Objectives: Calcineurin inhibitor-induced nephro­toxicity reduces long-term patient survival after heart transplant. Proliferation signal inhibitors, in combination with or replacing calcineurin inhibitors, may preserve or improve renal function. We evaluated the effect of calcineurin inhibitor-reduction and withdrawal in everolimus-based immuno­suppression on renal function after a heart transplant.

Materials and Methods: Twenty-four patients with creatinine clearance < 1 mL/s (60 mL/min) were switched from tacrolimus and mycophenolate mofetil to low-dose tacrolimus/everolimus if their heart transplant was ≤ 1 year ago (group 1, n=13) and to everolimus/mycophenolate mofetil if their heart transplant was > 1 year ago (group 2, n=11). Serum creatinine levels and calculated creatinine clearance were analyzed up to 12 months after conversion.

Results: The switch in immunosuppression was associated with a significant decrease/increase of serum creatinine/creatinine clearance in both groups between baseline and month 12 (group 1, creatinine, 221.0 ± 70.7 to 159.1 ± 44.2 μmol/L (2.5 ± 0.8 to 1.8 ± 0.5 mg/dL); creatinine clearance, 0.75 ± 0.45 to 1.01 ± 0.50 mL/s (45.1 ± 26.7 to 60.5 ± 29.7 mL/min) (P < .01 each); group 2, creatinine, 247.5 ± 79.6 to 159.1 ± 44.2 μmol/L (2.8 ± 0.9 to 1.8 ± 0.5 mg/dL), creatinine clearance, 0.57 ± 0.23 to 0.93 ± 0.33 mL/s (34.1 ± 13.8 to 55.7 ± 19.6 mL/min) [P < .05 each]) with no significant group difference in the creatinine and the creatinine clearance levels after switching. No acute rejections or deaths occurred during the 12-month follow-up. Four patients (36.4%) from group 2 and 1 patient (7.7%) from group 1 discontinued everolimus because of adverse events.

Conclusions: Everolimus allows calcineurin inhibitor-reduction and withdrawal after heart transplantion resulting in improved renal function. However, adverse effects are common and lead to a high reconversion rate.

Key words : Heart transplant, Everolimus, Tacrolimus, Calcineurin inhibitor-reduction, Renal insufficiency

Introduction

Calcineurin inhibitors (CNIs) have improved patient survival after heart transplantion (HT). However, CNI-induced nephrotoxicity is the main contributing factor to developing renal dysfunction that reduces long-term patient survival.¹ In this context, increasing serum creatinine levels have been identified as a risk factor for cardiac graft loss.² Thus, less nephrotoxic immunosuppressive protocols are necessary for improving patient survival while maintaining renal and graft function. Strategies to reduce CNI exposure include CNI avoidance, minimization, and withdrawal. The proliferation signal inhibitor everolimus (EVL) has been highly effective in preventing acute myocardial rejection episodes, and reducing the incidence and severity of cardiac allograft vasculopathy after HT.³ Preliminary data suggest that EVL as replacement of CNI or in combination with CNI-dosage minimization (low-dose CNI) may be a rational approach to reduce or even halt the development of renal dysfunction after HT.^4,5 Seeking to improve survival and quality of life after HT, our transplant program has evaluated various immunosuppressive regimens.

This report focuses on the experience with the first 24 patients receiving an EVL-based immuno­suppression in combination with mycophenolate mofetil (MMF) or low-dose tacrolimus (Tac). The combination of sirolimus and tacrolimus has shown promising results after HT.⁶ The combination of EVL and a low-dose Tac regimen has not been investigated after HT until now. We evaluated the effect of CNI-reduction and CNI-withdrawal after switching to an everolimus (EVL)-based immunosuppression regimen on renal function after HT.

Materials and Methods

Twenty-four HT recipients (21 men; mean age, 50.6 ± 16.2 y; mean time after the HT, 3.4 ± 4.6 y) received EVL to either withdraw or to reduce the dosage of Tac for renal dysfunction (serum creatinine > 168 μmol/L (1.9 mg/dL); creatinine clearance [CrCl] < 1 mL/s [60 mL/min]). All patients received Tac (target trough level, 8-12 ng/mL for the first year after HT and 6-10 ng/mL thereafter) and MMF (target trough level, 1.5-4 μg/mL) as baseline immunosuppression. Patients were divided into 2 groups: Those within the first year after receiving HT were switched to low-dose Tac/EVL regimen (group 1, n=13), and those who had lived longer than 1 year after their HT were switched to an EVL/MMF regimen (group 2, n=11). Target trough levels were 3 to 5 ng/mL for Tac, 4 to 6 ng/mL for EVL in group 1, with CNI-reduction, and 6 to 10 ng/mL for EVL in group 2 with CNI-withdrawal, and 1.5 to 4 μg/mL for MMF.

