Race/Ethnicity Influenced CD34+ Cell Mobilization Response

Race/ethnicity influenced CD34+ cell mobilization response across hematopoietic stem/progenitor cell (HPSC) donor types, according to the results of single-center study.

The study included 64 autologous donors and 48 allogeneic donors. The autologous donors included patients diagnosed with multiple myeloma (MM; n=48) or non-MM donors (n=16). Non-MM donors included patients with lymphoma, amyloidosis, and POEM syndrome. Of the 112 grafts, 40% were from African American (AA) donors, 31% were from White donors (W), and 28.57% were from Other (O) racial/ethnic groups.

AA had the highest pre-apheresis CD34+ cells compared with W or O racial/ethnic groups (P=.0123). In AA and O groups, non-MM donors had the lowest number of pre-apheresis peripheral blood CD34+ cells, as well as CD34 yields on the first day of leukapheresis product.

“The pre-apheresis CD34+ cell counts in the peripheral blood on the day of apheresis is a measure of the response to mobilization, however the CD34+ cell yield is impacted by a number of variables including vascular access, amount of blood volume processed, and type of apheresis equipment used,” the researchers explained. “Although both pre-apheresis CD34+ cell numbers and CD34+ cell yields are considered as indicators of mobilization response, pre-apheresis CD34+ cell numbers, being independent of external influences, can be considered as a more reliable indicator of HSPC mobilization.”

Multivariable analysis showed that among W patients there was no significant difference in diagnostic group CD34+ cell yields (MM vs. health donors and non-MM vs. healthy allogeneic donors). Among health allogeneic donors, race/ethnicity difference was no significant (AA vs. W and O vs W).

However, the researchers noted that although these difference were not significant among MM patients, they were among non-MM patients. AA non-MM patients and O non-MM patients had significantly lower CD34+ cell yields than W non-MM patients. Additionally, non-MM AA patients had significantly lower CD34+ cells yields than both MM AA and healthy AA donors. This finding is likely “linked with extent of chemotherapy received by the patients prior to HSPC collection,” the researchers wrote.

“The underlying biologic basis of the favorable mobilizing response observed in MM patients in AA and race/ethnicity differences observed in pre-apheresis CD34+ cell numbers, both in bivariate and multivariate regression analysis, indicate influence of race/ethnicity and underlying disease as strong predictors of optimal HSPC mobilization response,” the researchers wrote.