A retrospective Dutch study comparing T cell-depleted allogeneic blood stem cell transplantation vs T cell-depleted allogeneic bone marrow transplantation.

Retrospectively, a cohort of 43 hematological patients receiving an allogeneic T cell-depleted (TCD)-PBSCT between 1994 and 1997, was compared to a cohort of 435 patients, who received an allogeneic TCD-BMT between 1990 and 1996. Both cohorts were comparable with respect to diagnosis, risk status, age and sex. PB grafts contained four to five times more hematopoietic progenitor cells and T cells as compared to BM grafts. T cell depletion was performed by either elutriation, CD34 selection, E-rosetting, or Campath serotherapy. Conditioning was cyclophosphamide/TBI in the majority of patients of both cohorts. All patients received cyclosporin A as GVHD prophylaxis until day 90 post-transplant. Engraftment was significantly faster in the PBPCT cohort with a median time to neutrophil recovery (>0.5 x 10(9)/l) of 16 vs 21 days in the BMT cohort (P = 0.0009). Platelet recovery to 50 x 10(9)/l was 16 vs 34 days for the PB and BM cohort respectively (P < 0.0001). A median percentage of 76% of BMT patients recovered to 50 within 100 days post-BMT vs 91% of patients receiving a PB graft. The incidence of acute GVHD grades II, III and IV was similar in both cohorts. In contrast, the probability of developing chronic GVHD was 21% in the BM cohort vs 37% in the PB cohort. Relapse incidence was reduced in the PB cohort (9 vs 29%), while treatment-related mortality was not different for both cohorts. These favorable results require confirmation by a prospective randomized trial, which is currently being performed by several European centers.