Fludarabine and Busulfan versus Fludarabine, Cyclophosphamide, and Rituximab as Reduced-Intensity Conditioning for Allogeneic Transplantation in Follicular Lymphoma

Large, multicenter studies comparing commonly used reduced-intensity conditioning (RIC) approaches in follicular lymphoma (FL) have not been performed. Using the Center for International Blood and Marrow Transplant Research database, we report the outcomes of the 2 most commonly used RIC approaches, fludarabine and busulfan (Flu/Bu) versus fludarabine, cyclophosphamide, and rituximab (FCR) in FL patients. We evaluated 200 FL patients undergoing allogeneic hematopoietic cell transplantation (allo-HCT) who received RIC with either Flu/Bu (n = 98) or FCR (n = 102) during 2008 to 2014. All patients received peripheral blood grafts, and graft-versus-host disease (GVHD) prophylaxis was limited to calcineurin inhibitor–based approaches. Median follow-up of survivors in the Flu/Bu and FCR groups was 48 months and 46 months, respectively. On univariate analysis in the Flu/Bu and FCR groups, the 3-year rates of nonrelapse mortality (11% versus 11%, P = .94), relapse/progression (18% versus 15%, P = .54), progression-free survival (PFS) (71% versus 74%, P = .65), and overall survival (OS) (73% versus 81%, P = .18) were not significantly different. On multivariate analysis no difference was seen between the FCR and Flu/Bu cohorts in terms of grades II to IV (relative risk [RR], 1.06; 95% confidence interval [CI], .59 to 1.93; P = .84) or grades III to IV (RR, 1.18; 95% CI, .47 to 2.99; P = .72) acute GVHD, nonrelapse mortality (RR, .83; 95% CI, .38 to 1.82; P = .64), relapse/progression (RR, .99; 95% CI, .49 to 1.98; P = .97), PFS (RR, .92; 95% CI, .55 to 1.54; P = .76), or OS (RR, .70; 95% CI, .40 to 1.23; P = .21) risk. However, RIC with FCR was associated with a significantly reduced chronic GVHD risk (RR, .52; 95% CI, .36 to .77; P = .001). RIC with either Flu/Bu or FCR in patients with FL undergoing allo-HCT provides excellent 3-year OS, with acceptable rates of nonrelapse mortality. FCR-based conditioning was associated with a lower risk of chronic GVHD.