Maintenance treatment, mostly de-escalated cytotoxic regimens in combination with monoclonal antibodies after intensive induction treatment, was established in patients with metastatic colorectal cancer (mCRC) to maintain an initial response, to delay disease progression and to reduce toxicities.1, 2, 3 Common maintenance regimens comprise the application of fluoropyrimidines in combination with monoclonal antibodies directed against the vascular endothelial growth factor (VEGF; i.e. bevacizumab)1,2,4 or epidermal growth factor receptor (EGFR; i.e. cetuximab, panitumumab).3 This evidence concerns the gene VEGFA and metastatic colorectal cancer.