Circulating microRNA: Searching for new players in assessment of therapy response in colorectal cancer patients.

Abstract

183 Background: The identification of clinicopathological and molecular predictive and/or prognostic factors represents currently one the most challenging tasks in oncology. Significant efforts are currently being dedicated to identify patients who will or will not benefit from chemotherapy. In fact, drug resistance is a limiting factor of the efficacy of chemotherapy in colorectal cancer (CRC) treatment. However, despite modern surgical techniques and adjuvant systemic therapy, only 20% of patients with distant metastasis achieve long-term remission, while 60–70% of patients develop local or distant recurrence. Methods: Recently, we have identified by high-throughput approach that circulating microRNAs (miRNAs), namely, miR-122-5p and miR-142-5p show a high potential for CRC screening and early detection as well as for the assessment of patients’ outcomes and the effectiveness of treatment schedule. Results: In detail, the expression levels of these miRNAs were significantly different between CRC patients and controls. A year after diagnosis, miRNA expression profiles were significantly modified in patients responding to treatment and were no longer different from those measured in controls. On the other hand, patients not responding to therapy maintained low expression levels in their second sampling. As selection during metastasizing may shift molecular patterns by which CRC liver metastases retain their unique molecular profile, we thus elaborated our results on CRC patients with liver metastasis and measured these circulating miRNAs repeatedly over two years. The first sampling was performed at the time of post therapy developed liver metastasis (i.e., recurrence), and every 3 months depending on patients` conditions (i.e., covering the liver resection, administration of chemotherapy etc). Detailed results of the study will be presented during the meeting. Conclusions: The present study aimed to explain why patients with the same cancer stage may differ in treatment susceptibility and long-term outcomes.