Maximizing the clinical outcome with mTOR inhibitors in the renal transplant recipient: defining the role of calcineurin inhibitors

Design and rationale of the ATHENA study--A 12-month, multicentre, prospective study evaluating the outcomes of a de novo everolimus-based regimen in combination with reduced cyclosporine or tacrolimus versus a standard regimen in kidney transplant patients: study protocol for a randomised controlled trial

Background

Immunosuppression with calcineurin inhibitors remains the mainstay of treatment after kidney transplantation; however, long-term use of these drugs may be associated with nephrotoxicity. In this regard, the current approach is to optimise available immunosuppressive regimens to reduce the calcineurin inhibitor dose while protecting renal function without affecting the efficacy. The ATHENA study is designed to evaluate renal function in two regimens: an everolimus and reduced calcineurin inhibitor-based regimen versus a standard treatment protocol with mycophenolic acid and tacrolimus in de novo kidney transplant recipients.

Method/Design

ATHENA is a 12-month, multicentre, open-label, prospective, randomised, parallel-group study in de novo kidney transplant recipients (aged 18 years or older) receiving renal allografts from deceased or living donors. Eligible patients are randomised (1:1:1) prior to transplantation to one of the following three treatment arms: everolimus (starting dose 1.5 mg/day; C0 3–8 ng/mL) with cyclosporine or everolimus (starting dose 3 mg/day; C0 3–8 ng/mL) with tacrolimus or mycophenolic acid (enteric-coated mycophenolate sodium at 1.44 g/day or mycophenolate mofetil at 2 g/day) with tacrolimus; in combination with corticosteroids. All patients receive induction therapy with basiliximab. The primary objective is to demonstrate non-inferiority of renal function (eGFR by the Nankivell formula) in one of the everolimus arms compared with the standard group at month 12 post transplantation. The key secondary objective is to assess the incidence of treatment failure, defined as biopsy-proven acute rejection, graft loss, or death, among the treatment groups. Other objectives include assessment of the individual components of treatment failure, incidence and severity of viral infections, incidence and duration of delayed graft function, incidence of indication biopsies, slow graft function and wound healing complications, and overall safety and tolerability. Exploratory objectives include evaluation of left ventricular hypertrophy assessed by the left ventricular mass index, evolution of human leukocyte antigen and non-human leukocyte antigen antibodies, and a cytomegalovirus substudy.

Discussion

As one of the largest European multicentre kidney transplant studies, ATHENA will determine whether a de novo everolimus-based regimen can preserve renal function versus the standard of care. This study further assesses a number of clinical issues which impact long-term outcomes post transplantation; hence, its results will have a major clinical impact.

Trial registration

Clinicaltrials.gov: NCT01843348, date of registration – 18 April 2013; EUDRACT number: 2011-005238-21, date of registration – 20 March 2012

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-016-1220-9) contains supplementary material, which is available to authorized users.

Effects of Storage Temperature and Time on Stability of Serum Tacrolimus and Cyclosporine A Levels in Whole Blood by LC-MS/MS

Tacrolimus and cyclosporine A are immunosuppressant drugs with narrow therapeutic windows. The aim of this study was to investigate the stability of tacrolimus and cyclosporin A levels in whole blood samples under different storage conditions. Whole blood samples were obtained from 15 patients receiving tacrolimus and 15 patients receiving cyclosporine A. Samples were immediately analyzed and then stored at different conditions (room temperature (24°C−26°C) for 24 hours, +4°C for 24 and 48 hours, and −20°C for one month) and then analyzed again. For tacrolimus, there was a significant difference between samples analyzed immediately and those kept 24 hours at room temperature (P = 0.005) (percent change 32.89%). However, there were no significant differences between the other groups. For cyclosporine A, there was a significant difference between samples analyzed immediately and those kept 24 hours (P = 0.003) (percent change 19.47%) and 48 hours (P = 0.002) (percent change 15.38%) at +4°C and those kept 24 hours at room temperature (P = 0.011) (percent change 9.71%). Samples of tacrolimus should be analyzed immediately or stored at either +4°C or −20°C, while samples of cyclosporine A should be analyzed immediately or stored at −20°C.

