CD34+ cell dose predicts relapse and survival after T-cell-depleted HLA-identical haematopoietic stem cell transplantation (HSCT) for haematological malignancies


Professor Barrett BMT Unit, Hematology Branch, Bldg 10, Rm 7C103, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD 20894, USA.


Seventy-eight patients with haematological malignancies, received T-cell-depleted stem cell transplants and cyclosporin followed by delayed add-back of donor lymphocytes to prevent leukaemia relapse. The source of stem cells was bone marrow in 50 patients and granulocyte colony-stimulating factor (G-CSF)-mobilized peripheral blood in 28 patients. In univariate analysis, only the CD34+ cell dose (but not the stem cell source or the T lymphocyte dose) and disease status were predictive for transplant-related mortality, relapse and survival. Patients receiving ≥ 3 × 106 CD34+ cells/kg had an overall actuarial survival of 68% compared with 52%, 35% and 10%, respectively, for cell doses of 2–2.99, 1–1.99 and < 1 × 106/kg. Multivariate analysis of risk factors for relapse identified disease risk and CD34+ cell dose as the only factors. Relapse was 62.5% in 38 patients at high risk of relapse vs. 25% for 40 patients at intermediate or low risk. CD34+ cell doses of ≥ 3 × 106/kg were associated with a 13.5% relapse vs. 48% for recipients of lower doses. This favourable effect of CD34+ cell dose on relapse was apparent in both high- and intermediate- plus low-risk groups. Our results support the potential benefit of a high stem cell dose in lowering transplant-related mortality (TRM) and in reducing relapse after allogeneic marrow or blood stem cell transplants.