Background: FOLFOXIRI (fluorouracil, leucovorin, oxaliplatin, and irinotecan) plus bevacizumab has been shown to be one of the therapeutic regimens in first line with the highest activity profile in patients (pts) with metastatic colorectal cancer (mCRC) unselected for biomolecular alterations. Tumors co-opt the PD-1/PD-L1 signaling pathway as one key mechanism to evade immune destruction. Anti-PD-1 monoclonal antibodies are FDA approved only for DNA mismatch repair deficient/microsatellite instability-high (MMRd/MSI-H), which are only about 5% among all mCRC. Nowadays, there are no data demonstrating anti-PD1 activity in stable and proficient (MMRp/MSS) disease. Another critical therapeutic target is the Vascular Endothelial Growth Factor A (VEGF-A), which acts on endothelial cells to stimulate angiogenesis; his inhibition with bevacizumab increase immune cell infiltration, giving a strong rationale for combining VEGF targeted agents with immune checkpoint inhibitors. Based on evidence, we explore the combination of triplet chemotherapy (FOLFOXIRI) with bevacizumab and nivolumab in pts with mCRC all-RAS/BRAF mutant regardless of microsatellite status. Methods: This is a prospective, open-label, multicentric phase II trial where pts with mCRC RAS/BRAF mutant in first line will receive nivolumab in combination with FOLFOXIRI/Bevacizumab every 2 weeks for 8 cycles followed by maintenance with bevacizumab plus nivolumab every 2 weeks. Bevacizumab will be administered intravenously at dose of 5 mg/kg every 2 weeks and nivolumab intravenously as a flat dose of 240 mg every 2 weeks. The primary endpoint is the overall response rate (ORR) and our hypothesis is that the treatment is able to improve the ORR from 66% to 80%. Secondary endpoints include overall survival, safety, time to progression, duration of response. Collateral translational studies evaluate the tumor mutational burden, and genetic alterations by circulating free DNA (cfDNA) obtained from plasma samples. The trial is open to enrollment, 4 of planned 70 pts have been enrolled. Clinical trial information: EudraCT Number: 2018-002893-38. Clinical trial information: NCT04072198.