Rituximab-containing reduced-intensity conditioning improves progression-free survival following allogeneic transplantation in B cell non-Hodgkin lymphoma

Background: In B cell non-Hodgkin lymphoma (B-NHL), rituximab-containing reduced-intensity conditioning regimens (R-RIC) have been shown to provide favorable outcomes in single-arm studies; however, large multicenter studies comparing R-RIC and non-rituximab-containing reduced-intensity conditioning regimens (nonR-RIC) have not been performed. Using the CIBMTR database, we report the outcomes of R-RIC versus nonR-RIC regimens in B-NHL. Methods: We evaluated 1401 adult B-NHL patients undergoing allogeneic hematopoietic cell transplantation (allo-HCT) who received nonR-RIC (n = 1022) or R-RIC (n = 379) regimens. Graft-versus-host disease (GVHD) prophylaxis was limited to calcineurin inhibitor-based approaches. Results: Median follow-up of survivors in the R-RIC and nonR-RIC groups was 47 and 37 months, respectively. On multivariate analysis, no difference was seen between the R-RIC and nonR-RIC cohorts in terms of acute GVHD grade II-IV (RR = 1.14, 95%CI = 0.83-1.56, p = 0.43) or grade III-IV (RR = 1.16, 95%CI = 0.72-1.89, p = 0.54), chronic GVHD (RR = 1.15, 95%CI = 0.92-1.46, p = 0.22), non-relapse mortality (RR = 0.90; 95%CI = 0.67-1.22; p = 0.51), relapse/progression (RR = 0.79; 95%CI = 0.63-1.01; p = 0.055), and mortality (RR = 0.84, 95%CI = 0.69-1.02, p = 0.08) risk. However, R-RIC was associated with a significantly improved progression-free survival (RR = 0.76; 95%CI 0.62-0.92; p = 0.006). On subgroup analysis, mortality benefit was noted in the R-RIC group patients not receiving busulfan-based RIC (RR = 0.76; 95%CI = 0.60-0.96; p = 0.02) and with the use of a higher cumulative rituximab dose (RR = 0.43; 95%CI = 0.21-0.90; p = 0.02). Conclusion: Our analysis shows that inclusion of rituximab in RIC regimens improves progression-free survival in patients with B cell NHL. These data supports the use of R-RIC in B-NHL patients undergoing allo-HCT.