Safety and Efficacy of Pembrolizumab in Combination with Bevacizumab + CapeOX in the Neoadjuvant Treatment of RAS-mutated, BRAF Wild-type, Microsatellite-stabilized, Locally Advanced Colorectal Cancer

To explore the efficacy and safety of pembrolizumab in combination with bevacizumab and CapeOX neoadjuvant therapy for the treatment of RAS-mutated, BRAF wild-type, microsatellite-stabilized, locally advanced colorectal cancer. Methods and analysis: A prospective, open-label, single-arm, phase 2 clinical study protocol will enroll a total of 20 patients. The study is designed as a Simon II Optimal study involving 20 locally advanced rectal cancer (LACRC) patients. Initially, 9 patients will be recruited in the Simon I phase, and if more than 1 patient achieves a pathological complete response (pCR), the study will proceed to the II phase. Recruit up to 20 patients in Phase II, and if more than 4 patients achieve pCR, the trial will be considered successful. All enrolled patients will receive 2-4 cycles of neoadjuvant therapy with pembrolizumab + bevacizumab and CapeOX (bevacizumab + oxaliplatin + capecitabine). The primary efficacy endpoint is the pathological complete response (pCR) of the cancer following neoadjuvant therapy. Secondary efficacy endpoints include major pathological response (MPR), objective response rate (ORR), and assessment of adverse events (AEs). Ethics: Ethics approval has been obtained from the Ethics Committee at the First Affliated Hospital (Xijing Hospital)(KY20232402-F-1)