Durable event-free survival following autologous stem cell transplant for relapsed or refractory follicular lymphoma: positive impact of recent rituximab exposure and low-risk Follicular Lymphoma International Prognostic Index score.

Published studies have provided conflicting results regarding the curative potential of high dose chemotherapy and autologous stem cell transplant (HDT/ASCT) for follicular lymphoma (FL). Our objectives were to evaluate the long-term event-free (EFS) and overall (OS) survival rates following ASCT for FL, and to identify predictors of improved outcome. We conducted a retrospective analysis of the first 100 consecutive patients with relapsed or refractory FL treated with HDT/ASCT in Calgary from 1993 to 2008. With a median follow-up of 65 months (range 16-178) post-ASCT, 5-year EFS and OS rates were 56% (95% confidence interval [CI] 46-66%) and 70% (95% CI 61-79%), respectively. A plateau on the EFS curve is evident starting 6 years post-ASCT. Also, the EFS post-ASCT was markedly longer than the 12-month median EFS from last therapy prior to ASCT (p < 0.0001). Failure of rituximab pre-ASCT was not associated with EFS or OS. Severe toxicities included two early treatment-related deaths, and four late deaths from secondary leukemia. Independent predictors of EFS and OS in multivariate analysis were rituximab therapy within 6 months of ASCT, chemosensitivity and FLIPI (FL International Prognostic Index) score 0-1. In conclusion, our data suggest that over 50% of patients with relapsed/refractory FL who have failed 1-2 prior chemotherapy regimens achieve long-term EFS following HDT/ASCT.