Differential Pharmacokinetic Interaction of Tacrolimus and Cyclosporine on Everolimus

Everolimus Personalized Therapy: Second Consensus Report by the International Association of Therapeutic Drug Monitoring and Clinical Toxicology

ABSTRACT

The Immunosuppressive Drugs Scientific Committee of the International Association of Therapeutic Drug Monitoring and Clinical Toxicology established the second consensus report to guide Therapeutic Drug Monitoring (TDM) of everolimus (EVR) and its optimal use in clinical practice 7 years after the first version was published in 2016. This version provides information focused on new developments that have arisen in the last 7 years. For the general aspects of the pharmacology and TDM of EVR that have retained their relevance, readers can refer to the 2016 document. This edition includes new evidence from the literature, focusing on the topics updated during the last 7 years, including indirect pharmacological effects of EVR on the mammalian target of rapamycin complex 2 with the major mechanism of direct inhibition of the mammalian target of rapamycin complex 1. In addition, various concepts and technical options to monitor EVR concentrations, improve analytical performance, and increase the number of options available for immunochemical analytical methods have been included. Only limited new pharmacogenetic information regarding EVR has emerged; however, pharmacometrics and model-informed precision dosing have been constructed using physiological parameters as covariates, including pharmacogenetic information. In clinical settings, EVR is combined with a decreased dose of calcineurin inhibitors, such as tacrolimus and cyclosporine, instead of mycophenolic acid. The literature and recommendations for specific organ transplantations, such as that of the kidneys, liver, heart, and lungs, as well as for oncology and pediatrics have been updated. EVR TDM for pancreatic and islet transplantation has been added to this edition. The pharmacodynamic monitoring of EVR in organ transplantation has also been updated. These updates and additions, along with the previous version of this consensus document, will be helpful to clinicians and researchers treating patients receiving EVR.

Population pharmacokinetics of everolimus in renal transplant recipients receiving long-term multiple immunosuppressive therapy

Everolimus is used for immunosuppression after renal transplantation. This study aimed to develop a population pharmacokinetic (PopPK) model of everolimus using therapeutic drug monitoring (TDM) data of patients under long-term multiple immunosuppressive therapy, including tacrolimus. To develop the model, 185 renal transplant recipients with 3358 everolimus blood concentrations during a median postoperative period of 35.3 months were included. The PopPK model is described as a one-compartment model with first-order absorption. The population mean of apparent clearance is 8.92 L/h (relative standard error = 3.6%), and this negatively correlated with the dose-normalized concentration (C/D) of tacrolimus and hematocrit value, and positively correlated with a daily dose of everolimus (i.e. TDM effect). The usefulness of dose adjustment using the final popPK model was assessed by a simulation study. The ratio of the first trough measurement within the therapeutic range of 3-8 ng/mL increased from 69.8% in the original dose to 87.9% in the individual dose calculated by the final PopPK model. The tacrolimus C/D ratio before initiating everolimus therapy and the hematocrit value were useful to estimate the initial dose of everolimus and can improve the safety and effectiveness of immunosuppressive therapy involving everolimus.

Generic Medicinal Products in Immunosuppressive Therapy-Should It be a Challenge for Therapeutic Drug Monitoring?

ABSTRACT

Immunosuppressants have a narrow therapeutic index (NTIDs). Indisputably cyclosporine, tacrolimus, everolimus, and sirolimus have NTIDs, and only in the case of mycophenolic acid, a scientific discussion has not been yet concluded. Their specificities highlight the implications for generics introduced into the drug market, more precisely, with bioequivalence testing. In the European Union, the European Medicines Agency (EMA) released the "Guideline on the Investigation of Bioequivalence." The bioequivalence (BE) of the generic (tested, T) versus original (reference, R) product should be confirmed by obtaining a 90% confidence interval (CI) for the T:R ratio of each of the 2 decisive pharmacokinetic parameters, namely, the area under the curve (AUC) between 90.00% and 111.11%. A similar approach (90.00%-112.00%) for AUC was adopted by the Canadian Agency for Drugs and Technologies in Health (CADTH) for NTIDs; however, the US Food and Drug Administration is still based on classic acceptance criteria: 90% CI between 80.00% and 125.00% but with special requirements of BE testing. A discussion about long-expected global consensus was performed in this study based on the literature concerning BE testing in the case of NTIDs. The narrow acceptance criteria reduce the potential mean difference in bioavailability between generic and original products by a few percent. To identify this problem, special attention has been paid to switching drugs (generic-generic, original-generic) and therapeutic drug monitoring after conversion (TDM). There is no global consensus on the acceptance criteria for the BE of generic drugs; therefore, consensus and harmonization are strictly necessary. This study presents a review of the generic drug market and its classification by manufacturers, drug agencies, and dates of marketing authorization. Guidelines for TDM optimization (during switching/conversion) have been proposed. Physicians and clinical pharmacists should pay special attention to switching immunosuppressive drugs between original versus generic formulations, and generic versus generic formulations. Patients and their families should be educated on the risks associated with uncontrolled conversion.

Pharmacokinetic principles of dose adjustment of mTOR inhibitors in solid organ transplanted patients

WHAT IS KNOWN AND OBJECTIVES

mTOR inhibitors possess narrow therapeutic range and substantial pharmacokinetic variability and the consequences from suboptimal dosing are serious. The aim of this review is to summarize the current knowledge about the factors influencing mTOR inhibitors pharmacokinetics and the possibility of using these relationships in order to improve its therapy individualization in solid organ transplanted patients.

METHODS

Literature search from Pubmed and Web of Science databases were performed using Boolean search operators in order to identify relevant studies.

RESULTS AND DISCUSSION

A total of 701 reports were identified from the initial literature search. Out of which 40 studies dealt with relationships between various factors and pharmacokinetics of mTOR inhibitors and with relevance of these associations for dosage optimization.

WHAT IS NEW AND CONCLUSION

The overview of the current covariates for pharmacokinetic variability of mTOR inhibitors has been provided on the level of absorption, distribution and elimination, and consequences of these relationships for dosing optimization has been summarized.

No Influence of Everolimus on Mycophenolic Acid Area Under the Concentration-Time Curve: Limited Sampling Strategy for Mycophenolic Acid in Japanese Kidney Transplant Recipients Treated With Tacrolimus, Mycophenolate Mofetil, Steroid, and Everolimus

BACKGROUND

Despite a growing need for everolimus (EVR) to reduce calcineurin inhibitor toxicity in kidney transplantation (KTx), the influence of EVR on the pharmacokinetics of mycophenolic acid (MPA), a mycophenolate mofetil (MMF) active metabolite, is obscure, and no suitable limited sampling strategy (LSS) for MPA when EVR is concomitantly present exists. We aimed to investigate the influence of EVR on MPA pharmacokinetics in KTx.

