Table 1.

Detailed patient eligibility criteria for part 1 and 2 studies

Inclusion criteria

Exclusion criteria

1. Written informed consent 2. Age ≥ 19 years 3. ECOG performance status 0–1 (ECOG 0 required if age ≥ 70) 4. Histologically confirmed adenocarcinoma of the colon (including rectosigmoid colon above the peritoneal reflection) 5. Pathological stage II–III colon cancer with high-risk features, including one or more of the following:  • T4 lesion  • Poor differentiation  • Lymphatic or vascular invasion  • Bowel obstruction  • Fewer than 12 lymph nodes examined  • Perineural invasion  • Tumor perforation  • Positive resection margins  • Tumor budding 6. No evidence of distant metastasis on imaging (contrast-enhanced CT of the abdomen/pelvis and chest) performed within 4 weeks before or after surgery 7. apable and willing to comply with study procedures until study completion Part 1–Specific Criteria: 8. Planned initiation of adjuvant chemotherapy with FOLFOX or CAPOX within 6 weeks after curative (R0) resection 9. Agreement to participate in Part 2 if postoperative ctDNA testing indicates MRD positivity Part 2–Specific Criteria: 10. Completion of 6 cycles of FOLFOX or 4 cycles of CAPOX as adjuvant chemotherapy following R0 resection 11. Confirmed minimal residual disease (MRD) based on ctDNA testing performed 3–6 weeks postoperatively 12. Adequate bone marrow function:  • ANC ≥ 1,300/µL  • Platelets ≥ 75,000/µL  • Hemoglobin ≥ 8.0 g/dL (patients requiring intermittent transfusions may still be eligible) 13. Adequate hepatic function:  • Total bilirubin ≤ 1.5 × ULN  • AST and ALT ≤ 3 × ULN 14. Adequate renal function:  • Serum creatinine ≤ 1.5 × ULN  • Creatinine clearance ≥ 50 mL/min

1. Refusal to participate in, or medical unsuitability for, the Part 2 trial (mFOLFIRINOX therapy) 2. Non-adenocarcinoma histology 3. Planned adjuvant chemotherapy that does not include oxaliplatin 4. Prior chemotherapy or radiotherapy before or after curative resection 5. History of other malignancies within the past 3 years, except for completely treated basal cell carcinoma of the skin, carcinoma in situ of the cervix, or thyroid cancer 6. Incomplete resection (R1 or R2 resection) 7. Evidence of recurrence or residual tumor on imaging or clinical examination 8. Diagnosis of familial adenomatous polyposis (FAP) or other polyposis syndromes 9. Diagnosis of two or more synchronous colon cancers of clinical or pathological stage II or higher, either concurrently or within the past 3 years 10. Pregnancy or lactation 11. Uncontrolled serious infections or other uncontrolled comorbidities 12. Significant or unstable pre-existing medical or psychiatric conditions that, in the opinion of the investigator, may compromise patient safety during the study Part 2–Specific Criteria: 13. Sexually active males and females of childbearing potential who are unwilling to use effective contraception during the treatment period and for 6 months after the last dose 14. Clinically significant cardiovascular disease, including: • Unstable angina requiring treatment • Symptomatic coronary artery disease • Congestive heart failure (NYHA class II or higher) • Serious cardiac arrhythmias • Acute coronary syndrome (e.g., myocardial infarction) within the past 6 months 15. Active viral infections such as HIV (Note: hepatitis B carriers may be eligible at the investigator’s discretion, with prophylactic antiviral therapy permitted) 16. Symptomatic inflammatory bowel disease 17. History of allogeneic transplantation requiring immunosuppressive therapy 18. Participation in another clinical trial involving investigational drugs or devices after curative resection for colon cancer 19. Presence of grade ≥ 3 peripheral neuropathy according to CTCAE v5.0 20. History of severe unexpected adverse reactions to fluoropyrimidines or platinum agents (Patients with anticipated but manageable reactions may be eligible at the investigator’s discretion) 21. Known Gilbert’s syndrome, dihydropyrimidine dehydrogenase (DPD) deficiency, or homozygosity for UGT1A1*28 alleles