Background: Aflibercept (AFL) combined with FOLFIRI prolongs overall survival (OS) in patients (pts) with metastatic colorectal cancer (mCRC) who failed a prior oxaliplatin-based regimen. However, there is limited evidence on the efficacy and safety of AFL plus FOLFIRI in RAS /BRAF wild type pts previously treated with anti-epidermal growth factor receptor (EGFR) agents. Therefore, we conducted a phase II trial evaluating the efficacy and safety of AFL plus FOLFIRI in Japanese pts with mCRC failing a prior oxaliplatin-based chemotherapy combined with an anti-EGFR agent. Methods: This was a prospective open-label phase II trial. AFL (4 mg/kg iv) followed by FOLFIRI (irinotecan 180 mg/m2, leucovorin 200 mg/m2 iv, bolus 5-FU 400 mg/m2 and infusional 5-FU 2400 mg/m2/46 h) was given every 2 weeks until progression or unacceptable toxicities. The primary endpoint was progression-free survival (PFS) rate at 6 months; secondary endpoints included OS, PFS, overall response rate (ORR), disease control rate (DCR), adverse events, and relative dose intensity (RDI) for each drug. Given a PFS rate threshold at 6 months of 38.9% and an expected PFS rate of 58.4% with AFL plus FOLFIRI, a sample size of 41 pts was required (two-sided alpha, 0.1; beta, 0.2). Analyses were conducted in the full analysis set (FAS) of pts satisfying eligibility criteria. Results: Forty-three patients were enrolled between November 2019 and October 2022, and 43 were analyzed (median age 68 years (range 27-80); male, 69.8%; ECOG PS 0/1, 72.1%/27.9%; left sided primary tumor, 90.7%). The primary endpoint was met: 6-month PFS rate was 58.7% (90%CI, 45.5%-71.9%). Median PFS and OS were 7.3 months (95%CI, 5.5-11.0 months) and 18.8 months (95%CI, 12.9-26.6 months), respectively. The ORR was 23.3 % (95%CI, 11.8-38.6%) and DCR was 88.4% (95%CI, 74.9- 96.1%). Mean RDI of AFL, irinotecan, bolus 5-FU and infusional 5-FU were 75.3% (SD, 26.2), 50.6% (SD, 12.5), 31.6% (SD, 26.6), and 58.7% (SD, 7.21), respectively. The main grade ≥3 adverse events included hypertension (62.8%), neutropenia (55.8%), leukopenia (25.6%), febrile neutropenia (11.6%), fatigue (9.3%), anorexia (9.3%), proteinuria (9.3%) and diarrhea (7.0%). No deaths and no new safety signals with a causal relation to the study treatment were observed. Conclusions: Results of this prospective phase II study suggest that AFL plus FOLFIRI shows a high response rate and a manageable safety profile in Japanese pts with mCRC who failed a first-line oxaliplatin-based plus anti-EGFR regimen. Clinical trial information: jRCTs011190006.