Comparison of Thiotepa-based Conditioning Regimens for Older Adults with Primary Diffuse Large B-cell Lymphoma of the Central Nervous System Undergoing Autologous Hematopoietic Cell Transplantation

In this study, we compare outcomes of older patients with primary diffuse large B-cell lymphoma of the central nervous system (PCNSL) undergoing autologous hematopoietic cell transplantation (autoHCT) with either thiotepa/carmustine (BCNU/Thio) or thiotepa/busulfan/cyclophosphamide (TBC) conditioning. We used a postpublication dataset made available by the Center for International Blood and Marrow Transplantation Research including patients who were ≥65 years in age with PCNSL and underwent autoHCT as consolidation with TBC or BCNU/Thio conditioning. Out of 147 patients; n = 84 received BCNU/Thio and n = 63 received TBC. The 1-year NRM in the BCNU/Thio group was 10% versus 22% in the TBC group (P = .05) and the 2-year relapse rate was 5% versus 5%, respectively (P = 1.00). The 2-year progression-free survival (PFS) in the BCNU/Thio group was 85% versus 71% in the TBC group (P = .05) and 2-year overall survival (OS) was 86% versus 74% (P = .08). In a multivariable regression model, BCNU/Thio was associated with a lower risk for NRM (hazard ratio [HR], 0.33, P = .009), improved PFS (HR, 0.41, P = .008) and OS (HR, 0.37, P = .007), but there was no association with relapse risk. We found that in older adults with PCNSL undergoing consolidation with autoHCT, BCNU/Thio conditioning is associated with lower NRM and improved OS compared to TBC.