Decreased treatment failure in recipients of HLA-identical bone marrow or peripheral blood stem cell transplants with high CD34 cell doses.

Summary. We studied the association between CD34 cell dose and transplant outcomes in 359 bone marrow (BM) and 511 peripheral blood stem cell (PBSC) transplant recipients from human leucocyte antigen (HLA)-identical siblings, reported to the International Bone Marrow Transplant Registry (IBMTR). Transplants for leukaemia were performed between 1995 and 1998. Patients were divided into those receiving below or above the median CD34+ dose, for BM (3 × 106 /kg) and PBSC (6 × 106 /kg) grafts respectively. Cox proportional hazards regression was used to adjust for baseline patient-, disease- and transplant-related characteristics. Analysis of the BM recipients showed that high CD34 cell dose was associated with lower transplant-related mortality [relative risk (RR) = 0·60, P = 0·033] and treatment failure (inverse of leukaemia-free survival, RR = 0·69, P = 0·032). Among PBSC recipients, high CD34 dose was associated with faster recovery of neutrophils to > 0·5 × 109 /l (RR = 1·38, P < 0·001) and platelets to > 20 × 109 /l (RR = 1·34, P = 0·003), lower risk of relapse (RR = 0·62, P = 0·029) and treatment failure (RR = 0·74, P = 0·03). We conclude that higher CD34 cell doses decrease treatment failure in recipients of HLA-identical sibling BM and PBSC transplants. [ABSTRACT FROM AUTHOR]