Renal function parameters (serum creatinine and CrCl) at 3, 6, 9, and 12 months after conversion were compared with the baseline values before conversion. Creatinine clearance was calculated using the Cockcroft-Gault equation.⁷ A control echocardiography was performed 2 weeks, and 1, 3, 6, and 12 months after conversion to detect potential rejections requiring endomyocardial biopsy. In case of serious EVL-related adverse events, patients were reconverted to the baseline immunosuppression with Tac and MMF. All adverse events were recorded throughout the 12 months.

Before conversion, the oral Tac dosage was adjusted to reach target trough levels of 8 to 12 ng/mL in the first year and 6 to 10 ng/mL thereafter. The oral MMF dosage was adjusted to reach target trough levels of 1.5 to 4 μg/mL. Immunosuppressive conversion was conducted over 3 weeks. In group 1, EVL was introduced at an oral dosage of 0.75 mg 2 times daily and subsequently adjusted to a target trough level of 4 to 8 ng/mL. Tacrolimus was reduced until target trough levels of 3 to 5 ng/mL were reached and MMF was discontinued in group 1. In group 2, Tac was discontinued after reaching EVL trough levels of 6 to 10 ng/mL. Mycophenolate mofetil was continued and trough levels adjusted (1.5-4 μg/mL). Three patients in group 1, and no patients in group 2 were on prednisone maintenance therapy of 0.1 mg/kg/day when they were converted within the first 6 months after HT. Prednisone was tapered and finally discontinued 6 months after HT in all patients.

Statistical analyses
The paired Wilcoxon, chi-square, Mann-Whitney U, and t tests were used, as appropriate, to calculate differences before and after conversion of immuno­suppression. Values of continuous variables are expressed as mean ± standard deviation, values of categoric variables as total number and percentage. Differences were considered statistically significant if P < .05. Statistical analyses were performed with SPSS software (SPSS: An IBM Company, version 19.0, IBM Corporation, Armonk, NY, USA).

Results

Patients’ baseline demographic and clinical characteristics are summarized in Table 1. Table 2 shows the mean EVL, Tac, and MMF trough levels at different time points during the 12-month follow-up. Survival was 100% during this period, and all patients were free of acute rejection episodes.

Immunosuppressive therapy
Initial CNI trough levels were similar between the groups (Tac, 10.7 ± 1.4 ng/mL vs 10.7 ± 2.0 ng/mL [group 1 vs group 2; P = .9]) as were the initial MMF trough levels (2.7 ± 0.9 μg/mL vs 2.3 ± 0.9 μg/mL; P = .9). In group 1, CNI dosages and trough levels were significantly reduced. Mean Tac trough levels were 6.5 ± 1.9 ng/mL, 6.0 ± 1.7 ng/mL, 5.3 ± 1.3 ng/mL, 5.3 ± 2.1 ng/mL, and 6.1 ± 1.0 ng/mL after 1, 3, 6, 9, and 12 months. In group 2, there were no differences between MMF trough levels before or at 1, 3, 6, 9, and 12 months after conversion.

Renal function
Kidney parameters (serum creatinine, CrCl) remained mildly impaired but stable after the initial recovery, which was observed 3 months after conversion. Calcineurin inhibitor minimization and withdrawal using EVL was associated with a significant decrease in serum creatinine levels, and an increase of CrCl at 3, 6, 9, and 12 months after conversion. Baseline serum creatinine was 238.7 ± 70.7 μmol/L (2.7 ± 0.8 mg/dL) with CrCl of 0.68 ± 0.38 mL/s (40.6 ± 22.6 mL/min), 168.0 ± 53.0 μmol/L (1.9 ± 0.6 mg/dL) with CrCl of 0.92 ± 0.42 mL/s (55.2 ± 25.4 mL/min) (P < .001 and P < .001) at 3 months, 159.1 ± 53.0 μmol/L (1.8 ± 0.6 mg/dL) with CrCl of 0.98 ± 0.42 mL/s (58.8 ± 24.9 mL/min) at 6 months (P < .001 and P < .001), 159.1 ± 44.2 μmol/L (1.8 ± 0.5 mg/dL) with CrCl of 0.98 ± 0.37 mL/s (58.4 ± 22.1 mL/min) at 9 months (P < .001 and P < .001), and 159.1 ± 44.2 μmol/L (1.8 ± 0.5 mg/dL) with CrCl of 0.98 ± 0.42 mL/s (58.4 ± 25.1 mL/min) at 12 months after conversion (P < .001 and P < .001). The respective numbers per patient group are given in Table 3. There was no statistically significant difference in serum creatinine and CrCl levels at 3, 6, 9, and 12 months between groups.

