Analysis of KRAS mutations in circulating tumor DNA and colorectal cancer tissue

ABSTRACT

The mutation status of KRAS is important for anti-EGFR therapy in colorectal cancer (CRC) patients; however, detection of KRAS mutations in circulating tumor DNA (ctDNA) is problematic. We investigated tissue and plasma assays for KRAS mutations in CRC patients. The KRAS status of 407 CRC patients was evaluated using integration of amplification refractory mutation system polymerase chain reaction (PCR), melting curves and wild type DNA blocking (IAMB) in tissue and plasma samples. Disparate cases were re-evaluated by Sanger sequencing of tissue samples. General characteristics and tumor biomarkers including CEA, CA19-9 and CA125 were characterized. The prevalence of KRAS mutations was 40.8% in plasma and 49.1% in tissue. The overall percent agreement, positive percent agreement and negative percent agreement were 82.3, 76.3 and 90.8%, respectively. Older patients and higher TNM stage exhibited increased sensitivity for detecting KRAS mutations in plasma. We found 54.1% of patients with KRAS mutations using parallel analysis of tissue and plasma; only 36.4% of patients were detected by series analysis. We found that plasma based KRAS detection with IAMB technology is an alternative to tissue based KRAS testing. KRAS mutations can be identified more easily when both assays are used together

KEYWORDS:

• Anti-EGFR MoAbs
• DNA
• colorectal cancer
• human
• KRAS
• mutation
• tumor

Acknowledgment

The authors thank Xiufen Zhang, Wuxi Cancer Institute, Affiliated Hospital of Jiangnan University for her constructive suggestion.

Disclosure statement

The authors declare no conflict of interest.

Additional information

Funding

Our study was funded by Research Project of Health and Family Planning Commission of Wuxi [grant no. Q201758].