Immunophenotyping of diffuse large B-cell lymphoma (DLBCL) defines multiple sub-groups of germinal centre-like tumours displaying different survival characteristics

Diffuse large B-cell lymphoma (DLBCL) forms a heterogeneous collection of aggressive non-Hodgkin's Lymphoma in which three principle classes of neoplasia have been defined according to gene expression and immunophenotyping studies. The present investigation sought to examine the immunophenotype of proposed subgroups and relate these to patient survival. A series of 155 DLBCL treated uniformly with anthracycline therapy in clinical trials, were stratified upon the basis of common biomarker expression with combination immunophenotype being related to patient overall survival. Stratification of tumours with respect to combined expression profiles of the three biological markers (CD10, Bcl-6 and MUM-1) revealed six groups showing significant differences in survival (p=0.014). The greatest difference resided between distinct populations of germinal centre (GC) cell tumours; the first being CD10(-), Bcl-6(+), MUM-1(-) and the second CD10(+) Bcl-6(+) MUM-1(+) (p=0.002). The former group displayed median survival time of 143 months, the latter only 11 months. A third population of GC tumours (CD10+ Bcl-6(+) and MUM-1(-)) also displayed a relative short median survival (32 months). Of the three groups presenting a non-GC or activated B cell (NGC/ABC) phenotype, only one (CD10(-), Bcl-6(+) and MUM-1(+)) presented short-term median survival (27 months) comparable with poor prognosis GC sub-populations. Within the remaining ABC tumour groups (CD10(-) Bcl-6(-) MUM-1(-) and CD10(-) Bcl-6(-) MUM-1(+)) patients presented intermediate median survival times of 54 and 58 months, respectively. Thus, the GC phenotype did not act as a universal indicator of good clinical prognosis, but rather multiple groups of GC tumours were associated with distinct overall survival profiles. Ultimately, the data allowed definition of a predictive algorithm defining three groups predicting poor, intermediate and good clinical prognosis. The first of these comprised two patient subpopulations with GC-like tumours together with one subpopulation of NGC/ABC, the second two sub-populations of ABC-like tumours, and the final a single group of GC-like tumours associated with optimal long-term survival.