Loss of CD34+ Cells and Effect of the Number of Viable Cryopreserved CD34+ Cells in the Infused Blood Grafts on Hematologic Recovery, Progression-Free Survival and Overall Survival in NHL Patients After Autologous Stem Cell Transplantation

This post-hoc study aimed to find out factors affecting graft viable CD34+ cell loss during processing and cryopreservation in 129 non-Hodgkin lymphoma (NHL) patients receiving autologous stem cell transplantation (auto-SCT) and the impact of a low (< 2.0 × 106/kg, group A) and a decent number (≥ 2 × 106/kg, group B) of viable CD34+ cells infused on the hematologic recovery, progression-free survival (PFS) and overall survival (OS) after auto-SCT. The median loss of viable CD34+ cells during cryopreservation was higher in group A (47% vs. 19%, p < .001). A higher yield of CD34+ cells at the first apheresis in group B (p = .002) was linked with greater loss of viable graft CD34+ cells after cryopreservation. Filgrastim (FIL) use for mobilization seemed to associate with higher viable CD34+ cell loss compared to pegfilgrastim (PEG) or lipegfilgrastim (LIPEG) in both groups (in group A FIL 66 vs. PEG 35%, p = .006; in group B FIL 37 vs. PEG 15 vs. LIPEG 13%, p < .001). Hematologic recovery after auto-SCT was faster in group B. Neither viable CD34+ cell loss during storage nor viable CD34+ cell number < 2.0 × 106/kg infused affected on PFS or OS. G-CSF type used in mobilization and mobilization capacity were found to correlate with viable CD34+ cell loss during processing and storage. Most importantly, low infused viable CD34+ cell count did not seem to impact on PFS or OS. In this prospective study of 129 non-Hodgkin lymphoma patients, we found that higher mobilizing capacity and use of short-acting G-CSF in mobilization correlated with remarkable CD34+ cell loss during cryopreservation and processing. Most importantly, neither CD34+ cell loss during cryopreservation nor low number of viable infused thawed graft CD34+ cells had effects on PFS or OS.