Stem Cell Mobilization Performed with Different Doses of Cytarabine in Plasma Cell Myeloma Patients Relapsing after Previous Autologous Hematopoietic Cell Transplantation—A Multicenter Report by the Polish Myeloma Study Group.

Simple Summary: Autologous hematopoietic cell transplantation (auto-HCT) can be used to salvage at least a proportion of plasma cell myeloma patients who relapse after a previous auto-HCT. It may, however, occur that there is either no or an insufficient stem cell dose in storage to proceed to transplantation. Remobilization to procure new cells is then required. There are very limited data in the literature concerning the efficacy of stem cell remobilization after previous auto-HCT. In our previous report, we showed that remobilization with cytarabine was associated with a lower risk of remobilization failure in comparison to etoposide or cyclophosphamide. In the current study, we analyze the efficacy and safety of different doses of cytarabine (800, 1600, and 2400 mg/m2), showing that all doses are efficacious but that the dose of 2400 mg/m2 is associated with the most toxicity. Therefore, lower doses of cytarabine seem to be preferable, with plerixafor rescue when needed. Salvage autologous hematopoietic cell transplantation (auto-HCT) may be used to treat relapse of plasma cell myeloma occurring after previous auto-HCT. When an insufficient number of hematopoietic stem cells have been stored from the initial harvest, remobilization is necessary. Here, we aimed to analyze the efficacy and safety of different doses of cytarabine (total 800 vs. 1600 vs. 2400 mg/m2) for remobilization. Sixty-five patients, 55% male, with a median age at remobilization 63 years, were included. Remobilization was performed with cytarabine_800 in 7, cytarabine_1600 in 36, and cytarabine_2400 in 22 patients. Plerixafor rescue was used in 25% of patients receiving cytarabine_1600 and 27% of those receiving cytarabine_2400. Patients administered cytarabine_800 were not rescued with plerixafor. Remobilization was successful in 80% of patients (57% cytarabine_800; 86% cytarabine_1600; 77% cytarabine_2400; p = 0.199). The yield of collected CD34+ cells did not differ between the different cytarabine doses (p = 0.495). Patients receiving cytarabine_2400 were at the highest risk of developing severe cytopenias, requiring blood product support, or having blood-stream infections. One patient died of septic shock after cytarabine_2400. In summary, remobilization with cytarabine is feasible in most patients. All doses of cytarabine allow for successful remobilization. Cytarabine_2400 is associated with higher toxicity; therefore, lower doses (800 or 1600 mg/m2) seem to be preferable. [ABSTRACT FROM AUTHOR]