Stem Cell Mobilization for Multiple Myeloma Patients Receiving Daratumumab-Based Induction Therapy: A Real- World Experience

For patients with newly diagnosed multiple myeloma (MM) undergoing high-dose chemotherapy and autologous stem cell transplantation (HDT-ASCT), hematopoietic stem cell mobilization can be affected by induction chemotherapy. In clinical trials, the addition of daratumumab (dara) to a triplet backbone lowered hematopoietic stem cell yield, necessitating the administration of plerixafor to achieve the desired yield for ASCT. Here we describe our experience of stem cell mobilization and collection after dara-based and non-dara-based induction regimens. This single-center retrospective analysis included patients with newly diagnosed MM who had received induction chemotherapy and were candidates for upfront HDT-ASCT. Based on the induction regimen used, patients were divided into 2 groups, RVd (lenalidomide, bortezomib, and dexamethasone) and DRVd (RVd with the addition of dara). Based on our institutional practice, patients received pegylated growth colony-stimulating factor (G-CSF) on day -3 (at 0900 hours) in combination with plerixafor on day -1 (at 2300 hours) as a preemptive mobilization strategy. Patients continued apheresis for 1 to 3 days until the goal dose of hematopoietic stem cells was collected (2.5 × 106 cells/kg for one ASCT and 5.0 × 106 cells/kg for 2 ASCTs). Patients with a suboptimal stem cell yield on day 1 received additional doses of plerixafor with or without G-CSF. A total of 101 patients with newly diagnosed MM who underwent mobilization between July 2021 and June 2022 were analyzed. The median patient age was 61 years (range, 36 to 80 years), and 51.5% of the cohort was female. Patients received a median of 5 (range, 2 to 12) cycles of induction chemotherapy, with a median of 4 (range, 2 to 12) cycles of DRVd and 6 (range, 3 to 12) cycles of RVd. The median number of CD34+ cells collected in the DRVd and the RVd groups was 6.54 × 106/kg and 6.78 × 106/kg, respectively. Target CD34+ stem cells were collected in a median of 1 day (range, 1 to 4 day) in each group. On average, more patients in the DRVd group compared to the RVd group received additional doses of plerixafor (51% versus 43%) and additional doses of GCSF (19% versus 14%) to achieve the target stem cell yield. There were no mobilization failures or grade 3+ mobilization-related adverse events reported in either group. The addition of daratumumab to the RVd induction regimen did not lead to any clinically significant differences in stem cell yield or number of collection days, provided that the patient received preemptive G-CSF and plerixafor. Patients with suboptimal collection on day 1 were able to collect adequate stem cells with additional doses of plerixafor with or without G-CSF.