Patients with diffuse large B-cell lymphoma of germinal center origin with BCL2 translocations have poor outcome, irrespective of MYC status: a report from an International DLBCL rituximab-CHOP Consortium Program Study

Abstract

Diffuse large B-cell lymphoma can be classified by gene expression profiling into germinal center and activated B-cell subtypes with different prognoses after rituximab-CHOP. The importance of previously recognized prognostic markers, such as Bcl-2 protein expression and BCL2 gene abnormalities, has been questioned in the new therapeutic era. We analyzed Bcl-2 protein expression, and BCL2 and MYC gene abnormalities by interphase fluorescence in situ hybridization in 327 patients with de novo disease treated with rituximab-CHOP. Isolated BCL2 and MYC rearrangements were not predictive of outcome in our patients as a whole, but only in those with the germinal center subtype of lymphoma. The prognostic relevance of isolated MYC rearrangements was weaker than that of BCL2 isolated translocations, but was probably limited by the rarity of the rearrangements. Seven of eight patients with double hit lymphoma had the germinal center subtype with poor outcome. The germinal center subtype patients with isolated BCL2 translocations had significantly worse outcome than the patients without BCL2 rearrangements (P=0.0002), and their outcome was similar to that of patients with the activated B-cell subtype (P=0.30), but not as bad as the outcome of patients with double hit lymphoma (P<0.0001). Bcl-2 protein overexpression was associated with inferior outcome in patients with germinal center subtype lymphoma, but multivariate analysis showed that this was dependent on BCL2 translocations. The gene expression profiling of patients with BCL2 rearrangements was unique, showing activation of pathways that were silent in the negative counterpart. BCL2 translocated germinal center subtype patients have worse prognosis after rituximab-CHOP, irrespective of MYC status, but the presence of combined gene breaks significantly overcomes the prognostic relevance of isolated lesions.

Figure 1.

Overall survival and progression-free survival of patients with DLBCL according to (A) the presence of BCL2 translocations alone or concomitant MYC breaks stratified by GEP-defined subgroups; (B) BCL2 translocations stratified with GEP subgroups in the validation set. DHL: double hit lymphoma.

Figure 2.

Box plot graphs for the distribution of Bcl-2 expression in 327 patients with DLBCL according to GEP and FISH analysis. Reported P values were calculated with the Mann-Whitney test. Only significant differences are reported. SD= standard deviation. (A) Bcl-2 protein expression in GEP-defined subgroups; (B) Bcl-2 protein expression in correlation with BCL2 and MYC gene aberrations in GEP-defined subgroup. UC: unclassified; DHL: double hit lymphoma.

Figure 3.

Overall survival and progressionfree survival of patients with DLBCL according to Bcl-2 protein expression in GEP-defined subgroups.

Figure 4.

Overall survival and progression-free survival of 103 patients with GCB-DLBCL, stratified according to Bcl-2 protein expression and BCL2 translocations. Patients with double hit lymphoma were excluded from this analysis. For OS: P=0.79 and P=0.58 between A and B, and C and D, respectively; P=0.23 and P=0.04 between A and D, and B and C, respectively. For PFS: P=0.61 and P=0.94 between A and B, and C and D, respectively; P=0.01 and P=0.01 between A and D, and B and C, respectively.

Figure 5.

Gene expression profile and representative FISH analysis of DLBCL patients. (A). Gene expression profile of 139 GCB-DLBCL patients stratified according to the presence or absence of BCL2 translocations; (B). Gene expression profile of 80 DLBCL patients with BCL2 translocations stratified between GCB-DLBCL (n=78) and ABC-DLBCL (n=12); (C). Representative FISH of BCL2 amplification (upper image) and translocation (lower image) using a locus-specific identifier BCL2 dual-color break-apart probe.