Effect of the Amount of Autologous Hematopoietic Stem Cells on Survival and Engraftment in Multiple Myeloma

Autologous stem cell transplantation (ASCT) is currently a gold standard treatment for eligible multiple myeloma (MM) patients. The recommended dose of CD34+ hematopoietic progenitor cells (HPCs) for adequate engraftment is above 2 × 106 cells/kg.

This study aimed to evaluate the relationship between the number of CD34+ HPCs and the survival in MM patients who underwent ASCT in the Hematology Department of Abdurrahman Yurtaslan Ankara Oncology Training and Research Hospital, Ankara, Turkey.

The statistical population of this consisted of 200 MM patients who underwent ASCT within 2009-2019. The clinical characteristics of the patients, disease status pre-SCT, number of infused CD34+ cells, neutrophil, and platelet engraftment days were recorded. The patients were divided into two groups, based on whether the re-infused CD34+ HPCs dose was < 5 × 106 cells/kg (Group 1) or ≥ 5 × 106 cells/kg (Group 2). The groups were compared in terms of engraftment and overall survival (OS) times.

A total of 200 patients were included in our study. Group 1 (n=125) included patients with < 5 × 106 cells/kg CD34+ HPC re-infusion, and Group 2 (n=75) consisted of patients with ≥ 5 × 106cells/kg CD34+ HPC re-infusion. The patients’ median age scores in Group 1 and Group 2 were 57 (25-71) and 56 (33-72) years, respectively. The median follow-up period was 33 months (6-130). The median OS of all patients was 71 months (95% confidence interval, 59.1-82.9). The median neutrophil and platelet engraftment times were similar between the groups (P=0.4 and P=0.4, respectively). In both groups, the median OS time was 71 months (P=0.8), which was similar.

The greater number of CD34+ HPCs re-infusion for ASCT after high dose melphalan chemotherapy in MM patients did not affect platelet and neutrophil engraftment time and OS; therefore, this amount of reinfusion was not required.