Liquid biopsy has come under the spot light in clinical practices recently due to its low invasive-ness and its ability to provide genetic information on heterogeneity. However, in metastatic colorectal cancer (mCRC) with first line anti-EGFR based treatment, there is limited liquid biopsy data available of RAS testing. In this study, the tumor samples and the baseline plasma samples of 92 mCRC patients with KRAS exon-2 wild type were retrospectively analyzed for their RAS status by NGS and BEAMing in the CAPRI-GOIM trial. Both tumor tissue and plasma identified RAS mutations in 33 patients (35.9%). The concordance rate was 78.3%. The discordance was contributed by 10 cases that have RAS tissue mutant and plasma wild-type, and another 10 cases have tissue wild-type and plasma mutant. The median progression free survival of RAS mutant and wild-type based on tissue samples were 7.9 and 12.6 months, and liquid biopsy testing were 7.8 and 13.8 months. The median overall survival of RAS mutant and wild-type according to tissue were 22.1 and 35.8 months, and liquid biopsy testing were 19.9 and 35.8 months. These results indicated that liquid biopsy and tissue had highly concordant RAS testing result.
Normanno N, Esposito Abate R, Lambiase M, et al., Annals of Oncology, 2017