A Clinico-Genotypic Prognostic Index for De Novo Composite Diffuse Large B-Cell Lymphoma Arising from Follicular Lymphoma in the Rituximab Era

Abstract

Aim Composite follicular lymphoma with diffuse large B-cell lymphoma (FL/DLBCL) is an uncommon hematological neoplasm. The aim of this study was to examine clinico-pathological features of patients with FL/DLBCL and investigate relevant predictors of survival outcome. Methodology Patients with histologically-proven FL/DLBCL at diagnosis (n=106) and who were subsequently treated with Rituximab-based chemotherapy from 2002-2017 at the National Cancer Centre Singapore were retrospectively analyzed. Survival analyses were performed using the Kaplan-Meier method and multivariate Cox proportional models. Results The cohort consisted of 72 men and 34 women with a median age of 59 years (range, 24-82). The cell of origin by Han's algorithm was GCB in 37.7%, ABC in 58.5% and unknown in 3.8%. Eight patients (7.5%) were double-hit for c-MYC, BCL2 and/or BCL6 rearrangements. In a multivariate model inclusive of known clinico-pathological parameters at diagnosis, presence of B symptoms (p = 0.0122), stage 3 or 4 lymphoma (p = 0.0166) and double-hit genotype (p = 0.0045) were independently prognostic for worse overall survival (OS). These factors, excluding B symptoms, were similarly prognostic for progression-free survival (PFS). Including first-line treatment data in the multivariate model, lack of complete response (p < 0.0001) and use of chemotherapy regimens other than R-CHOP (p = 0.0360) alongside presence of B symptoms (p = 0.0022), were the only remaining independent prognostic variables for worse OS. Classification by cell of origin was not prognostic. A Clinico-Genotypic Index derived from point-wise addition of all five adverse parameters (score of 0, 1, 2, 3-4) revealed four prognostic risk groups accounting for 25%, 30%, 25% and 20% of the cohort, with a predicted 5-year OS of 100%, 95%, 57% and 19% respectively (p < 0.0001). Conclusion A Clinico-Genotypic Index derived from clinical and molecular factors can classify patients with composite FL/DLBCL into distinct prognostic groups. Han's algorithm has no prognostic value in this disease entity. Figure. Figure. Disclosures No relevant conflicts of interest to declare.