Identification of outcome predictors in diffuse large B-cell lymphoma. Immunohistochemical profiling of homogeneously treated de novo tumors with nodal presentation on tissue micro-arrays.

BACKGROUND AND OBJECTIVES: Patients with diffuse large B-cell lymphoma (DLBCL) could benefit from integration of well-established bioclinical prognostic factors with new tools - such as micro-arrays - exploring aberrant gene and/or protein expression. DESIGN AND METHODS: Tissue micro-arrays (TMA) were constructed for the paraffin blocks of 68 patients with de novo DLBCL with nodal presentation, who underwent MACOP-B and were provided with complete clinical information. TMA were tested with specific antibodies against CD10, CD20, CD30, CD79a, CD138, Bcl-2, Bcl-6, IRF4, and IRTA1.
RESULTS: The following phenotypic subclassification was made: a) CD10 +/Bcl-6 + or Bcl-6+/IRF4 +, but Bcl-2-/CD30-/CD138-- suggesting B-cells gathering/leaving the germinal center (group 1; n=36); b) Bcl-2+/CD10-/Bcl-6- and CD30+ or CD138+ corresponding to putative non-germinal center B-cells with features of activation or plasmablastic/plasmacellular differentiation (group 2; n=17); c) CD30-/CD138- with extensive Bcl-2 positivity and variable CD10, Bcl-6 and IRF4 combinations (group 3; n=15). Mean IPI scores were 0.6, 1.9 and 1.1 for groups 1, 2 and 3, respectively (p= 0.001). Complete remission (CR) rates were 89%, 53% and 73% (p= 0.015). The 3-year relapse-free survival (RFS) rates are 86%, 41% and 63% (p=0.001) and 42-month overall survival (OS) rates are 91%, 38% and 66% (p=0.0002). INTERPRETATION AND
CONCLUSIONS: The present TMA-based study suggests an immunophenotypic profiling system for patients with de novo DLBCL that seems to provide additional prognostic information and contributes to the existing debate on the identification of suitable immunohistochemical surrogates of gene expression profiling results.