Stem cell mobilization in patients with dialysis-dependent multiple myeloma: Report of the Polish Myeloma Study Group.

INTRODUCTION: High-dose chemotherapy with autologous hematopoietic stem cell transplantation (auto-HSCT) improves the outcome of patients with multiple myeloma (MM). It seems that auto-HSCT is also a feasible therapeutic option in MM dialysis-dependent (MMDD) patients. However, to perform transplantation, a sufficient number of stem cells must be collected.

MATERIALS AND METHODS: Given that data on mobilization of auto-HSC efficacy and safety in dialysis-dependent patients are limited, we report data from all Polish Centers belonging to the Polish Myeloma Study Group. Twenty-eight dialysis-dependent MM-patients were enrolled into this retrospective analysis. The study population comprised patients diagnosed between 2004 and 2015 in whom an attempt to collect auto-HSC was made (68%: women, median age: 56). Patients received granulocyte-colony stimulating factor (G-CSF) alone or in combination with chemotherapy and autologous peripheral blood stem cells (auto-PBSCs) were collected by leukapheresis.

RESULTS AND CONCLUSIONS: The success rate in terms of obtaining sufficient number of CD34(+) cells/kg for an auto-HSCT (≥2 × 106 cells/kg body weight) during the first mobilization attempt was 92% (26/28 patients), and for 2 auto-HSCTs (≥4 × 106 cells/kg) - was 75% (21/28 patients). After the second mobilization attempt (undertaken in 8 patients), a sufficient number of CD34(+)/kg cells for an auto-HSCT was obtained for all patients and the number of CD34(+)/kg collected cells was sufficient for 2 auto-HSCT in 6 additional patients. Hematologic toxicity and infections were the most frequent complications. Higher doses of cytarabine (>1.6 g/m2 ) and cyclophosphamide (> 2 g/m2 ) should be avoided in MMDD patients due to toxicity. Further studies are needed to establish mobilization regimens, confirm their safety, and dosing in MMDD patients.