Prospective Pilot Feasibility Study Comparing Envarsus Once-a-day to Tacrolimus Twice-a-day Immunosuppressive Regimen on Drug Bioavailability in Hispanic First Time Kidney Transplant Recipients

Adequate drug dosing is essential to prevent allograft rejection and subsequent allograft loss. Many studies have shown that serum levels of immunosuppressant medications can be strongly influenced by the patient's genetic profile. Genetics has been shown to influence tacrolimus drug dosing in both liver and kidney transplant recipients 1. Whether these genetic differences influence care in clinical practice though is not known. Several genetic influences have been identified in Hispanic patients, such as polymorphisms in Cytochrome genes 1 and Nuclear Factor-kappa B genes 2, that might influence tacrolimus dosing and blood levels. In a study of Hispanic children, significant correlations were found to suggest that ethnic differences resulted in the need for higher or more frequent tacrolimus doing in Hispanic children 3. According to the Centers for Disease Control, Hispanics are 1.5 times as likely as non-Hispanic whites to develop ESRD 4 and Hispanics are the largest minority with the fastest growth of ESRD in the United States 5. Therefore it is likely that the unanswered question of whether there are differences in bioavailability of Envarsus in Hispanic patients will become even more relevant over time. Strategies that target improved bioavailability have the opportunity to significantly improve outcomes for all recipients of kidney transplants. Specifically, vulnerable patient populations, such as Hispanic patients, need to be studied to better understand the potential for altered bioavailability of immunosuppressive medications based on inherited pharmacologic traits.

Providing patients a once-a-day option for their immunosuppressive medication dosing is predicted to improve adherence, but whether once daily Envarsus provides adequate drug levels in Hispanic patient groups is not known. This study will carefully evaluate drug levels as a primary endpoint in this investigator-initiated study. Additional secondary outcomes to be measured over the two years of the study will be allograft rejection and allograft loss. The hypothesis of this study is that kidney transplant recipients receiving once-a-day extended release tacrolimus (Envarsus) will have outcomes that are not inferior to those who received twice-a-day tacrolimus during the two-year study period.