Safety
There were no acute rejection episodes during the 12-month follow-up; leukocyte and thrombocyte counts did not change significantly (Table 4). Mean cholesterol, LDL, and triglyceride levels were similar between the groups and remained stable under statin therapy (Table 5). Statins were administered to all patients regardless of the presence or absence of elevated total or LDL-cholesterol levels. Adverse events occurred more frequently in group 2 (n=6 [54.5%]) than they did in group 1 (n=2 [15.4%]). Everolimus was withdrawn in 5 patients (group 1, n=1 [7.7%] vs group 2, n=4 [36.4%]).

Infection was the most common adverse effect, occurring in 4 patients (16.7%). Initially, 2 patients (8.3%) developed fulminant pneumonia requiring antibiotic therapy. Both patients were reconverted to the baseline immunosuppression. With growing experience, infections were treated with antibiotics and adjustment of the immunosuppressive therapy. Other adverse events that might be EVL-related were refractory pleural effusions requiring pleural drainage in 2 patients (8.3%). Peripheral edema presented as a frequent adverse event in 5 patients (20.8%). In 2 patients (8.3%), EVL trough levels were reduced owing to aphthous stomatitis. Overall, 5 patients were reconverted to the initial immunosuppressive regimen because of adverse effects.

Discussion

According to the International Society for Heart and Lung Transplantation (ISHLT) registry data, 36% of HT recipients develop renal failure after 10 years. The Society reports that major renal impairment occurs during the first year after HT when CNIs are applied at maximal dosages. Renal insufficiency is a strong predictor of survival after HT, and renal failure is identified as the primary cause of death in many patients after HT.⁸ Proliferation signal inhibitors permit CNI reduction without compromising efficacy.⁹ Thus, developing renal dysfunction after HT can be reduced or even avoided by switching patients to CNI-free or low-dose CNI immunosuppressive regimens with proliferation signal inhibitors.^4,5,10,11 However, most of the scientific evidence for proliferation signal inhibitors was obtained with sirolimus, and explicit data for EVL especially in the combination with Tac is still lacking.^12-14

In this study, we investigated administering EVL with progressive reduction of Tac and CNI-free immunosuppression with EVL and MMF. We report the results of the first 24 patients at our center receiving an EVL-based immunosuppression regimen combined with MMF or low-dose Tac. Renal function, as assessed by serum creatinine and CrCl, significantly improved after 3 months, and remained stable after the initial recovery after conversion, especially after complete CNI withdrawal. The results coincide with those from other studies showing improved renal function with EVL instead of CNIs or in combination with low-dose CNIs: Rothenburger and associates presented their results of a CNI-free immuno­sup­pression regimen using EVL from 60 HT recipients switched to EVL because of CNI-associated adverse effects. Renal function improved significantly after 6 months (serum creatinine 185.6 ± 53.0 μmol/L (2.1 ± 0.6 mg/dL) vs 132.6 ± 79.6 μmol/L (1.5 ± 0.9 mg/dL); P = .001; CrCl 0.70 ± 0.36 mL/s (42.2 ± 21.6 mL/min) vs 1.03 ± 0.39 mL/s (61.8 ± 23.4 mL/min); P = .018). Although 8 patients (13.3%) experienced adverse effects, investigators concluded that CNI-free immuno-suppression regimen using EVL is safe, with excellent efficacy in maintenance HT recipients.⁵

Moro López and associates studied 56 HT recipients in whom the CNI (cyclosporine) had been withdrawn because of renal dysfunction and replaced by EVL with target trough levels of 3 to 8 ng/mL in combination with MMF and steroids. Again, serum creatinine significantly decreased at 6 and 12 months (169.7 ± 61.9 vs 147.6 ± 53.0 and 149.4 ± 53.0 μmol/L (1.92 ± 0.7 vs 1.67 ± 0.6 and 1.69 ± 0.6 mg/dL); P = .047) and CrCl significantly increased (0.73 ± 0.28 vs 0.88 ± 0.38 and 0.86 ± 0.37 mL/s (43.9 ± 17 vs 52.5 ± 23 and 51.3 ± 22.3 mL/min); P = .024).15 The possibility of complete CNI withdrawal in HT recipients has been evaluated before.

