Donor T-lymphocyte infusion for unrelated allogeneic bone marrow transplantation with CD3+ T-cell-depleted graft

In T-cell-depleted allogeneic bone marrow transplantation (TCD-BMT) using unrelated donors, the role of donor lymphocyte infusion (DLI) for survival and disease control has not been defined. In a study of 116 patients (92 matched, 24 mismatched) who received CD3+ T-cell-depleted marrow graft, sequential infusions of escalated doses of donor T lymphocytes up to 1×106 CD3+ cells/kg were prospectively investigated. T cells were administered while patients were on cyclosporine, provided ≥grade II acute graft-versus-host-disease (GVHD) had not occurred. Acute GVHD of ≥grade II occurred in 27 of 110 (25%) patients before DLI and in 39 of 79 (49%) patients after DLI. In total, 12 of 27 (44%) patients without DLI and 44 of 72 (61%) patients who received DLI developed chronic GVHD. A total of 19 patients died of GVHD, with 17 of acute and two of chronic GVHD. Overall survival (OS) and event-free survival (EFS) at 5 years were 27 and 21%, respectively. The 2-year incidence of relapse was 14%. In multivariate analysis, only chronic GVHD was a good prognostic factor for both OS: hazard ratio (HR) 1.4, P=0.04, and EFS: HR 1.6, P=0.01. Both acute and chronic GVHD were favorable prognostic factors for relapse probability: HR 1.9 for both, P=0.02, 0.01, respectively. The 1-year cumulative incidence of transplant-related mortality (TRM), excluding cases of GVHD, was 42%. The two most common causes of 1-year non-GVHD death were viral infection (9%) and idiopathic pneumonia syndrome (12%). Although the incidence of relapse was low, the study suggests that the current scheme of DLI in unrelated TCD-BMT would not improve survival unless TRM decreases significantly.