Transformed follicular lymphoma (tFL): consolidation therapy may improve survival

Retrospective study to evaluate the outcome of patients with transformed follicular lymphoma (tFL) treated with rituximab-containing chemotherapy and consolidation.

Patients diagnosed with tFL from 2003 to 2013 treated with consolidation therapy with last follow-up in December 2015 were identified from the institutional lymphoma database and included in this study. Data collected included age, gender, stage, interval to tFL diagnosis, R-IPI score, histological diagnosis and therapy. The treatment algorithm used was stratified for age, performance status (PS) and sibling donor availability using R-chemotherapy induction followed by consolidation with allogeneic stem cell transplant (SCT), autologous SCT, Zevalin or rituximab maintenance (RM). Patients with B-cell lymphoma with features intermediate between diffuse large B-cell lymphoma and Burkitt's lymphoma (BCL-U), with FISH-proven t(14;18) and t(8;14) and their variants were excluded.

Four hundred patients were diagnosed with FL of whom 26 (7%) developed histologically proven tFL. The group was predominantly male (73%) with a median age at transformation of 53 (range 27-72) years and 85% presented with stage III/IV disease. Thirteen (50%) patients presented with de novo tFL and the remainder had previously diagnosed FL, with a median time to transformation of 5.7 (range 1-15) years. The median follow-up time from tFL diagnosis to December 2015 is 8 (range 4-14) years. All patients received immuno-chemotherapy achieving an overall response rate (ORR) of 100%. Fourteen (54%), patients were transplant eligible and based on donor availability, six had an auto-SCT only, five had an allo-SCT only and three had a matched unrelated allo-SCT for a post-auto-SCT relapse. The 12 patients (46%) who were not transplant eligible were consolidated with rituximab maintenance (RM) in nine (35%) and Zevalin in three (11%) cases. The overall survival (OS) and progression-free survival (PFS) for the series at 5 years were, 92 and 73%, respectively.

This consecutively treated series of 26 patients with tFL have had a better outcome than expected which may be due to the use of rituximab-chemotherapy and a consolidation strategy based on age, PS and availability of a sibling donor.