Bioequivalence of twice-daily oral tacrolimus in transplant recipients: More evidence for consensus?

A Randomized Controlled Trial of Envarsus Versus Immediate Release Tacrolimus in Kidney Transplant Recipients With Delayed Graft Function

BACKGROUND

The incidence of delayed graft function (DGF) among kidney transplant recipients (KTRs) in the United States continues to increase. The effect of immediate-release tacrolimus (tacrolimus) compared with extended-release tacrolimus (Envarsus) among recipients with DGF is unknown.

METHODS

This was a single-center open-label randomized control trial among KTRs with DGF (ClinicalTrials. gov, NCT03864926). KTRs were randomized either to continue on tacrolimus or switch to Envarsus at a 1:1 ratio. Duration of DGF (study period), number of dialysis treatments, and need for adjustment of calcineurin inhibitor (CNI) doses during the study period were outcomes of interest.

RESULTS

A total of 100 KTRs were enrolled, 50 in the Envarsus arm and 50 in the tacrolimus arm; of those, 49 in the Envarsus arm and 48 in the tacrolimus arm were included for analysis. There were no differences in the baseline characteristics, all P > .5, except donors in the Envarsus arm had higher body mass index (mean body mass index 32.9 ± 11.3 vs 29.4 ± 7.6 kg/m2 [P = .007]) compared with the tacrolimus arm. The median duration of DGF (5 days vs 4 days, P = .71) and the number of dialysis treatments (2 vs 2, P = .83) were similar between the groups. However, the median number of CNI dose adjustments during the study period in the Envarsus group was significantly lower (3 vs 4, P = .002).

CONCLUSIONS

Envarsus patients had less fluctuation in the CNI level, requiring fewer CNI dose adjustments. However, there were no differences in the DGF recovery duration or number of dialysis treatments.

Meeting Regulatory Requirements for Drugs with a Narrow Therapeutic Index: Bioequivalence Studies of Generic Once-Daily Tacrolimus

Despite growing clinical confidence in generics and their potential to reduce long-term healthcare costs, the transplant community have had real concerns about the use of generic immunosuppressants. One such immunosuppressant is tacrolimus, a cornerstone of lifelong treatment for patients who have undergone a solid organ transplant. Tacrolimus has a narrow therapeutic index (NTI), giving rise to questions about the potential for clinically relevant altered drug exposure. Its use in transplant patients also gives rise to questions about the most discriminative subject population for bioequivalence studies. The recognised need for stringent criteria to support approval of generic drugs with an NTI led the European Medicines Association and Health Canada to provide detailed information on requirements for bioequivalence studies and introduce tighter bioequivalence limits for these drugs, including tacrolimus. The aim of this article is to illustrate how regulatory guidance is implemented during the clinical development of generic immunosuppressants, using a generic, once-daily prolonged-release formulation of tacrolimus as an example.

Generic Tacrolimus (Tacrobell®) Shows Comparable Outcomes to Brand-Name Tacrolimus in the Long-Term Period After Adult Deceased Donor Liver Transplantation

Background

Generic tacrolimus (Tacrobell^®) is commonly used in liver transplant patients in Korea. No previous studies have assessed the long-term efficacy and safety of generic tacrolimus for adult deceased donor liver transplantation (DDLT) patients. The aim of the present study was to evaluate the long-term efficacy and safety of generic tacrolimus compared to brand-name tacrolimus (Prograf^®) in adult DDLT recipients.

Methods

Two hundred sixty-five adult DDLTs were performed in our center between 2003 and 2017. To determine the efficacy and safety of generic tacrolimus, renal function (estimated glomerular filtration rate [eGFR] and creatinine), infectious complications, rejection-free survival rates, and patient survival rates were investigated.

Results

Of 265 patients, 193 were selected and divided into a generic tacrolimus group (n=147) and a brand-name group (n=46). Mean follow-up duration was 63.2 ± 44.3 months. The 1-year, 3-year, 5-year, and 10-year patient survival rates were 89.1%, 86.9%, 84.5%, and 75.2%, respectively, in the generic tacrolimus group and 95.7%, 88.9%, 86.3%, and 83.7% in the brand-name tacrolimus group. There were no statistically significant differences in the infectious complications, new-onset diabetes, and renal dysfunction included mean serum creatinine level or eGFR after DDLT between the two groups. Increased recipient age, continuous renal replacement therapy (CRRT) in the pre-transplant phase, and acute rejection were predisposing factors for patient death.

Conclusion

The present study shows that generic tacrolimus is an alternative comparable to brand-name tacrolimus in adult DDLT patients.