The Same Players, Better Results: How Experience and Growth Factors Better Usage Improve Peripheral Blood Stem Cells Collection Outcome

The use of peripheral blood stem cells (PBSC) has been established as the gold standard procedure for both autologous and allogeneic transplantation with few medical exceptions. In order to improve the existing techniques, systematic recording is required. The aim of the current study was to gather, analyze and evaluate results of PBSC mobilizations and collections from our center.

The study is a single-center, retrospective study, conducted at a Hematology Department and HCT unit of a tertiary Hospital after approval from local Ethics Committee. Donors informed consents were obtained in accordance with the Declaration of Helsinki. Overall, 1052 individuals were included during the period 2013-2021, 638 male (60.6%) and 414 (39.4%) female with a median age of 42 years. 473 cases of them concerned healthy allograft donors divided to unrelated volunteers (20.72%) and haploidentical or siblings (79.28%). Out of total 602 autologous collections, 52.17% concerned patients with lymphomas and the rest with multiple myeloma.

The standard mobilization regimen which was used in all cases was 10 μg/kg GCSF (filgrastim) administered subcutaneously for 4-5 consecutive days. Leukapheresis was performed targeting of collecting a minimum of 5x10⁶/kg patient's weight CD34+ cells for allografts and 2x10⁶/kg patient's weight CD34+ cells for autologous transplants. COBE Spectra apheresis platform initially and Spectra Optia system later were used for PBSC harvesting. Collection timing was determined by monitoring CD34+ cells in healthy donor's or patient's blood from the 3rd day of growth factor administration. In case of poor mobilization on day 4, plerixafor was used in both autologous and allogeneic donors with equal success and scarce side effects including mainly bone pain, nausea, headache, and fatigue.

Mean number of CD34+ cells in healthy donor's or patient's peripheral blood was 62.49x10⁶/kg in male and 49.61x10⁶/kg in female individuals without statistical difference according to different age groups or plerixafor's use. There were no statistical differences among hematocrit mean values or absolute mean values of CD34+ cells in both allogeneic and autologous transplants. The use of plerixafor didn't increase the absolute number of the collected CD34+ cells per transplant but allowed the possibility of successful collection in cases where the administration of GCSF alone would have failed. Total average collections per donor were 1.28 sessions for allo-transplants and 1.17 sessions for auto-transplants, with female donors/patients tended to require a second collection day.

Overtime there was a characteristic and remarkable continued reduction of the required number of collections per person, a fact that reflects the staff's familiarity with the mobilization procedures and growth factors better usage.

No relevant conflicts of interest to declare.

Use of plerixafor to mobilize haematopoietic progenitor cells in healthy donors - real life data