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

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.
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Submitted on : Thursday, July 21, 2022 - 10:08:36 AM
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Claire Bocciarelli, Justine Cohen, Romain Pelletier, Jeanne Tran van Nhieu, Jonathan Derman, et al.. Evaluation of the Idylla system to detect the EGFRT790M mutation using extracted DNA. Pathology - Research and Practice, Elsevier, 2020, 216 (1), pp.152773. ⟨10.1016/j.prp.2019.152773⟩. ⟨hal-03489789⟩



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