Steady‐state versus chemotherapy‐based hematopoietic cell mobilization after anti‐CD38‐based induction therapy in newly diagnosed multiple myeloma

Background The incorporation of anti‐CD38 monoclonal antibodies (mAb) in induction regimens of newly diagnosed transplant‐eligible multiple myeloma (MM) patients has been established as a new standard. However, the optimal strategy of stem cell mobilization in this context is not yet clear. Study Design and Methods From May 2020 till September 2022, we retrospectively reviewed patients receiving anti‐CD38 mAb‐based induction therapy followed by stem cell mobilization either in a steady‐state protocol (SSM) using 10 μg/kg granulocyte colony‐stimulating factor (G‐CSF) for 5 days or in a chemotherapy‐based protocol (CM) using 1–4 g/m2 cyclophosphamide and G‐CSF. Results Overall, 85 patients (median age 61 years) were included in the analysis. In total, 90 mobilization attempts were performed, 42 with SSM and 48 with CM. There was no significant difference in the median concentration of CD34+ cells in peripheral blood (PB) prior to apheresis between SSM and CM (61/μL vs. 55.4/μL; p = .60). Cumulative CD34+ yields did not differ between the groups with median of 6.68 and 6.75 × 106/kg body weight, respectively (p = .35). The target yield (≥4 × 106 CD34+ cells/kg body weight) was reached in 88% (CM) and 86% (SSM), with a high proportion even after a single apheresis session (76% vs. 75%). Plerixafor was found to be more frequently used in SSM (52%) than in CM (23%; p