Comparison of stem cell mobilization methods in multiple myeloma.

Abstract

The advent of novel therapeutic agents has improved the prognosis of multiple myeloma (MM). However, autologous stem cell transplantation (ASCT) remains a key treatment option for eligible patients. While stem cell mobilization using cyclophosphamide and granulocyte colony-stimulating factor (G-CSF) has long been the standard approach, the introduction of plerixafor (PLER) has led to broader adoption of G-CSF±PLER-based mobilization, offering improved scheduling flexibility. Nevertheless, real-world data on current mobilization practices and their effects on post-ASCT outcomes remain limited. We evaluated mobilization strategies and their associations with clinical outcomes in MM patients who underwent ASCT between 2019 and 2022. A total of 3,319 patients were analyzed, including 743 patients mobilized with cyclophosphamide and 2,576 mobilized with G-CSF±PLER. The primary endpoint was 2-year overall survival (OS). Multivariate analysis and propensity score matching were performed to identify factors associated with superior OS. The 2-year OS rates were 89.7% (95% CI: 87.0-91.8) and 93.2% (95% CI: 91.8-94.3) in the cyclophosphamide and G-CSF groups, respectively. Multivariate analysis showed that age <65 years (P < 0.001), lower ISS stage (P < 0.001), good performance status (P < 0.001), G-CSF mobilization (P = 0.005), and deep response pre-ASCT (P < 0.001) were independent predictors of superior OS. Propensity score matching analysis demonstrated significantly better OS in the G-CSF group than in the cyclophosphamide group (P = 0.041). Among patients achieving complete or very good partial response (CR/VGPR) pre-ASCT, OS did not differ between the groups; however, among patients who did not reach CR or VGPR pre-ASCT, the G-CSF group showed significantly better OS than the cyclophosphamide group. G-CSF‒based mobilization may offer prognostic advantages after ASCT, particularly in patients with suboptimal pre-ASCT response.