Evaluation of EGFR Mutation Testing Concordance Between Next-Generation Sequencing and Biocartis Idylla Console in...

The aim of this study was to evaluate the concordance of in-house epidermal growth factor receptor (EGFR) mutation testing using the Biocartis Idylla (Idylla) platform compared with next-generation sequencing (NGS) for formalin-fixed, paraffin-embedded (FFPE) and liquid based cytology (LBC) samples. A secondary objective was to investigate the role of rapid on-site evaluation (ROSE) in optimising sample adequacy, ensuring sufficient material is collected to facilitate comprehensive molecular testing in cases of lung adenocarcinoma.

This retrospective study used data collected on patients between November 2022 and September 2024, a total of 180 samples, in which EGFR mutations were tested for using MiSEQ Next generation sequencing (NGS) platform or the Idylla Console. The source of the data was from the Royal Cornwall Histopathology Department.

Among 180 samples tested, 14 (7.78%) expressed various EGFR mutations by either NGS and/or the Idylla platform. Concordance was observed in 12 of the 14 cases (86%). However, NGS identified 2 mutations in which Idylla was unable to identify. Whilst Idylla was able to identify one EGFR Exon 21 L858R mutation in a sample in which NGS was unable to test due to insufficient material. LBC samples consistently demonstrated a higher sample quality for testing. With significantly lower CQ values on average 20.94 compared to 22.28 than that of FFPE samples (p = 0.00151 3.s.f).

The Idylla Console demonstrates high concordance with NGS and effectively complements molecular diagnostics in resource and time-constrained settings. 5.5% of cases tested using the NGS resulted in insufficient or failed testing suggesting a need for multi-platform testing. LBC samples, particularly with the utilisation of ROSE, enhance testing quality and efficiency, offering a robust alternative to FFPE samples.