SAFETY AND FEASIBILITY OF DELAYED INFUSION OF STEM CELL PRODUCTS: A PILOT STUDY

ABSTRACT

Background & Aim: In allogeneic hematopoietic cell transplantation (HCT), NMDP guidelines are for stem cell product (SCP) infusion within 48 hrs or as soon as feasible after collection. However, given the possibility of long transit times, staffing limitations, and travel disruptions from natural disasters or pandemics, delays occur in the timing of infusions. We performed a pilot study to evaluate the safety of delayed SCP infusions. Methods, Results & Conclusion: We prospectively determined total transit time (time from end of collection to end of HCT infusion, TTT), viability, and product characteristics of SCP infused <48 or ≥48 hrs after collection. Differences in post-HCT outcomes were determined using Kaplan-Meier analysis and two-tailed t tests. We also retrospectively analyzed an independent cohort of SCP that required mandatory cryopreservation during the COVID- 19 pandemic. [Figure presented] In the <48 hr cohort (n=36), median TTT was 34.9 hrs. Median viability on arrival and at time of HCT were each 100%, with median infused CD34 dose of 5.58E6/kg. In the ≥48 hr cohort (n=23) median TTT was 58.1 hrs. Median product viability on arrival and at time of HCT were 100% and 99%, and median infused CD34 dose was 5.91E6/kg. Median time to neutrophil engraftment was longer for <48 hr cohort (p=0.048). Grade III/IV infusion reactions were 2.8% for <48 hr cohort, and primary graft failure was 2.8%;neither event occurred in >48 hrs cohort. Acute GVHD was 50% and 56.5%, and death from any cause was 39.9% versus 39.1%, in the <48 vs. ≥48 hr cohort groups. Death from any cause was seen in 39.9% versus 39.1% subjects, with median follow-up of 21 vs 13 months. 44 patients with SCPs (PBSC 86.4%, BM 13.6%) cryopreserved prior to HCT due to the COVID-19 pandemic response were also reviewed. Median infused CD34/kg was 5.5E6, with a median of 16 and 25 days for neutrophil and platelet engraftment. Grade III/IV infusion reactions and secondary graft failure were seen in 1 patient each (2.3%). Death from any cause was seen in 20.5% with a median follow-up of 5 months. Infusion of SCP products?>48 hrs was associated with no adverse outcomes post-HCT, compared to published parameters. In comparison, cryopreserved products during COVID-19 pandemic showed a delayed time to engraftment. While more definitive randomized studies are necessary, our preliminary results suggest that holding products for >48 hrs may be an acceptable alternative to cryopreservation in times of possible transit delay. [Table presented]