A Study to Investigate the Safety, Tolerability, Pharmacokinetics, and Anti-tumor Activity of CBI-1214 T Cell Engager in Participants With Advanced or Metastatic MSS/MSI-L Colorectal Cancer

This early-phase study is testing a new drug called CBI-1214, which works by helping your immune system's T cells recognize and attack colon cancer cells. It is for people with advanced colorectal cancer that has not responded well to previous treatments. **You may be eligible if...** - You have advanced or metastatic colorectal cancer (a type called MSS or MSI-low) - You have already received at least one standard chemotherapy treatment that stopped working - If your tumor has specific genetic changes (like BRAF or HER2), you must have already tried those targeted treatments - You are able to provide a tumor tissue sample **You may NOT be eligible if...** - Your tumor is the type called MSI-high or mismatch repair deficient (dMMR) - You have untreated brain metastases - You have an active autoimmune disease requiring treatment in the last 2 years - You have had a recent serious viral infection (like shingles, EBV, or CMV) - You are HIV positive or have active hepatitis B or C requiring antiviral therapy - You have had a serious skin reaction to prior medications (like Stevens-Johnson syndrome) - You have a history of organ transplant Talk to your doctor to see if this trial is right for you.