Plerixafor is effective given either preemptively or as a rescue strategy in poor stem cell mobilizing patients with multiple myeloma

Background Harvest of more than one CD 34+ stem cell transplant has become the standard, to ensure the option for a second autologous transplantation in patients with relapsed or progressive multiple myeloma ( MM ). Additional administration of the CXCR ‐4 inhibitor plerixafor has been shown to increase the efficiency of CD 34+ stem cell harvest. However, the algorithm when to apply plerixafor is still under debate. Study Design and Methods I n this retrospective study, 46 MM patients were categorized into four groups according to their CD 34+ stem cell count in peripheral blood ( PB ) and mobilization with or without plerixafor: G roup A comprised poor mobilizers with CD 34+ cell counts of fewer than 20 × 10 6 /L in PB . G roup B included inadequate mobilizers with CD 34+ cell counts of 20 × 10 6 / L or more in PB and a low CD 34+ stem cell yield in the first leukapheresis session. Patients receiving plerixafor preemptively ( G roup A 1) and as a rescue strategy ( G roup B 1) were compared to patients continuing stem cell collection with granulocyte–colony‐stimulating factor alone ( G roups A 2 and B 2). Results In both, the preemptive and the rescue settings, plerixafor enhanced the CD 34+ stem cell yield significantly. Poor mobilization and administration of plerixafor was not associated with delayed engraftment. Conclusion Our data demonstrate that administration of plerixafor is safe and effective and facilitates a significantly higher CD 34+ stem cell harvest. Based on the presented data, we propose an algorithm for the use of plerixafor for CD 34+ stem cell mobilization and harvesting in poor mobilizing myeloma patients.