Cryopreserved versus fresh peripheral blood allogeneic stem cell transplantation outcomes in patients receiving post-transplant cyclophosphamide for graft-versus-host prophylaxis during the COVID-19 pandemic: a single center experience

A Retrospective Analysis of Fresh versus Cryopreserved Allogenic Bone Marrow Transplant within a Pediatric Population: A Change in Practice Due to the COVID-19 Pandemic

BACKGROUND

Several adult studies show mixed reports in clinical outcomes between cryopreserved and fresh stem cell products, with majority reporting no significant differences and others report that there are differences in outcomes. There is limited literature reporting its impact on outcomes in pediatric hematopoietic cell transplantation (HSCT).

OBJECTIVE

To compare clinical outcomes between fresh vs cryopreserved stem cell treatment in pediatric HSCT.

STUDY DESIGN

A retrospective chart review was conducted on allogenic HSCT at Phoenix Children's Hospital between January 1, 2016, and March 31, 2023. The study included 181 patients, with 105 receiving fresh stem cell products and 76 receiving cryopreserved products. Clinical outcomes including, neutrophil and platelet recovery, graft versus host disease, immune reconstitution and survival outcome were compared.

RESULTS

Study subjects had median follow-up of 997 (range 12-2642) days. 92 patients were treated for a malignant disease (leukemia/lymphoma) and 89 were treated for a non-malignant disease (hemoglobinopathies, immunodeficiency/immune dysregulation, and bone marrow failure). 124 stem cell products were from bone marrow and 57 were from peripheral blood. Comparisons between fresh vs cryopreserved treatments found no significant difference in days to neutrophil engraftment (P = .47) or platelet engraftment (p=0.94). No difference in the incidence of acute graft versus host disease or chronic graft versus host disease (p = 0.70) between both groups. Immune reconstitution at 365 days post-transplant did not vary significantly between treatment groups for CD4+ T cells, CD8+ T cells, CD19+ B cells, and CD56/16+ NK cells. Overall survival at 2 years was similar in the fresh vs cryopreserved (86.7% vs 84.2%; P = .64).

CONCLUSION

These observations suggest that cryopreserved stem cell product is a reasonable alternative with comparable efficacy and potentially offering logistical advantages. Further research with larger pediatric cohorts is recommended to confirm non-inferiority of cryopreserved treatments in pediatric HSCT.

Pros and Cons of Cryopreserving Allogeneic Stem Cell Products

The COVID-19 pandemic has precipitously changed the practice of transplanting fresh allografts. The safety measures adopted during the pandemic prompted the near-universal graft cryopreservation. However, the influence of cryopreserving allogeneic grafts on long-term transplant outcomes has emerged only in the most recent literature. In this review, the basic principles of cell cryopreservation are revised and the effects of cryopreservation on the different graft components are carefully reexamined. Finally, a literature revision on studies comparing transplant outcomes in patients receiving cryopreserved and fresh grafts is illustrated.

The effect of cryopreservation on engraftment kinetics in fully matched allogeneic stem cell transplantation: Real-life data and literature review

INTRODUCTION

The standard approach for allogeneic stem cell transplantation (allo-SCT) is to administer donor cells on the same day as a fresh product to a patient who has been given a preparative regimen. The difficulty in collecting and transporting donor cells, especially during the COVID-19 pandemic, has made it essential to collect and cryopreserve the grafts before the recipient begins the transplant preparation regimen. However, the short- and long-term impacts of cryopreservation on transplant outcomes remain controversial.

MATERIALS AND METHODS

This retrospective study included 93 patients who underwent allo-SCT between January 2012 and August 2022 at the Stem Cell Transplant Unit of Bursa Uludag University Faculty of Medicine using frozen and fresh products of peripheral blood stem cells from a fully matched sibling donor. The effect of cryopreservation of donor grafts on engraftment kinetics was investigated.

RESULTS

Frozen and fresh products were used in 37 and 56 patients, respectively. The majority of patients had acute myeloid leukemia and acute lymphoblastic leukemia. The median age at transplantation was 41 years. Neutrophil engraftment time was similar between the two groups (median: 14 vs. 16 days, p = 0.393). Platelet engraftment time was longer in the frozen product group (median: 12 vs. 15 days, p < 0.001). There was no statistically significant difference between freezing time and viability. The acute graft-versus-host disease (GVHD) rate was 37.8 % in the frozen product group and 28.6 % in the fresh product group (p = 0.349). There was no significant difference between the two groups in terms of primary and secondary graft failure, chronic GVHD, 30-day chimerism, relapse, overall survival, progression-free survival, and nonrelapse mortality.

CONCLUSION

Having donor cells ready before transplantation significantly prevents donor-induced adverse events and provides confidence and practicality to both the clinician and the recipient. Allo-SCT with frozen products is a successful method that can be safely applied, especially when disruptions in donor-derived cell collection or transportation are foreseen.

Fresh or frozen grafts for allogeneic stem cell transplantation: conceptual considerations and a survey on the practice during the COVID-19 pandemic from the EBMT Infectious Diseases Working Party (IDWP) and Cellular Therapy & Immunobiology Working Party (CTIWP)

The COVID-19 pandemic has had a significant impact on medical practices, including the delivery of allogeneic hematopoietic cell transplantation (HCT). In response, transplant centers have made changes to their procedures, including an increased use of cryopreservation for allogeneic haematopoietic progenitor cell (HPC) grafts. The use of cryopreserved grafts for allogeneic HCT has been reviewed and analysed in terms of potential benefits and drawbacks based on existing data on impact on cell subsets, hematological recovery, and clinical outcomes of approximately 2000 patients from different studies. A survey of European Society for Blood and Marrow Transplantation centers was also conducted to assess changes in practice during the pandemic and any unnecessary burdens on HPC donors. Before the pandemic, only 7.4% of transplant centers were routinely cryopreserving HPC products, but this percentage increased to 90% during the pandemic. The results of this review and survey suggest that cryopreservation of HPC grafts is a viable option for allogeneic HCT in certain situations, but further research is needed to determine long-term effects and ethical discussions are required to balance the needs of donors and patients when using frozen allografts.