Plerixafor on demand in ten healthy family donors as a rescue strategy to achieve an adequate graft for stem cell transplantation

BACKGROUND: In allogeneic hematopoietic stem cell (HSC) transplantation, the collection of an appropriate number of HSCs while maintaining a high level of safety for healthy donors is fundamental. Inadequate HSC mobilization can be seen with the standard use of granulocyte-colony-stimulating (G-CSF). Plerixafor (PL) is a chemokine receptor CXC Type 4-stromal-derived factor 1 inhibitor; its HSC-mobilizing properties are synergistic with G-CSF in poor mobilizing patients. The use of PL as adjuvant or alternative to G-CSF in healthy donors has shown a good safety profile but is so far off-label. STUDY DESIGN AND METHODS: We report 10 healthy HSC donors treated with PL because of insufficient response to G-CSF alone or contraindication to G-CSF. Eight donors did not mobilize enough CD34+ cells with G-CSF alone because poor mobilizers or because insufficient HSCs were harvested according to the clinical need of the patient; in two cases G-CSF administration and marrow harvest were unfeasible or contraindicated in the donor. RESULTS: The use of PL for mobilization increased the number of circulating CD34+ cells by 2.8-fold and the CD34+/kg collection by 3.0-fold. Only mild adverse events were reported (bone pain or discomfort) and not univocally attributable to PL. Rate of engraftment and graft-versus-host disease were similar to those seen in recipients of grafts from G-CSF only-mobilized donors. CONCLUSION: We exposed 10 allogeneic donors to mobilization with PL. PL was well tolerated in all cases and ensured procurement of an adequate graft for transplantation resulting in a normal hematopoietic engraftment.