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Idylla assay and next generation sequencing: an integrated EGFR mutational testing algorithm
  1. Caterina De Luca1,
  2. Alessandra G Rappa2,
  3. Gianluca Gragnano1,
  4. Umberto Malapelle1,
  5. Giancarlo Troncone1,
  6. Massimo Barberis2
  1. 1 Department of Public Health, University of Naples Federico II, Naples, Italy
  2. 2 Division of Pathology and Laboratory Medicine, Istituto Europeo di Oncologia, Milan, Italy
  1. Correspondence to Professor Giancarlo Troncone, Department of Public Health, University of Naples Federico II, Naples I-80131, Italy; giancarlo.troncone{at}


Aims Any reference laboratory testing non-small cell lung cancer samples for predictive biomarkers needs to develop and validate a wide range of different molecular techniques, each with a specific time requirement and application. Updated international guidelines suggest that next generation sequencing (NGS) to be the initial procedure. However, in a non-negligible subset of cases, library generation may fail or amplicon coverage may be insufficient. In these NGS ‘invalid’ cases, the Idylla system may represent a viable option for rapid epidermal growth factor receptor (EGFR) genotyping.

Methods This retrospective study included 68 archival DNA samples previously processed by Ion Torrent NGS assay. Out of these, 43 cases, including 24 EGFR mutant samples, had a valid NGS result, whereas 25/68 (37%) were invalid. All samples were retested by directly pipetting the DNA inside the EGFR Idylla assay cartridge.

Results In all 43 cases with a valid NGS result, Idylla confirmed the EGFR mutational status. In particular, 24/24 (100%) of EGFR mutant samples as detected by NGS were confirmed by Idylla. Moreover, a large portion of cases (20/25; 80%) whose assessment by NGS was invalid were adequately processed by Idylla. Noteworthy, in 4/25 (16%) of cases, Idylla detected actionable EGFR mutations.

Conclusions Idylla assay could be very useful to quickly process cases for which NGS does not allow genotyping.

  • lung cancer
  • predictive biomarkers
  • EGFR
  • NGS
  • Idylla

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  • Handling editor Runjan Chetty.

  • Contributors CDL, GT and MB conceived the study and wrote the paper. GT and MB contributed as pathologists. CDL, AR, GG and UM performed the experiments.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Patient consent Obtained.

  • Provenance and peer review Not commissioned; internally peer reviewed.