Utilization of Backup Stem Cells for Stem Cell Boost and Second Transplant in Patients with Multiple Myeloma Undergoing Autologous Stem Cell Transplantation: backup stem cell utilization in autologous stem cell transplantation

Abstract Background : Autologous hematopoietic stem cell transplantation (ASCT) is a standard treatment for multiple myeloma (MM). Consensus guidelines recommend collecting sufficient stem cells in case there is need for stem cell boost for delayed/poor engraftment or for future second ASCT. However, collecting and storing backup stem cells in all patients requires significant resources and cost, and the rates of backup stem cell utilization are not well studied Objective : To examine the utilization of backup stem cells (BSCs) in patients with MM undergoing ASCT Study Design : Patients with MM aged ≥18 years old who underwent first ASCT at our institution from January 2010 through December 2015 and collected sufficient stem cells for at least two transplants were included in this single-center retrospective study. This timeframe was selected to allow for adequate follow-up Results : A total of 393 patients were included. The median age was 58 years (range 25-73). After a median follow-up of 6 years, the median mean PFS of the cohort was 3 years. 61% (n = 240) of patients progressed or relapsed. Chemotherapy based mobilization was used in almost all patients (98%). The median total CD34+ cells collected was 18.2 × 106/kg (range 3.4-112.4). A median of 5.7 × 106 CD34+ cells/kg (range 1.8-41.9) were infused during the first ASCT and a median of 10.1 × 106 CD34+ cells/kg (range 1.5-104.5) were cryopreserved for future use. 6.9% (n = 27) of patients utilized backup stem cells, with 2.3% (n = 10) using them for stem cell boost, 4.6% (n = 18) for a second salvage ASCT, including 1 patient for both stem cell boost and second ASCT. Rates of backup stem cell use amongst patients aged Conclusions : With new salvage therapies for relapsed MM, the rates of second ASCT are very low. The low rates of utilization suggest that institutional policies regarding universal BSC collection and long-term storage should be reassessed and individualized. However, need for stem cell boost in 2.3% of patients may present a challenge to that.