Association of miR-125b, miR-17 and let-7c Dysregulations With Response to Anti-epidermal Growth Factor Receptor Monoclonal Antibodies in Patients With Metastatic Colorectal Cancer

Background/Aim: MicroRNAs (miRs) play an important role in the regulation of cancer-related processes and are promising candidates for cancer biomarkers. The aim of the study was to evaluate the association of response to anti-EGFR monoclonal antibodies (mAbs) with selected miR expression profiles, including miR-125b, let-7c, miR-99a, miR-17, miR-143 and miR-145 in metastatic colorectal cancer (mCRC) patients. Patients and Methods: This retrospective study included 46 patients with mCRC harbouring wild-type RAS gene treated with cetuximab or panitumumab combined with chemotherapy in first- or second-line therapy. The miR expression was assessed using qRT-PCR. Results: Down-regulation of miR-125b and let-7c and up-regulation of miR-17 were found in the tumour tissue (p=0.0226, p=0.0040, p<0.0001). Objective response rate (ORR) was associated with up-regulation of miR-125b (p=0.0005). Disease control rate (DCR) was associated with up-regulation of miR-125b and let-7c (p=0.0383 and p=0.0255) and down-regulation of miR-17 (p=0.0464). MiR-125b showed correlation with progression free and overall survival (p=0.055 and p=0.006). Conclusion: The results show that up-regulation of miR-125b is associated with higher ORR and DCR and longer survival; let-7c up-regulation and miR-17 downregulation are associated with higher DCR in mCRC patients treated with anti-EGFR mAbs.