The Major Adverse Transplant Events (MATE) Score Applied to a Cohort of Pediatric Heart Transplant Recipients

Purpose The MATE score evaluates a surrogate end-point comprised of MATEs that predict graft loss. The first major pediatric heart transplant (PHTX) drug study, TEAMMATE, will use the MATE score as a primary end point. We have applied a calcineurin inhibitor (CNI) minimization strategy via early transition to a proliferation signal inhibitor (PSI) since 03/11, similar to the protocol employed in the TEAMMATE study. We sought to apply the MATE score to our population. Methods All PHTX patients between 03/11-12/14 surviving to 4-mo post-HTX with 36-mo of follow-up formed the study cohort. An equal number of HTX patients from a similar prior period formed the control cohort. Study subjects followed the early transition to PSI protocol, while the control subjects remained on mycophenolate (MMF). Statistical analyses were similar to those described for the TEAMMATE study. Results Twenty-seven subjects formed each group. At study end, 77% of study subjects vs. 24% of control subjects remained on protocol. A baseline-adjusted comparison of mean MATE-3 scores at 36-mo post-HTX did not suggest a difference in efficacy between the groups (ANCOVA p  = 0.50). The longitudinal linear mixed effects regression (lmer) model assessing differences in MATE-3 scores over time was not different between the groups either ( p  = 0.74). Safety, assessed by Tukey's Honest Significant Difference between 36-mo MATE-6 scores, was similar between the groups as well. An upper 95% confidence limit difference of +0.56 was found and is within the acceptable safety range. Lower age ( p  = 0.02; lmer p  = 0.04). In non-infants, there was a trend toward lower MATE-3 scores in the PSI group (Figure 1). Conclusion In this small group of PHTX patients following treatment regimens similar to those found in the TEAMMATE study with a high control cross over rate, safety and efficacy seem to be similar. In older patients however, early transition to a PSI-based regimen may improve long-term outcomes.