Neoantigen-based Peptide Vaccine and Conventional Third-line Therapy for CRC Progressed After Second-line Treatment

This study tests whether adding a personalized neoantigen peptide vaccine (made from mutations specific to a patient's own tumor) to standard third-line chemotherapy can improve outcomes for people with colorectal cancer that has progressed through two prior treatments. **You may be eligible if...** - You have confirmed colorectal cancer that progressed after standard second-line therapy - You are between 18 and 70 years old - You are in reasonably good health (ECOG score 0–1) - Your blood counts and organ function meet required standards - Expected survival of at least 3 months **You may NOT be eligible if...** - You have active hepatitis, HIV/AIDS, syphilis, or other active infections - Your blood or organ function values fall outside required ranges - You are pregnant or planning pregnancy within 6 months - It has been fewer than 2 weeks since your last cancer treatment Talk to your doctor to see if this trial is right for you.