P1358: WILL COVID-19 PANDEMIC CHANGE MOBILIZATION STRATEGY OF HEMATOPOIETIC STEM CELLS IN MULTIPLE MYELOMA PATIENTS FOR THE BETTER?

Abstract

Background: Autologous hematopoietic stem cell transplantation (ASCT) is the current standard of care for younger patients (pts) with multiple myeloma (MM), improving overall survival (OS) and progression free survival (PFS). According to EBMT, use of chemotherapy, typically cyclophosphamide (Cy), in combination with granulocyte colony-stimulating factor (G-CSF) is the preferred strategy for hematopoietic stem cell (HSC) mobilization to peripheral blood (PB). However, major disadvantages are therapy-related toxicity and higher mobilization failure. Plerixafor plus G-CSF has been shown to be superior to G-CSF alone, leading to higher CD34+ yields in fewer apheresis sessions; however there are few data in comparison to chemomobilization. Since the beginning of COVID-19 pandemic, our center adopted G-CSF ± Plerixafor as initial strategy to mobilize HSC in MM pts. Aims: To evaluate the efficacy, length of hospitalization and safety of G-CSF ± Plerixafor mobilization of HSC in MM pts, compared to chemomobilization. Methods: We performed a retrospective study of MM pts submitted to mobilization and 1st ASCT between 2018 and 2021. Pts who underwent mobilization with Cy (1.5 g/m2) plus pegylated G-CSF were included in group A; pts who received G-CSF ± Plerixafor were included in group B. Group B only received Plerixafor if they presented PB CD34+ cells < 15/mL on day 4 of mobilization with G-CSF. Results: We identified a total of 126 pts, excluded 4 (2 under hemodialysis and 2 receiving different protocols) and included 122 pts, 83 (68%) in group A and 39 (32%) in group B. Demographic characteristics and disease stage (ISS and R-ISS) were similar between the groups, presenting a male predominance (n=73, 60%) and a median age of 61 years. Since frontline protocol in MM changed recently, induction therapy in group A and B was, respectively, VCD 60 vs 26%; VRD 30 vs 75%; VTD 10 vs 0% (P<0.001). No differences were observed in pre-ASCT quality of responses (89.2 vs 89.7% ≥VGPR; P=0.532). The impact of apheresis in terms of length of hospitalization (4 vs 2 days, P<0.001) and median time from the 4th day of mobilization with G-CSF until first apheresis was lower in group B; 2 vs 1 days, P<0.001). There was no difference in the number of apheresis sessions (1 vs 1; P=0.260). The volume of DMSO was higher in group B (22 vs 30 mL, P=0.001). In group B, 16 (41%) pts did not need Plerixafor and there were no differences in length of hospitalization or the number of apheresis sessions compared with those who received Plerixafor. Mobilization failure was only seen in group A, (n=14, 17%, P=0.006). Poor mobilizers were remobilized with G-CSF + Plerixafor and presented longer hospitalization (4 vs 2 days, P=0.001) and number of apheresis sessions (2 vs 1 days, P=0.001) when compared to group B. During mobilization, grade ≥3 complications were observed in 8.4% (n=3) in group A, being febrile neutropenia the most frequent; mobilization was interrupted in 2 pts. All pts presented neutrophil and platelet engraftment and there was no difference in time of engraftment after ASCT between groups A and B (12 days in both, P=0.711). No differences were observed in PFS (74.5 vs 40 months, HR 0.8[0.2-2.9], P=0.782) or OS (82.6 vs NR, HR 1.1[0.2-6.0], P=0.839) between groups. Summary/Conclusion: The mobilization protocol changed, due to COVID-19 pandemic, from chemomobilization to G-CSF ± Plerixafor and resulted in less hospital resource utilization and less febrile neutropenia, without compromising ASCT success. Unlike prior reports, number of apheresis sessions after mobilization with G-CSF alone was similar to G-CSF + Plerixafor.