The Outcome of Autologous Stem Cell Transplantation and the Risk of Relapse in Myeloma and Lymphoma Patients Mobilized Using Plerixafor Compared to Standard Mobilization Regimen

Abstract 4399

Autologous stem cell transplantation (ASCT) is a method of choice in many hematological malignancies enabling the patients (pts) to achieve remission or to prolong life. Commonly used mobilizing regimens include high dose chemotherapy followed by G-CSF administration. Unfortunately up to 35% pts fail to mobilize the successful number of stem cells (SC).

16 pts aged 48 (23–69) were mobilized with plerixafor in our clinic over one-year period. All of the them failed to mobilize to collect satisfactory number of SC after standard mobilizing regimen. The protocol included G-CSF (10μg/kg) administered subcutaneously for 4 days, followed by plerixafor administration (240μg/kg s.c.). Only two pts failed to collect satisfactory number of SC after plerixafor. 14/16 collected the median of 2.24×10⁶/kg (0.8–15,8), all of them underwent the ASCT. The outcome of ASCT in this group was compared to the posttransplant period in pts mobilized with standard mobilizing regimen (control group; CG).

The amount of CD34+cells x10⁶/kg was significantly higher in the CG (2.24 vs. 4.4, p<.05). The proportion of CD34+ cells among total nucleated cells was significantly lower in the plerixafor group compared to the CG (0.22 vs 1.72, p<.004). The high nucleated cell count translated into high volume of SC product (median 1650mL; 800–2800mL). The volume of frozen SC product was significantly higher in the plerixafor group compared to the CG (1650 vs. 800mL, p<.00). The length of hospital stay (median: 26 days in both groups), incidence of serious infections (41% in plerixafor group vs. 40% in the CG), use of i.v. antibiotics (median: 15 vs. 16 days), number of RBC and platelet (PLT) transfusions (median: 2 vs. 3 units for both RBC and PLT), time to ANC engraftment (ANC>0.5G/l) −10 vs. 14 days, and to PLT engraftment (PLT>20G/l) – 11vs. 14 days, were not different significantly. 43% pts relapsed in plerixafor group with a median follow-up of 14 months and 37% pts in the CG with a median follow up of 11 months (p>.05).SC mobilization with plerixafor and G-CSF provides solution for majority of pts requiring ASCT and failing mobilization with G-CSF in combination with chemotherapy. However, due to high leukocytosis, this protocol may require modification of SC collection and freezing procedures in order to avoid large volumes. In general, pts mobilized with plerixafor had similar post transplant outcome as pts who were mobilized using standard regimen.