Table 1 Patient inclusion and exclusion criteria

Inclusion criteria

1. Personal written informed consent is obtained after the study has been fully explained

2. The lead investigator deems that the patient can be treated according to the protocol (the patient is suitable for enrollment)

3. Histologically confirmed colon or rectal adenocarcinoma

4. RAS mutation analysis at enrollment identifies RAS status as either the wild type or mutant type

5. Patients with unresectable CRC or mCRC who received FOLFOXIRI plus bevacizumab as first-line therapy for at least two courses. First-line therapy is discontinued due to progressive disease (PD)

a. Patients with unresectable CRC or mCRC who discontinued first-line therapy with FOLFOXIRI plus bevacizumab

b. Patients who underwent adjuvant chemotherapy and FOLFOXIRI plus bevacizumab treatment following recurrence (the date of recurrence confirmation should be at least 6 months from the final day of adjuvant therapy.)

c. Patients who discontinued 5-FU/LV plus bevacizumab as a maintenance therapy (FOLFOXIRI plus bevacizumab as induction therapy will be administered for no more than 12 cycles.)

7. Age ≥ 20 years at enrollment

8. ECOG performance status (PS) score of 0 or 1

9. Measurable lesion in accordance with RECIST ver. 1.1 criteria on contrast-enhanced chest, abdominal, or pelvic (trunk) CT (required within 28 days of enrollment)

(Measurable lesions should be 10 mm or more on the major axis using a CT scan with a 5 mm slice. For metastatic lymph nodes, the minor axis should exceed 15 mm in length.)

10. Patients with sufficient oral ingestion function

11. Vital organ functions meet the following criteria within 14 days before enrollment.

If multiple test results are available in that period, the results closest to enrollment is used. No blood transfusions or hematopoietic factor administration is permitted within 2 weeks before the date on which measurements are taken.

a. White blood cell count: ≥3000 /mm³, ≤12,000/mm³

b. Neutrophil count: ≥1500/mm³

c. Platelet count: ≥7.5 × 104/mm³

d. Hemoglobin concentration: ≥9.0 g/dL

e. Total bilirubin: ≤1.5 mg/dL

f. AST, ALT: ≤100 IU/L (≤200 IU/L for liver metastases)

g. Serum creatinine: ≤1.5 mg/dL, or creatinine clearance: ≥50 mL/min

h. Urine protein: ≤1+ (1+ or < 1.0 g/24 h)

12. Life expectancy ≥3 months

13. UGT1A1 polymorphism is wild type or single heterozygous type

14. Radiation therapy was not administered to the target lesion. However, patients can be included if they:

a. Have received neoadjuvant or adjuvant radiation therapy.

b. Have received radiation therapy against non-target lesions.

Exclusion criteria

1. Patients with hypertension (> 160 mmHg systolic or > 100 mmHg diastolic for > 4 weeks) that cannot be adequately controlled with 2 antihypertensive agents*

*One antihypertensive treatment containing two antihypertensive agents counts as two antihypertensives.

2. Patients with diabetes mellitus that cannot be adequately controlled with medication.

3. Patients with heart disease that may cause problems during the conduct of the study, such as congestive heart failure, angina pectoris requiring medication, clear evidence of transmural myocardial infarction on ECG, clinically evident valvular heart disease, symptomatic coronary disease, poorly controlled arrhythmia, and a previous history of myocardial infarction within the last 12 months.

4. Patients with severe pulmonary disease, including interstitial pneumonia, pulmonary fibrosis and severe emphysema.

5. Patients with an active infection.

6. Patients with clinically significant ascites and pleural effusion.

7. Patients who have severe drug hypersensitivity (particularly to 5-FU, irinotecan, or aflibercept).

8. Patients with active multiple cancers. Lesions consistent with carcinoma in situ or intramucosal carcinoma that have been cured by local treatment are not classified as active multiple cancers.

9. Patients with a psychiatric disorder that may pose a problem, or a history of central nervous system dysfunction.

10. Patients who have brain metastases.

11. Patients who have had a gastrointestinal perforation and/or a gastrointestinal fistula up to 6 months prior to enrollment.

12. Watery diarrhea or diarrhea Grade ≥ 2 at the time of enrollment.

13. Patients who have had deep vein thrombosis, pulmonary embolism, or some other major form of thromboembolism (portal vein or catheter thrombosis and superficial venous thrombosis qualify as major forms) up to 3 months prior to enrollment.

14. The patient has experienced any arterial thromboembolic events, including but not limited to myocardial infarction, transient ischemic attack, cerebrovascular accident, or unstable angina, within 6 months prior to the first dose of protocol therapy.

15. Daily treatment with high-dose aspirin (≥325 mg/day).

16. Non-steroidal anti-inflammatory medications and immune suppressive or steroidal medications.

17. Patients receiving phenytoin, warfarin potassium, or flucytosine.

18. Women who are pregnant, breast feeding, or who wish to conceive.

19. Men who wish to conceive.

20. Patients with active gastrointestinal tract bleeding requiring repeated transfusions.

21. Patients who underwent resection after FOLFOXIRI+bevacizumab because of conversion and experienced disease progression.

22. Patients who are unable to tolerate aflibercept, 5-FU or irinotecan.

23. Patients with a severe stenosis due to primary CRC. However, primary patients with CRC resection or colostomy can be included.

24. Patients with hepatic cirrhosis or active hepatitis.

25. Patients whom a lead investigator or primary physician deems are not appropriate for this study.