Molecular subtype classification of formalin-fixed, paraffin-embedded diffuse large B-cell lymphoma samples on the ICEPlex® system.

Abstract

Microarray gene expression profiling (GEP) has been used to identify molecular subtypes of diffuse large B-cell lymphoma (DLBCL) based on the similarity of GEP to a putative “cell of origin” (COO) and defines two molecular subtypes: activated B-cell-like (ABC) DLBCL and germinal centre B-cell-like (GCB) DLBCL (Alizadeh, et al 2000). This dichotomization has prognostic and biological significance, with the ABC subtype having a worse outcome and distinct pathobiology that includes activation of the B-cell receptor and nuclear factor (NF)-κB pathways (Lenz, et al 2008). Attempts to reduce this subclassification to practice using immunohistochemistry are fraught with technical and interpretive issues such that a need for practical quantitative molecular assays exists (Coutinho, et al 2013, de Jong, et al 2007, de Jong, et al 2009, Salles, et al 2011). Indeed, studies have refined this COO concept using limited gene sets, including a 14-gene model to assign ABC and GCB DLBCL subtype developed by Wright et al (2003) as well as a recently-described DLBCL subtyping assay based on parsimonious digital gene expression (Nanostring) technology (Scott, et al 2014). In order to support clinical trials for therapies targeting populations enriched in ABC DLBCL and to offer prognostic information for DLBCL patients as part of our clinical service, we developed a novel multiplex, single-tube, gene expression assay on the ICEPlex® system (PrimeraDx, Mansfield, MA), which allows differentiation between GCB and ABC DLBCL subtypes in formalin-fixed paraffin-embedded (FFPE) specimens using a Food and Drug Administration-cleared platform.