MATERIALS AND METHODS

This study complied with all principles of the Declaration of Helsinki. Twenty patients were initially administered tacrolimus, MMF, and methylprednisolone and then received EVR 4 months after KTx. Approximately 4 weeks before and after EVR administration, the estimated value of the area under the concentration-time curve for MPA from 0 to 12 hours (MPA-AUC0-12) was calculated using MPA blood concentration just before and 1, 2, 4, and 6 hours after MMF administration. We compared several MPA pharmacokinetics parameters before and after EVR addition and determined the best estimation equation for LSS of MPA-AUC0-12.

RESULTS

Although MPA-C6 per dose (MPA-C6/D) significantly decreased after EVR addition (from 3.4 [±2.2] ng/mL/g to 2.5 [±0.9] ng/mL/g), MPA-C0/D, -C1/D, -C2/D, -C4/D, and MPA-AUC0-12/D showed no significant change. MPA-AUC0-12/D did not correlate with EVR-AUC0-12/D. The best estimation equation for LSS of MPA-AUC0-12 by 2 time points was [(2.94 × C2) + (5.09 × C4) + 5.32] (R² = 0.73) and [(5.70 × C0) + (1.39 × C1) + 22.45] (R² = 0.72) before and after EVR addition, respectively.

CONCLUSIONS

EVR can be safely combined with MMF after KTx once our results have been reevaluated.

An overview of the efficacy and safety of everolimus in adult solid organ transplant recipients

As the risk of graft loss due to acute rejection has declined, the goal of post-transplant management has switched to long-term preservation of organ function. Minimizing calcineurin inhibitor (CNI)-related nephrotoxicity is a key component of this objective. Everolimus is a mammalian target of rapamycin inhibitor/proliferation-signal inhibitor with potent immunosuppressive and anti-proliferative effects. It has been widely investigated in large randomized clinical studies that have shown it to have similar anti-rejection efficacy compared with standard-of-care regimens across organ transplant indications. With demonstrated potential to facilitate the reduction of CNI therapy and preserve renal function, everolimus is an alternative to the current standard-of-care CNI-based regimens used in de novo and maintenance solid organ transplantation recipients. Here, we provide an overview of the evidence from the everolimus clinical study program across kidney, liver, heart, and lung transplants, as well as other key data associated with its use in CNI reduction strategies in adult transplant recipients.

Pharmacodynamic Drug-Drug Interaction on Human Peripheral Blood Mononuclear Cells Between Everolimus and Tacrolimus at the Therapeutic Concentration Range in Renal Transplantation

Background

Everolimus (EVL) plus tacrolimus (TAC) therapy is effective and safe in renal transplantation. However, the pharmacokinetic and pharmacodynamic information for EVL combined with TAC is limited. We investigated the pharmacodynamic drug–drug interaction between EVL and TAC at their therapeutic concentration range.

Material/Methods

Isolated peripheral blood mononuclear cells (PBMCs) from 22 healthy participants aged 22 to 24 years were cultured with concanavalin A (Con A) in the presence of EVL and/or TAC for 4 days, and the proliferation rate of the PBMCs was calculated.

Results

TAC promoted the inhibitory efficacy of EVL against the mitogen-activated proliferation of PBMCs at the EVL therapeutic concentration range. When 0.175 ng/mL or more of TAC was combined with 30 ng/mL or more of EVL, the antagonistic effect of TAC on the inhibitory efficacy of EVL against the mitogen-activated proliferation of PBMCs was observed. Conversely, when 0.4 ng/mL TAC and 10 ng/mL or more of EVL were combined, the antagonistic effect of EVL on the inhibitory efficacy of TAC against the mitogen-activated proliferation of PBMCs was observed.

Conclusions

The pharmacodynamic synergistic efficacy of EVL and TAC in combination on mitogen-activated PBMCs was evident at the therapeutic concentration range, which is used in renal transplantation. However, these drugs antagonize each other to suppress the proliferation of activated PBMCs at concentrations higher than those clinically used.

Optimal dose of everolimus administered with tacrolimus in living donor kidney transplantation

Everolimus (EVR) is often administered with cyclosporine A (CsA), according to an established protocol. Although the administration protocol of EVR with tacrolimus (TAC) has not been established, it has been clinically demonstrated that a higher dose of EVR is necessary when used in combination with TAC than with CsA. In this study, we aimed to determine the optimal dose of EVR administered with TAC to maintain a similar EVR level in the blood to that observed when EVR is administered with CsA. Between June 2009 and January 2016, 22 patients who underwent living donor kidney transplantation were enrolled in this study. Among them, 12 patients were administered steroids, basiliximab, CsA, and EVR (CsA + EVR group) and 10 were administered steroids, basiliximab, TAC, and EVR (TAC + EVR group). Blood samples were collected at different time points from patients in both CsA + EVR and TAC + EVR groups, after drug administration. The trough EVR level in both groups was maintained within 3-8 ng/mL during the perioperative period. The optimal EVR doses for both groups were estimated by using a population pharmacokinetic analysis. Overall, the optimal dose of EVR for the TAC + EVR group was 3.59-fold higher than that for the CsA + EVR group to maintain a similar trough level to that of the latter group. Thus, administration of a higher EVR dose is recommended when provided in combination with TAC than with CsA to prevent adverse events caused by under immunosuppression, that could lead to acute kidney rejection.

Immunosuppressants in Organ Transplantation

The goal of immunosuppressive therapy post-transplantation in pediatric renal transplant recipients is to prevent acute and chronic rejection while minimizing drug side effects. Most therapies alter immune response mechanisms but are not immunologically specific, and a careful balance is required to find the dose that prevents rejection of the graft while minimizing the risks of overimmunosuppression leading to infection and cancer. While this chapter because of space constraints focuses on immunosuppressive therapy in pediatric renal transplant recipients, many aspects can be applied on pediatric recipients of other solid organ transplants such as the liver and heart. The major maintenance immunosuppressive agents currently used in various combination regimens are tacrolimus, cyclosporine, mycophenolate mofetil, azathioprine, everolimus, sirolimus, and glucocorticoids (steroids). Although data from adult renal transplantation trials are used to help guide management decisions in pediatric patients, immunosuppressive therapy in pediatric renal transplant recipients often must be modified because of the unique dosage requirements and clinical effects of these agents in children, including their impact on growth and development. The optimal immunosuppressive therapy post-transplant is not established. The goal remains to find the best combination of immunosuppressive agents that optimizes allograft survival by preventing acute rejection while limiting drug toxicities.

