Traces of Epstein Barr virus (EBV) are not involved in the pathogenesis of Diffuse Large B cell lymphoma (DLBCL)

MANGIATERRA T; ALONSO R; DE DIOS SOLER, M; DE MATTEO E; RODRIGUEZ PINILLA SM; PAOLA ANDREA CHABAY

Lugano

Congreso; 17th International Congres on Malignant Lymphoma; 2023

Foundation for the Institute of Oncology Research (IOR)

INTRODUCTIONEpstein-Barr virus-positive DLBCL (EBV+ DLBCL) was defined by the WHO, with＞80% EBERs+ cells, although 20% was used as cut off. The detection of traces of EBV was reported by more sensitive methods than EBERs in situ hybridization (ISH). The aim was to analyze immune response markers in EBV+ DLBCL, and to compare them in cases with or without traces of EBV infection.METHODSFifty DLCBL cases were studied by EBERs ISH. The expression of immune response genes was evaluated by Lymph2Cx. LMP1 and EBNA2 transcripts were detected by double ISH with ViewRNA ISH Tissue 2-Plex Assay to define the presence of traces of EBV. LMP1+, EBNA2+, and double LMP1+/EBNA2+ cells were counted in tumor cells. Viral load was measured by RT- qPCR. Immunohistochemistry (IHC) for CD68, CD163, LAG3 and PDL1 at the TME, and PDL1/PAX5 in tumor cells was performed.RESULTSEBV was detected by EBERs ISH in 12/50 cases. A cut-off of 20% of EBERs+ cells was used to define EBV+DLBCL. Viral transcripts were detected in 19/45 cases (5 EBV+ and 14 EBV-) with good quality for analysis. 19 and 5 cases expressed LMP1 and EBNA2 transcripts (Fig.1), respectively. Only EBV+DLBCL cases displayed detectable viral load. When the expression of immune response genes by Lymph2Cx was compared in EBV+ vs EBV- DLBCL, higher expression of CD274 (PDL1), LAG3, CD68, among others, was observed (Fig.2). This increased expression was not observed when cases with traces of viral transcripts were compared with its negative counterpart. The expression of LAG3,CD68 and PDL1 in the TME and PDL1/PAX5 in tumor cells was assessed by IHC to validate gene expression results. PDL1+/ PAX5+ and CD68+ cell count was higher in EBV+ DLBCL (p