Extended-Release Tacrolimus Following Liver Transplantation

PURPOSE

To assess the impact of Envarsus on toxicity and clinical outcomes in participants following liver transplant. Tacrolimus-based immunosuppression is the standard of care following liver transplantation (LT). This medication is associated with significant toxicity including renal dysfunction, increased risk of diabetes and neurotoxicity. Of note, both nephrotoxicity and neurotoxicity occur at elevated peak serum tacrolimus blood concentrations and improve when the dose is reduced or discontinued. Envarsus does not have the high peak seen with initial dosing in the other formulations. This may be one of the reasons Envarsus use improves tremor associated with tacrolimus use.

HYPOTHESES

Use of extended-release tacrolimus following LT will be: 1. Effective and safe. 2. Without any difference in rejection. 3. Less nephrotoxic with reduced incidence of renal impairment. 4. Better with regard to features of metabolic syndrome including myosteatosis. 5. Less neurotoxic. 6. Better with regard to both graft and patient survival when compared to immediate-release tacrolimus (Prograf®).

JUSTIFICATION

Tacrolimus-associated toxicity, especially renal dysfunction is common following LT (up to 25%) and is associated with increased mortality. Showing extended-release tacrolimus (Envarsus) is safe and efficacious will lead to broader use in the post-transplant setting. Use of this regimen leads to decreased maximum concentration and in some studies has shown benefit with regards to renal function. Such benefit will no doubt translate into improved long-term outcomes including survival and reduced healthcare costs.

OBJECTIVES/AIMS

The aim of this study is to assess the feasibility, safety and efficacy of using Envarsus in comparison to the immediate-release tacrolimus (Prograf®) following LT. Additional objectives include impact on renal function, metabolic syndrome, myosteatosis (fatty infiltration of skeletal muscle; reflects poor quality and function and correlated with poor outcomes), cardiovascular events, neurotoxicity, graft and patient survival.

METHODS

Basic study design

This will be a randomized control trial where participants will be randomized 1:1 to two groups: i) Prograf (dose 0.10 - 0.15mg/Kg daily; divided into BID dosing), ii) Envarsus (0.11 - 0.13 mg/Kg/day); both groups will be on mycophenolate (dose 1g BID) and will receive basiliximab (dose 20 mg) for induction at POD 0 and 4. Participants will be enrolled prior to transplant or up to 90 days following LT. The first dose will be administered within 90 days of LT. Randomization will be done at the first post-transplant outpatient visit (30-90 days post-transplant). Randomization will be stratified according to gender, bilirubin (< 50 and ≥ 50 umol/L), albumin (<30 and ≥ 30 g/L) and diagnosis of diabetes and renal function (according to the category of estimated GFR (45 to <60 ml, or 60 to <90 ml per minute per 1.73 m2)) to ensure that all groups are homogeneous. Tacrolimus will be taken orally with water, twice daily in the immediate-release group and once daily in the extended-release group for the duration of the study. Participants will take tacrolimus at approximately the same time each day (1 hour before meals). Participants will be instructed to swallow the tablet whole (no chewing, dividing, or crushing the tablet).

All participants who have received a liver transplant at the University of Alberta in Edmonton, Canada who are at least 18 years of age will be eligible for enrollment (18 month period following study initiation).

The primary analysis will be at 1-year, however, there will be a 10 year period of follow up off-trial. This will include participant outcomes (hospitalizations, complications of rejection, diabetes, renal dysfunction, cardiovascular events, graft and participant survival). The study will be carried out in compliance with the International Conference on Harmonization Harmonized Tripartite Guideline for Good Clinical Practice.

Covariates of interest

Baseline participant characteristics - Participant demographics; height, weight, BMI and waist circumference; etiology of cirrhosis; co-morbidities including diabetes, dyslipidemia, hypertension, smoking status and cardiovascular disease. History of malignancies at the time of transplant evaluation will also be noted. Immunosuppression (IS) following LT (at discharge, 1-, 3-, 6-, 12-, 60-months following LT and at end of follow up) and levels and dose of IS will also be recorded. Any changes, or adverse events including neurotoxicity due to IS will also be recorded. Finally, any episodes of rejection (based on biopsy) will be recorded. Biopsy will be obtained if clinically indicated at any time during the post-transplant course based on the participants presentation (persistently elevated liver enzymes or liver function tests, or abnormal FibroScan (liver stiffness > 9 kPa)). FibroScan will be done at one year, two years post-transplant and then every 2-years until end of follow up.

Biochemistry - serum creatinine, INR, sodium and bilirubin will be acquired. Data on albumin, transaminases, GGT, electrolytes, and CBC will also be collected. Values for lipid profiles, random and fasting blood glucose, insulin levels, and hemoglobin A1C will be recorded.

Analysis plan

Safety and efficacy - will be assessed descriptively. All participants who received at least one dose of Envarsus® will be included for analysis in the Envarsus® group. Only treatment related adverse events will be analyzed (complications following surgery such as bile leak, vascular thrombus, etc. will not be reported). The difference between the groups with regards to number of adverse events will be determined using poisson regression.

Incidence of acute rejection will be reported; Cox regression will be used to determine if there is a difference between the 2 study groups.

Impact of extended-release tacrolimus on secondary endpoints:

Impact on renal function - Proportion of participants with renal impairment (change in GFR 10%), number of episodes of AKI, incidence of AKI and CKD will be reported. The investigators will use Cox regression to determine if there is a difference between the 2 study groups with regards to renal function. Participants will be analyzed according to the treatment group to which they were randomized and not based on medication taken during the course of the study.

Incidence of diabetes, metabolic syndrome, and neurotoxicity will be reported. Rates of hospitalization, incidence of myosteatosis and patient and graft survival will be reported. Cox regression will be used to determine if there is a difference between the 2 study groups with regards to neurotoxicity and development of myosteatosis. The investigators will use poisson regression to determine difference between groups with regards to hospitalization rates. The investigators will use ANCOVA to determine if there is a difference between groups with regards to features of metabolic syndrome (diabetes, glycemic control, dyslipidemia, weight gain and hypertension). Difference in LOS between groups will be determined using linear regression. The investigators will use Kaplan Meier curves and log-rank test to determine if there is a difference in graft survival or mortality between the two arms (p-value will be provided).

Sample size calculation

This is a feasibility study thus no sample size calculation was required. The investigators will aim to enroll 94 participants over a 18 month period. Recruitment should not be a problem as approximately 90-100 LT are done each year at the University of Alberta.