PO-525 Molecular signatures of circulating microRNAs as early breast cancer biomarkers

Abstract

focused on microRNAs (miRs), the most abundant class of small RNAs in these samples. Informed consent was given by all patients. Results and discussions On average, we detected 233 miRs in tumours and 175 in exosomes that were classified as present/ absent and interrogated across samples. Cross-sectional analysis: same timepoint across patients. Longitudinal analysis: tumour and exosomes from the same patient. Cross-sectional analysis identified 49 miRs shared by all tumours, 33 by all exosomes collected before surgery, 83 by all exosomes collected after surgery. To pinpoint miRs useful to monitor tumour dynamics in each patient, three criteria were defined: 1) miRs present both in tumours and exosomes before surgery, and; 2) miRs present in tumours and absent in exosomes soon-after surgery. We found 133 miRs in patients A, 50 in B, 34 in C and 11 in D. Combining the cross-sectional and longitudinal analysis, we found two miRs fulfilling the above criteria that were shared by three out of four patients. These two miRs were still detected in Patient D exosomes soon after surgery, likely reflecting non-curative surgery. Validation of these data is currently ongoing in a larger series of patients. Conclusion Overall, this study pinpointed two miRs that may prove useful to monitor tumour dynamics and response to treatment in GC. The longitudinal analysis holds the promise of revealing a set of miRs with clinical utility for anticipating disease relapse, on a personalised manner.