Adequacy of Initial Everolimus Dose, With and Without Calcineurin Inhibitors, in Kidney Transplant Recipients

BACKGROUND

This study investigates the adequacy of initial everolimus (EVR) dose, with and without calcineurin inhibitors (CNI), in kidney transplant recipients.

METHODS

This retrospective cohort analysis involved data from 305 kidney transplant recipients participating in 3 randomized trials receiving reduced dose cyclosporin A (CsA) combined with EVR 0.75 mg BID (CSA/EVR0.75, N = 32) or 1.5 mg BID (CSA/EVR1.5, N = 31), reduced dose tacrolimus (TAC) combined with EVR 1.5 mg BID (TAC0.05/EVR1.5, N = 83), standard dose TAC combined with EVR 1.5 mg BID (TAC0.1/EVR1.5, N = 93), and EVR 1.5 mg BID (EVR1.5, N = 66) with TAC introduction after day 5. The adequacy of the initial EVR dose, based on EVR whole blood trough between 3 and 8 ng/mL, was compared using first EVR blood concentrations obtained at day 3 after transplantation.

RESULTS

Recipient age, proportion of patients with diabetes mellitus, and proportion of grafts from living donors were different among the groups. Dose-corrected EVR concentrations were higher in patients receiving CsA than in those receiving TAC or no calcineurin inhibitors (6.7 ± 5.9 versus 5.4 ± 2.2 versus 2.4 ± 0.8 versus 2.5 ± 0.9 versus 2.2 ± 0.7, P = 0.000). No differences were observed comparing dose adjusted EVR concentrations combined with TAC or alone (P = 0.073). The proportion of patients with EVR concentration below <3 ng/mL was lower when EVR was combined with CsA (25 versus 3 versus 43 versus 33 versus 50%, P = 0.000). Later introduction of TAC did not influence EVR concentrations. There were no differences in mean CsA concentrations comparing patients receiving EVR 0.75 or 1.5 mg BID (240 ± 143 versus 213 ± 105 ng/mL). On the other hand, mean TAC concentrations were higher according to the initial TAC dose regimen (6.4 ± 3.9 versus 9.8 ± 5.9 ng/mL).

CONCLUSIONS

In de novo kidney transplant recipients, the choice of the initial dose of EVR should consider the type of calcineurin inhibitor to reach target EVR concentration within the first week in a higher proportion of patients, maximizing the efficacy/toxicity profile.

Everolimus immunosuppression for renal protection, reduction of allograft vasculopathy and prevention of allograft rejection in de-novo heart transplant recipients: could we have it all?

PURPOSE OF REVIEW

De-novo introduction of everolimus (Eve) in heart transplant recipients opens for early reduction of calcineurin inhibitors (CNI) and potential of preserving renal function, attenuate progression of coronary allograft vasculopathy (CAV) and maintain rejection efficacy.

RECENT FINDINGS

The first trials demonstrated adequate rejection prophylaxis and favorable outcomes on CAV, but observed enhanced nephrotoxicity because of insufficient CNI reduction. The SCHEDULE trial compared de-novo Eve with significantly reduced CNI exposure and conversion to CNI-free treatment week 7-11 postheart transplant, with standard CNI immunosuppression. Improved renal function and attenuation of CAV was found among Eve patients, with higher numbers of treated acute rejections observed. With sustained superior renal and CAV related data also after 36 months with the Eve protocol, cardiac function was equally well preserved in both groups. According to the International Society of Heart and Lunge Transplantation registry, mammalian target of rapamycin inhibitor treatment is uncommon during the first postoperative year, with a prevalence of 20% in patients after 5 years.

SUMMARY

Current evidence suggests a greater benefit from these immunosuppressives if introduced at an earlier timepoint. Immunosuppressive protocols based on Eve treatment in de-novo patients should be further investigated and developed, enabling CNI avoidance before accelerating side-effects lead to irreversible damage.

Everolimus and reduced calcineurin inhibitor therapy in pediatric liver transplant recipients: Results from a multicenter, prospective study

In a 24-month, multicenter, single-arm, prospective study, 56 pediatric liver transplant patients with or without basiliximab induction were converted at 1-6 months post-transplant from standard calcineurin inhibitor (CN) therapy (± mycophenolic acid), to everolimus with reduced exposure to CNI (tacrolimus n=50, cyclosporine n=6). Steroid therapy was optional. Recruitment was stopped prematurely due to high rates of PTLD, treatment-related serious infections leading to hospitalization and premature study drug discontinuation. Subsequently, patients aged <7 years reverted to local standard-of-care immunosuppression. Mean tacrolimus concentration was above or near the upper end of the maintenance target range (2-5 ng/mL) until after month 6 post-enrollment. The primary variable, mean (SD) change in eGFR from baseline to month 12 (last observation carried forward), was +6.2 (19.5) mL/min/1.73 m² . Two patients experienced treated biopsy-proven acute rejection. No graft losses or deaths occurred. PTLD occurred in five patients (8.9%) (3/25 [12.0%] patients <2 years, 2/31 aged 2-18 years [6.5%]). Adverse events, serious adverse events, and discontinuation due to adverse events were reported in 100.0%, 76.8%, and 44.6% of patients, respectively. In conclusion, everolimus with reduced CNI improved renal function while maintaining antirejection potency in pediatric liver transplant patients but safety outcomes suggest that patients were overimmunosuppressed.

Longitudinal Pharmacokinetics of Everolimus When Combined With Low-level of Tacrolimus in Elderly Renal Transplant Recipients

BACKGROUND

Although the proportion of elderly patients among renal transplant recipients has increased, pharmacokinetic (PK) studies of immunosuppressants rarely include older patients.

METHODS

We studied 12-hour everolimus (EVL) PK in 16 elderly renal transplant recipients (all whites; 10 men; mean age, 64 ± 2 years (61-71 years), in 4 separate timepoints (at 7, 30, 60, and 150 days) after EVL introduction, corresponding to a mean postrenal transplantation day: PK1 (43 ± 4 days), PK2 (65 ± 7 days), PK3 (106 ± 17 days), and PK4 (206 ± 40 days). Patients received EVL (target trough level (Ctrough, 3-8 ng/mL), prednisone, and tacrolimus (TCL) (target Ctrough, 2-5 ng/mL).

