed rectal adenocarcinoma with the distal margin of the tumor located within 12 cm of the anal verge.
• MRI-based clinical stage T3-T4 or any T with lymph node-positive (N+) disease.
• Adequate hematologic, hepatic, and renal function defined as: absolute neutrophil count \>=1.5 x 10\^9/L; platelet count \>=75 x 10\^9/L; serum total bilirubin \<=1.5 x upper normal limit (UNL); aspartate aminotransferase \<=2.5 x UNL; alanine aminotransferase \<=2.5 x UNL; serum creatinine \<=1.5 x UNL.
• Eastern Cooperative Oncology Group (ECOG) performance status 0 or 1.