Diagnostic Utility of Expression Imbalance in Idylla GeneFusion Assay for Non-Small Cell Lung Cancer

The Idylla GeneFusion Assay (Biocartis) detects gene fusions with fusion-specific and expression imbalance methods. The purpose of this study was to evaluate the diagnostic utility of detecting fusions with expression imbalance alone in non-small cell lung cancer. Results of ALK, ROS1, and RET fusion detection with expression imbalance were compared with results of orthogonal testing. Of 1,982 cases reviewed from October 2022 through August 2024, 63 (3.2%) had fusions detected with the expression imbalance method alone, including 47 ALK, 10 ROS1, and 7 RET fusions.