P20-2 Observational study to evaluate RAS status in ctDNA for mCRC patients with RAS mutant tumor: RASMEX study (JACCRO CC-17)

Abstract

RAS status in tumor tissue is a predictive factor for the efficacy of anti-epidermal growth factor receptor (EGFR) antibodies (Abs) in patients (pts) with metastatic colorectal cancer (mCRC). Recently, several studies have shown that CRC tissue had heterogeneity of gene profiling, and the analysis of circulating tumor DNA (ctDNA) in blood samples could detect the change of gene alterations in tumors which were caused by chemotherapy. Bouchahda et al., demonstrated that nearly half of the pts with RAS mutant mCRC had no detectable RAS mutation (mut) in ctDNA after first-line chemotherapy.