Further investigation needed on the effect of cryopreserved allogeneic HCT outcomes

While allogeneic transplants are classically infused fresh, cryopreservation is occasionally used to address complications with graft collection logistics or to accommodate changes in the patient’s condition that prevent administration of grafts, like additional chemotherapy, infections, etc. The effects of cryopreservation of allogeneic donor grafts are not well understood with previous studies limited to small sample sizes with bone marrow and PBSC graft sources often combined in the analysis.

The investigators evaluated the effect of cryopreservation on bone marrow (BM) and peripheral blood stem cell (PBSC) grafts on alloHCT for HCT performed between 2013 and 2018. The study compared engraftment, acute graft-vs-host disease (aGVHD), relapse, transplant related mortality (TRM), disease free survival (DFS), and overall survival (OS) between fresh and cryopreserved grafts. All patients received conventional calcineurin-based GVHD prophylaxis strategies.

The cryopreserved graft recipients (n=1,883) were divided into three cohorts based on graft source and donor type:

  • Matched related (MRD) PBSC (n=1,051)
  • Matched unrelated (MUD) PBSC (n=678)
  • Matched related or unrelated bone marrow donors (n=154)

Cryopreservation of PBSC, but not bone marrow grafts, appears to be associated with worse outcomes such as platelet engraftment and GVHD in the matched related cohort, and inferior survival in the matched unrelated cohort. A subset analysis of unrelated donor PBSC transplants where the reason for cryopreservation was known found that cryopreservation associated with the patient’s condition resulted in inferior survival compared to other reasons and may be a surrogate for other factors. Thus, the results of this analysis highlight the need for further investigation of allogeneic grafts where cryopreservation was planned in advance.

Hsu, J, et. al., Blood