Diffuse large B-cell lymphoma: risk stratification and management of relapsed disease

The clinical factors described by the International Prognostic Index (IPI) provide a model for risk stratification in diffuse large B-cell lymphomas (DLBCLs). However, there is variability in outcome within IPI risk groups, indicating the biological and clinical heterogeneity of these diseases. Studies of gene expression profiling (GEP) in DLBCL are uncovering biological heterogeneity with prognostic significance. Various gene expression signatures with predictive value independent of the IPI are now recognized. Immunophenotypic features of DLBCL have also been shown to have prognostic value. The use of fluorodeoxyglucose-positron emission tomography (FDG-PET) scanning may provide additional predictive information when used at diagnosis or soon after initiation of treatment. Future prognostic models in DLBCL are likely to incorporate functional imaging, immunophenotype and GEPs as well as clinical data in risk stratification and choice of treatment. Treatment of relapsed DLBCL remains a major problem. High-dose therapy (HDT) and stem cell transplantation (SCT) has been shown to produce superior overall survival (OS) compared with conventional dose salvage therapy in patients with relapsed, chemosensitive DLBCL. However, only 20% to 30% of patients are cured by this approach, and the effectiveness of HDT and SCT in patients treated with rituximab-based combinations as first-line therapy is unknown. Although new transplant techniques including non-myeloablative allogeneic SCT are being investigated, their role is unclear. New treatment strategies are needed for these patients. The use of molecular techniques such as GEP is identifying many potential new therapeutic targets in DLBCL including histone deacetylase, HLA-DR, bcl-2, bcl-6, mTOR and TRAIL.