Safety and efficacy of the early introduction of everolimus with reduced-exposure cyclosporine a in de novo kidney recipients

BACKGROUND

Everolimus and cyclosporine A (CsA) exhibit synergistic immunosuppressive activity when used in combination. We examined the safety and efficacy of the use of everolimus with a cyclosporine-sparing strategy in de novo renal transplant recipients.

METHODS

A comparative, parallel, randomized, open-label 1-year study has been performed in 148 patients from five transplant centers to compare the efficacy and tolerability of everolimus and reduced exposure CsA (the investigational group) or enteric-coated mycophenolate sodium and standard-exposure CsA (the control group) in combination with basiliximab and steroids. The eligible subjects were randomly assigned at 1 month after transplantation. Efficacy failure (biopsy-proven acute rejection, death, graft loss, or loss to follow-up), safety, and renal function were evaluated.

RESULTS

One graft loss has been reported in the control group and no patient death were reported in either group. The incidence of biopsy-proven acute rejection until 12 months after transplantation of the investigational group was 7.5%, compared to 11.1% of the control group (P=0.565). The mean estimated glomerular filtration rates of the investigational group at 12 months after transplantation was significantly higher (68.1 ± 16.8 ml/min/1.73 m(2)) than that of the control group (60.6 ± 15.8 ml/min/1.73 m(2); P=0.016). There was no significant difference (P>0.05) in the incidence of discontinuations and serious adverse events between the groups.

CONCLUSION

The results of this study provide the evidences that (1) the calcineurin inhibitor (CNI) minimization by the introduction of everolimus after 1-month posttransplantation keeps the incidences of acute rejection and additional risks as low as the conventional immunosuppression; (2) it allows minimizing CNI exposure, consequently reducing CNI nephrotoxicity and preserving renal function.

Everolimus inhibits anti-HLA I antibody-mediated endothelial cell signaling, migration and proliferation more potently than sirolimus

Antibody (Ab) crosslinking of HLA I molecules on the surface of endothelial cells triggers proliferative and pro-survival intracellular signaling, which is implicated in the process of chronic allograft rejection, also known as transplant vasculopathy (TV). The purpose of this study was to investigate the role of mammalian target of rapamycin (mTOR) in HLA I Ab-induced signaling cascades. Everolimus provides a tool to establish how the mTOR signal network regulates HLA I-mediated migration, proliferation and survival. We found that everolimus inhibits mTOR complex 1 (mTORC1) by disassociating Raptor from mTOR, thereby preventing class I-induced phosphorylation of mTOR, p70S6K, S6RP and 4E-BP1, and resultant class I-stimulated cell migration and proliferation. Furthermore, we found that everolimus inhibits class I-mediated mTORC2 activation (1) by disassociating Rictor and Sin1 from mTOR; (2) by preventing class I-stimulated Akt phosphorylation and (3) by preventing class I-mediated ERK phosphorylation. These results suggest that everolimus is more effective than sirolimus at antagonizing both mTORC1 and mTORC2, the latter of which is critical in endothelial cell functional changes leading to TV in solid organ transplantation after HLA I crosslinking. Our findings point to a potential therapeutic effect of everolimus in prevention of chronic Ab-mediated rejection.

