Comparison of methodologies for KRAS mutation detection in metastatic colorectal cancer

Cetuximab and panitumumab are two monoclonal antibodies targeting the epidermal growth factor receptor that have been approved for treatment of metastatic colorectal cancer. Recent clinical trials found an association between KRAS mutation status and resistance to anti-epidermal growth factor receptor therapy, leading to the recommendation to perform KRAS mutation analysis before cetuximab or panitumumab treatment. This study was designed to compare and evaluate the efficacy of four different methodologies--high resolution melting, Sanger sequencing, DxS kit, and SNaPshot--for KRAS mutation detection in a clinical setting. In total, 372 samples from patients with metastatic colorectal cancer were analyzed by high resolution melting and SNaPshot, with 184 of those being further analyzed by Sanger sequencing and 188 with the DxS kit. Sensitivities were compared after consensus findings were determined by the presence of the same result in two of the three methodologies used in each case. The frequency of KRAS codon 12 and 13 mutations in our population was 43.5%, and a discordant finding was observed in 22 samples. Comparing to Sanger sequencing, significantly more consensus mutations were detected by the DxS kit (P=0.0139), high resolution melting (P=0.0004), and SNaPshot (P=0.00001), but no statistically significant differences were found among the three methodologies with higher sensitivity.