BACKGROUND

A combination of chemotherapy plus granulocyte-colony-stimulating factor (G-CSF) (chemomobilization) is commonly used to mobilize CD34+ cells to circulation. Plerixafor, a chemokine CXCR4 antagonist, increases the mobilization of CD34+ cells and may also have effect on graft composition.

STUDY DESIGN AND METHODS

We have analyzed lymphocyte subsets in grafts collected on the next morning after plerixafor injection in 13 chemomobilized patients with non-Hodgkin's lymphoma (NHL) mobilizing poorly. As controls we had the first leukapheresis products from 11 NHL patients mobilized with chemotherapy plus G-CSF. The analyses were performed from cryopreserved apheresis products.

RESULTS

The median counts of both total CD3+ T cells and natural killer (NK) cells (CD3-CD16/56+) in the graft were significantly higher in plerixafor-treated group compared to the control group. Both helper T-lymphocytes (CD3+CD4+) and suppressor T-lymphocytes (CD3+CD8+) were significantly increased in the plerixafor-treated group so that CD4+/CD8+ ratio in the graft did not differ between the groups. CD19+ cells were evident only at very small amounts in few patients in both groups, and the CD34+ cell content of the graft did not differ between the groups. Engraftment after high-dose therapy was comparable between the groups.

CONCLUSION

Plerixafor added to chemomobilization in poor mobilizers seems to mobilize more T cells and NK cells than chemomobilization. Larger patient numbers and longer follow-up is needed in regard to evaluate posttransplant complications and risk of relapse in patients receiving plerixafor due to poor mobilization.