Experience with plerixafor for hematopoietic cell mobilization in nine patients with germ cell tumors.

STUDY OBJECTIVE To evaluate the efficacy of plerixafor as a just-in-time therapy for patients with germ cell tumors who were identified as poor hematopoietic cell mobilizers after the initiation of apheresis. DESIGN Case series. SETTING National Cancer Institute-designated cancer center. PATIENTS Nine patients with germ cell tumors who received plerixafor as an adjunct to granulocyte colony-stimulating factor (G-CSF) for hematopoietic cell mobilization in an attempt to prevent mobilization failure between January 2009 and December 2012. MEASUREMENTS AND MAIN RESULTS Patients were heavily pretreated, having received at least four prior treatment cycles. A median of three total apheresis days (range 1-4 days) was required for all patients, but a median of two apheresis days (range 1-2 days) was needed after the initiation of plerixafor. A median of 0.9 x 10(6) CD34(+) cells/kg (range 0.3-1.5 x 10(6) CD34(+) cells/kg) was harvested with G-CSF mobilization alone; in addition, a median of 2.6 x 10 6 CD34(+) cells/kg (range 0.6-32 x 10(6) CD34(+) cells/kg) was harvested using plerixafor. All nine patients received high-dose carboplatin and etoposide followed by hematopoietic cell transplantation. The median time to neutrophil engraftment was 11 days (range 8-12 days). The median time to platelet engraftment was 16 days (range 10-22 days). CONCLUSIONS The use of plerixafor in addition to G-CSF as just-in-time therapy permits patients with germ cell tumors to pursue potentially curative therapy with high-dose chemotherapy followed by autologous stem cell rescue.