Simplified algorithm for genetic subtyping in diffuse large B-cell lymphoma

Abstract

Genetic classification helps to disclose molecular heterogeneity and therapeutic implications in diffuse large B-cell lymphoma (DLBCL). Using whole exome/genome sequencing, RNA-sequencing, and fluorescence in situ hybridization in 337 newly diagnosed DLBCL patients, we established a simplified 38-gene algorithm (termed 'LymphPlex') based on the information on mutations of 35 genes and rearrangements of three genes (BCL2, BCL6, and MYC), identifying seven distinct genetic subtypes: TP53^Mut (TP53 mutations), MCD-like (MYD88, CD79B, PIM1, MPEG1, BTG1, TBL1XR1, PRDM1, IRF4 mutations), BN2-like (BCL6 fusion, NOTCH2, CD70, DTX1, BTG2, TNFAIP3, CCND3 mutations), N1-like (NOTCH1 mutations), EZB-like (BCL2 fusion, EZH2, TNFRSF14, KMT2D, B2M, FAS, CREBBP, ARID1A, EP300, CIITA, STAT6, GNA13 mutations, with or without MYC rearrangement), and ST2-like (SGK1, TET2, SOCS1, DDX3X, ZFP36L1, DUSP2, STAT3, IRF8 mutations). Extended validation of 1001 DLBCL patients revealed clinical relevance and biological signature of each genetic subtype. TP53^Mut subtype showed poor prognosis, characterized by p53 signaling dysregulation, immune deficiency, and PI3K activation. MCD-like subtype was associated with poor prognosis, activated B-cell (ABC) origin, BCL2/MYC double-expression, and NF-κB activation. BN2-like subtype showed favorable outcome within ABC-DLBCL and featured with NF-κB activation. N1-like and EZB-like subtypes were predominated by ABC-DLBCL and germinal center B-cell (GCB)-DLBCL, respectively. EZB-like-MYC⁺ subtype was characterized by an immunosuppressive tumor microenvironment, while EZB-like-MYC^- subtype by NOTCH activation. ST2-like subtype showed favorable outcome within GCB-DLBCL and featured with stromal-1 modulation. Genetic subtype-guided targeted agents achieved encouraging clinical response when combined with immunochemotherapy. Collectively, LymphPlex provided high efficacy and feasibility, representing a step forward to the mechanism-based targeted therapy in DLBCL.