Soluble JAG1 was detected in conditioned media, with higher levels following combination treatment in HCT15 cells.<h4>Conclusions</h4>High tumour JAG1 expression identifies metastatic CRC patients with poorer outcomes when treated with a bevacizumab-containing regimen, supporting its potential as a prognostic biomarker. This evidence concerns the gene JAG1 and colorectal carcinoma.