ABSTRACT
Background & Aim: During the COVID pandemic the National Marrow Donor Program® (NMDP)/Be The Match® required cryopreservation of unrelated hematopoietic stem cell (HPSC) products prior to initiation of recipient conditioning to minimize risks associated with logistical complications. Transplant centers are still evaluating cryopreservation associated risk factors due to reported concerns on poor postthaw graft quality compared to fresh products. We evaluated the effect of cryopreservation on engraftment outcomes. Methods, Results & Conclusion: Data from patients receiving either unrelated HPSC fresh or cryopreserved products obtained through the NMDP were included in this study. There were 43 fresh infusions during (Table Presented) during 2019 and 54 cryopreserved infusions between January 2020 and January 2022. Neutrophil and platelet engraftments were our primary endpoints. Absolute neutrophil count (ANC) recovery was defined as an ANC of ≥ 0.5×109/L for three consecutive laboratory values obtained on different days. While platelet engraftment was determined as the first day of three consecutive measurements, obtained on different days, where the platelet count is ≥ 20×109/L without a platelet transfusion in the previous seven days. Medians for two unpaired groups were compared by using Mann-Whitney U test. Two-sided p-values < 0.05 were considered statistically significant. Of the total of fresh transplants, 62.8% of patients underwent reduced intensity conditioning (RIC) while 37.2% underwent myeloablative conditioning (MAC). Regardless of the diagnosis category and in accordance with the American Society of Blood and Marrow Transplantation (ASBMT) Standardized Request for Information (RFI), 11.6% of recipients were classified as a high risk, 20.9% as an intermediated risk, 41.9% as a low risk and 25.6% unclassified. Whereas 52.8% of patients who received cryopreserved products underwent RIC and 47.2% underwent MAC;according to ASBMT-RFI classification, 18.9% were considered as a high risk, 24.5% as an intermediated risk, 41.5% as a low risk and 15.1% unclassified. Engraftment characteristics for both groups of patients is summarized in Table I. No statistically significant differences in engraftment were observed. Our analysis suggests that compared to outcomes of fresh product transplantation, cryopreservation does not negatively effect allograft quality in terms of neutrophil and platelet engraftment.
ABSTRACT
Background & Aim: Prior to the COVID-19 pandemic, allogeneic transplants were typically performed with fresh hematopoietic stem cell (HPSC) products. Unrelated donor (UD) cells are obtained through the National Marrow Donor Program (NMDP). The logistics for coordinating collection, transport, and delivery of fresh products with preconditioning of recipients is complicated under the best circumstances. The pandemic created uncertainty and disruptions in the UD HPSC process. In March 2020 the NMDP required cryopreservation of UD HPSC products, with rare exceptions, prior to patient conditioning. The impacts of cryopreservation on allogeneic HPSC engraftment are not well defined and conflicting outcomes based on transport time and cell concentration have been published. We aimed to determine if cryopreservation, transport time and pre-processing cell concentration negatively impacted patient engraftment. Methods, Results & Conclusion: Methods: Between July 2021 and January 2022, we analyzed UD HPSC products from 24 patients for CD34+ pre- and post-thaw cell recovery and viability based on transit time and pre-processing cell concentration. Transit time, defined as the interval from end of collection to start of processing, was divided into 3 cohorts: 1-20 h, 21-40 h, and >40 h. Pre-processing nucleated cell counts were divided into 2 cohorts: <200 x106 cells/mL and >200 x106 cells/mL. Neutrophil and platelet engraftment data were obtained from the patients’ medical record. Medians for 2 unpaired groups were compared by using Mann-Whitney U test. Three or more unpaired groups were compared using one-way ANOVA with Tukey’s multiple comparisons or Kruskal Wallis non-parametric test with Dunn’s test for post hoc analysis, as appropriate. For paired data a mixed model ANOVA with Geisser-Greenhouse correction was applied. Results: Information regarding patient diseases and product characteristics are shown in Table I. There were no statistically significant differences between the nucleated cell count in the product bag reported by the collection center and those measured at the time of processing. When these parameters were evaluated based on transit time and pre-processing cell concentration, no statistically significant differences were observed. Conclusion: Although our data set is small, the results suggest that transit time and cell concentration of the HPSC product bag does not negatively impact allograft quality and engraftment. (Table Presented)