Mobilization regimen, including Plerixafor, does not impact CD34 recovery after automated post-thaw processing

Abstract

Background & Aim Autologous Hematopoietic stem cell (HSC) transplantation is still widely used to overcome hematologic toxicity after high dose chemotherapy for patients with hematological malignancies such as multiple myeloma or lymphoma among others. In most cases, HSC are collected by apheresis after an appropriate mobilization regimen. At our institution, cryopreserved autologous grafts are thawed and washed before infusion. All these processing steps can be performed manually or via automated processes or devices. We aimed to evaluate the impact of mobilization regimen on rh-G-CSF or Plerixafor graft quality when using standardized, automated processes. Methods, Results & Conclusion Methods Between 2016 and 2019, 535 patients received an autologous transplant at our institution. From this cohort, we extracted 260 patients (n=170 myeloma and n=90 myeloma) for whom processing of the apheresis product was comparable, i.e. cryopreservation the same day of the HSC procurement in 2 bags, standardized thawing using Smartmax followed by automated washing using the Sepax-2. Among this cohort, 90 patients (n=75 myeloma and n=15 lymphoma) received Plerixafor + rh-G-CSF as a mobilization regimen, and 170 patients (n=95 myeloma and n=75 lymphoma) received a standard regimen (either rh-G-CSF alone or rh-G-CSF in addition to chemotherapy for lymphoma). Measurable outputs were CD34+ cells/ kg before and after thawing, CD34+ cells recovery and viability, CD45+ cells/kg, neutrophils and myelemia before cryopreservation and CD45+ cells viability after thawing. Results Apheresis products collected from patients mobilized with Plerixafor versus rh-GCSF showed lower HSC content (3,2 × 106/kg versus 5 × 106/kg respectively) and lower myelemia (7 × 106/kg versus 12,9 × 106/kg respectively, p=0.005). Total CD45+ and neutrophils contents were similar (median 50 × 109 and 3 × 109 respectively, p = NS). CD45+ and CD34+ viabilities were comparable between the two regimen (around 83% and 85% respectively p = NS). For both groups, viable CD34+ cells recovery was similar (median 79% for the plerixafor group versus 76% for the rh-G-CSG group p = NS). Conclusions Our data show that CD34+ cells recovery is not affected by the nature of mobilization agents when using standardized automated processing post-cryopreservation.