Good Engraftment but Quality and Donor Concerns for Cryopreserved HPC Products Collected During the COVID-19 Pandemic.

Abstract Background Changes to donor availability, collection centre capacity and travel restrictions during the early phase of the COVID-19 pandemic led to routine cryopreservation of most unrelated donor products for haematopoietic transplantation prior to the recipient commencing the conditioning regimen. Objective We investigated the effect of this change on unrelated donor product quality and clinical outcomes. Study Design Product information was requested from transplant centres in Australia and New Zealand, and clinical outcome data from the Australasian Bone Marrow Transplant Recipient Registry (ABMTRR). Results 191 products were collected between 01 April 2021 and 30 September 2021 and most (74%) were from international collection centres. Median post-thaw CD34 recovery was 78% (range 25%-176%) and median post-thaw CD34 viability was 87% (range 34-112%). Median time to neutrophil recovery was 17 days (inter-quartile range 10 to 24 days) and graft failure occurred in 6 patients (4%). These clinical outcomes were similar to those of ‘fresh’ unrelated donor transplants reported to the ABMTRR in 2019. However, recipient transplant centres reported problems with 29% of products in the form of damage during transit, low cell dose, inadequate labelling, missing representative samples or missing documentation. These problems were critical in 7 cases (4%). At last follow-up, 22 products (12%) had not been infused. Conclusions Routine cryopreservation of unrelated donor HPC products has enabled safe continuation of allogeneic transplant services during the COVID-19 pandemic. However, practices for product tracing, documentation and transportation can be optimised, and measures to reduce the incidence of unused unrelated donor product are required.