Evaluation of the Idylla system to detect the EGFRT790M mutation using extracted DNA

Pathol Res Pract. 2020 Jan;216(1):152773. doi: 10.1016/j.prp.2019.152773. Epub 2019 Dec 2.

Abstract

Introduction: During the last few years, detection of epidermal growth-factor-receptor (EGFR)-activating mutations has become a routine part of clinical practice because of their importance in choosing the optimal treatment strategy for non-small-cell lung cancers (NSCLCs). The emergence of third-generation EGFR-tyrosine-kinase inhibitors required the implementation of sensitive methods to detect the subclonal EGFRT790M mutation. Clinical implications make it essential to rapidly search for the T790M mutation, which is a real challenge for laboratories. The aim of this study was to compare performances of next-generation sequencing (NGS), one of the most frequently used molecular biology methods, and Idylla EGFR-Mutation Assay (henceforth Idylla), a fully automated real-time polymerase chain reaction (PCR) that is increasingly used in pathology laboratories, to detect the EGFRT790M mutation using DNA.

Methods: This retrospective study used 47 DNA samples extracted from NSCLC biopsies that previous NGS identified as: 29 harboring EGFR and T790M resistance mutations, 11 EGFR-activating mutation without T790 M and 7 wild-type EGFR. EGFRT790M limit-of-detection (LOD) experiments used a commercial DNA known to harbor that mutation.

Results: Idylla detected primary EGFR-activating mutations and the T790 M mutation in 97.5 % and 65.5 % of the cases, respectively. The results of this retrospective analysis and LOD experiments showed that the Idylla should only be used to detect EGFR mutations in samples with > 25 ng of DNA and > 10 % tumor cells.

Conclusions: Idylla was able to rapidly detect EGFR-activating mutations but detecting subclone mutations, like T790M, with < 25 ng of good-quality DNA or < 10 % tumor cells (variant allele frequency below the assay's validated LOD) was not always reliable.

Keywords: EGFRT790M; Extracted DNA; Idylla; Lung cancer; Next-generation sequencing.

MeSH terms

  • Carcinoma, Non-Small-Cell Lung / genetics*
  • DNA / genetics*
  • Drug Resistance, Neoplasm / genetics*
  • ErbB Receptors / genetics
  • Humans
  • Lung Neoplasms / genetics
  • Lung Neoplasms / pathology
  • Mutation / genetics

Substances

  • DNA
  • EGFR protein, human
  • ErbB Receptors