Efficacy of bevacizumab-containing chemotherapy in metastatic colorectal cancer and CXCL5 expression: Six case reports

BACKGROUND In metastatic colorectal cancer(mCRC),the anti-vascular endothelial growth factor drug bevacizumab(BVZ)plus chemotherapy significantly improves progression-free survival compared to chemotherapy(CT)alone.This benefit is not,however,observed in all patients.While increased chemokine CXCL5 gene expression promoting angiogenesis has been proposed as a prognostic mCRC biomarker,few studies have examined its relationship with drug efficacy.This study sought to analyze tumor CXCL5 gene expression in six patients with different efficacy of BVZ-containing CT in terms of the tumor response to treatment.CASE SUMMARY We report six cases of stage IV KRAS-mutated mCRC.Patients were given first line treatment with BVZ-containing chemotherapy in University Hospital of Fuenlabrada.The six patients differed in terms of primary tumor location(right/left side),tumor burden(mostly hepatic and peritoneal disease)and clinical disease course.Before treatment onset,total RNA was isolated from paraffinated tumor biopsy specimens and CXCL5 gene expression quantified through conventional RT-qPCR procedures.Our main finding was that CXCL5 expression levels were several times higher in three patients with lower progression free survival(under 6 mo)from the start of treatment.CONCLUSION A higher expression of CXCL5 was observed in the three patients showing worse tumor response to treatment.