Young Male Donors Provide the Best Chance of Meeting Requested Cell Dose for PBSC and Bone Marrow Transplantation

Background: Be The Match Registry^® facilitated over 3,300 peripheral blood stem cell (PBSC) transplants and over 1,000 bone marrow (BM) transplants in 2011. The dose of CD34+ cells for PBSC and total nucleated cell (TNC) count for BM impact engraftment after unrelated allogeneic transplant. This study was performed to evaluate the frequency of unrelated donor PBSC and BM collections that meet the transplant physician's requested dose and the role of the potential donor factors including age and gender.

Methods: A cohort of 1,020 BM and 3,469 PBSC collections from June 2011 through September 2012 were analyzed to compare whether the collected cell dose achieved the requested dose.  Male and female donors were stratified in age groups according to their age at the time of collection (18-30, 31-40, 41-50, 51+) and assessed for the frequency their donated product met the requested cell dose and the number of cells collected per kg of donor weight.

Results: Of 1,020 BM collections analyzed, a median cell dose of 5.0 x 10^8 TNC/kg was requested with a median cell dose of 4.2 x 10^8 TNC/kg collected, resulting in 403 (39.5%) meeting the requested TNC dose. Of 3,469 PBSC collections, a median cell dose of 5.0 x 10^6 CD34+/kg was requested with a median cell dose of 8.1 x 10^6 CD34+/kg collected, resulting in 2,740 (79.0%) meeting the requested CD34+ dose. Increasing donor age resulted in a reduction of the donor's ability to supply the requested dose for both PBSC and BM collections.  A statistically significant reduction in the number of cells collected per kg of donor weight was observed for PBSC collections, but not BM collections (Table 1). In addition, male donors met the requested cell dose more frequently than female donors for both BM (42% vs 35%) and PBSC (85% vs 65%) collections, as well as providing a significantly larger CD34+ cells/kg donor weight for PBSC (8.54 vs 7.59).

Conclusions: This study shows that younger donor age results in an increased likelihood of meeting the transplant physician's requested TNC or CD34+ dose.  Lower donor age also increases the CD34+ cells/kg that are obtained from PBSC collections but not the TNC/kg obtained from marrow collections. In addition, male donors provided increased CD34+ cells/kg donor weight than female donors.  Transplant center practice is often to select young male donors for patients, and this data provides evidence to support that such practice may increase the likelihood of a providing a product meeting a center's request.

Table 1

	Bone Marrow					PBSC
Donor Age (Gender)	Requested Cell Dose Met	TNC X 10^8/kg Donor Weight	p Value			Requested Cell Dose Met	CD34+ X 10^6/kg Donor Weight	p Value
18-30	43%	2.95				80%	8.54
31-40	39%	2.88	0.188			80%	8.15	0.002
41-50	32%	2.83	0.052			75%	7.66	< 0.0001
51-60	25%	2.96	0.906			72%	6.78	< 0.0001
18-60 (M)	42%	2.84				85%	8.54
18-60 (F)	35%	3.05	0.004			65%	7.59	< 0.0001