Clinical outcomes in kidney transplant recipients receiving long-term therapy with inhibitors of the mammalian target of rapamycin

Abstract

Inhibitors of the mammalian target of rapamycin (mTOR), sirolimus and everolimus, reduce the incidence of acute rejection following kidney transplantation, but their impact on clinical outcomes beyond 2 years after transplantation is unknown. We examined risks of mortality and allograft loss in a prospective observational study of 993 prevalent kidney transplant recipients who enrolled a median of 72 months after transplantation. During a median follow-up of 37 months, 87 patients died and 102 suffered allograft loss. In the overall population, use of mTOR inhibitors at enrollment was not associated with altered risk of allograft loss, and their association with increased mortality was of borderline significance. However, history of malignancy was the strongest predictor of both mortality and therapy with an mTOR inhibitor. Among patients without a history of malignancy, use of mTOR inhibitors was associated with significantly increased risk of mortality in propensity score-adjusted (hazard ratio [HR] 2.6; 95% CI, 1.2, 5.5; p = 0.01), multivariable-adjusted (HR 3.2; 95% CI, 1.5, 6.5; p = 0.002) and one-to-one propensity score-matched analyses (HR 5.6; 95% CI 1.2, 25.7; p = 0.03). Additional studies are needed to examine the long-term safety of mTOR inhibitors in kidney transplantation, especially among recipients without a history of malignancy.

Figure 1. Cumulative incidence plots of allograft loss (A) and all-cause mortality (B) in the overall population, and all-cause mortality among those without a history of malignancy (C) according to baseline use versus non-use of mTOR inhibitors

The mortality plots considered allograft loss as a competing risk, and the allograft loss considered death as a competing risk. Study participants who remained event-free were censored at the end of the 3-year observation period. No participants were prematurely lost to follow-up.