Simultaneous determination of cyclosporine A, tacrolimus, sirolimus, and everolimus in whole-blood samples by LC-MS/MS

Objectives. Cyclosporine A (CyA), tacrolimus (TRL), sirolimus (SIR), and everolimus (RAD) are immunosuppressive drugs frequently used in organ transplantation. Our aim was to confirm a robust sensitive and selective liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for determination of CyA, TRL, SIR, and RAD in whole-blood samples. Materials and Methods. We used an integrated online solid-phase extraction-LC-MS/MS system and atmospheric pressure ionization tandem mass spectrometry (API-MS/MS) in the multiple reaction monitoring (MRM) detection mode. CyA, TRL, SIR, and RAD were simultaneously analyzed in whole blood treated with precipitation reagent taken from transplant patients. Results. System performance parameters were suitable for using this method as a high-throughput technique in clinical practice. The high concentration of one analyte in the sample did not affect the concentration of other analytes. Total analytical time was 2.5 min, and retention times of all analytes were shorter than 2 minutes. Conclusion. This LC-MS/MS method can be preferable for therapeutic drug monitoring of these immunosuppressive drugs (CyA, TRL, SRL, and RAD) in whole blood. Sample preparation was too short and simple in this method, and it permits robust, rapid, sensitive, selective, and simultaneous determination of these drugs.

Conversion from sirolimus to everolimus in kidney transplant recipients receiving a calcineurin-free regimen

BACKGROUND

Everolimus (EVL) and sirolimus (SRL) were introduced into immunosuppressive regimens, in an attempt to replace or reduce the dose of the nephrotoxic calcineurin inhibitors (CNI). In our institution, due to an administrative decision, conversion from SRL to EVL, was carried out, providing us the opportunity to investigate the effectiveness and safety profile of both drugs and to review the practical conversion dose between them.

METHODS

We retrospectively analyzed the medical records of 51 maintenance kidney transplant recipients receiving an SRL-based CNI-free regimen, who were switched to EVL. SRL dose was concentration controlled to a through level of 4-8 ng/mL. Patients were converted to a variable dose of EVL that was adjusted to achieve a trough concentration of 3-8 ng/mL.

RESULTS

SRL mean dose at time of conversion was 2.0 ± 0.9 mg/d. Initial EVL mean dose was 1.3 ± 0.5 mg/d. Six months after conversion, mean EVL trough level was 6.2 ± 2.8 ng/mL. EVL dose at this point was 2.0 ± 0.9 mg/d, which was not statistically different from SRL dose at the time of conversion (p = 0.575), suggesting a conversion factor of 1:1. During this six month period post conversion, no significant changes were observed in serum creatinine, hematocrit level, platelet count, proteinuria or lipid levels. No patient experienced an acute rejection episode.

CONCLUSIONS

Conversion from SRL to EVL in renal transplant recipients receiving a CNI-free immunosuppressive regimen can be performed safely with a low trough level range of EVL. We report for the first time a conversion factor between SRL and EVL.

Dermatologic management, sun avoidance and vitamin D status in organ transplant recipients (OTR)

It is well known that skin cancer, especially cutaneous squamous cell carcinoma (SCC), in organ transplant recipients (OTRs) has higher incidence rates, behaves more aggressively and has higher rates of metastasis. OTRs who have been treated for many years with immunosuppressive medication are at the highest risk for developing malignant skin tumors. Protection against solar and artificial UV-radiation is crucial to prevent skin cancer in OTRs. However, investigations have revealed that solar UV-B-exposure and serum 25(OH)D levels positively correlate with decreased risk for various internal malignancies (e.g. breast, colon, prostate, and ovarian cancer) and other severe diseases. Therefore, it is important to detect and treat vitamin D deficiency in OTRs. This review discusses guidelines for the optimal management of these patients, that require communication between the transplant teams, the treating dermatologist and other clinicians.

Calcineurin inhibitor minimization protocols in liver transplantation

Liver transplant recipients are at increasingly high risk for suffering from impaired renal function and probable need of renal replacement therapy. Extended criteria organs and transplantation of patients with higher model for end-stage liver disease scores further increase this problem. Acute and chronic nephrotoxicity are the trade-off in immunosuppression with potent calcineurin inhibitors (CNIs). As a good renal function is associated with better graft and patient survival, CNI minimization protocols have been developed. Current strategies to overcome CNI toxicity include reduction or withdrawal of CNIs concurrently with switching over to mammalian target of rapamycin inhibitor or mycophenolate mofetil (MMF)-based regimens. This strategy caused an improvement in renal function in a significant number of liver transplantation patients according to several studies. However, total CNI avoidance seems to result in higher rejection rates. To prevent chronic renal dysfunction in patients prone to or with acute renal failure, CNI delay - with induction therapy for bridging - followed by low-dose CNI in combination with MMF are proven strategies without risking higher rejection rates. An individualized, tailor-made immunosuppressive regime, with a special focus on renal function is recommended. This review gave an overview on CNI minimization protocols in liver transplantation also focusing on recently analyzed studies.

