Another study applied a panel of ctDNA biomarkers (selected from tumor tissue analysis) in a patient with mCRC with first-line treatment with FOLFOX and second-line treatment with FOLFIRI (de Figueiredo Barros et al., 2018) and showed that the baseline sample had high frequency of KRAS and TP53 MAF which fell below the detection limit after one month of chemotherapy. Here, KRAS is linked to neoplasm.