Posttransplant diffuse large B-cell lymphoma: new genetic findings

Molecular pathogenesis of posttransplant (PT) lymphoproliferative disorder, including the most prevalent diffuse large B cell lymphoma (DLBCL), is largely unknown. We have recently showed that Epstein-Barr Virus (EBV)+ and EBV- PT-DLBCL are biologically different, but gene expression profile of the latter lymphoma is similar to that of immunocompetent (IC) DLBCL. To validate these findings on a genomic level, we performed array CGH analysis of 21 EBV+ and 6 EBV- PT-DLBCL, and 11 control IC-DLBCL. Genomic and transcriptomic data were subsequently integrated. Notably, EBV+ and EBV- PT-DLBCL revealed only one shared recurrent imbalance, while EBV- PT-DLBCL displayed at least 10 aberrations recurrent in IC-DLBCL, among others gain of 3/3q and 18q, and loss of 6q23/TNFAIP3 and 9p21/CDKN2A. EBV+ PT-DLBCL showed distinct aberrations, including the most prevalent gain/amplification of 9p24.1 targeting PDCD1LG2/PDL2. Significant differential representation/expression of 3p13/FOXP1 and 9p21/CDKNA2 in EBV+ PT-DLBCL when compared with EBV- PT-/IC-DLBCL, suggests that the oncogene FOXP1 and the tumor suppressor gene CDKNA2 are not implicated in pathogenesis of EBV+ PT-DLBCL. In summary, genomic profiling of PT-/IC-DLBCL confirmed biological distinctness of EBV+ and EBV- PT-DLBCL, and relationship between EBV- PT-DLBCL and IC-DLBCL. These findings support the hypothesis that EBV- PT-DLBCL are coincidental lymphomas in transplant recipients We performed a copy number alteration (CNA) analysis in combination with gene expression profiling of a series of thoroughly characterized PT-DLBCL and control IC-DLBCL.