Evaluation and validation of the IntPlex® test was examined in response to the pressing need to determine the KRAS/BRAF mutational status before anti-EGFR therapy in CRC patients. As a consequence, the method was adapted to detect the six more frequent KRAS mutations in CRC (G12D, G12V, G13D, G12S, G12C, G12A) and the BRAF V600E. We then carried out the first blinded prospective study to compare KRAS and BRAF mutational status data obtained from the analysis of tumor tissue by routine gold standard methods and of plasma DNA using our original method (ASCO oral communication). The mutational status was determined by both methods in 70 patient samples. Our results clearly showed for the first time that ccfDNA analysis for KRAS mutation could replace advantageously tumor-section analysis. CcfDNA analysis showed 100% specificity and sensitivity for the BRAF V600E mutation. For the six tested KRAS point mutations, the method exhibited 100% specificity and 87% sensitivity with a concordance value of 96%.