Validation of a Modular Gene Expression Assay for Risk Stratification and Subtyping Lymphomas

Gene expression signatures are important for classifying lymphoid malignancies, although routine diagnostic workflows predominantly use immunohistochemical staining and fluorescence in situ hybridization. These traditional methods are labor intensive and may misclassify the underlying oncogenic signatures, leading to inaccurate prognostication. To address this issue, an RNA expression panel was developed, the Lymphoma Expression Analysis (LExA120) 120 gene expression panel, using the NanoString platform for rapid, modular analysis of various lymphoma subtypes. The LExA120 panel targets 95 genes and 25 housekeeping genes to evaluate aggressive B-cell lymphomas, including: diffuse large B-cell lymphoma cell-of-origin, dark zone, and primary mediastinal large B-cell lymphoma signatures; Epstein-Barr virus (EBV) status; and a classical Hodgkin lymphoma posttransplant risk. Fifty-four formalin-fixed, paraffin-embedded tissue samples were tested with known diagnoses and 51 samples with known EBV status. The panel showed high concordance with previously validated methods according to Pearson correlation coefficients of the signature scores. The assay also displayed high reproducibility in repeated tests and across different clinical laboratories. This study confirmed the panel's ability to stratify EBV-positive and EBV-negative lymphomas with high diagnostic certainty. Although EBER in situ hybridization confirmation was needed in approximately 12% of cases, synergizing with traditional techniques may facilitate more rapid and cost-effective diagnoses. The LExA120 panel offers a multiplexed approach to lymphoma classification, enhancing the efficiency and accuracy for subtyping lymphomas.