The effects of immunosuppression on regulatory CD4(+)CD25(+) T cells: impact on immunosuppression selection in transplantation

During immune response and T-cell activation, both effector T cells and regulatory T(T(reg)) cells are activated and regulated simultaneously by both positive and negative pathways. CD4(+)CD25(+) T(reg) cells play a critical role in immune tolerance to self antigens as well as to allografts in some transplant settings. Effective immunosuppressive regimens significantly reduced the incidence of acute allograft rejection in patients following organ transplantation. However, the impact of immunosuppressive treatment on the potential induction of transplant tolerance has not been well determined. In this review we summarize the effects of immunosuppressive reagents on CD4(+)CD25(+) T(reg) cells in order to bring attention to this issue, which may affect the choice of immunosuppressive regimen in the clinical setting.

Mycophenolate mofetil in organ transplantation: focus on metabolism, safety and tolerability

Mycophenolate mofetil (MMF) received its first approval for the prevention of renal allograft rejection in 1995 and has now become the most frequently used antiproliferative agent in maintenance immunosuppressive therapy for kidney, pancreas, liver and heart transplantation. In addition, its use for the treatment of autoimmune diseases steadily increases. This review focuses on the miscellaneous pharmacodynamic properties of the drug, its pharmacokinetics in healthy subjects, recipients of different organ transplants and combination therapy with other pharmaceuticals, as well as its safety profile. The immunosuppressive activity of MMF is thought to derive mainly from the potent and selective inhibition of purine synthesis in both T and B lymphocytes. In contrast to other immunosuppressants on the market, it is metabolised primarily by glucuronidation and lacks nephrotoxicity, cardiovascular toxicity or diabetogenic potential, thus making it a suitable candidate for combination regimens. The most important side effects under MMF include gastrointestinal disorders, of which the underlying mechanisms are not yet fully understood, but seem to be complex and related to both effects of mycophenolic acid and its acyl glucuronide, as well as to decreased -immunity due to general immunosuppression after transplantation.

[Skin tumors in organ-transplant recipients]

Skin cancers are a significant medical problem for organ-transplant recipients. Squamous cell carcinoma and basal cell carcinoma are most common tumors. An increasing incidence of melanoma, Kaposi sarcoma, Merkel cell carcinoma, as well as uncommon skin malignancies, is also seen. Predisposing factors include cumulative sun exposure, cumulative immunosuppression, age, gender, skin type, virus detection and genetic alterations. Skin tumors grow rapidly and their number continues to increase in the years following transplantation. Large numbers of tumors, aggressive courses and appearance in young patients are other characteristics of these skin tumors. More general awareness of the need for preventive measures and regular dermatological examinations is desirable. In addition standardized registries are needed to assure the comparability of data, to better correlate immunosuppression with skin tumors and to plan therapeutic studies.

Renal calcium handling after rapamycin conversion in chronic allograft dysfunction

