Continuous versus intermittent tacrolimus for graft-versus-host disease prophylaxis in pediatric hematopoietic stem cell transplantation patients (Tic Tac).

BackgroundTacrolimus is administered via a continuous or intermittent IV infusion to prevent acute graft versus host disease (aGvHD) in pediatric hematopoietic stem cell transplant (HSCT) recipients. Limited comparison data is available.ObjectivesThe primary objective was to compare the proportion of therapeutic tacrolimus trough levels in the first 30 days post-stem cell infusion. Secondary outcomes were prevalence of aGvHD, intra-patient variability (IPV) and safety.Study DesignThis was a retrospective cohort study that included pediatric HSCT recipients between March 1, 2015 and October 31,2021 at BC Childrens Hospital. Adverse events were assessed using the Naranjo scoring tool.ResultsOverall, 60 transplants in 59 patients were included; n = 36 intermittent IV and n = 24 continuous IV. Median proportion of blood levels (intermittent and continuous) within 8-12 ug/L was 38% and 56%, respectively (p = 0.04). IPV was 33% and 31% and aGvHD was 39% and 38% in intermittent and continuous respectively. There was a higher proportion of adverse effects in the intermittent group with the exception of hypomagnesemia.ConclusionsContinuous IV tacrolimus provided a higher proportion of levels within therapeutic range. Neither achieved therapeutic trough levels in more than 56% of transplants. However, there was large intra-patient variability in both groups.