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Volume 14, Issue 4, Pages 449-457 (April 2008)


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Impact of Graft Cell Dose on Transplant Outcomes following Unrelated Donor Allogeneic Peripheral Blood Stem Cell Transplantation: Higher CD34+ Cell Doses Are Associated with Decreased Relapse Rates

Ryotaro Nakamura1Corresponding Author Informationemail address, Nademanee Auayporn1, David D. Smith2, Joycelynne Palmer2, Joel Y. Sun1, Jeffrey Schriber3, Vinod Pullarkat1, Pablo Parker1, Roberto Rodriguez1, Anthony Stein1, Joseph Rosenthal1, Shirong Wang4, Chatchada Karanas1, Karl Gaal5, David Senitzer1, Stephen J. Forman1

Received 13 December 2007; accepted 6 February 2008.

Abstract 

Peripheral blood stem cells (PBSC) have been increasingly used in the matched unrelated donor (MUD) transplant setting, but the impact of CD34+ cell dose on outcomes in this setting have not been well characterized. We analyzed 181 consecutive patients who underwent MUD-PBSC transplantation at the City of Hope between August 2000 to December 2004. Patients were conditioned with either full-intensity regimen or reduced-intensity regimen. There was a significant inverse relationship between higher CD34+ cell dose and faster neutrophil engraftment (r = −0.16, P = .035). By univariate analysis, a CD34+ cell dose ≥4.2 × 106/kg (above the lowest quartile) was associated with significantly lower relapse risk (hazard ratio [HR] = 0.67, P = .0126), with a trend for corresponding improvement for disease-free survival (HR = 0.84, P = .12) but not overall survival (HR = 0.91, P = .46). The impact of the CD34+ cell dose remained significant in multivariate analysis. The higher CD34+ cell dose was significantly associated with faster recovery of absolute lymphocyte counts on day +30 posttransplant. Subset analysis demonstrated that the higher CD34+ cell dose was associated with (1) greater reduction in relapse in myeloid malignancies than that in lymphoid malignancies, (2) greater reduction in reduced-intensity conditioning than in full-intensity conditioning, (3) greater reduction in relapse when there is a inhibitory killer-cell immunoglobulin-like receptor ligand (iKIRL)-mismatch in the gravft-versus-host (GVH) direction, and (4) greater reduction in relapse when there is a lack of iKIRL, suggesting that the protective effect of CD34+ cell dose against relapse may be immune-mediated, possibly through NK cell recovery.

1 Division of Hematology/Hematopoietic Cell Transplantation, City of Hope National Medical Center, Duarte, California

2 Department of Biostatistics, City of Hope National Medical Center, Duarte, California

4 Department of Transfusion Medicine, City of Hope National Medical Center, Duarte, California

5 Department of Anatomic Pathology, City of Hope National Medical Center, Duarte, California

3 City of Hope/Samaritan Hematopoietic Cell Transplantation Program, Phoenix, Arizona

Corresponding Author InformationCorrespondence and reprint requests: Ryotaro Nakamura, MD, Division of Hematology/Hematopoietic Cell Transplantation, City of Hope National Medical Center, 1500 East Duarte Road, Duarte, California 91010-3000.

 These authors contributed equally to this article.

PII: S1083-8791(08)00070-0

doi:10.1016/j.bbmt.2008.02.005


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