Impact of infused CD34+ stem cell dosing for allogeneic peripheral blood stem cell transplantation with post-transplant cyclophosphamide.

Higher infused total nucleated cell dose (TNC) in allogeneic bone marrow transplant (BMT) with post-transplant cyclophosphamide (PTCy) is associated with improved overall survival. As many centers prefer peripheral blood stem cell grafts (PBSCT) with PTCy, the effect of cell dose on outcomes with this platform also requires elucidation. We retrospectively evaluated 144 consecutive adult patients who received allogeneic T-cell replete PBSCT with PTCy-based graft-versus-host disease (GVHD) prophylaxis for a hematologic malignancy from 2012-2018. The infused CD34+ cell dose was stratified into low ( 10 × 106/kg) dose level groups. In multivariate analysis, the low CD34+ cell dose group had worse non-relapse mortality (HR = 4.51, 95% CI: 1.92-10.58, p 5 × 106 cells/kg may result in improved survival. Thus, this study supports targeting a CD34+ cell dose of >5 × 106 cells/kg for allogeneic PBSCT with PTCy.