RESULTS

Mean TCL-Ctrough was 7.2 ± 3.8, 4.9 ± 2.2, 4.9 ± 2.2, and 4.5 ± 1.2 ng/mL at PK1, PK2, PK3, and PK4, respectively. There were no differences among timepoints for mean EVL daily dose (data shown as PK3) (3.5 ± 1.3 mg/d), Ctrough (4.7 ± 2.5 ng/mL), AUC0-12h (106 ± 51 ng/h per mL), Caverage (8.8 ± 4.2 ng/mL), Cmax (19.2 ± 9.7 ng/mL), apparent Half-life (11.7 ± 4.2 hours), estimated total body clearance (0.39 ± 0.27 L/h), or fluctuation (166 ± 65%). Also, none of those PK parameters differed statistically when adjusted for body weight. EVL-Ctrough showed a very high correlation (r = 0.849) with AUC0-12h.

CONCLUSIONS

Our data indicate that elderly renal transplant recipients starting EVL 1 month after transplantation along with a steady-state TCL level, present stable EVL-PK parameters without significant changes in dose or exposure during the first 6 months after renal transplantation.

Association of Clinical Events With Everolimus Exposure in Kidney Transplant Patients Receiving Low Doses of Tacrolimus

A key objective in the use of immunosuppression after kidney transplantation is to attain the optimal balance between efficacy and safety. In a phase 3b, multicenter, randomized, open-label, noninferiority study, the incidences of clinical events, renal dysfunction, and adverse events (AEs) were analyzed at 12 months in 309 de novo renal transplant recipients receiving everolimus (EVR), low-dose tacrolimus (LTac), and prednisone. Cox proportional hazard regression modeling was used to estimate the probability of clinical events at specified combinations of time-normalized EVR and Tac trough concentrations. At 12 months, the highest incidence of treated biopsy-proven acute rejection (tBPAR) and graft loss occurred most often in patients with EVR trough concentration <3 ng/mL (64.7% and 10.5%, respectively). At 1 month and 12 months, increasing EVR levels were associated with fewer tBPAR events (both p < 0.0001). Low estimated glomerular filtration rate (eGFR) and decreased eGFR occurred more often in patients with lower EVR and higher Tac levels. AEs were most often observed in patients with EVR levels <3 ng/mL. This study supports maintaining an EVR trough concentration of 3-8 ng/mL, when combined with LTac, to achieve balanced efficacy and safety in renal transplant recipients.

TRIAL REGISTRATION

NCT01025817.

Recommendations of everolimus use in liver transplant

Mammalian target of rapamycin (mTOR) inhibitors, everolimus (EVL) and sirolimus are immunosuppressive agents with a minor nephrotoxic effect, limited to the development of proteinuria in some cases. The combination of EVL and low-dose tacrolimus has proven to be as safe and effective as standard therapy with tacrolimus for the prevention of acute cellular rejection. Early initiation of EVL-based immunosuppressive regimens with reduced exposure to calcineurin inhibitors has been shown to significantly improve renal function of LT recipients during induction and maintenance phases, with comparable efficacy and safety profiles. In patients with established kidney failure, initiating EVL may enable clinicians to reduce calcineurin inhibitors exposure, thereby contributing to the improved renal function of these patients. Although there is not sufficient evidence to recommend their use to prevent the recurrence of hepatocellular carcinoma and the progression of de novo tumours, they are used in this context in routine clinical practice.

Renal function in heart transplant patients after switch to combined mammalian target of rapamycin inhibitor and calcineurin inhibitor therapy

BACKGROUND

A calcineurin inhibitor (CNI)-based immunosuppression combined with mammalian target of rapamycin inhibitors (mTORs) seems to be attractive in patients after heart transplantation (HTX) in special clinical situations, for example, in patients with adverse drug effects of prior immunosuppression. Previous studies in patients after HTX detected advantageous effects regarding renal function of a tacrolimus (TAC)-based vs cyclosporine-A (CSA)-based immunosuppression (in combination with mycophenolate mofetil). However, data regarding renal function after HTX in mTOR/CNI patients remain limited.

AIM

Primary end point of the present study was to analyze renal function in HTX patients 1 year after switch to an mTOR/CNI-based immunosuppression.

METHODS

Data of 80 HTX patients after change to mTOR/CNI-based immunosuppression were retrospectively analyzed. Renal function was assessed by measured serum creatinine and by estimated glomerular filtration rate (eGFR) calculated from Modification of Diet in Renal Disease equation.

RESULTS

Twenty-nine patients received mTOR/CSA-based treatment and 51 patients received mTOR/TAC-based therapy. At time of switch and at 1-year follow-up, serum creatinine and eGFR did not differ significantly between both study groups (all P=not statistically significant). Analysis of variances with repeated measurements detected a similar change of renal function in both study groups.

CONCLUSION

The present study detected no significant differences between both mTOR/CNI study groups, indicating a steady state of renal function in HTX patients after switch of immunosuppressive regimen.

Influence of everolimus on the pharmacokinetics of tacrolimus in Japanese renal transplant patients

OBJECTIVES

To examine whether a trough concentration of everolimus in the therapeutic range of 3-5 ng/mL affects the pharmacokinetics of tacrolimus in renal transplant patients.

METHODS

A total of 52 Japanese renal transplant patients receiving tacrolimus were enrolled in this study. In 28 of them, everolimus was co-administered on day 14 after surgery. Changes in the dose-adjusted blood trough concentration of tacrolimus from day 14 to 28 after surgery were investigated.

RESULTS

The dose-adjusted blood trough concentration of tacrolimus on day 28 was affected by CYP3A5*3/*3 and hemoglobin level (P < 0.001 and P = 0.007), but not by everolimus (P = 0.171). In addition, there was no change in the dose-adjusted blood trough concentration of tacrolimus in patients before or after everolimus coadministration (P = 0.165). On day 28, there was no correlation between the rate of change in the dose-adjusted blood trough concentration of tacrolimus and the blood trough concentration or area under the plasma concentration-time curve from 0 to 12 h for everolimus after initiation of combination therapy (r = 0.341, P = 0.076 and r = 0.234, P = 0.231).