To study the effect of rapamycin on calcium balance, we conducted a prospective study on transplant recipients. The patients were converted to rapamycin and observed for 6 months (C). Urinary Ca and P, ALK-p, Ca, P, and intact parathyroid hormone (iPTH) were examined before and 6 months after conversion. A nonconversion group (N) was found for comparison. Sixteen patients entered the study. There were increases of ALK-p (C: 67.4 +/- 32.9 to 79.6 +/- 37.0*; N: 67.3 +/- 25.1 to 67.8 +/- 14.7 IU) (*P < 0.05), Ca(2+) (C: 8.7 +/- 0.3 to 9.5 +/- 0.2*; N: 8.8 +/- 0.4 to 8.7 +/- 0.5 mg/dl), urinary P excretion (C: 287.6 +/- 257.1 to 439.4 +/- 260.9*; N: 233.9 +/- 117.2 to 264.8 +/- 143.4 mg/day) and iPTH (C: 133.7 +/- 149.6 to 200.6 +/- 171.5*; N: 128.4 +/- 57.1 to 136.3 +/- 40.4 pg/ml). Serum P (C: 5.3 +/- 1.4 to 3.6 +/- 0.6*; N: 5.2 +/- 0.8 to 5.1 +/- 0.9 mg/dl) and urinary Ca(2+) (C: 93.9 +/- 52.6 to 31.8 +/- 45.1*; N: 84.6 +/- 38.3 to 75.9 +/- 38.4 mg/day) were decrease. Rapamycin was associated with decreased urinary Ca(2+) and increased P excretion. The alteration might come from the increased parathyroid hormone.

Sirolimus in de novo heart transplant recipients with severe renal impairment

Two patients with end-stage heart failure and advanced renal dysfunction (under chronic dialysis therapy) underwent heart transplantation. In order to avoid further renal impairment, a calcineurine inhibitor-free immunosuppression regimen based on the sirolimus was used. Although temporary perioperative support with hemofiltration and dialysis was needed, both patients eventually regained a reasonable renal function with no episodes of clinical rejection and normal cardiac function at 13 and 11 months, respectively, after transplantation. Sirolimus-based immunosuppression might be an interesting alternative to calcineurine inhibitors in the management of patients with significant renal impairment.

Marked erythrocyte microcytosis under primary immunosuppression with sirolimus

The preliminary observation of marked erythrocyte microcytosis in patients treated with sirolimus (SRL) and mycophenolate mofetil (MMF) has been evaluated as part of a prospective study comparing SRL and cyclosporin A (CsA) as a primary immunosuppressant. Normal risk de novo kidney recipients were randomized either to SRL or to CsA. Additional immunosuppressants consisted of MMF and prednisone. In patients with erythrocyte microcytosis, iron deficiency was excluded by measuring serum ferritin and transferrin saturation rate. Fifty-nine patients (30 in SRL and 29 in CsA) were included. Mean corpuscular volume (MCV) (fl) on day 7 was 91.7 +/- 4.8 in SRL group versus 91.4 +/- 4.2 in CsA group (P = 0.77), whereas mean MCV on day 183 post-transplant was 78.5 +/- 3.8 in SRL group versus 88.4 +/- 3.4 in CsA group (P < 0.0001). Hemoglobin concentration (g/dl) was not significantly different. Only two patients in SRL group presented decreased transferrin saturation rate. Marked erythrocyte microcytosis without persistent anemia was observed in patients treated with SRL and MMF.

Sirolimus-associated hepatotoxicity in the kidney graft recipient

The aim of our paper was to describe hepatotoxicity of sirolimus (SRL) in a kidney graft recipient. We report the case of a 30-year-old male after kidney transplantation, treated with steroids, cyclosporin A and SRL, with steroid-resistant acute rejection in anamnesis. At 16th month after transplantation, elevation of serum aminotransfereases was observed. After exclusion of common reasons of this condition, liver biopsy was performed. Nonspecific changes were observed, with probability of drug-induced injury. SRL was changed to mycophenolate mofetil, which was followed by quick normalization of serum aminotransferase levels. Hepatoxicity is a rare complication of SRL therapy and may be connected with some diagnostic and/or therapeutic problems. Conversion to another immunosuppressant seems to be an appropriate procedure in this condition.

