A fast and convenient new technique to detect the therapeutic target, K-ras mutant, from peripheral blood in non-small cell lung cancer patients

Abstract 

Activating mutation of the K-ras gene was one of the earliest discoveries of genetic alterations in lung cancer. Moreover, K-ras somatic mutations might be suggested for predicting resistance to molecular antibodies targeting the epidermal growth factor receptor (EGFR). However, activated K-ras mutant detection methods are limited to traditional techniques. The techniques are complicated and are used only in tissue samples, which are limited for clinical applications. In a previous study, we established a low-cost, convenient, and easy technique for detecting activated K-ras in a small number of circulating tumor cells by the colorimetric membrane array method (CLMA). However, the sensitivity still needs further improvement. The aim of this study is to develop a new platform with chemiluminescence as reporter and weighted values of target genes on the chip in order to achieve a more sensitive, easier to read, and more accurate platform-weighted chemiluminecent membrane array (WCHMA). In advance, we collected 209 peripheral blood samples of non-small cell lung cancer (NSCLC) from patients to evaluate clinical K-ras activation detection using Activating KRAS Detection Chip both conducted by CLMA and WCHMA. Results show 71 specimens with K-ras mutation, of which 59 were identified as positive through CLMA and 66 were positive through WCHMA. After statistical analysis, the sensitivity of CLMA was found to be 83% and the specificity was 96%. On the other hand, the sensitivity of WCHMA increased to 93% and the specificity remained at 94%. Results of the detection limitation of peripheral blood on two platforms are: 3cancer cells/cm³ blood using WCHMA, which is better than 5cancer cells/cm³ blood using CLMA. Further analysis on the correlation between the test results and clinical pathological features shows that the mean score obtained using WCHMA is significantly correlated to TNM stage, tumor size, and metastasis.

Keywords: Non-small cell lung cancer, Activating KRAS Detection Chip, Epidermal growth factor receptor (EGFR), Colorimetric membrane array method (CLMA), Weighted chemiluminecent membrane array (WCHMA)