Ultra-Sensitive Detection of the Pretreatment EGFR T790M Mutation in Non-Small Cell Lung Cancer Patients with an EGFR-Activating Mutation Using Droplet Digital PCR

• Published in: Clinical cancer research 2015-08, Vol.21 (15), p.3552-3560
• Main Authors: Watanabe, Masaru, Kawaguchi, Tomoya, Isa, Shun-ichi, Ando, Masahiko, Tamiya, Akihiro, Kubo, Akihito, Saka, Hideo, Takeo, Sadanori, Adachi, Hirofumi, Tagawa, Tsutomu, Kakegawa, Seiichi, Yamashita, Motohiro, Kataoka, Kazuhiko, Ichinose, Yukito, Takeuchi, Yukiyasu, Sakamoto, Kazuhiro, Matsumura, Akihide, Koh, Yasuhiro
• Format: Article
• Language: English
• Subjects: Adult; Aged; Aged, 80 and over; Carcinoma, Non-Small-Cell Lung - drug therapy; Carcinoma, Non-Small-Cell Lung - genetics; Carcinoma, Non-Small-Cell Lung - pathology; Drug Resistance, Neoplasm - genetics; Female; Gene Frequency; Humans; Male; Middle Aged; Mutation - genetics; Polymerase Chain Reaction - methods; Precision Medicine; Protein Kinase Inhibitors - therapeutic use; Receptor, Epidermal Growth Factor - genetics; Receptor, Epidermal Growth Factor - isolation & purification
• ISSN: 1078-0432; 1557-3265
• DOI: 10.1158/1078-0432.CCR-14-2151

The resistance to the EGFR tyrosine kinase inhibitors (TKI) is a major concern in non-small cell lung cancer (NSCLC) treatment. T790M mutation in EGFR accounts for nearly 50% of the acquired resistance to EGFR-TKIs. Earlier studies suggested that T790M mutation was also detected in TKI-naïve NSCLCs in a small cohort. Here, we use an ultra-sensitive droplet digital PCR (ddPCR) technique to address the incidence and clinical significance of pretreatment T790M in a larger cohort. ddPCR was established as follows: wild-type or T790M mutation-containing DNA fragments were cloned into plasmids. Candidate threshold was identified using wild-type plasmid, normal human genomic DNA, and human A549 cell line DNA, which expresses wild type. Surgically resected tumor tissues from 373 NSCLC patients with EGFR-activating mutations were then examined for the presence of T790M using ddPCR. Our data revealed a linear performance for this ddPCR method (R(2) = 0.998) with an analytical sensitivity of approximately 0.001%. The overall incidence of the pretreatment T790M mutation was 79.9% (298/373), and the frequency ranged from 0.009% to 26.9%. The T790M mutation was detected more frequently in patients with a larger tumor size (P = 0.019) and those with common EGFR-activating mutations (P = 0.022), as compared with the others. The ultra-sensitive ddPCR assay revealed that pretreatment T790M was found in the majority of NSCLC patients with EGFR-activating mutations. ddPCR should be utilized for detailed assessment of the impact of the low frequency pretreatment T790M mutation on treatment with EGFR-TKIs.