An independent validation study of candidate micrornas as predictive biomarkers for bevacizumab-based therapy in patients with metastatic colorectal cancer

Abstract

Background/Aim: The monoclonal antibody bevacizumab is a standard drug used in combination with oxaliplatin (FOLFOX) or irinotecan (FOLFIRI) based chemotherapy in the first or second-line treatment of metastatic colorectal cancer (mCRC). Our previous study identified and subsequently validated 4 microRNAs in a small group of patients as predictors of the therapeutic response to bevacizumab combined with chemotherapy. The aim of this follow-up study is to confirm the predictive ability of these tissue miRNAs in a larger independent cohort of mCRC patients. Patients and Methods: The retrospective study included 92 patients with generalized-radically inoperable tumors treated with the combined therapy of bevacizumab/FOLFOX in a standard regimen. Results: Expression levels of candidate miRNA biomarkers (miR-92b- 3p, miR-3156-5p, miR-10a-5p and miR-125a-5p) were determined in tumor tissue specimens and statistically evaluated. MiR-92b-3p and miR-125a-5p were confirmed to be associated with radiological response according to RECIST criteria (p=0.005 and 0.05, respectively) and to be up-regulated in responders to bevacizumab/FOLFOX therapy. Higher levels of miR-92b-3p were also significantly associated with extended progression-free survival (p=0.024). Conclusion: We have successfully confirmed miR- 92b-3p to be up-regulated in tumor tissue of mCRC patients with good response to bevacizumab/FOLFOX therapy.