# Evaluation of the Idylla IDH1-2 Mutation Assay for the Detection of IDH Variants in Solid Tumors and Hematological Malignancies

## TL;DR

This study evaluates a new test for detecting IDH mutations in tumors and blood cancers, showing it is fast and reliable compared to existing methods.

## Contribution

The study introduces a validated, rapid IDH1-2 mutation assay with high accuracy for clinical use in solid tumors and leukemias.

## Key findings

- The Idylla IDH1-2 assay achieved 97.1% agreement with NGS for IDH variant detection.
- The assay detected IDH1 R132H and IDH2 R172K variants at low allelic frequencies (1.6% and 0.5%, respectively).
- The assay is suitable for fixed tissue and DNA extracts but requires caution for low-quality DNA samples.

## Abstract

Isocitrate dehydrogenase (IDH) variants can lead to the development and/or progression of various solid tumors and hematological malignancies. IDH testing can guide diagnosis, prognosis, and therapeutic choice and typically relies on NGS, IHC, or PCR-based assays. Here, we evaluated the analytical performance of the Idylla IDH1-2 mutation assay for IDH variant detection using 70 fixed samples from patients with solid tumors and 36 DNA extracts from patients with acute myeloid leukemias previously characterized by NGS +/− IHC. Idylla IDH1-2 mutation assay gave 98.1% of valid results with an overall agreement, sensitivity, and specificity of 97.1%, 96.2%, and 98.1%, respectively, compared to NGS. Using commercial DNA standards, the limit of detection of the assay was 1.6% and 0.5% for IDH1 R132H and IDH2 R172K variants, respectively. Based on these data, the Idylla IDH1-2 mutation assay represents a fast and reliable alternative to detect IDH hotspot variants in solid tumors and hematological malignancies using either fixed tissue sections or DNA extracts. Particular attention, however, is needed for the interpretation of cases with cycle of quantification values of the internal controls over 35, for which a variant with low allelic frequency could be missed due to low DNA quantity or quality.