Tacrolimus monitoring parameters are not associated with acute cellular rejection following lung transplantation

The purpose of this study was to evaluate the impact of tacrolimus drug monitoring parameters on the incidence of acute cellular rejection (ACR) in lung transplant recipients (LTRs).

This was a retrospective study of patients who underwent lung transplantation at a single center. LTRs who were given tacrolimus during the first 6 months after transplantation and who underwent at least one bronchoscopy with biopsy were included. Tacrolimus time in therapeutic range (TTR) was calculated using Rosendaal's method. Time to therapeutic level, coefficient of variance (CoV), and median trough concentrations were also determined.

The study included 157 LTRs. ACR ≥ A1 grade was present in 46.5% of patients, and ACR ≥ A2 grade was present in 17.2%. There was no difference between tacrolimus TTR in patients with ACR ≥ A1 compared with those without ACR (47.4 ± 16.1 versus 46.2 ± 18.9%, p = 0.67) or in patients with ACR ≥ A2 grade compared with those with A0 or A1 ACR (46.0 ± 16.3 versus 47.0 ± 17.9%, p = 0.81). When comparing patients with any ACR grade A1 or higher with those without ACR, there was no difference in tacrolimus CoV (42.7 ± 11.0 versus 44.6 ± 12.4, p = 0.30), median tacrolimus trough concentration (9.9 ± 1.3 versus 9.8 ± 1.4 ng/mL, p = 0.66), or days to therapeutic level (9 versus 12 days, p = 0.057).

The results suggest that tacrolimus TTR, time in therapeutic range, and variability are not related to the presence of ACR in LTRs.