LAUSR

During 2020, the concurrent novel COVID-19 pandemic lead to widespread cryopreservation of allogeneic HCT grafts based on NMDP and EBMT recommendations, in order to secure grafts before the start of conditioning chemotherapy. We sought to examine the impact of this change in practice on patient outcomes. We analyzed the outcomes of 483 patients who received HSCT between August 2017 and August 2020, at Princess Margaret Cancer Centre, Canada, in the retrospective study, comparing the outcomes between those who received cryopreserved or fresh peripheral blood stem cell grafts. Overall compared to those who received fresh grafts (n=348), patients who received cryopreserved grafts (n=135) had reduced survival and GRFS, reduced incidence of chronic GvHD, delay in neutrophil engraftment and higher graft failure, with no significant difference in relapse incidence or acute GvHD. However, recipients of cryopreserved matched related donor HSCT showed significantly worse OS, NRM, GRFS compared to fresh grafts. Multivariable analysis of the entire cohort showed significant impact of cryopreservation on OS, relapse, cGvHD, graft failure and GRFS. We conclude that cryopreservation was associated with inferior outcomes post-HSCT, possibly due to the combination of ATG and post-transplant cyclophosphamide impacting differential tolerance to cryopreservation on components of the stem cell graft; further studies are warranted to elucidate mechanisms for this observation.