Long-Term Outcomes with Prolonged-Release Tacrolimus in Kidney Transplantation: A Retrospective Real-World Data Analysis

BACKGROUND Long-term real-world outcomes data for kidney transplant recipients (KTRs) converting from immediate-release tacrolimus (IRT) to prolonged-release tacrolimus (PRT) are limited. MATERIAL AND METHODS A retrospective, non-interventional review of adult KTRs treated with PRT for ≥1 month was conducted in Germany. Data were extracted from time of transplant (2008-2014) to 2018. Primary composite endpoints (graft loss, biopsy-confirmed acute rejection, graft dysfunction) and secondary endpoints (all-cause mortality, kidney function course, and tacrolimus dose/trough levels) were analyzed for sub-cohorts: de novo PRT, early conversion from IRT (within 6 months post-transplant), and late conversion (7 months to 3 years). RESULTS Analysis included 163 patients (101 de novo, 12 early converters, and 50 late converters). The overall Kaplan-Meier estimate of freedom from efficacy failure through 5 years was 0.537, (95% confidence interval (CI) 0.455-0.612) (de novo: 0.512 [0.407-0.608]; early converters: 0.500 [0.208-0.736]; late converters: 0.594 [0.443-0.717]). The overall survival rate was 0.925 (95% CI 0.872-0.957) (de novo: 0.900 [0.823-0.945]; early converters: 0.917 [0.539-0.988]; late converters: 0.977 [0.846-0.997]). During follow-up, there was a gradual reduction in tacrolimus dose and trough levels; kidney function remained stable in all cohorts. Multivariable analysis found re-transplantation, organ donor quality, best estimated glomerular filtration rate 8-12 weeks after transplant, and treatment center (between-center differences in age, sex, donor status/quality) were significantly associated with efficacy failure. CONCLUSIONS There was no difference in long-term survival profiles between KTRs who received PRT de novo vs those who converted from IRT, with 5-year survival remaining high in both groups.

Efficacy of Prolonged-release Tacrolimus After Conversion From Immediate-release Tacrolimus in Kidney Transplantation: A Retrospective Analysis of Long-term Outcomes From the ADMIRAD Study

Prolonged-release tacrolimus (PRT) may offer improved outcomes after kidney transplantation compared with immediate-release tacrolimus (IRT). However, data on outcomes beyond 5-y posttransplantation are lacking.

Methods

A retrospective, noninterventional chart review study examined long-term graft survival in adult kidney transplant participants in the Adherence Measurement in Stable Renal Transplant Patients Following Conversion From Prograf to Advagraf (ADMIRAD) clinical trial at 4 Belgian sites. Patients were randomized to receive once-daily PRT or twice-daily IRT for 6 mo, followed by treatment as per real-world clinical practice. Data were collected retrospectively from randomization day until December 31, 2018. Primary endpoints included efficacy failure, defined as a composite endpoint of graft loss, biopsy-confirmed acute rejection, and graft dysfunction. Secondary endpoints included overall patient survival and course of kidney function.

Results

This analysis included 78.5% of patients from ADMIRAD (n = 108 PRT; n = 64 IRT). The Kaplan-Meier survival rate without efficacy failure from randomization to year 5 was 0.741 (95% confidence interval [CI]: 0.647, 0.813) for the PRT group (n = 80), and 0.667 (95% CI: 0.536, 0.768) for the IRT group (n = 42) and remained higher for PRT throughout 10 y follow-up (P = 0.041). The Kaplan-Meier estimate of overall survival from the time of last transplant was 0.981 (95% CI: 0.928, 0.995) and 0.880 (95% CI: 0.802, 0.928) at 5 and 10 y in the PRT group. Kidney function parameters and tacrolimus trough levels remained stable over the follow-up period.

Conclusions

Patients in the ADMIRAD study who received PRT for up to 10 y had improved long-term outcomes compared with patients receiving IRT, with a consistent effect on both graft and patient survival.

Validation of a Capillary Dry Blood Sample MITRA-Based Assay for the Quantitative Determination of Systemic Tacrolimus Concentrations in Transplant Recipients

BACKGROUND

Tacrolimus is a narrow therapeutic index medication, which requires therapeutic drug monitoring to optimize dosing based on systemic exposure. MITRA microsampling offers a convenient, minimally invasive approach for the collection of capillary blood samples from a finger prick versus conventional venous blood sampling for quantitation of tacrolimus blood concentrations. However, the suitability of MITRA microsampling for the determination of tacrolimus concentrations requires assessment in clinical settings.

METHODS

Paired venous (2 mL) and capillary (10 μL) blood samples were collected pre-tacrolimus dose and 1 and 3 hours postdose during routine outpatient visits from stable adult liver or kidney transplant patients receiving prolonged-release tacrolimus. Tacrolimus concentrations were determined by liquid chromatography-tandem mass spectrometry, and the concentrations obtained by the 2 sampling methods were compared by linear regression and Bland-Altman agreement analyses.