The “Spare the Nephron Trial” compared HT recipients with the usual triple-drug immuno­suppression (CNI, MMF, steroids) versus sirolimus, MMF, and steroids with CNI withdrawal 12 weeks after HT. However, the study was discontinued after inclusion of 15 patients because of an unexpected high incidence of rejection in the CNI withdrawal arm.¹⁶ The study raised concerns that CNI withdrawal early after HT may be associated with an increased risk of rejection; thus, being more feasible in patients late after HT. This strategy has turned out to be safe and effective in several observational studies by improving serum creatinine after CNI withdrawal up to 25%.^5,13,17-19 However, renal function did not improve in all patients, mainly long-term HT patients. This finding agrees with those of the prospective study of Moro Lopéz and associates who reported that not all 56 patients improved after 12 months under replacement of CNI by EVL combined with MMF and steroids.¹⁵

The present analysis shows that the metabolic and hematologic adverse effects of EVL are low, while mean cholesterol, LDL triglyceride, and hemoglobin levels remain stable. However, these observations might have been because of the application of corrective measures such as statin therapy, the administration of iron, and the adjustment of immunosuppressive levels. The same observations were made by Moro and associates,²⁰ they evaluated the effects on renal function after switching from a CNI to a proliferation signal inhibitor in 23 HT patients. There was no significant difference regarding serum creatinine and CrCl values after a mean follow-up of 11 ± 6 months. However, in the subgroup of patients switched to the proliferation signal inhibitor because of renal deterioration, serum creatinine improved slightly to 210.4 ± 35.4 μmol/L (2.38 ± 0.4 mg/dL), but the improvement was not statistically significant. Therefore, the investigators concluded that switching to proliferation signal inhibitors is capable of delaying progression of renal dysfunction in long-term HT patients.¹⁰

Despite the excellent effectiveness of preventing acute rejection and improving renal function, EVL-based immunosuppression is also associated with adverse effects. Aphthous ulcers occurred in 2 patients with elevated EVL trough levels and were treated by EVL dosage reduction. This kind of wound healing problem can be explained by the antiproliferative effect that proliferation signal inhibitors have.

Well-known EVL adverse effects were mostly associated with EVL trough levels above our current target range of 4 to 6 ng/mL (group 1) or 6 to 10 ng/mL (group 2), which were reduced when adverse effects occurred. Overall, adverse events were common, but rarely severe. Especially at the beginning of our conversion program, patients had to be switched to the previous regimen because our initial target trough levels of 8 to 10 ng/mL were too high. With increased experience, adverse events were managed by dosage reduction of EVL.
Our results are preliminary because the number of patients was limited and the study was not randomized. Nevertheless, our results suggest that conversion to a CNI-free or low-dose Tac immunosuppression regimen with EVL is a safe and successful strategy for HT patients with renal impairment. In conclusion, EVL allows early CNI-reduction and late withdrawal after HT resulting in improved and stable renal function.

References:

