Safety and efficacy of G-CSF alone with pre-emptive plerixafor for autologous peripheral blood hematopoietic stem cell mobilization in newly diagnosed multiple myeloma.

BACKGROUND

Mobilization failure remains a challenge in autologous stem cell transplantation for multiple myeloma (MM). Chemotherapy-based mobilization protocols, though effective, are associated with toxicity, hospitalization, and delay in transplant timing. We developed an algorithm-based protocol for peripheral blood stem cell (PBSC) mobilization using G-CSF alone, with pre-emptive Plerixafor based on peripheral blood CD34+ cell counts.

METHODS

This retrospective study included MM patients who underwent stem cell collection between July 2013 and November 2023 at Saskatoon Cancer Centre. The mobilization protocol aimed to collect ≥ 4 × 106 CD34+ cells/kg, using daily CD34 count monitoring to determine the use of Plerixafor. Predefined thresholds guided the decision for Plerixafor administration and apheresis timing.

RESULTS

Out of 176 patients (median age 61 years), 100 % achieved successful mobilization. Preemptive Plerixafor was required in 13.6 % of patients (n = 24), with 1-3 doses administered. The median number of apheresis days was 2 (range: 1-4). The median CD34 yield was 6.4 × 106 cells/kg. All patients received high-dose melphalan and underwent autologous transplant, with median neutrophil and platelet engraftment at 12 and 15 days, respectively. All patients were alive at day 100 post-transplant.

CONCLUSION

An algorithm-driven, G-CSF-only mobilization with pre-emptive Plerixafor use based on CD34 counts resulted in 100 % successful collections, early engraftment, minimal plerixafor use, and no mobilization failures. This approach avoids chemotherapy toxicity, optimizes Plerixafor use, and prevents transplant delays.