Hematopoietic Stem Cell Collection in Multiple Myeloma Patients: Influence of the Lenalidomide-Based Therapy and Mobilization Regimen Prior to Auto-HSCT

Abstract

Background. A prompt graft acceptance is essential for positive autologous hematopoietic stem cell transplantation (auto-HSCT) outcome in multiple myeloma patients (MM). Prompt and favourable hematopoietic regeneration is associated with CD34+ cell count in a transplant. Although the indicators of low autotransplant cellularity have been defined, the practical application of new drug products and HSC mobilization regimens strengthens the relevance of determining their influence on the transplant quality. Aim. To determine the factors that are associated with low efficacy of auto-HSCT in MM patients and to evaluate the impact of lenalidomide during induction period and of vinorelbine as a mobilization regimen on the prognosis. Materials & Methods. The authors performed a retrospective analysis of autotransplant collection results in 68 MM patients treated with two mobilization regimens: 3 g/m² cyclophosphamide with granulocyte colony-stimulating factor (G-CSF) and 30 mg/m² vinorelbine with G-CSF. Mobilization was aimed at collecting not less than 2-4 х 10⁶ CD34+ cells per kg body mass. CD34+ cell count was determined by four-color analysis on the Cytomics FC 500 laser flow cytometer. Results. The analysis showed that age or MM immunochemical specificity were not associated with CD34+ cell count in the transplant. Prior lenalidomide treatment compared to therapy without immunomodulators (4.1 х 10⁶/kg vs. 7.76 х 10⁶/kg) tends to decrease CD34+ count (р = 0.066). Cyclophosphamide included into mobilization regimen compared to vinorelbine (3.96 х 10⁶/kg vs. 6.8 х 10⁶/kg) significantly increased CD34+ cell count (р = 0.022). Conclusion. The decrease of CD34+ cell count in the autotransplant of the MM patients treated with lenalidomide prior to auto-HSC collection, and a lower mobilization activity of vinorelbine provide a basis for a differentiated selection of mobilization regimens. Vinorelbine may be administered to patients with a single auto-HSCT, i.e. elderly people and patients with complete response. In case of substantial lena-lidomide treatment prior to auto-HSCT, intermediate-dose cyclophosphamide is preferred.