Stem Cell Mobilisation Failure in Auto HSCT and Its Factors: A Single Centre Experience.

Objective: To determine the mobilisation failure rate and identify its associated factors in this part of the world in order to identify patients at risk of mobilisation failure and to promptly explore alternative treatment.

Study Design: A descriptive study. Place and Duration of the Study: Department of Clinical Haematology, The Armed Forces Bone Marrow Transplant Centre, Rawalpindi, Pakistan, from January 2014 to July 2023.

Methodology: Clinical records of 115 patients due for autologous haematopoietic stem cell transplantation (auto HSCT) and undergoing mobilisation regimen were analysed. Poor mobilisers were defined as patients who failed to achieve minimum PBSC collection of CD34 >2 x 106/kg of recipient body-weight or required an additional dose of Plerixafor after Cyclophosphamide GCSF mobilisation to achieve the target dose.

Results: Among the mobilisation regimes, 85 (74%) were mobilised with Cyclophosphamide followed by GCSF (Cyclo-G), 28 (24%) with GCSF and Plerixafor (G-Plerixafor), and only 2 (2%) with GCSF alone. After the first mobilisation regimen, 84% of patients achieved PBSC collection of CD34 count of >2 x 10^6/kg. The entire mobilisation failure rate was 16%. Successful stem cell collection was significantly correlated with age, lymphoma group and its transplant indication, previous chemotherapy lines, exposure to the type of myelotoxic medicines, steady-state CD34 count, and use of Plerixafor. However, at multivariate analysis, only use of Plerixafor was found associated with successful mobilisation.

Conclusion: Plerixafor significantly improved mobilisation regimens' yield and cost-effectiveness by greatly increasing mobilisation success rates, particularly in heavily pre-treated lymphoma patients.

Key Words: Haematopoietic stem cell mobilisation, Plerixafor, Lymphoma, Multiple myeloma, Plasma cell dyscrasias.