Liquid Biopsies For Personalized Medicine: The Omiterc Project

Abstract
OMITERC is a data-sharing project sponsored by Regione Toscana, Italy, with the objective to develop an electronic registry that aggregates and links cancer genomic and pharmacogenetics-pharmacogenomics data with clinical outcomes from wild-type BRAF metastatic melanomas and RAS mutated metastatic colorectal cancers. The project aims to aggregate, harmonize and share clinical and molecular data obtained during routine medical practice. To reach this goal the implementation of a comprehensive database including all the clinical and molecular data deriving from the analysis of the primary tumor and the liquid biopsy in the case study is ongoing. Twenty RAS-mutated metastatic colorectal cancer patients and eleven BRAF-wild-type metastatic melanoma patients were enrolled in the study and submitted to serial blood sampling before therapy and at different time intervals during the follow up. We present the data deriving from the analysis of the liquid biopsy before and during therapeutic treatment in metastatic colorectal cancer patients: circulating tumor cell (CTC) detection and counting by CellSearch and mutational analysis by targeted NGS of cell-free DNA (cfDNA) and single CTCs (in a subset of cases). CTCs were detected in 7 patients at baseline and were not found in subsequent blood draws during the follow up except for 4 subjects. On the whole the presence of CTCs showed a prognostic significance and was correlated to the efficacy of treatment. KRAS mutational status in cfDNA from colon cancer patients at baseline was concordant with that of the primary tissue in 90% of cases. The longitudinal study of cfDNA allowed a dynamic monitoring of the disease through the assessment of the presence of specific tumor-related mutations and the evaluation of their allelic frequency over time. From the results emerges that it is important to study both CTCs and cfDNA, since they represent two different aspects of the liquid biopsy that can be integrated into a non-invasive approach to cancer patients.