Plerixafor Plus G-CSF Versus Etoposide Combined With Cyclophosphamide and G-CSF for Autologous Stem Cell Mobilization in Multiple Myeloma in the Era of Novel Agents: A Single Center Observational Propensity Score-Matched Cohort Study.

Autologous stem cell transplantation (ASCT) is the standard of care for eligible patients with multiple myeloma (MM). The optimal stem cell mobilization strategy for these patients remains a matter of debate in the era of novel agents. To compare the efficacy and outcomes of peripheral blood stem cells mobilization with plerixafor (PXF) and granulocyte-colony stimulating factor (G-CSF) against etoposide combined with cyclophosphamide (EC) plus G-CSF in MM patients. We included 119 patients with MM who underwent stem cell mobilization in our center, 56 patients received PXF + G-CSF and 63 received EC + G-CSF. Propensity score matching between two cohorts at a 1:1 ratio was performed according to baseline characteristics to minimize bias. After propensity matching, 37 versus 37 patients in the PXF + G-CSF versus EC + G-CSF cohorts. Compared to patients treated with EC + G-CSF, the PXF + G-CSF group was associated with significantly higher median concentration peripheral blood CD34+ cell counts (79 vs. 65.1 cells/μL, p = 0.038) and higher CD34+ cell yields (9.58 vs. 5.70 × 106/kg, p = 0.009). All patients in the PXF + G-CSF group experienced successful mobilization, compared to 72% of patients (p = 0.002) in the EC + G-CSF group. Higher median lymphocyte counts in the stem cell products were observed in the PXF + G-CSF group compared with the EC + CSF group (241.59 vs. 120.87 × 106/kg, p = 0.021). Mobilization with PXF + G-CSF was associated with decreased episodes of neutropenia grade ≥ 4 (13.51% vs. 51.35%, p = 0.001), lower use of antibiotics (p = 0.001), and less need for blood transfusions (RBC: 0 vs. 0 units, p = 0.021; PLT: 0 vs. 0 units, p = 0.019). Besides, PXF + G-CSF leaded to faster neutrophil and platelet engraftment after ASCT (neutrophil: 11 vs. 12 days, p = 0.034; platelet: 10 vs. 11 days, p = 0.023). Survival analysis showed that no major differences in PFS and OS were observed between the PXF and EC groups. PXF + G-CSF is a more effective and less toxic mobilizing agent than the chemotherapy-based regimen (EC + G-CSF), and is associated with faster hematopoietic reconstruction without increasing the risk of tumor progression. This regimen may be considered a valuable option for stem cell mobilization.