Optimal chemo-mobilization for the collection of peripheral blood stem cells in patients with multiple myeloma.

Background: For successful autologous stem cell transplantation, the collection of a sufficient number of hematopoietic stem cells after induction therapy is essential for transplant candidates with multiple myeloma (MM).

Methods: In this study, we compared the efficacy and safety of stem cell mobilization using cyclophosphamide (CY; 3.0 g/m on day 1) or etoposide (VP-16; 375 mg/m on days 1 and 2) in patients with MM. Granulocyte-colony stimulating factor (G-CSF, 10 μg/kg/day, subcutaneously) was administered from the onset of neutropenia to the final day of collection.

Results: Sixty-five patients were mobilized with a combination of CY and G-CSF, and 63 were mobilized with a combination of VP-16 and G-CSF. All patients were mobilized within 7 months of beginning frontline treatment. The median number of CD34 cells collected was significantly higher in the VP-16 mobilization group than in the CY mobilization group (27.6 ×  10 CD34/kg vs. 9.6 × 10 CD34/kg, P <  0.001). The rate of mobilization failure, defined as < 2.0 × 10 CD34/kg collected in three apheresis procedures, was lower in the VP-16 group than in the CY group (1.6% vs. 10.8%, P = 0.062). Severe infections during the mobilization period were more frequent in the CY group than in the VP-16 group (18.5% vs. 7.9%, P = 0.117).

Conclusion: In conclusion, an intermediate dose of VP-16 with G-CSF appears to be an effective and tolerable chemo-mobilization method compared to CY and G-CSF, particularly in cases where use plerixafor in MM is difficult.