Tacrolimus/Everolimus vs. Tacrolimus/MMF in Pediatric Heart Transplant Recipients Using the MATE Score

Median survival after pediatric heart transplantation (HT) is 15 years in the current era. This means that a substantial fraction of patients transplanted during childhood fail to survive to adulthood, or require heart re-transplantation, because of complications related to heart transplant. These complications include heart transplant rejection, infection, coronary artery disease, post-transplant lymphoproliferative disorder (PTLD; a form of lymphoma seen in transplant recipients), and kidney failure. Most complications stem not from the heart transplant itself, but from the drugs commonly used to suppress the immune system in order to prevent rejection. In the US, tacrolimus (TAC) and mycophenolate mofetil (MMF), have emerged over the past decade as the standard of care for pediatric heart transplant immunosuppression. While pediatric survival has improved significantly in the era of TAC and MMF, post-HT complications remain a major problem that limits median survival to 15 years. Recently, everolimus (EVL) has emerged as a potential alternative immunosuppressant that may prevent rejection, coronary artery disease and kidney failure more effectively than TAC/MMF when administered in combination with low-dose tacrolimus (LDTAC). Preliminary studies suggest that EVL, and its first-generation analog sirolimus, are well tolerated in children after HT, regardless of whether it is started in response to coronary artery disease, in response to chronic kidney disease, or empirically 4-6 months after transplant in an effort to prevent the development of these complications1. However, studies are generally limited to single-center experiences using historical controls and have inadequate statistical power to demonstrate treatment differences. This will be the first multicenter randomized clinical trial of maintenance immunosuppression in pediatric heart transplantation to systematically evaluate the safety and efficacy of EVL with LDTAC vs. TAC/MMF to prevent long-term complications which lead to death/graft loss. The major adverse transplant event (MATE) score will serve as the primary endpoint to power the trial. Because no Food \& Drug Administration (FDA)-approved immunosuppressants currently exist for children after heart transplant (all prescriptions are off-label) and market incentives to support a trial are limited, the investigators have funded the trial through a Fiscal Year 2016 Peer Reviewed Medical Research Program Clinical Trial Award sponsored by the Department of Defense office of the Congressionally Directed Medical Research Programs. It is worth noting that in contrast to adults, children have a substantially longer potential life expectancy if post-transplant complications can be minimized, making the prevention of late complications an urgent priority for the pediatric heart transplant community.