Project description:The most frequent mature aggressive B-cell lymphomas are diffuse large B-cell lymphoma (DLBCL) and Burkitt lymphoma (BL). Patients suffering from molecularly defined BL (mBL) but treated with a regimen developed for DLBCL show an unfavorable outcome compared to mBL treated with chemotherapy regimens for BL. Distinguishing BL from DLBCL by conventional histopathology is challenging in lymphomas that have features common to both diseases (aggressive B-cell lymphoma unclassifiable with features of DLBCL and BL [intermediates]). Moreover, DLBCL are a heterogeneous group of lymphomas comprising distinct molecular subtypes: the activated B-cell (ABC)-like, the germinal center B-cell-like (GCB) and the unclassifyable subtype as defined by gene expression profiling (GEP). Attempts to replace GEP with techniques applicable to formalin-fixed paraffin-embedded (FFPE) tissue led to algorithms for immunohistochemical stainings (IHS). Disappointingly, the algorithms yielded conflicting results with respect to their prognostic potential, raising concerns about their validity. Furthermore, IHS algorithms did not provide a fully resolved classification: They did not identify mBL; nor did they separate ABC from unclassified DLBCL. 29 diffuse large B-Cell lymphoma samples were hybridized to HGU133A Affymetrix GeneChips. In addition, this study contains 22 already published samples whereas 11 of them contribute to GSE22470, 6 contribute to GSE10172, 3 to GSE44164 and 2 to GSE4475. No re-normalisation of published samples was performed. We used digital multiplexed gene expression (DMGE) with FFPE derived RNA to classify agressive B-cell lymphomas. Our assay comprised only 30 genes (10 for the detection of mBL and 20 for the detection of ABC and GCB). We chose these genes by reanalysis of the microarray data reported in a previous study. 39 samples from mature aggressive B-cell lymphomas were analyzed using DMGE (nCounter, NanoString Technologies Inc., Seattle, WA, USA) of FFPE- and fresh-frozen derived RNA. All cases were previously characterized by the Molecular Mechanisms of Malignant Lymphoma (MMML) consortium using the Affymetrix GeneChip technology (gold standard of classification). Please note that there are total 40 FFPE-derived and 50 fresh-frozen derived samples, with 39 samples derived from both materials (allowing direct comparison).

Dataset Information

Gene expression profiles uncover molecular classifiers for the prediction of progression-free survival in diffuse large B-cell lymphoma: results of a DASL assay from formalin fixed paraffin embedded tissue

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