ABSTRACT
Background: The use of cryopreservation for stem cell grafts for both autologous stem cell and allogeneic cord blood transplant has been utilized for years. For other allogeneic stem cell transplant sources, the use of fresh collected grafts has been preferred due to concerns that cryopreservation may result in impaired graft function. With the onset of the COVID-19 pandemic a shift was made at our institution to exclusive use of cryopreservation Methods: In this retrospective single-center analysis a total of 133 patients undergoing allogeneic stem cell transplant at the University of Minnesota between 1/2018-6/2021 for a variety of malignancies were included, with 62 patients receiving fresh stem cell product and 71 patients receiving frozen stem cell product. Univariate statistical analysis was performed. Result(s): There was no significant difference between the two groups with regards to product type, sex, age, diagnosis (acute leukemia vs other), disease risk index, conditioning regimen, Karnofsky score, co-morbidity index, or cell dose (Table 1). Donor type was notably different between the two groups (p<0.01): matched sibling grafts were more commonly used for fresh products than frozen (85% vs. 35%), while matched unrelated donors were used more frequently for frozen than for fresh products (54% vs. 6%). Use of frozen product was associated with delayed neutrophil and platelet engraftment compared to fresh (median days to engraftment 15 vs 12 for neutrophils, 23 vs 17 for platelets, p<0.01 for both). Two-year relapse rates were significantly lower for frozen products (4%) than fresh (24%) (Table 2). This may be partially attributable to differences in follow up between the groups, as fresh products had a total of 910 days of follow up vs 432 for frozen products (P<0.0001). The difference in follow up remained statistically significant if the data was censored at 730 days (P<0.0001). Of note, the use of frozen products was associated with a lower rate of chronic graft-versus-host disease at one year post-transplant (p<0.01). There was no significant difference in the rates of acute GVHD between the groups. There were significant differences in GVHD prophylaxis regimens between the fresh and frozen groups (p<0.01). (Figure Presented)Two-year overall survival did not differ between groups (p=0.96). Conclusion(s): Use of cryopreserved stem cell products is associated with similar efficacy and outcomes as those seen with the use of fresh stem cell products. Although the data presented here suggest novel finding of decreased risk of relapse and chronic GVHD with the use of frozen stem cell products, additional follow up may abrogate these differences. Regardless, the logistical benefits of cryopreservation make this an attractive option for continued use in allogeneic transplants and our data presented here suggests that cryopreserved products remain an appropriate option for allogeneic stem cell transplant.Copyright © 2023 American Society for Transplantation and Cellular Therapy