CONCLUSIONS

A pharmacokinetic interaction between tacrolimus and everolimus was not observed clinically in renal transplant patients. Safe and reliable immunosuppressive therapy in renal transplant patients might be achieved using a combination of tacrolimus and everolimus.

Efficacy and Safety of Elective Conversion From Sotrastaurin (STN) to Tacrolimus (TAC) or Mycophenolate (MPS) in Stable Kidney Transplant Recipients

BACKGROUND

This study aimed to evaluate the efficacy and safety outcomes of conversion strategies in stable kidney transplant recipients after premature termination of the sotrastaurin (STN) development program.

METHODS

This is an exploratory and prospective study, including 38 stable renal transplant recipients. Tacrolimus (TAC) group [STN → mycophenolate sodium (MPS)] consisted of 9 patients receiving TAC, STN, and prednisone that were converted from STN to MPS. Everolimus (EVR) group (STN → TAC) consisted of 29 patients receiving EVR, STN, and prednisone that were converted from STN to TAC.

RESULTS

In TAC (STN → MPS) group, dose-adjusted TAC concentrations decreased from baseline to first week (2.3 ± 1.1 versus 1.5 ± 1.0 ng·mL·mg, P < 0.05). Two patients experienced a first acute rejection episode. Conversion to MPS was associated with a higher incidence of adverse events. In EVR (STN → TAC) group, dose-adjusted EVR concentrations decreased from baseline to first week (3.6 ± 2.3 ng·mL·mg versus 1.9 ± 0.8 ng·mL·mg, P < 0.01). The proportion of patients with donor-specific antibodies was lower in TAC (STN → MPS) (11%) compared to EVR (STN → TAC) (31%) before conversion. Conversion from STN to TAC was associated with a reduction in estimated glomerular filtration rate (69.6 ± 16.9 versus 61.0 ± 18.8 mL·min·1.73 m, P < 0.01) and a decreased proportion of patients with donor-specific antibodies (31% versus 14%) at 12 months.

CONCLUSIONS

Conversion from TAC/STN to TAC/MPS or from EVR/STN to TAC/EVR was associated with significant pharmacokinetic changes in both TAC and EVR whole-blood trough concentrations due to known drug-to-drug interaction, which were associated with changes in efficacy and safety.

Everolimus in de novo liver transplant recipients: a systematic review

BACKGROUND

Everolimus has no nephrotoxicity and is used to treat patients with post-liver transplant chronic renal insufficiency. The present systematic review was to evaluate the efficacy and safety of everolimus in de novo liver transplant patients.

DATA SOURCES

Randomized controlled trials comparing everolimus for de novo liver transplant in PubMed, the Cochrane Library, and ScienceDirect published up to March 31, 2014 were searched by two independent reviewers. Mean differences and 95% confidence interval (95% CI) for renal function, relative risk (RR) and 95% CI for treated biopsy-proven acute rejection (tBPAR), graft loss, death, neoplasms/tumor recurrence, and adverse events were collected. Meta-analyses were performed with RevMan version 5.10.

RESULTS

A total of four randomized controlled trials covering 1119 cases were included. The meta-analyses revealed that compared with standard exposure of calcineurin inhibitors (CNIs), everolimus combined with reduced CNIs improved creatinine clearance (calculated with the Cockcroft-Gault formula) by 5.13 mL/min at one year (95% CI: 0.42-9.84; P=0.03), and decreased tBPAR (RR: 0.56; 95% CI: 0.35-0.90; P=0.02). Everolimus initiation with CNIs elimination improved glomerular filtration rate (GFR, measured with the modification of diet in renal disease formula) of 10.42 mL/min/1.73 m2 (95% CI: 3.44-17.41; P<0.01) one year after treatment, but increased tBPAR (RR: 1.71; 95% CI: 1.15-2.53; P<0.01). Everolimus decreased the risk of neoplasms/tumor recurrence after liver transplant (RR: 0.60; 95% CI: 0.34-1.03; P=0.06), but was associated with greater risk of adverse events which resulted in drug discontinuation (RR: 1.98; 95% CI: 1.49-2.64; P<0.01).

CONCLUSIONS

Early introduction of everolimus combined with low-dose or no CNI in de novo liver transplant significantly improves renal function one year post treatment. Everolimus combined with low-dose CNI decreases the risk of tBPAR one year after liver transplant, but everolimus administered without CNIs increases tBPAR.

A randomized trial of everolimus and low-dose cyclosporine in renal transplantation: with or without steroids?

This multicenter, randomized, prospective, controlled trial (EVIDENCE study) aimed to determine short-term effects of early steroid withdrawal in renal transplant patients initially treated with everolimus, low-dose cyclosporine (CsA), and steroids. Patients were randomized to standard triple therapy with CsA, everolimus twice daily and steroids (group A), steroid-free immunosuppression (group B), or triple therapy once daily (group C). However, since patient enrollment was slower than expected, group C randomization was prematurely discontinued. The primary end point was treatment failure rate (composite end point of death, graft loss, biopsy-proven acute rejection, and loss to follow-up) between randomization and month 12. Patients evaluable for the primary end point included 139 randomized patients. According to intention-to-treat analysis, 2.8% of patients in group A and 14.7% in group B experienced treatment failure (95% upper confidence limit 19.7%). As this was higher than the predefined noninferiority limit of 10%, noninferiority could not be proved. No conclusive statements can be made on noninferiority of the steroid withdrawal regimen vs the standard regimen in these patients. Additional studies with longer follow-up are required to determine the efficacy of steroid-free immunosuppression in renal transplant recipients receiving everolimus.

Pharmacokinetics and Long-Term Safety and Tolerability of Everolimus in Renal Transplant Recipients Converted From Cyclosporine

BACKGROUND

Conversion from cyclosporine (CsA) to everolimus (EVR) in kidney transplant recipients receiving mycophenolate sodium (MPS) and corticosteroids has been used to reduce CsA associated toxicities. Nevertheless, exposures produced by the initial EVR dose, the steady state pharmacokinetic and long-term safety and tolerability have not been explored in detail.

METHODS

Twenty-four stable kidney transplant recipients receiving CSA, MPS, and corticosteroids were converted from CSA to EVR. The initial EVR dose was 3 mg BID. Weekly monitoring of EVR blood concentrations was followed by a full 12 hour pharmacokinetic profile 28 days after conversion. Therapeutic drug monitoring, safety, and tolerability were analyzed during 5 years of follow-up.

