Performance of the Idylla microsatellite instability test in endometrial cancer.

DNA mismatch repair (MMR) deficiency (dMMR) testing is now recommended in endometrial cancer. Defect identification in the molecules participating in this pathway, or the presence of microsatellite instability, are commonly employed for this purpose. Novel methods are continuously evolving to report dMMR/microsatellite instability and to easily perform routine diagnoses. The main aim of this study was to compare the concordance of the Idylla microsatellite instability test for the identification of dMMR endometrial cancer samples defined by immunohistochemistry and MMR genomic status. We applied the Idylla MSI test to 126 early-stage endometrial cancer cases with MMR testing by immunohistochemistry and genomic characterization (methylation in MLH1 and sequence alterations in MLH1, PMS2, MSH2 and MSH6). Individual markers and overall specific performance indicators were explored. The Idylla platform achieved a higher global concordance rate with MMR genomic status than with immunohistochemistry (75% and 66%, respectively). Sensitivity and specificity are also higher (75% vs 66% and 96% vs 90%, respectively). Clustering analysis split the patients into 2 well-differentiated clusters, the pMMR and the dMMR group, represented by MLH1/PMS2 loss and the MLH1 methylated promoter. Overall, immunohistochemistry and MMR genomic status identified more dMMR cases than did the Idylla test, although correlations were improved with a modified Idylla test cut-off. Performance of the Idylla test was better correlated with MMR genomic status than MMR immunohistochemistry status, which improved with a modified test cut-off. Further studies are needed to confirm the cut-off accuracy.

Informations de copyright

Copyright © 2024. Published by Elsevier Ltd.

Déclaration de conflit d'intérêts

Declaration of Competing Interest MM reports having received honoraria (MSD, AstraZeneca and GSK), research grant/funding to her institution (Eisai and PharmaMar), and travel/accommodation/expenses (Biocartis, AstraZeneca, GSK, PharmaMar, Roche and Pfizer) outside the submitted work. AR reports having received honoraria and providing advisory/consultancy services (MSD, AstraZeneca, Roche, GSK, Clovis, PharmaMar, Lilly, Amgen), as well as having received research grant/funding to his institution (Eisai, PharmaMar, Roche), travel/accommodation/expenses (AstraZeneca, Tesaro: A GSK Company, PharmaMar, Roche), and participating in a speaker’s bureau (MSD, AstraZeneca, Roche, GSK, Clovis, PharmaMar) outside the submitted work. The remaining authors declare no conflicts of interest.