Comparison of different methods for detecting epidermal growth factor receptor mutations in peripheral blood and tumor tissue of non-small cell lung cancer as a predictor of response to gefitinib

Fei Xu,^1,* Jingxun Wu,^2,* Cong Xue,^1,* Yuanyuan Zhao,¹ Wei Jiang,³ Liping Lin,⁴ Xuan Wu,⁵ Yachao Lu,⁶ Hua Bai,⁷ Jiasen Xu,⁸ Guanshan Zhu,⁶ Li Zhang<sup>1

1</sup>State Key Laboratory of Oncology in South China, Department of Medical Oncology, Sun Yat-Sen University Cancer Center, Guangzhou, Guangdong, People's Republic of China; ²Department of Medical Oncology, The First Affiliated Hospital of Xiamen University, Xiamen, Fujian, People's Republic of China; ³Department of Medical Oncology, Cancer Hospital of Guangxi Medical University and Guangxi Autonomous Regional Cancer Hospital, Nanning, Guangxi, People's Republic of China; ⁴Department of Oncology and Hemotology, Panyu Central Hospital, Guangzhou, Guangdong, People's Republic of China; ⁵Department of Chemotherapy, The Fifth Affiliated Hospital of Sun Yat-sen University, Zhuhai, Guangdong, People's Republic of China; ⁶Innovation Center China, AstraZeneca Global R&D, Shanghai, People's Republic of China; ⁷Department of Thoracic Medical Oncology, Peking University School of Oncology, Beijing Cancer Hospital and Institute, Beijing, People's Republic of China; ⁸SurExam Bio-Tech Co, Ltd, Science City, Guangzhou, People's Republic of China

^*These authors contributed equally to this work

Background: Previous studies have reported that epidermal growth factor receptor (EGFR) mutation in tumor tissue and peripheral blood can predict the response to EGFR tyrosine kinase inhibitor (TKI) in non-small cell lung cancer (NSCLC). However, the heterogeneity of the sample sources makes it difficult to evaluate the detecting methodologies. The goal of this study is to compare different methods for analyzing EGFR mutation in blood and tumor tissue.
Materials and methods: Fifty-one advanced NSCLC patients treated with gefitinib were included in the study. The EGFR mutation status of each patients' blood was analyzed by denaturing high-performance liquid chromatography (DHPLC), mutant-enriched liquidchip (ME-Liquidchip), and Scorpion Amplification Refractory Mutation System (Scorpion-ARMS) kits. EGFR mutation information in paired tumor samples detected by Scorpion-ARMS served as a reference. Comparative analyses were performed on mutation status results obtained from different methods and on the association between the clinical outcome of TKI treatment and EGFR mutation status.
Results: The response rate (RR) in the whole group was 33.3%. EGFR mutation rates were identified as 15.7%, 27.5%, and 29.4% by DHPLC, ME-Liquidchip, and Scorpion-ARMS in blood, respectively. In 34 cases that had paired tumor samples, the mutation rate in tissue was 41.2%. The RRs of patients with mutation detected by different methods were 71.4% (tumor), 62.5% (blood, DHPLC), 50.0% (blood, ME-Liquidchip), and 66.7% (blood, Scorpion-ARMS). EGFR mutation detected by Scorpion-ARMS in blood and tumor tissues had better prediction of RR to EGFR-TKI (P = 0.002 and P = 0.001) than mutation detected with DHPLC and ME-Liquidchip.
Conclusion: Tumor tissue sample is the best source for EGFR mutation analysis in NSCLC patients. Peripheral blood samples may be used as an alternative source only in special conditions. Scorpion-ARMS, DHPLC, or ME-Liquidchip methods are all optional for detecting tumor EGFR mutation from blood.

Keywords: non-small cell lung cancer, EGFR mutation, mutation detection methods, gefitinib