P-322: Non-Cryopreserved Stem Cell Transplantation in Multiple Myeloma (MM) Patients: A Case Series Report

Introduction: Despite numerous recent advancements in therapies for multiple myeloma, stem cell transplantation remains an effective and critical treatment. Recent studies indicate that the use of non-cryopreserved cells is both safe and effective, and could simplify the transplantation process, especially in resource-limited settings by eliminating the need for cell freezing. This approach may also reduce treatment-related complications while preserving cell functionality. This study aims to evaluate the outcomes of non-cryopreserved stem cell transplant, focusing on the procedural feasibility and initial clinical outcomes in a retrospective cohort of MM patients.

Methods: We analyzed data from multiple myeloma (MM) patients who underwent autologous stem cell transplantation (ASCT) between January 2022 and July 2023. Patients were mobilized using G-CSF, and stem cell collection was planned on the fourth day, guided by peripheral CD34+ cell counts. In cases of mobilization failure, plerixafor was administered according to institutional protocols. Collected cells were preserved for up to 48 hours at a controlled temperature of 4°C (±2°C) and were infused 24 hours after a single-dose 200 mg/m² melphalan infusion.

Results: Thirty-five patients were treated between April 2021 and July 2023. The median age was 59 years (range: 44-69). The male-to-female ratio was 1.3:1. Procedural adherence was achieved in all cases, with no patient requiring cryopreservation of the cells. The average number of collected and infused stem cells was 5.02 x 10^6 cells/kg (range: 2.92-10). All patients demonstrated successful marrow engraftment, except for one 63-year-old female who experienced sudden cardiovascular death on day +9 post-transplant. All other patients were alive at day +100 post-transplant. The median number of days to neutrophil engraftment was 10 (range: 9-12), with a typical hospital stay of 19 days (range: 14-26).

Conclusions: This case series demonstrates that non-cryopreserved stem cell transplantation is a viable and effective option for multiple myeloma patients, with engraftment and hospitalization durations comparable to traditional methods. The successful implementation of this technique in a resource-limited setting, without the need for cryopreservation, underscores its potential to simplify the transplantation process while maintaining safety and efficacy standards.