Immune cells in a heterotopic lamb-to-pig bronchial xenograft model

We developed our porcine model to elucidate the cellular rejection mechanisms of xenografts. Bronchial segments from a donor lamb were implanted into domestic pigs. The immunosuppressive regimens consisted of no immusuppression, or of daily oral cyclosporine A (CsA) 15 mg/kg, or of everolimus, 1.5 mg/kg, or of both. Implants were serially harvested during 17 days. Epithelial damage and obliteration were graded histologically, followed by a count of CD4+, CD8+, MHC class II-expressing cells, and macrophages. Furthermore, we studied the pharmocokinetics of everolismus. Epithelial damage preceded luminal obliteration, which was eventually total, except when both drugs had been given. In xenografts, an influx of cells with CD8+ cells dominating peaked on day 9, thereafter declining, except in the combination drug group. There, the immunological reaction was delayed and blunted, with CD4+ cells dominating. More macrophages appeared in xenografts than in allografts except with the combination CsA and everolimus. A dose of 1.5 mg/kg everolimus yields adequate blood concentrations for porcine studies. In this xenograft model, chronic rejection appears to be caused by an immune response to the graft, but it is more short-lived than the response in allografts. The combination of CsA and everolimus was able to blunt the response and delay the subsequent obliteration.

2005 immunosuppressive strategies in kidney transplantation: which role for the calcineurin inhibitors?

The calcineurin inhibitors (CNIs) cyclosporine and tacrolimus have been the cornerstones of immunosuppressive strategies in clinical transplantation. Currently, regimens that are most widely used for induction and maintenance therapy include CNIs. However, many clinical trials aiming at reducing or eliminating CNIs have been performed in recent years. Here, we review and discuss current and future immunosuppressive strategies with a special emphasis on the role of CNIs, in the light of recent studies in the field of kidney transplantation. In the current era, CNIs still play an important role.

Clinical experience with everolimus (Certican) in elderly recipients: the "old-for-old" concept

BACKGROUND

With an increasing number of elderly patients now waiting for a kidney transplant, and the percentage of kidney donors over 55 years also rising, harvesting older kidneys specifically for use in older recipients is a way of extending the donor pool for renal transplantation.

METHODS

Two case studies from an everolimus (Certican) Phase III trial (A2306) are presented. They illustrate clinical experience of achieving stable graft function in the "old-for-old" kidney transplant program at the Ramon y Cajal Hospital in Madrid, Spain.

RESULTS

The first case study demonstrates that stable graft function can be achieved in an "old-for-old" kidney transplant patient, who receives everolimus in combination with reduced-exposure cyclosporine (CsA). To optimize graft function in the long-term, CsA C(2) blood levels should be <400 ng/ml. The second case study highlights how "old-for-old" renal transplant recipients can be at risk of calcineurin-inhibitor (CNI)-induced nephrotoxicity. Here, graft function did not improve following CsA dose reduction; thus, CsA was withdrawn 1 year posttransplant. Stable graft function that is acceptable for an "old-for-old" kidney transplant was then achieved with everolimus trough blood levels of 10-15 ng/ml and low-dose prednisone.

CONCLUSIONS

In these cases, everolimus was used safely and effectively in the "old-for-old" kidney transplant setting. Its combination with reduced-exposure CsA, or its facilitation of CsA withdrawal, minimized the risk of nephrotoxicity in the older renal graft. These findings need to be confirmed in larger studies specific to this population.

Sirolimus: a new option in transplantation

This review of immunosuppression in renal transplantation has allowed us to highlight the deleterious effect of calcineurin inhibitor nephrotoxicity and to emphasise the importance of sirolimus. Now, a whole new set of possibilities has opened up in immunosuppression: sirolimus-based immunosuppression without calcineurin inhibitors; sirolimus in combination with calcineurin inhibitors in reduced doses; early calcineurin inhibitor withdrawal from a regimen that combines sirolimus, calcineurin inhibitors and steroids; and calcineurin inhibitor conversion to sirolimus when the first signs of graft nephrotoxicity appear. These new strategies in immunosuppression in renal transplantation are associated with good results in graft and patient survival in year 1, and with better renal function. Therefore, we can hope for better long-term results in transplantation, with a significant increase in the graft half-life and in the patient survival.