Relationships Between Tacrolimus Exposure and Adverse Events in Renal Transplant Patients: The ExpoTac Study

Abstract

In transplantation, the association of tacrolimus exposure with efficacy is better known than with adverse effects. The ExpoTac study explored the relationships between tacrolimus exposure and adverse events (AEs) in kidney transplant patients who benefited from at least 3 measurements of tacrolimus area under the curve (AUC) within 2 years of transplantation. The relationships between tacrolimus AUC, trough concentration C0, peak concentration Cmax, and AEs were explored using univariate analysis and Cox models in 386 patients (1281 sets of exposure biomarkers). Headaches and renal impairment potentially induced by tacrolimus were associated with significantly lower mean dose-standardized exposure biomarkers and a higher proportion of Cmax values above the median. Patients with tremor displayed significantly higher mean AUC0–24 (343 ± 79 versus 308 ± 63 hours·mcg/L, P = 0.041). Cox analysis revealed a significant association between (1) the time to the first headache report and mean Cmax, mean AUC0–24, and the proportion of Cmax values above the median (hazard ratios [95% confidence interval] = 0.237 [0.007–0.538]; 7.499 [1.508–29.713]; 5.055 [1.577–17.137]) and (2) the time to first renal impairment report and the proportion of C0 values above the median (0.401 [0.098–0.681]). Refining AUC, Cmax, and C0 upper limits would help to refine tacrolimus therapeutic ranges and limit the risks of AEs after kidney transplantation.