RESULTS

Samples were available for 82 transplant recipients (kidney, n = 41; liver, n = 41). A high correlation was observed between tacrolimus concentrations in capillary and venous blood samples (Pearson correlation coefficient, 0.97; Lin concordance coefficient, 0.87; slope of the fitted line, >1.0). Tacrolimus concentrations in capillary samples were 22.5% higher on average than in the corresponding venous blood samples (95% limits of agreement, 0.5%-44.6%). Similar results were observed in both transplant subgroups.

CONCLUSIONS

MITRA finger prick sampling provides a convenient alternative to venipuncture for therapeutic drug monitoring in transplant recipients maintained on prolonged-release tacrolimus. When using the finger prick MITRA method, the positive bias in tacrolimus concentrations observed with this technique, when compared with venipuncture, needs to be taken into consideration.

Long-term, prolonged-release tacrolimus-based immunosuppression in de novo kidney transplant recipients: 5-year prospective follow-up of the ADHERE study patients

The objectives of this study were to assess long-term graft survival, patient survival, renal function, and acute rejections in de novo kidney transplant recipients, treated with once-daily prolonged-release tacrolimus-based therapy. The study was a 5-year non-interventional prospective follow-up of patients from the ADHERE study, a Phase IV 12-month open-label assessment of patients randomized to receive prolonged-release tacrolimus in combination with mycophenolate mofetil (MMF) (Arm 1) or sirolimus (Arm 2). From 838 patients in the randomized study, 587 were included in the long-term follow-up, of whom 510 completed the study at year 5. At 1 year post-transplant, graft and patient survival rates were 93.0% and 97.8%, respectively, and at 5 years were 84.0% and 90.8%, respectively. Cox proportional hazards analysis showed no association between graft loss, initial randomized treatment arm, donor age, donor type, or sex. The 5-year acute rejection-free survival rate was 77.4%, and biopsy-confirmed acute rejection-free survival rate was 86.0%. Renal function remained stable over the follow-up period: mean ± SD eGFR 4-variable modification diet in renal disease formula (MDRD4) was 52.3 ± 21.6 ml/min/1.73 m² at 6 months and 52.5 ± 23.0 ml/min/1.73 m² at 5 years post-transplant. These findings support the role of long-term once-daily prolonged-release tacrolimus-based immunosuppression, in combination with sirolimus or MMF, for renal transplant recipients in routine clinical practice.

Solid-phase enzyme immunoassay for serum ferritin

We describe a solid-phase enzyme immunoassay for ferritin in human serum, with use of a horseradish peroxidase-labeled antibody and a highly sensitive chromogen, 2,2'-azino-di(3-ethyl-benzthiazoline-6-sulfonate). The assay requires only 10 microL of serum per assay, relatively less time and labor than other assys for ferritin, and as little as 10 pg of ferritin can be measured. We believe this assay offers a reliable alternative to radioimmunoassay for serum ferritin.

Solid-phase enzyme immunoassay for serum ferritin

We describe a solid-phase enzyme immunoassay for ferritin in human serum, with use of a horseradish peroxidase-labeled antibody and a highly sensitive chromogen, 2,2'-azino-di(3-ethyl-benzthiazoline-6-sulfonate). The assay requires only 10 microL of serum per assay, relatively less time and labor than other assys for ferritin, and as little as 10 pg of ferritin can be measured. We believe this assay offers a reliable alternative to radioimmunoassay for serum ferritin.

Enzymic assay for lecithin in amniotic fluid

We describe an enzymic method for determining lecithin in amniotic fluid. Phospholipase D from savoy cabbage is used to liberate choline from lecithin, and the liberated choline is oxidized to betaine and hydrogen peroxide by choline oxidase from Arthrobacter globiformis. The hydrogen peroxide forms a colored complex with phenol and 4-aminoantipyrene in the presence of horseradish peroxidase, and this color is measured spectrophotometrically. The method is relatively easy, precise, and accurate, requires less time and sample than other methods, and offers a reliable alternative to the lecithin/sphingomyelin ratio techniques for assessing fetal lung maturity.

Enzymic assay for lecithin in amniotic fluid

We describe an enzymic method for determining lecithin in amniotic fluid. Phospholipase D from savoy cabbage is used to liberate choline from lecithin, and the liberated choline is oxidized to betaine and hydrogen peroxide by choline oxidase from Arthrobacter globiformis. The hydrogen peroxide forms a colored complex with phenol and 4-aminoantipyrene in the presence of horseradish peroxidase, and this color is measured spectrophotometrically. The method is relatively easy, precise, and accurate, requires less time and sample than other methods, and offers a reliable alternative to the lecithin/sphingomyelin ratio techniques for assessing fetal lung maturity.