RESULTS

The study population was relatively young (mean of 42 years) with a predominance of males (62%) and White (67%) recipients of kidneys from living (54%) or deceased (46%) donors. Mean time of the conversion was 61 months after transplantation. In the first 7 patients, the initial EVR dose of 3 mg BID resulted in mean EVR trough blood concentration of 14.7 ± 3.7 ng/mL at day 7. The initial EVR dose was then reduced to 2 mg BID for the following 17 patients. Four weeks after conversion, mean EVR dose was 1.7 ± 0.5 mg BID (7 patients were receiving 1 mg BID and 17 were receiving 2 mg BID) resulting in mean EVR trough blood concentration of 4.0 ± 1.4 ng/mL. Whereas mean maximum concentration (13.4 ± 2.8 versus 22.9 ± 7.4 ng/mL, P = 0.003) and mean apparent clearance (232 ± 79 versus 366 ± 173 mL/min, P = 0.016) were higher, mean area under the curve (78.2 ± 22.1 versus 102.5 ± 38.5 ng.h/mL, P = 0.067) and mean C0 (3.7 ± 1.3 versus 4.1 ± 1.5 ng/mL, P = 0.852) were no different comparing patients receiving 1 mg and 2 mg EVR BID. Mean inter-subject variability of area under the curve, trough concentration, and maximum concentration was 38%, 36%, and 38%. EVR treatment was discontinued in 29% of patients due to proteinuria (N = 2), pneumonia (N = 2), dyslipidemia (N = 2), and anemia (N = 1) and MPS dose was reduced in 58% of patients.

CONCLUSIONS

The initial 3 mg BID dose produced high EVR trough blood concentrations. The 2 mg BID dose appears to be the appropriate initial dose to provide therapeutic concentrations but still requires initial intensive therapeutic monitoring to achieve and maintain blood concentrations within the therapeutic target concentration. The combination of EVR and full dose MPS has limited long-term tolerability and safety.

Estimating the contribution of everolimus to immunosuppressive efficacy when combined with tacrolimus in liver transplantation: a model-based approach

Determining the efficacy contribution of an investigational drug as part of a novel combination regimen that also includes a previously untested dose of a standard treatment is challenging, particularly when "placebo control" data (combination regimen minus the investigational drug) is not available for comparison. This situation was encountered in a phase III trial that tested the combination of the investigational drug everolimus with a dose of tacrolimus lower than used in standard liver transplantation therapy. The challenge was addressed by predicting the efficacy of the placebo control from the study data using a pharmacometric-based exposure-response analysis, selected to account for features specific to the transplant setting: systematic change in drug exposure over time and sparse pharmacokinetic sampling. The efficacy contribution of everolimus was then demonstrated by comparing this prediction to the efficacy of the combination regimen. This pharmacometrics-based approach may contribute to characterization of therapeutic agents in real-world settings.

The role of everolimus in liver transplantation

During the last 5 decades, liver transplantation has witnessed rapid development in terms of both technical and pharmacologic advances. Since their discovery, calcineurin inhibitors (CNIs) have remained the standard of care for immunosuppression therapy in liver transplantation, improving both patient and graft survival. However, adverse events, particularly posttransplant nephrotoxicity, associated with long-term CNI use have necessitated the development of alternate treatment approaches. These include combination therapy with a CNI and the inosine monophosphate dehydrogenase inhibitor mycophenolic acid and use of mammalian target of rapamycin (mTOR) inhibitors. Everolimus, a 40-O-(2-hydroxyethyl) derivative of mTOR inhibitor sirolimus, has a distinct pharmacokinetic profile. Several studies have assessed the role of everolimus in liver transplant recipients in combination with CNI reduction or as a CNI withdrawal strategy. The efficacy of everolimus-based immunosuppressive therapy has been demonstrated in both de novo and maintenance liver transplant recipients. A pivotal study in 719 de novo liver transplant recipients formed the basis of the recent approval of everolimus in combination with steroids and reduced-dose tacrolimus in liver transplantation. In this study, everolimus introduced at 30 days posttransplantation in combination with reduced-dose tacrolimus (exposure reduced by 39%) showed comparable efficacy (composite efficacy failure rate of treated biopsy-proven acute rejection, graft loss, or death) and achieved superior renal function as early as month 1 and maintained it over 2 years versus standard exposure tacrolimus. This review provides an overview of the efficacy and safety of everolimus-based regimens in liver transplantation in the de novo and maintenance settings, as well as in special populations such as patients with hepatocellular carcinoma recurrence, hepatitis C virus-positive patients, and pediatric transplant recipients. We also provide an overview of ongoing studies and discuss potential expansion of the role for everolimus in these settings.

Everolimus in heart transplantation: an update

The evidence base relating to the use of everolimus in heart transplantation has expanded considerably in recent years, providing clinically relevant information regarding its use in clinical practice. Unless there are special considerations to take into account, all de novo heart transplant patients can be regarded as potential candidates for immunosuppression with everolimus and reduced-exposure calcineurin inhibitor therapy. Caution about the use of everolimus immediately after transplantation should be exercised in certain patients with the risk of severe proteinuria, with poor wound healing, or with uncontrolled severe hyperlipidemia. Initiation of everolimus in the early phase aftertransplant is not advisable in patients with severe pretransplant end-organ dysfunction or in patients on a left ventricular assist device beforetransplant who are at high risk of infection or of wound healing complications. The most frequent reason for introducing everolimus in maintenance heart transplant patients is to support minimization or withdrawal of calcineurin inhibitor therapy, for example, due to impaired renal function or malignancy. Due to its potential to inhibit the progression of cardiac allograft vasculopathy and to reduce cytomegalovirus infection, everolimus should be initiated as soon as possible after heart transplantation. Immediate and adequate reduction of CNI exposure is mandatory from the start of everolimus therapy.

Growing experience with mTOR inhibitors in pediatric solid organ transplantation

Controlled trials of mTOR inhibitors in children following solid organ transplantation are scarce, although evidence from prospective single-arm studies is growing. Everolimus with reduced CNI therapy has been shown to be efficacious and safe in de novo pediatric kidney transplant patients in prospective trials. Prospective and retrospective data in children converted from CNI therapy to mTOR inhibition following kidney, liver, or heart transplantation suggest preservation of immunosuppressive efficacy. Good renal function has been maintained when mTOR inhibitors are used de novo in children following kidney transplantation or after conversion to mTOR inhibition with CNI minimization. mTOR inhibition with reduced CNI exposure is associated with a low risk for developing infection in children. Growth and development do not appear to be impaired during low-dose mTOR inhibition, but more studies are required. No firm conclusions can be drawn as to whether mTOR inhibitors should be discontinued in children requiring surgical intervention or whether mTOR inhibition delays progression of hepatic fibrosis after pediatric liver transplantation. In conclusion, current evidence suggests that use of mTOR inhibitors in children undergoing solid organ transplantation is efficacious and safe, but a number of issues remain unresolved and further studies are required.

