Aim The rapid and fully automated Idylla EGFR Mutation Assay has been specifically designed to process formalin-fixed, paraffin-embedded sections without requiring preliminary DNA extraction. This study evaluates whether this approach can also process archival smears from patients with non–small cell lung cancer (NSCLC) by scraping the stained cellular material directly into the cartridge.
Methods The study was divided into two parts. In the first part, we carried out Idylla EGFR Mutation Assay on archival stained smears from 39 patients with NSCLC. Among these, 14 cases harboured a mutation in either exon 19 (n=11) or exon 21 (n=3), previously detected on DNA extracts by fragment length and TaqMan assays. In the second part, we evaluated whether de-staining of the smears could reduce background fluorescence.
Results The Idylla EGFR Mutation Assay confirmed the presence of EGFR mutation in 11 instances (78.6%). However, concordance was higher for exon 19 deletions (10/11) than for exon 21 p.L858R assessments. Raw data showed a high background fluorescence in channel 2, where the EGFR exon 21 p.L858R mutation was detected. This interference, due to dye residues from the original staining, was partially reduced by de-staining the cytological material.
Conclusions Our data, although preliminary, show that the Idylla EGFR Mutation Assay can reliably process most archival smears without requiring preliminary DNA extraction. Results may be further improved by de-staining the cellular material before insertion into the cartridge.
- lung cancer
- molecular cytopathology
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Handling editor Runjan Chetty.
Contributors CDL and GT conceived of the study. FC, GG and PG performed the experiments. AL, MS, PP and UM contributed as molecular pathologists. EV, CB and LRG contributed as pathologists. CDL, FC, PP and GT wrote the paper. All authors approved the final version of the manuscript.
Funding This work was supported by a grant from Regione Campania SATIN Project 2018-2020.
Competing interests None declared.
Patient consent for publication Not required.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement Data are available in a public, open-access repository. All data relevant to the study are included in the article or uploaded as online supplementary information.
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