1. Myers BD, Ross J, Newton L, Luetscher J, Perlroth M. Cyclosporine-associated chronic nephropathy. N Engl J Med. 1984;311(11):699-705.
   CrossRef - PubMed
2. Kobashigawa JA, Starling RC, Mehra MR, et al. Multicenter retrospective analysis of cardiovascular risk factors affecting long-term outcome of de novo cardiac transplant recipients. J Heart Lung Transplant. 2006;25(9):1063-1069.
   CrossRef - PubMed
3. Eisen HJ, Tuzcu EM, Dorent R, et al. Everolimus for the prevention of allograft rejection and vasculopathy in cardiac-transplant recipients. N Engl J Med. 2003;349(9):847-858.
   CrossRef - PubMed
4. Lindenfeld J, Miller GG, Shakar SF, et al. Drug therapy in the heart transplant recipient: part II: immunosuppressive drugs. Circulation. 2004;110(25):3858-3865.
   CrossRef - PubMed
5. Rothenburger M, Teerling E, Bruch C, et al. Calcineurin inhibitor-free immunosuppression using everolimus (Certican) in maintenance heart transplant recipients: 6 months' follow-up. J Heart Lung Transplant. 2007;26(3):250-257.
   CrossRef - PubMed
6. Meiser B, Kaczmarek I, Mueller M, et al. Low-dose tacrolimus/sirolimus and steroid withdrawal in heart recipients is highly efficacious. J Heart Lung Transplant. 2007;26(6):598-603.
   CrossRef - PubMed
7. Cockcroft DW, Gault MH. Prediction of creatinine clearance from serum creatinine. Nephron. 1976;16(1):31-41.
   CrossRef - PubMed
8. Stehlik J, Edwards LB, Kucheryavaya AY, et al. The Registry of the International Society for Heart and Lung Transplantation: twenty-seventh official adult heart transplant report--2010. J Heart Lung Transplant. 2010;29(10):1089-1103. doi: 10.1016/j.healun.2010.08.007.
   CrossRef - PubMed
9. Zuckermann A, Manito N, Epailly E, et al. Multidisciplinary insights on clinical guidance for the use of proliferation signal inhibitors in heart transplantation. J Heart Lung Transplant. 2008;27(2):141-149. doi: 10.1016/j.healun.2007.08.014.
   CrossRef - PubMed
10. Moro J, Almenar L, Martínez-Dolz L, et al. mTOR inhibitors: do they help preserve renal function? Transplant Proc. 2007;39(7):2135-2137.
    CrossRef - PubMed
11. Ruiz JC, Sánchez A, Rengel M, et al. Use of the new proliferation signal inhibitor everolimus in renal transplant patients in Spain: preliminary results of the EVERODATA registry. Transplant Proc. 2007;39(7):2157-2159.
    CrossRef - PubMed
12. Groetzner J, Kaczmarek I, Landwehr P, et al. Renal recovery after conversion to a calcineurin inhibitor-free immunosuppression in late cardiac transplant recipients. Eur J Cardiothorac Surg. 2004;25(3):333-341.
    CrossRef - PubMed
13. Groetzner J, Meiser B, Landwehr P, et al. Mycophenolate mofetil and sirolimus as calcineurin inhibitor-free immunosuppression for late cardiac-transplant recipients with chronic renal failure. Transplantation. 2004;77(4):568-574.
    CrossRef - PubMed
14. Gustafsson F, Ross HJ, Delgado MS, Bernabeo G, Delgado DH. Sirolimus-based immunosuppression after cardiac transplantation: predictors of recovery from calcineurin inhibitor-induced renal dysfunction. J Heart Lung Transplant. 2007;26(10):998-1003.
    CrossRef - PubMed
15. Moro López JA, Almenar L, Martínez-Dolz L, et al. Progression of renal dysfunction in cardiac transplantation after the introduction of everolimus in the immunosuppressive regime. Transplantation. 2009;87(4):538-541. doi: 10.1097/TP.0b013e31819452ce.
    CrossRef - PubMed
16. Hunt J, Bedánová H, Starling RC, et al. 398: Premature termination of a prospective, open label, randomized, multicenter study of sirolimus to replace calcineurin inhibitors (CNI) in a standard care regimen of CNI, MMF and corticosteroids early after heart transplantation. J Heart Lung Transplant. 2007;26(2 suppl 1):S203.
    CrossRef
17. Hunt J, Lerman M, Magee MJ, Dewey TM, Herbert M, Mack MJ. Improvement of renal dysfunction by conversion from calcineurin inhibitors to sirolimus after heart transplantation. J Heart Lung Transplant. 2005;24(11):1863-1867.
    CrossRef - PubMed
18. Bestetti R, Theodoropoulos TA, Burdmann EA, Filho MA, Cordeiro JA, Villafanha D. Switch from calcineurin inhibitors to sirolimus-induced renal recovery in heart transplant recipients in the midterm follow-up. Transplantation. 2006;81(5):692-696.
    CrossRef - PubMed
19. Raichlin E, Khalpey Z, Kremers W, et al. Replacement of calcineurin-inhibitors with sirolimus as primary immunosuppression in stable cardiac transplant recipients. Transplantation. 2007;84(4):467-474.
    CrossRef - PubMed
20. Moro J, Almenar L, Martínez-Dolz L, et al. mTOR inhibitors and their secondary effects in cardiac transplant recipients: a descriptive study. Transplant Proc. 2007;39(7):2365-2367.
    CrossRef - PubMed