Background: Both anti-EGFR and anti-VEGF therapies have shown clinical benefit when they are added in first and second-line in L-sided CRC. The conflicting results in anti-VEGF vs. anti-EGFR studies (FIRE-3, PEAK and CALGB/SWOG 80405 studies) suggest that the sequence of targeted therapies added to FOLFOX or FOLFIRI regimens in first- and second-line treatment could be an important factor in the overall survival (OS) of mCRC patients. Currently, there are no randomized data on the sequential use of an anti-EGFR followed by an anti-VEGF or vice versa. Therefore, the aim of this randomized clinical trial is to compare the efficacy of two treatment sequences, panitumumab followed by bevacizumab versus bevacizumab followed by panitumumab in combination with FOLFOX chemotherapy in first-line and with FOLFIRI in second-line in patients with wild-type RAS, primary L-sided, metastatic colorectal cancer (mCRC). Methods: A phase III, multicentre, open-label and randomized two-arm clinical trial. Untreated patients with wild-type RAS mCRC (determined locally), primary L-sided and unresectable will be screened for this trial. Eligible patients will be randomized 1:1 to receive first-line (1L) panitumumab plus FOLFOX and then bevacizumab plus FOLFIRI as second-line (2L) treatment (Seq. 1) or bevacizumab plus FOLFOX as 1L and then panitumumab plus FOLFIRI as 2L treatment (Seq. 2). Randomization will be stratified by number of metastatic organs involved (1 vs > 1). Primary objective is the comparison of the progression free survival (PFS) rate at 35 months (m) of Seq 1 vs Seq. 2. Secondary objectives: PFS from randomization to 2^nd progression or death, OS rate at 35 months and OS of Seq. 1 vs Seq. 2; PFS, objective response rate, disease control rate, early tumour shrinkage, Depth of Response, duration and time to response and safety in 1L treatment and in 2L treatment in each Sequence arm. Exploratory objectives: impact of baseline biomarkers predictive of the efficacy in each Sequence arm and the clinical impact of clonal dynamics by longitudinal analysis of circulating tumour deoxyribonucleic acid (ctDNA) in plasma. The trial is in progress; 28 of up to 370 planned patients have been recruited at the end of January 2019 (first patient in 31 October 2018). Clinical trial information: NCT03635021