How I treat patients who mobilize hematopoietic stem cells poorly

L. Bik To, Jean-Pierre Levesque and Kirsten E. Herbert


Transplantation using 2-5 x 106 mobilized CD34+cells/kg body weight (BW) lowers transplant costs and mortality. Mobilization is most commonly performed with recombinant human granulocyte colony stimulating factor (G-CSF) with or without chemotherapy but a proportion of patients/donors fail to mobilize sufficient cells. Bone marrow (BM) disease, prior treatment and age are factors influencing mobilization but genetics also contributes. Mobilization may fail because of the changes affecting the hematopoietic stem/progenitor cell (HSC)/BM niche integrity and chemotaxis. Poor mobilization affects patient outcome and increases resource utilization. Until recently increasing G-CSF dose and adding stem cell factor (SCF) have been used in poor mobilizers with limited success. However plerixafor through its rapid direct blockage of the CXCR4/CXCL12 chemotaxis pathway and synergy with G-CSF and chemotherapy has become a new and important agent for mobilization. It efficacy in upfront and failed mobilizers are well established. To maximize HSC harvest in poor mobilizers the clinician needs to optimize current mobilization protocols and to integrate novel agents like plerixafor. These include when to mobilize in relation to chemotherapy, how to schedule and perform apheresis, how to identify poor mobilizers and what are the criteria for pre-emptive and immediate salvage use of plerixafor.

  • Submitted June 3, 2011.
  • Accepted July 29, 2011.