Discussion
multiple myeloma, bone marrow toxicity, MM
MULTIPLE MYELOMA, LYSING, BONE MARROW TOXICITY
This academic single centre study provides novel data on the impact of different state-of-the-art induction regimen on PBSC mobilization and collection metrics in patients with newly diagnosed MM. While several factors have been described as being harmful to PBSC collection [Quadruplet induction therapies such as daratumumab, lenalidomide, bortezomib, and dexamethasone (Dara-RVd) or daratumumab, bortezomib, thalidomide, and dexamethasone (Dara-VTd) are now standard-of-care for transplant-eligible patients with newly diagnosed multiple myeloma [In the phase II GRIFFIN trial, lower stem cell yield (8.3 versus 9.4 × 10In contrast to the data on daratumumab, our results suggest that isatuximab does not increase the risk for relative collection failure although the total number of collected stem cells is lowered. Furthermore, utilization of plerixafor was required in a minority of patients (34%) and upfront application to all patients might not be necessary after 18 weeks of isatuximab-RVd, thus limiting the economic burden of this regimen. However, a direct comparison between daratumumab and isatuximab regarding stem cell collection yield cannot be drawn from our data. The observation is in line with an extensive in vitro study, in which isatuximab did not induce bone marrow toxicity in vitro while effectively lysing MM cells [This study also aimed to compare induction regimen in newly diagnosed MM patients receiving lenalidomide in either a standard regimen (4 cycles, 25 mg/day for 14 days) or a prolonged regimen (6 cycles, 25 mg/d for 14 days). No significant differences regarding PBSC mobilization and collection metrics were observed in our study. The previously reported data on lenalidomide treatment prior to PBSC collection reveals contradictory results. Initially, Kumar et al. suggested a negative impact of lenalidomide on stem cell collection in patients treated with lenalidomide-dexamethasone [The SLAMF7 antibody elotuzumab is an established therapeutic option in relapsed MM [Limitations of our study include its single centre design and its retrospective nature. While patients were treated within randomized trials, stem cell collection was not an endpoint of either trial. Comparisons with outcomes in other trials or other centres might therefore be impaired. The collection results presented represent outcomes after quadruplet therapy followed by cyclophosphamide-based mobilization chemotherapy and might not be transferable to steady-state mobilization.