Impact of CD34+ Cell Dose on Reduced Intensity Conditioning Regimen Haploidentical Hematopoietic Stem Cell Transplantation

OBJECTIVES: Haploidentical hematopoietic stem cell transplant (haplo-SCT) has been associated with higher rates of graft rejection, and a higher dose of CD34+ cell dose is frequently requested. We aim to explore the impact of CD34+ cell dose in peripheral blood stem cell (PBSC) grafts using reduced intensity conditioning (RIC) in haplo-SCT. METHODS: Sixty-eight consecutive haplo-SCT in adult patients were included. Graft-vs-host disease (GVHD) prophylaxis consisted on ATG, PTCy, and CsA. The cohort was divided in two groups using CD34+ dose of >/= 9 x 10(6) CD34+/Kg as cutoff point. Median follow-up was 8.9 months. RESULTS: Median cell dose infused was 9.32 x 10(6) CD34+/Kg. Forty (58.8%) recipients received grafts with CD34+ cells >/=9 x 10(6) /kg. The infusion >/= 9 x 10(6) CD34+/Kg cell dose had a negative impact in overall survival (P = .03) after adjusting for age at transplant. The cumulative incidence of acute GVHD and graft failure were not significantly influenced per CD34+ cell dose. Only four recipients had grade III aGVHD, and all of them received grafts with a CD34+ cell dose >/= 9 x 10(6) . CONCLUSION: In RIC haplo-SCT, recipients may not benefit from PBSC grafts with a CD34+/kg cell dose higher than 9 x 10(6) cells/kg, as it can have an adverse impact in post-transplant outcome.