Microsatellite Stable (MSS) Colon Cancer

The goal of this clinical trial is to learn if giving two medicines together, porustobart and pembrolizumab, before surgery can treat a common type of colon cancer called microsatellite stable (MSS) colon cancer in adults. This type of cancer can be removed with surgery and has not spread to other parts of the body. Both medicines work by helping the immune system fight cancer. The main questions this study wants to answer: How well do the medicines destroy the cancer before surgery? What side effects do participants have when taking the medicines? Researchers will compare two groups to see which treatment schedule works better and is safer. Both groups get pembrolizumab. One group gets one dose of porustobart (Day 1 only), and the other group gets two doses (Day 1 and Day 22). Participants will: Complete certain tests and procedures to make sure they are eligible Get the medicines through a vein on Day 1 and Day 22 then have surgery 6-9 weeks after starting treatment Return for checkups and tests every 6 months for up to 3 years after surgery

This study aims to evaluate the use of node-sparing short-course radiotherapy combined with chemotherapy and Sintilimab, or chemotherapy alone, as neoadjuvant therapy for MSS-type locally advanced colon cancer. The goal is to explore the efficacy and safety of combining node-sparing short-course radiotherapy with chemotherapy and immunotherapy in the neoadjuvant setting for MSS-type locally advanced colon cancer, while also investigating the specific role of regional lymph nodes in tumor immunotherapy.