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Salvage autologous hematopoietic stem cell transplantation (auto-HSCT) constitutes a therapeutic option for a group of well-selected patients with relapsed multiple myeloma (MM). However, if an insufficient number of stem cells were harvested and stored before the first auto-HSCT, stem cells need to be remobilized. Patients diagnosed with MM who following relapse after auto-HSCT, had remobilization and afterward, auto-HSCT with remobilized cells were included in this retrospective analysis. Thirty-three patients, 61% males, the median age 61 years, were included. With a median follow-up of 1.8 years, 2-year progression-free survival was 56.2%, non-relapse mortality 4.8%. The 2-year cumulative incidence of t -MDS was 4.9%. Factors important for the outcome were: the quality of response, previous radiotherapy, the time between the first and salvage auto-HSCT. To conclude, salvage auto-HSCT performed with cells procured after the previous auto-HSCT can be efficacious in relapsed MM, especially if a sufficiently long response had been obtained to the first auto-HSCT(s).

Background: Salvage autologous hematopoietic stem cell transplantation (autoHSCT) may be used to treat relapse of multiple myeloma occurring after previous autoHSCT. When insufficient number of hematopoietic stem cells was stored from the initial harvest, remobilization of stem cells is necessary., Purpose: The analysis of stem cell remobilization after previous autoHSCT., Patients and Methods: Fifty-eight patients, 60% males, median 59 years, were included. Median time interval between autoHSCT and remobilization was 42 months. The first remobilization was performed mostly after chemotherapy: cyclophosphamide (33%), cytarabine (43%), and etoposide (19%)., Results: The first remobilization was successful in 67% patients. About 19% patients required plerixafor rescue, among whom it allowed for successful harvesting in 14%. Use of cyclophosphamide, cytarabine, and etoposide allowed for successful remobilization in 53%, 84%, and 55% patients, respectively. Patients treated with cytarabine had the highest yield of CD34+ cells (median 7.5 × 10 6 /kg vs 5.8 and 2.4 for etoposide and cyclophosphamide, P = .001). Higher percentage of patients was able to collect ≥2 × 10 6 CD34+ cells/kg during one leukapheresis after cytarabine (76% vs 21% for cyclophosphamide vs 36% for etoposide, P = .001). Cytarabine use was associated with lower risk of remobilization failure OR = 0.217, P = .02. Toxicity comprised mostly hematological toxicity (thrombocytopenia and neutropenia). One patient succumbed to septic shock., Conclusion: Remobilization after previous autoHSCT is feasible only in a proportion of patients. Cytarabine is associated with the highest rate of successful mobilization and the highest yield of mobilized CD34+ cells. The toxicity requires careful surveillance of these patients., (© 2021 Wiley Periodicals LLC.)

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]

Introduction: Salvage autologous hematopoietic cell transplantation (auto-HCT) constitutes a therapeutic option for multiple myeloma patients who experience relapse after a previous auto-HCT. When insufficient number of hematopoietic stem cells was stored from the initial harvest, remobilization of stem cells is necessary. The data on the efficacy and safety of different remobilization protocols are scarce, including the data on cytarabine dosing. Material i methods: A retrospective analysis of multiple myeloma patients who experienced relapse after a previous auto-HCT and afterwards underwent remobilization with cytarabine. Results: Sixty-five patients, 55% males, median age at remobilization 63 (37-71) years, were included. 80% patients did have a single, 20% a tandem auto-HCT before remobilization. The median time between the most recent auto-HCT and remobilization was 42 (8-239) months. The total cytarabine dose administered for remobilization was 2400 mg/m² in 29%, 2000 mg/m² in 2%, 1600 mg/m² in 58%, and 800 mg/m² in 11% patients. Plerixafor rescue was used in 23% patients (29% from the group 1600 mg/m², 20% ― 2000-2400 mg/m²). Successful remobilization (>2 × 106 CD34+ cells//kg) was possible in 82% patients; 80% in a group 2000-2400 mg/m², 87% 1600 mg/m², and 57% 800 mg/m². The total yield of CD34+ cells (× 106/kg) after the first remobilization for patients for whom any collection was possible was: 8.22 (0.65-18.49) for cytarabine 2400 mg/m², 4.87 (0.98-33.6%) 1600 mg/m², and 5.36 (1.52-9.07) 800 mg/m². Toxicity was mostly hematological. Remobilization was associated with one death due to septic shock. Conclusion: Remobilization with cytarabine after previous auto-HCT was feasible only in a proportion of patients. Cytarabine dose of 800 mg/m² was associated with the lowest rate of successful remobilization, the group was however small and not rescued with plerixafor. Future research is needed to elucidate whether the 800 mg/m² is similarly efficient to higher doses. [ABSTRACT FROM AUTHOR]