Sirolimus in De Novo Heart Transplant Recipients Reduces Acute Rejection and Prevents Coronary Artery Disease at 2 Years

Abstract

Background-Sirolimus reduces acute rejection in renal transplant recipients and prevents vasculopathy in nonhuman primates and in-stent restenosis in humans. Its effects on rejection and transplant vasculopathy in human heart transplant recipients are unknown. Methods and Results-In a randomized, open-label study, sirolimus was compared with azathioprine in combination with cyclosporine and steroids administered from the time of cardiac transplantation. We report 6-month rejection rates (primary end point), 12-month safety and efficacy data, and 6-and 24-month graft vasculopathy data in 136 cardiac allograft recipients randomly assigned (2:1) to sirolimus (nϭ92) or azathioprine (nϭ44). At 6 months, the proportion of patients with grade 3a or greater acute rejection was 32.4% for sirolimus 3 mg/d (Pϭ0.027), 32.8% for sirolimus 5 mg/d (Pϭ0.013), and 56.8% for azathioprine. Patient survival at 12 months was comparable among groups. Intracoronary ultrasound at 6 weeks, 6 months, and 2 years demonstrated highly significant progression of transplant vasculopathy in azathioprine-treated patients. At 6 months, a highly significant absence of progression in intimal plus medial proliferation and significant protection against luminal encroachment was evident in sirolimus-treated patients, and these effects were sustained at 2 years. Conclusions-Sirolimus use from the time of transplantation approximately halved the number of patients experiencing acute rejection. The measurable development of transplant vasculopathy at 6 months and 2 years in patients receiving azathioprine was not observed in patients receiving sirolimus.

Mycophenolate Acid Inhibits Endothelial NAD(P)H Oxidase Activity and Superoxide Formation by a Rac1-Dependent Mechanism

“…We speculate that this effect of MPA was caused by depletion of cellular GTP content, which was the likely cause for subsequent attenuation of Rac1 activity. Although mTOR inhibitors, such as rapamycin or everolimus, have been observed to have beneficial effects on CAV in clinical settings as well, 42,43 we did not observe an effect of rapamycin on endothelial O 2 Ϫ release in vitro.…”

Downstream coronary effects of drug-eluting stents

“…[19][20][21][22] A variety of studies investigating coronary artery disease in heart transplant patients, who have baseline endothelial dysfunction, have shown that antiproliferatives such as sirolimus attenuate the rate of atherosclerotic progression. 29,30 In addition, paclitaxel is a well-known immunomodulatory agent and has also been associated with atherosclerotic regression in animal models, as well as reduced inflammation in stented porcine arteries. 23,31 Furthermore, given that the product labeling and pharmacokinetic studies in sirolimus-eluting stents describe serum detectability of antiproliferative agents for over 2.5 weeks and an estimated 3 month elution period after implantation (depending on stent type), one would expect these drugs to have long-term effects on the downstream vascular bed.…”

“…37,38 In addition, oral administration of cell-cycle inhibitors prevent in-stent restenosis as well atherosclerotic progression in heart transplant patients, suggesting that serological delivery of drug, without high tunical concentrations, is able to affect stenotic progression. 9,29 Downstream endothelial effects should therefore be expected, in addition to effects on circulating macrophages and lymphocytes that are central to the development and progression of atherosclerotic plaques.…”

Canadian Cardiovascular Society Consensus Conference update on cardiac transplantation 2008: Executive Summary

“…The 48-month follow-up results of this trial demonstrated fewer rejections in the everolimus-treated patients (62). A smaller trial of rapamycin (63) in de novo transplant patients also showed fewer rejection episodes and less coronary allograft vasculopathy. To date, none of the TOR inhibitor trials in heart transplantation have demonstrated increased survival.…”

“…Some data suggest that a tacrolimus-based immunosuppressive regimen is associated with less coronary intimal thickening than with a cyclosporine-based regimen (84). Newer immunosuppressive agents, including sirolimus and everolimus (85)(86)(87)(88)(89), have shown some early promise in reducing intimal thickening, but their routine use for this purpose requires additional study.…”