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Cell-of-Origin Subtyping Diffuse Large B-Cell Lymphoma (DLCBL) by Using a 32-Gene Expression Assay in Formalin-Fixed Paraffin-Embedded Tissues

ABSTRACT: Objection: To evaluate a qPCR-based 32-gene expression assay to determine the cell-of-origin (COO) of diffuse large B-cell lymphoma (DLBCL) with formalin-fixed paraffin-embedded (FFPE) tissue. Methods: The most established subtyping algorithm, the COO model, categorizes DLBCL into activated B-cell (ABC) and germinal center B-cell (GCB)-like subgroups through gene expression profiling. Biopsy of DLBCL patients with paired FFPE and fresh frozen tissue were collected to assign COO based on the immunohistochemistry (IHC) algorithm (Han’s algorithm), qPCR-based 32-gene expression assay (DLBCL-COO assay) and global gene expression profiling with RNA-seq. Results: The DLBCL-COO assay demonstrated a significantly superior concordance of COO determination with the “gold standard” RNA-seq, comparing with the IHC assignment with Han’s algorithm (91.9% versus 77.5%; P = 0.005). Furthermore, overall survival of GCB patients defined by DLBCL-COO assay was superior significantly towards the ABC patients (Figure 2B, P = 0.023). This effect was not seen when tumors were classified by IHC algorithm. Conclusions: The DLBCL-COO assay provides flexibility and accuracy in DLBCL subtype characterization. These subtype distinctions should help guiding prognostic and therapeutic options for the patients in our daily practice.

ORGANISM(S): Homo sapiens

PROVIDER: GSE147986 | GEO | 2020/04/22

REPOSITORIES: GEO

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Project description:Primary bone diffuse large B-cell lymphoma (PB-DLBCL) is a rare extranodal lymphoma subtype. This retrospective study elucidates the currently unknown genetic background of a large clinically well-annotated cohort of DLBCL with osseous localizations (O-DLBCL), including PB-DLBCL. 103 O-DLBCL patients were included and compared with 63 (extra)nodal non-osseous (NO)-DLBCLs with germinal center B-cell phenotype (NO-DLBCL-GCB). Cell-of-origin (COO) was determined by immunohistochemistry and gene-expression-profiling (GEP) using (extended)-NanoString/Lymph2Cx. Mutational profiles were identified with targeted next-generation deep-sequencing, including 52 B-cell lymphoma-relevant genes. O-DLBCLs, including 34 PB-DLBCL, were predominantly classified as GCB-phenotype based on immunohistochemistry (74%) and NanoString analysis (88%). Unsupervised hierarchical clustering of an extended-NanoString/Lymph2Cx demonstrated significantly different GEP-clusters for PB-DLBCL as opposed to NO-DLBCL-GCB (P<0.001). Expression levels of 23 genes of two different targeted GEP-panels, indicated a centrocyte–like phenotype for PB-DLBCL, whereas NO-DLBCL-GCB showed a centroblast-like constitution. PB-DLBCL had significantly more frequent mutations in four GCB-associated genes, i.e. B2M, EZH2, IRF8, and TNFRSF14, compared to NO-DLBCL-GCB (P=0.031, P=0.010, P=0.047, and P=0.003). PB-DLBCL with its corresponding specific mutational profile were significantly associated with a superior overall survival compared to equivalent Ann Arbor limited-stage I/II NO-DLBCL-GCB (P=0.011). This study is the first to demonstrate that PB-DLBCL is characterized by a GCB-phenotype, with a centrocyte-like GEP-pattern and a GCB-associated mutational profile (both involved in immune surveillance) and a favorable prognosis. These novel biology-associated features provide evidence that PB-DLBCL represents a distinct extranodal DLBCL entity and its specific mutational landscape holds potential for targeted therapies (e.g. EZH2-inhibitors). The NanoString analsyis consisted out of 219 probes for Lymph2Cx classifier (COO), MYC-activity GEP score, CNV-associated GEP signature, consensus clustering, and immune-ratio signature. This custome probeset was used to differentiate GEPs between osseous and non-osseos DLBCL of the GCB-phenotype.

Dataset Information

Cell-of-Origin Subtyping Diffuse Large B-Cell Lymphoma (DLCBL) by Using a 32-Gene Expression Assay in Formalin-Fixed Paraffin-Embedded Tissues

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