SCRT-NALIRIXELOX+Sintilimab as TNT for High-Risk LARC

This trial is testing a combination treatment for locally advanced rectal cancer (cancer in the last part of the large intestine that has grown into nearby tissue but not spread to distant organs). The treatment combines short-course radiation, chemotherapy drugs (including a newer drug called nalirixelox), and an immunotherapy drug (sintilimab), given before surgery. **You may be eligible if...** - You are between 18 and 75 years old - You have been confirmed to have rectal cancer (adenocarcinoma) that is locally advanced and high-risk - Your tumor is located within 10 cm of the anal opening - You have not had any prior treatment for this cancer - Your tumor tests show it is not the type that responds to immunotherapy alone (pMMR/MSS) - Your blood counts and organ function are adequate - You are in good general health (ECOG 0 or 1) **You may NOT be eligible if...** - You have another active cancer diagnosed in the last 5 years - You are pregnant or breastfeeding - You have cancer that has spread to the brain or spinal fluid - You have an active autoimmune disease requiring treatment - You have had a major operation in the last 4 weeks - You have active HIV, hepatitis B, hepatitis C, or tuberculosis Talk to your doctor to see if this trial is right for you.