Pre-Transplant Rituximab Therapy Is Associated with Improved Progression-Free and Overall Survival in Patients Undergoing Autologous Hematopoietic Stem Cell Transplantation for Diffuse Large B-Cell Lymphoma (DLBCL).

Outcomes following first-line therapy for patients (pts) with DLBCL have improved significantly with the availability of the chimeric anti-CD20 monoclonal antibody rituximab (R). Despite this progress, many pts develop refractory or recurrent DLBCL and are considered candidates for autologous hematopoietic stem cell transplantation (AuHCT). For such pts, it is possible that R given pre-transplant and/or during conditioning therapy affects the natural history of DLBCL, such that traditional methods of risk assessment and patient selection for AuHCT may need revision. We therefore studied the outcomes of 1,006 pts who underwent peripheral blood AuHCT for DLBCL between 1996 and 2003 reported to the CIBMTR, analyzed according to whether R was (n=188, “+R” group) or was not (n=818, “-R” group) administered prior to AuHCT. Using the chi-square statistic for categorical and the Kruskal-Wallis for continuous variables, there were no significant differences between the +R and -R groups with regard to gender, pre-transplant performance status, disease status at transplant, pre-transplant chemosensitivity, second-line aa-IPI score distribution, Ann Arbor stage at transplant, interval from diagnosis to transplant, bulky disease, bone marrow involvement, post-transplant radiation therapy, or post-transplant myeloid growth factor therapy. The +R group had a higher proportion of pts age 61 or older (40% vs. 23%, p<0.001). AuHCT occurred between 1999–2003 in 96% of pts in the +R group, and between 1996–2001 in 93% of the -R pts (p<0.001). For the +R pts, 94% received R only with pretransplant chemotherapy, 3% only with conditioning therapy, and 3% with both pretransplant chemotherapy and conditioning therapy. Conditioning regimens were similar in the +R and -R groups, with the majority receiving the BEAM regimen. In univariate analysis, platelet and neutrophil engraftment were not affected by use of R. Treatment-related mortality (TRM) at 1, 3, or 5 years did not differ significantly between the +R and -R groups. Progression-free survival (PFS) at 1 and 3 years was superior in the +R group (62% vs. 49% at 1 year, p=0.002; 49% vs. 38% at 3 years, p=0.010). Overall survival (OS) was superior in the +R group (68% vs. 60% at 1 year, p=0.032; 57% vs. 45% at 3 years, p=0.003). In multivariate analysis, later year of transplant (2000–2003) and age <55 were associated with lower TRM, but pre-transplant R was not. Conversely, pre-transplant R, age <55, and fewer than 3 lines of chemotherapy were associated with improved PFS, while year of transplant was not. Finally, pre-transplant R, age <55, fewer than 3 lines of chemotherapy, and year of transplant 2000–2003, were all associated with improved OS. We conclude that pre-transplant rituximab is associated with improved PFS and OS following AuHCT for DLBCL, with no evidence of impaired engraftment or increased TRM.