Thiotepa-based conditioning for allogeneic stem cell transplantation in acute lymphoblastic leukemia-A survey from the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation.

In this study, we analyzed a thiotepa-based conditioning regimen for allogeneic stem cell transplantation in adults with acute lymphoblastic leukemia, using the EBMT database. A total of 323 patients were identified. The median age was 43 years. Disease status at transplant was first complete remission (CR1) in 48.9%, CR2 in 21.7%, CR3 in 6.2%, while 23.2% of the patients had an active disease at the time of transplant. This was performed from a HLA-matched sibling (49.8%) or a matched-unrelated donor (51.2%). The incidence of acute graft-versus-host disease (GvHD) (grade> II) was 26.6%, while chronic GvHD occurred in 35.9% of the patients at one year (24.6% with extensive disease). With a median follow-up of 16.8 months, the non-relapse mortality was 12.4% and 25.3% at 100 days and one year, respectively. The relapse incidence at one year was 33.3% with no difference for patients in CR1 (27%). The one-year leukemia-free survival (LFS) and overall survival (OS) were 57% and 66%, respectively for the entire cohort and 50% and 66%, respectively in patients in CR1. Thiotepa/busulfan±melphalan (n=213) in comparison to thiotepa/other (n=110) conditioning regimen resulted in higher relapse incidence at one year (34.9% vs 30.3%, p=0.016) and lower LFS (38.8% vs 45.9%, p=0.0203), while non-relapse mortality (23.8% vs 26.3%, n.s.) and OS (59.6% vs 51.1%, p=0.109) did not differ. This large study suggests that a thiotepa-based conditioning for allogeneic transplantation in acute lymphoblastic leukemia is feasible and effective, with the main outcomes being comparable to those achieved with other regimens. This article is protected by copyright. All rights reserved.