Hematopoietic stem cell mobilization: current status and future perspective

Autologous stem cell transplantation (ASCT), high-dose chemotherapy followed by hematopoietic stem cell rescue, is a widely used therapeutic strategy especially for some patients with hematological malignancies such as malignant lymphoma or multiple myeloma (MM). Because successful ASCT is crucial in these patients for improving overall survival [1], collection of a sufficient number of hematopoietic stem cells for restoring the bone marrow function is very important. Although most hematopoietic stem cells are located within the bone marrow, BM harvest is accompanied by procedure related risk and relatively lower yield. Therefore, the mobilization of hematopoietic stem cells by using growth factors such as granulocyte colony-stimulating factor (G-CSF) either as a single agent or in combination with chemotherapy (chemo-mobilization) and the collection of mobilized peripheral blood (PB) hematopoietic stem cells are essential processes for using the peripheral blood stem cell (PBSC) as a stem cell source. However, these classical PBSC mobilization methods fail to collect sufficient number of PBSCs in 5–40% of patients [1]. Plerixafor is a reversible CXCR4 chemokine receptor antagonist and blocks binding of stromal cell-derived factor 1-alpha, resulting in mobilization of CD34 cells to the PB. The additional use of plerixafor to G-CSF resulted in a significantly higher probability of achieving the optimal PBSC targets in patients who failed at least one PBSC mobilization attempt [1, 2]. Plerixafor gained Food and Drug Administration (FDA) approval in 2008 and has been reimbursed from the Korean Health Insurance Review and Assessment Service (HIRA) since 2012 in Korea. Its Korean reimbursement guideline was expanded in 2015. Plerixafor is used for non-Hodgkin lymphoma (NHL) or MM patients who failed to collect sufficient number of PBSCs at the previous PBSC mobilization attempt in Korea. Therefore, the appropriate use of plerixafor would increase the number of patients receiving ASCT and improve the overall treatment outcomes of these hematological malignancies. Herein, we review the current issues in PBSC mobilization including the definition of mobilization failure and suggest the future perspectives of PBSC mobilization.