The Prognostic Value of MYC, BCL2 and BCL6 Translocations and Protein Expressions in Young Patients with High-Risk Diffuse Large B-Cell Lymphoma Treated with R-CHOEP

Background: In young patients with high-risk diffuse large B-cell lymphoma (DLBCL) treatment with R-CHOEP (R-CHOP + etoposide) has been associated with improved outcome. Whether established prognostic markers in R-CHOP treated patients are prognostic in R-CHOEP treated patients remain to be investigated. In addition predictive markers for response to R-CHOEP need to be investigated.

Methods: A Danish population based cohort of 140 young (age 18-60) patients with high-risk (2 ≥ additional risk factors including advanced stage, elevated s-LDH, and performance status >1) primary DLBCL diagnosed between 2004 and 2008 was investigated. Patients were treated with R-CHOP (n=84) or R-CHOEP (n=56). Formalin fixed paraffin embedded tumor tissue specimens were analysed for MYC-, BCL2- and BCL6- protein expression by semiquantitative immunohistochemistry (IHC) and genetic translocations by Fluorescence In Situ Hybridization (FISH).

Results: MYC protein expression ≥ 40% was seen in 67/106 patients (71%), BCL2 protein expression > 0 and BCL2 protein expression ≥ 70% was seen in 106/138 (77%) and 81/117 patients (69%) respectively. BCL6 expression ≥ 30% was seen in 96/114 patients (84%). Concurrent expression of MYC≥40% and BCL2≥70% (IHC double hit (DH)) was seen in 50/106 patients (47%). Concurrent MYC≥40%, BCL2 >0 or BCL6<30% (Triple hit (TH) score score 2-3) was seen in 61/103 patients (59%). MYC, BCL2 and BCL6 translocation was seen in 14/104 (13%), 31/104 (30%) and 27/104 (26%) patients respectively. Concurrent MYC BCL2/BCL6 translocation (DH) was seen in 8/102 (8%) patients. MYC over-expression was not associated with reduced progression free survival (PFS) in either R-CHOP or R-CHOEP treated patients. BCL2 expression (>0%) and BCL2 overexpression (≥70%) was associated with reduced PFS in R-CHOP (HR: 0.3; 95%CI:0.1-0.9; p=0.03 and HR: 0.4; 95%CI: 0.2-0.9; p=0.02) - but not in R-CHOEP treated patients (HR: 0.9; 95%CI:0.3-3.2; p=0.9 and HR: 0.5; 95%CI: 0.1-1.9; p=0.3). IHC DH was associated with a trend towards reduced PFS in R-CHOP - but not in R-CHOEP treated patients (HR: 0.6; 95%CI:0.3-1.1; p=0.08 and HR: 1.2; 95%CI: 0.4-4.0; p=0.7 respectively). TH score 2-3 was associated with reduced PFS in R-CHOP - but not in R-CHOEP treated patients (HR: 0.4; 95%CI:0.2-0.9; p=0.015 and HR: 0.8; 95%CI: 0.2-2.8; p=0.74). There was no statistical significant interaction between treatment modality and BCL2 expression, IHC DH or TH score 2-3. MYC, BCL2 and BCL6 translocations were not prognostic markers with respect to PFS in either R-CHOP or R-CHOP treated patients. DH translocations were too few to perform meaningful statistical analyses.

Conclusions: BCL2 expression, IHC DH and TH score 2-3 had prognostic value in R-CHOP treated patients but this was not seen in R-CHOEP treated patients in this study suggesting the need for novel prognostic markers in R-CHOEP treated patients. Neither BCL2 expression, IHC DH nor TH score 2-3 were however predictive markers for response to treatment with R-CHOEP in this cohort of patients. This could possibly be due to the limited number of patients investigated. MYC BCL2/BCL6 DH translocations were too few to perform meaningful statistical analyses and whether DH translocation will retain a prognostic value in R-CHOEP treated patients also remains to be investigated in larger patient cohorts. A possible predictive value of DH translocation also needs further investigation.