Effectiveness of thrombopoietin (TPO) in stem cell mobilization for multiple myeloma and lymphoma patients

Abstract Background: Thrombopoietin (TPO) shows promise for hematopoietic stem cell mobilization. This study evaluated TPO as a single-agent mobilizer in autologous stem cell transplantation (ASCT). Study Design and Methods: A single-center retrospective study compared TPO mobilization (61 patients: 16 multiple myeloma, 45 lymphoma) to a non-TPO control (41 patients: 21 multiple myeloma, 20 lymphoma). All received chemotherapy-based mobilization. The TPO group received rhTPO (300U/kg/day SC) when platelets were <50x10⁹/L during leukocyte recovery, stopping at ≥50x10⁹/L. Peripheral blood stem cells (PBSCs) were collected via apheresis (Fresenius Kabi) when WBC ≥10x10⁹/L until CD34+ cells reached ≥5x10⁶/kg or after 3 maximum collections. Mobilization failure was defined as <2x10⁶ CD34+ cells/kg collected. Primary outcomes were CD34+ cell count and infused stem cell count. Secondary outcomes included mononuclear cell (MNC) count and number of apheresis sessions. Results: The TPO group achieved comparable peak CD34+ cell counts to controls (p>0.05) but required significantly fewer apheresis sessions (median 1 vs. 1.5, p=0.0036) and had a higher infused CD34+ cell dose (p=0.0354). MNC counts were lower in the TPO group (p=0.0478). Discussion: TPO significantly reduced the number of collections needed and increased the infused stem cell dose, potentially enhancing mobilization efficiency. While associated with lower MNC counts, its ability to streamline collection suggests clinical utility. Further prospective studies with larger cohorts and longer follow-up are warranted to confirm TPO's long-term efficacy and safety in ASCT.