Population pharmacokinetics of everolimus in cardiac recipients: comedications, ABCB1, and CYP3A5 polymorphisms

BACKGROUND

The aim of this study was, using routine drug monitoring data, to identify patient characteristics that may influence everolimus (EVE) pharmacokinetic parameters and to develop a population pharmacokinetic model to predict EVE whole blood concentrations in cardiac recipients.

METHODS

Fifty-nine patients were enrolled in the prospective study. Patient's characteristics were recorded including biological covariates and treatments. CYP3A5 and ABCB1 polymorphisms were determined. Seven hundred seventy-five EVE blood samples were collected for routine drug monitoring. Population pharmacokinetic modeling was carried out using the nonlinear mixed-effects modeling program. Results were analyzed according to a 1-compartment pharmacokinetic model with linear absorption and elimination. The model was evaluated using a bootstrap method and a visual predictive check procedure.

RESULTS

The pharmacokinetic of EVE in cardiac recipients was best described by a 1-compartment model. Interindividual variability was best described by an exponential error model and residual error by a proportional plus additive error model. Estimation of EVE apparent clearance (3.33 ± 0.20 L/h) and apparent volume of distribution (146 ± 33 L) were in accordance with previously published data. Bilirubinemia and cyclosporine significantly influenced EVE clearance. Some covariates that were expected to influence EVE clearance, for example, ABCB1 and CYP3A5 polymorphisms, were not evidenced. No covariates influenced the volume of distribution of EVE.

CONCLUSIONS

This study is the first population pharmacokinetic model of EVE in heart transplantation patients. It allows a better description of the pharmacokinetics of EVE. The present population pharmacokinetic model allows estimating a priori and a posteriori EVE concentrations in cardiac recipients and could limit the over and under drug exposure in this population.

Interactions between oral antineoplastic agents and concomitant medication: a systematic review

INTRODUCTION

In recent years, the number of oral antitumoral agents has considerably increased. Oral administration increases the risk of interactions, because most oral anticancer drugs are taken on a daily basis. Interactions can increase exposure to antitumoral agents or cause treatment failure. Many antitumoral drugs undergo enzymatic metabolism by cytochrome P450. As some act as inducers or inhibitors of one or more isoenzymes, they can lead to decreases or increases in plasma concentrations of concomitant drugs. Hence, cytostatic drugs can act not only as victims but also as perpetrators. P-glycoprotein, an efflux transporter, can also be involved in pharmacokinetic interactions.

AREAS COVERED

A Medline search was performed to summarize the available evidence of the most clinically relevant interactions between oral chemotherapy agents and other drugs. The search covered the period from 1966 until August 2012 for each antitumoral drug using the medical subject headings 'Drug Interactions' OR 'Pharmacokinetics'. While the present review is not exhaustive, it aims to increase clinicians' awareness of potential drug-drug interactions.

EXPERT OPINION

As cancer patients are often polymedicated and treated by different physicians, the risk of drug interactions between antitumoral agents and other medications is high. More clinical interaction studies are encouraged to ensure appropriate antineoplastic pharmacokinetics in clinical practice.

A drug safety evaluation of everolimus in kidney transplantation

INTRODUCTION

Calcineurin inhibitors (CNI) have greatly reduced the rate of acute rejection and improved short-term graft survival after organ transplantation, however, long-term survival has hardly changed since their introduction. CNIs are believed to contribute to graft fibrosis, have side effects that adversely affect cardiovascular risk, and are associated with an increased rate of post-transplant malignancies. Everolimus, a mammalian target of rapamycin (mTOR) inhibitor, is not associated with graft fibrosis, has a superior cardiovascular risk profile to CNI therapy and has shown potential for the prevention and treatment of diverse forms of cancer.

AREAS COVERED

This review summarizes key aspects of everolimus, including its mechanism of action, pharmacokinetics, pharmacodynamics, drug-drug interactions and pivotal clinical studies with a focus on safety and efficacy.

EXPERT OPINION

Everolimus is effective in improving graft function in selected kidney transplant patients. Most adverse events are present for a short time after the introduction of everolimus, and are manageable. Everolimus has the potential to become an important agent in de novo and maintenance immunotherapy in kidney transplant recipients.

Drug choices in autoimmune hepatitis: part B--Nonsteroids

Nonsteroidal medications, previously unfamiliar in the management of autoimmune hepatitis, can supplement or replace conventional corticosteroid regimens, especially in problematic patients. Mycophenolate mofetil is a next-generation purine antagonist that has been useful in treating patients with azathioprine intolerance. It has been less effective in salvaging patients with steroid-refractory disease. Azathioprine is the choice as a corticosteroid-sparing agent in treatment-naive patients and in individuals with corticosteroid intolerance, incomplete response and relapse after drug withdrawal. Tacrolimus is preferred over cyclosporine for recalcitrant disease because of its established preference in organ transplantation, but replacement with cyclosporine should be considered if the disease worsens on treatment. Rapamycin has antiproliferative and proapoptotic actions that warrant further study in autoimmune hepatitis. The nonstandard, nonsteroidal medications are mainly salvage therapies with off-label indications that must be used in highly individualized and well-monitored clinical situations.

