Impact of Single-Dose Plerixafor as an Adjunct to Granulocyte Colony-Stimulating Factor–Based Peripheral Blood Stem Cell Mobilization on the Graft Composition and Outcome for T Cell–Replete Haploidentical Peripheral Blood Stem Cell Transplantation with Post-Transplantation Cyclophosphamide: A Comparative Study

We conducted a prospective study on T and natural killer (NK) cell subset composition of graft and transplant outcomes in T cell–replete haploidentical transplantation with a single dose of subcutaneous plerixafor (Px) added to granulocyte colony-stimulating factor (G-CSF)-based mobilization in allogeneic donors to collect 10 × 10 6 /kg CD34 + hematopoietic stem cells (HSCs) at single apheresis. Twnety-six donors received G-CSF + Px and 25 G-CSF alone for mobilization. Despite significantly lower peripheral blood (PB) CD34 + HSCs on day 4 in the G-CSF + Px group (33 [range, 6-47] cells/µL versus 81 [range, 50-168] cells/µL in the G-CSF group; P = .0001), PB CD34 + HSC count (median 136 versus 139 cells/µL) on day 5 as well as that in the graft (2.7 versus 2.3 × 10 6 /mL, P = .1) were comparable between the 2 groups. The total nucleated cell count was higher (3.4 versus 3.1 × 10 8 /mL, P = .05), but CD4 + T cells (2.3 versus 2.7 × 10 7 /mL, P = .09) were lower in the G-CSF group with mobilization of regulatory T cells being similar. NK cells were skewed toward the CD56 + /16 − subset in both groups, varying significantly from the steady-state NK subset ratio in PB. The time to engraftment, incidences of acute and chronic graft-versus-host disease, nonrelapse mortality, and overall survival were also similar. Addition of single-dose Px to G-CSF mobilization improves CD34 recovery and does not significantly alter the T and NK cell composition of the graft, including regulatory T cells, with no adverse impact on transplant outcomes.