Work

Effect of Prior Daratumumab Treatment on Hematopoietic Progenitor Cell Mobilization in Newly Diagnosed Multiple Myeloma

Year: 2025

Type: article

Abstract: Introduction Hematopoietic progenitor cell (HPC) mobilization has been shown to be affected by prior induction therapy. The monoclonal CD38 antibody daratumumab (dara) has been increasingly used as part of frontline treatment or salvage therapy in patients with new multiple myeloma (MM) who are eligible for autologous hematopoietic cell transplantation (HCT). It has been previously suggested that patients treated with dara have decreased yield of HPC mobilization. However, there has been significant variability in these results among institutions. More data are needed to clarify how treatment with dara affects mobilization in these patients. Objectives In this study, we analyze mobilization outcomes at our institution for patients who received dara as part of induction therapy compared to those who did not. Methods We retrospectively collected HPC mobilization data on patients undergoing HCT for MM from 1/1/2024 to 7/2/2024 at our institution. All patients were mobilized with G-CSF ± plerixafor based on institutional protocol. For each patient we determined the day 1 CD34 yield, total CD34 yield, number of apheresis sessions, doses of daratumumab , and mobilizing regimen. Student's t-test or Wilcoxon rank sum test were used to compare numeric variables. Fisher's exact test was used to compare the choice of mobilization regimen. Results 53 patients with MM underwent HPC mobilization from 1/1/2024 to 7/2/2024. Of these, 37 had previous treatment with dara and 16 did not. The CD34 collection target at our institution is 4 × 10^6 / kg CD34 cells with a minimum of 2 × 10^6 / kg to proceed. Median day 1 CD34 collection was 0.92 × 10^6 / kg (IQR 0.38, 1.6) for patients who received dara and 2.3 × 10^6 / kg (IQR 0.78, 3.8) for those who did not (p = 0.02). Total CD34 collection was 3.5 × 10^6 / kg (SD = 1.9) on average for the dara group and 4.2 × 10^6 / kg (SD = 1.6) for the no dara group (p = 0.22. The dara group required on average 2.5 days (SD = 0.99) of apheresis to complete collection while the no dara group required 1.9 (SD = 0.89) days on average (p = 0.02). There was no significant difference in mobilization regimen. 29.7% (11/37) of the dara group were mobilized with G-CSF + plerixafor while 18.8% (3/16) of the no dara group were mobilized with this regimen (p = 0.51). Patients who received dara received a median of 6 doses (Range = 1, 32). Conclusion We show that patients who received induction therapy with dara collected significantly fewer CD34 cells on day 1 and required significantly more days to complete collection. Our present institutional mobilization algorithm is relatively conservative in regards to upfront plerixafor and does not take prior treatment with dara into account. The results described here argue for strong consideration of upfront plerixafor in patients who have received induction therapy with dara, especially with the recent implementation of generic plerixafor which has reduced cost.

Source: Transplantation and Cellular Therapy

DOI: 10.1016/j.jtct.2025.01.302