As a proof of concept, we further applied AutoCAR-3 for the detection of ctDNA with an oncogenic mutation (PIK3CA H1047R) in blood plasma of mice with orthotopic human colorectal cancer xenografts (3 animal groups: normal mice, mice bearing human colorectal cancer (CRC-mice), and X-ray treated CRC-mice)38. The gene discussed is PIK3CA; the disease is colorectal cancer.