Total Neoadjuvant Treatment for pMMR Locally Advanced Low Rectal Cancer: Anti-PD-1 Antibody With FOLFOXIRI and Preoperative Radiation Therapy

For locally advanced rectal cancer, the initial goal of neoadjuvant chemoradiotherapy is to reduce local recurrence, but the pathologic complete response (PCR) rate is low, and distant metastasis becomes the main treatment failure pattern. With the gradual optimization of neoadjuvant chemotherapy regimens, the tumor regression efficacy in patients has improved, leading to increased organ preservation and reduced distant metastasis. Therefore, neoadjuvant treatment for locally advanced rectal cancer has transitioned from an era focused on local control of recurrence to an era focused on improving tumor regression, organ preservation, and long-term survival. Thus, there is a trend towards intensifying the whole course of neoadjuvant treatment for rectal cancer to preserve organ function. The combination of chemotherapy, immunotherapy, and radiotherapy is currently the most powerful approach to maximize tumor regression and achieve organ preservation in low rectal cancer. Currently, several clinical studies on the use of PD-1 inhibitors in combination with preoperative chemoradiotherapy for locally advanced rectal cancer are ongoing internationally, with the majority focusing on PD-1 monotherapy or PD-1 combined with the CapOX regimen in combination with synchronous chemoradiotherapy as neoadjuvant treatment. However, there is no specific research reported on the use of PD-1 combined with FOLFOXIRI regimen in combination with synchronous chemoradiotherapy as a whole course neoadjuvant treatment for pMMR (proficient mismatch repair) locally advanced rectal cancer. Based on the above evidence from evidence-based medicine, we plan to conduct a phase II prospective clinical study to explore the efficacy and treatment safety of PD-1 monoclonal antibody and FOLFOXIRI chemotherapy combined with intensity-modulated radiotherapy as a whole course neoadjuvant treatment in pMMR locally advanced low rectal cancer. The results of this study may open up new treatment approaches for