Validating a fully automated real-time PCR-based system for use in the molecular diagnostic analysis of colorectal carcinoma: a comparison with NGS and IHC.
Colling R., Wang LM., Soilleux E.
BACKGROUND: Molecular testing is increasingly needed in colorectal carcinoma (CRC) and the current clinically relevant mutations are in BRAF, KRAS and NRAS. This study aimed to further validate a new alternative polymerase chain reaction (PCR) platform (Idylla, Biocartis) against existing next-generation sequencing (NGS) and immunohistochemistry (IHC) assays. METHODS: 56 Idylla tests were performed on 43 CRC cases, in a total of 74 comparisons against an NGS panel (Ion Torrent) and the VE1 (anti-BRAF) antibody IHC. Discrepant cases were also compared with either conventional (Cobas) or droplet digital PCR (Bio-Rad). RESULTS: Idylla showed an overall concordance of 100% (95% CI 93% to 100%) with comparator molecular testing and indications were that Idylla is likely to be more sensitive than routine NGS. BRAF IHC showed 90% concordance with NGS (95% CI 70% to 97%). CONCLUSIONS: This study validates Idylla in formalin-fixed, paraffin-embedded CRC tissue. BRAF IHC, however, is an unreliable substitute for molecular testing in CRC.