Everolimus plus early tacrolimus minimization: a phase III, randomized, open-label, multicentre trial in renal transplantation

There is increasing interest in tacrolimus-minimization regimens. ASSET was an open-label, randomized, 12-month study of everolimus plus tacrolimus in de-novo renal-transplant recipients. Everolimus trough targets were 3-8 ng/ml throughout the study. Tacrolimus trough targets were 4-7 ng/ml during the first 3 months and 1.5-3 ng/ml (n = 107) or 4-7 ng/ml (n = 117) from Month 4. All patients received basiliximab induction and corticosteroids. The primary objective was to demonstrate superior estimated glomerular filtration rate (eGFR; MDRD-4) at Month 12 in the tacrolimus 1.5-3 ng/ml versus the 4-7 ng/ml group. Secondary endpoints included incidence of biopsy-proven acute rejection (BPAR; Months 4-12) and serious adverse events (SAEs; Months 0-12). Statistical significance was not achieved for the primary endpoint (mean eGFR: 57.1 vs. 51.7 ml/min/1.73 m(2)), potentially due to overlapping of achieved tacrolimus exposure levels (Month 12 mean ± SD, tacrolimus 1.5-3 ng/ml: 3.4 ± 1.4; tacrolimus 4-7 ng/ml: 5.5 ± 2.0 ng/ml). BPAR (months 4-12) and SAE rates were comparable between groups (2.7% vs. 1.1% and 58.7% vs. 51.3%; respectively). Everolimus-facilitated tacrolimus minimization, to levels lower than previously investigated, achieved good renal function, low BPAR and graft-loss rates, and an acceptable safety profile in renal transplantation over 12 months although statistically superior renal function of the 1.5-3 ng/ml tacrolimus group was not achieved.

Everolimus in combination with cyclosporin a as pre- and posttransplantation immunosuppressive therapy in nonmyeloablative allogeneic hematopoietic stem cell transplantation

Everolimus (RAD001) is an mTOR inhibitor that has been successfully used as an immunosuppressant in solid-organ transplantation. Data in allogeneic hematopoietic stem cell transplantation (HSCT) is limited. This study aimed to investigate pharmacokinetics, safety, and efficacy of RAD001 in a canine allogeneic HSCT model. First, pharmacokinetics of RAD001 were performed in healthy dogs in order to determine the appropriate dosing. Doses of 0.25 mg RAD001 twice daily in combination with 15 mg/kg cyclosporin A (CsA) twice daily were identified as appropriate starting doses to achieve the targeted range of RAD001 (3-8 μg/L) when orally administered. Subsequently, 10 dogs were transplanted using 2 Gy total body irradiation (TBI) for conditioning and 0.25 mg RAD001 twice daily plus 15 mg/kg CsA twice daily for pre- and posttransplantation immunosuppression. Seven of the 10 transplanted dogs were maintained at the starting RAD001 dose throughout the study. For the remaining 3 dogs, dose adjustments were necessary. RAD001 accumulation over time did not occur. All dogs initially engrafted. Five dogs eventually rejected the graft (weeks 10, 10, 13, 27, and 56). Two dogs died of pneumonia (weeks 8 and 72) but were chimeric until then. Total cholesterol rose from median 4.1 mmol/L (3.5-5.7 mmol/L) before HSCT to 6.0 mmol/l (5.0-8.5 mmol/l) at day 21 after HSCT, but remained always within normal range. Changes in creatinine and triglyceride values were not observed. Long-term engraftment rates were inferior to sirolimus/CsA and mycophenolate mofetil (MMF)/CsA regimen, respectively. RAD001/CsA caused a more pronounced reduction of platelet counts to median 2 × 10(9)/L (range: 0-21 × 10(9)/L) and longer time to platelet recovery of 21 days (range: 14-24 days) compared with MMF/CsA. CsA c(2h) levels were significantly enhanced in the RAD001/CsA regimen, but c(0h) and area under the curve from 0 to 12 hours (AUC(0-12h)) values did not differ compared with an MMF/CsA immunosuppression. In summary, immunosuppression consisting of RAD001 and CsA is well tolerated but not as efficient as with other established immunosuppressants in a canine nonmyeloablative HSCT regimen. Hence, our study does not support the application of RAD001/CsA as standard practice in this setting.

In vivo CYP3A activity is significantly lower in cyclosporine-treated as compared with tacrolimus-treated renal allograft recipients

In vitro studies have identified cyclosporine and tacrolimus as CYP3A inhibitors. In the current study in renal allograft recipients, we used intravenously and orally administered midazolam as a drug probe to assess whether the study drugs at doses that are generally used in clinical practice have differential effects on in vivo hepatic and first-pass CYP3A activities. Systemic and apparent oral midazolam clearance were 24% (269 ± 73 vs. 354 ± 102 ml/min, P = 0.022) and 31% (479 ± 190 vs. 688 ± 265 ml/min, P = 0.013), respectively, lower in cyclosporine-treated patients (n = 20) than in matched tacrolimus-treated patients (n = 20). The latter displayed midazolam clearances similar to those in two larger cohorts of nonmatched tacrolimus-treated patients (n = 58 and n = 80) and to those receiving a calcineurin inhibitor-free regimen (n = 6). This implies that in vivo hepatic and first-pass CYP3A activities are significantly lower in patients receiving cyclosporine than in those receiving tacrolimus, indicating that, at the doses generally used in clinical practice, cyclosporine is the stronger of the two with respect to CYP3A inhibition. This observation has important implications in the context of drug-drug interactions in transplant recipients.

Optimal everolimus concentration is associated with risk reduction for acute rejection in de novo renal transplant recipients

BACKGROUND

Everolimus (Evl) plus tacrolimus (Tac) in de novo renal transplantation is effective and safe. Whether the concentration of Evl affects efficacy and safety in a Tac-based regimen has not been previously reported.

AIM

To evaluate whether the concentration of Evl affects biopsy-proven acute rejection (BPAR), renal function, adverse events (AEs); and to assess for pharmacokinetic (PK) interactions.

METHODS

Data were from a prospective, multicenter, open-label, randomized, exploratory 6-month study of 92 renal transplant patients treated de novo with concentration-controlled Evl (target trough levels > or =3 ng/mL) plus low-dose Tac or Evl plus standard-dose Tac; both groups received basiliximab and corticosteroids. Data were pooled across study arms to examine BPAR rates in patients with Evl trough levels less than 3 (n=26), 3 to 8 (n=62), or more than 8 ng/mL (n=4). Groups were stratified by both Evl and Tac trough levels to evaluate glomerular filtration rate and AEs. Evl and Tac PK interactions were evaluated in a subset of 14 patients.

RESULTS

Evl trough level of more than or equal to 3 ng/mL was associated with significantly lower rates of BPAR as compared with a trough level of less than 3 ng/mL. Glomerular filtration rate was similar at 6 months for both the low and standard Tac groups. No apparent PK interactions were observed between Evl and Tac. AEs were infrequent and did not seem to be associated with the Evl or Tac level.

CONCLUSIONS

Evl trough levels > or =3 ng/mL plus Tac are associated with low rates of BPAR without adversely affecting renal function. No evident PK interaction exists between Evl and Tac.