CO70 | Comparative assessment of targeted next-generation sequencing panels and algorithms for optimal molecular subtyping of diffuse large B-cell lymphoma in clinical practice

Background: Molecular classification of diffuse large B-cell lymphoma (DLBCL) represents a critical step toward precision medicine, enabling the identification of biologically and clinically distinct subtypes associated with specific genetic programs and therapeutic vulnerabilities. Among available classifiers, LymphGen—based on whole-exome sequencing (WES)—is considered the reference framework for molecular taxonomy but remains difficult to implement in diagnostic settings due to cost, turnaround time, and computational complexity.In contrast, LymphPlex, a targeted NGS-based algorithm recently adopted in the ongoing phase 3 randomized GUIDANCE-2 trial (NCT0535134), provides a more practical approach for clinical laboratories. However, its concordance with WES-based classifiers and its reproducibility across different targeted gene sets remain to be comprehensively assessed.Methods: We evaluated three targeted NGS panels including 54, 73, and 60 lymphoma-associated genes, respectively, against the LymphGen (WES-based) and LymphPlex algorithms. Analyses were restricted to overlapping genomic regions. Concordance and subtype assignment accuracy were assessed using Cohen’s Kappa, confusion matrices, and sensitivity/specificity analyses in two large, clinically annotated DLBCL cohorts (n = 574 and n = 664), representing the corresponding gold-standard datasets for LymphGen and LymphPlex, respectively.Results: When compared with LymphGen, the 73-gene panel showed poor agreement (K = 0.03) with reduced sensitivity for EZB (21%) and MCD (20%), while maintaining high specificity (>90%). The 54-gene panel yielded similar concordance (K = 0.035), with sensitivities of 21.3% (EZB) and 20% (MCD) but specificity >90% for most classes. Likewise, the 60-gene panel achieved very low agreement (K = 0.01) and limited sensitivity (