CapeOX Combined With Bevacizumab Plus Anti-PD1 Antibody as Neoadjuvant Therapy for Microsatellite Stable Locally Advanced Rectal Cancer

This study is testing whether adding immunotherapy (an anti-PD-1 antibody) to standard chemotherapy and a targeted anti-blood-vessel drug (bevacizumab) before surgery improves outcomes for people with locally advanced rectal cancer that does not have a specific genetic feature (microsatellite stable, or MSS) that usually predicts a response to immunotherapy. **You may be eligible if...** - You have confirmed rectal cancer that has grown through the bowel wall and spread to nearby lymph nodes, but not to distant organs - Your cancer is MSS/pMMR (a specific genetic status confirmed by testing) - You are in good physical health - You have not received prior chemotherapy, targeted therapy, or recent radiation for this cancer **You may NOT be eligible if...** - Your cancer has spread to distant parts of the body - Your cancer is MSI-high (a different genetic status) - You have poor organ function (liver, kidney, blood counts) - You have recently received chemotherapy or radiation Talk to your doctor to see if this trial is right for you.