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

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:TP53Mut(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.TP53Mut 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.