Neoadjuvant chemoradiation is the standard treatment for locally advanced rectal cancer. Neoadjuvant chemoradiotherapy can achieve a pathological complete response rate (pCR) of about 20%. However, radiotherapy can cause tissue edema and fibrosis, increasing the risk of anastomotic leakage, resulting in rectal, urinary, and sexual dysfunction. Neoadjuvant chemotherapy or immunotherapy can avoid these adverse reactions, but the pCR rate of chemotherapy is significantly lower than that of neoadjuvant radiotherapy, and immunotherapy is less effective for MSS patients with weak immunogenicity. This study is a prospective, single-arm, single-center trial. The study will enhance the local killing effect of oxaliplatin through rectal artery infusion and induce immunogenic cell death (ICD) to enhance tumor antigen presentation, and then combine anti-PD1 antibody for neoadjuvant therapy. The study will address whether this treatment combination achieves pCR rates that are non-inferior to neoadjuvant RT for MSS-type locally advanced rectal cancer. It is known that the effective rate of oxaliplatin-containing intravenous chemotherapy for colorectal cancer is about 60%. In this study, 2 cycles of XELOX induction chemotherapy were firstly performed to screen out patients who were sensitive to chemotherapy. These patients were then infused with oxaliplatin via the superior rectal artery and oral capecitabine, combined with anti-PD1 antibody therapy for 2 cycles, and then underwent TME surgery. The primary endpoint of the study was the pCR rate.
The purpose of this study is to explore whether rectal artery infusion chemotherapy combined with anti-PD1 antibody is an effective neoadjuvant therapy for the microsatellite stable locally advanced rectal cancer.