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

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).

In this study, we compared the efficacy and safety of stem cell mobilization using cyclophosphamide (CY; 3.0 g/m² on day 1) or etoposide (VP-16; 375 mg/m² 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.

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 ×  10⁶ CD34⁺/kg vs. 9.6 × 10⁶ CD34⁺/kg, P <  0.001). The rate of mobilization failure, defined as < 2.0 × 10⁶ 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).

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.