Clinical experience with plerixafor as a mobilization regimen for autologous peripheral blood stem cell transplantation in patients with refractory germ cell tumors.

The purpose of this study was to report our experience with administration of plerixafor for the mobilization of hematopoietic stem cells (HSCs) in patients with refractory or recurrent germ cell tumors who were candidates for salvage therapy with high-dose chemotherapy and HSC transplantation and for whom mobilization of HSCs had not been achieved by standard therapies. This retrospective and observational study selected patients who were eligible for autologous HSC transplantation (AHSCT) and received plerixafor after failure of HSC mobilization by granulocyte colony-stimulating factor (G-CSF). A total of 5 patients (4 male and 1 female), aged 19-41 years (mean age, 29.6 years) were initially selected. Four patients (80%) achieved an adequate HSC mobilization with plerixafor and subsequently received high-dose chemotherapy followed by HSC transplantation. In these patients, the number of CD34+ cells collected following plerixafor mobilization was 1.8×106-10.3×106 cells/kg, with a peak CD34+ cell count of 7.0-32.0 cells/μl. Following HSC infusion, these 4 patients achieved a neutrophil count of >0.5×103/mm3 and a platelet count of >20,000/μl between days 10 and 14. Therefore, patients with high-risk germ cell tumors eligible for AHSCT who are refractory to mobilization by G-CSF, may benefit from the use of plerixafor, possibly to the same extent as patients with lymphoma and multiple myeloma.