Everolimus in de novo liver transplant recipients: a systematic review

Cheng-Yong Tang, Ai Shen, Xu-Fu Wei, Qing-Dong Li, Rui Liu, He-Jun Deng, Yong-Zhong Wu and Zhong-Jun Wu

Chongqing, China

Everolimus in de novo liver transplant recipients: a systematic review

Cheng-Yong Tang, Ai Shen, Xu-Fu Wei, Qing-Dong Li, Rui Liu, He-Jun Deng, Yong-Zhong Wu and Zhong-Jun Wu

Chongqing, China

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.

(Hepatobiliary Pancreat Dis Int 2015;14:461-469)

everolimus;

calcineurin inhibitors;

liver transplantation;

systematic review

Introduction

Calcineurin inhibitors (CNIs) are the first line therapy for liver transplantation (LT) patients,[1,2]but they have side effects such as chronic nephrotoxicity that progressively reduces renal function. Approximately 10% of the patients suffer from chronic renal failure within five years after liver transplantation because of CNI treatment.[3]

Everolimus, an immunosuppressant of the mammalian target of rapamycin (mTOR),[4-6]has been approved for heart and renal transplantation[7,8]and can be used with or without CNIs to reduce CNI-induced drug toxicity.[8,9]Everolimus given with a low dose of CNI or without CNI significantly improves renal function after LT,[10-13]allowing FDA approval for use of this drug after LT as well.[14]Still, the outcomes of everolimus-based immunosuppression in LT recipients have not been systematically reviewed. The present study was to evaluate the efficacy and safety of everolimus in de novo LT patients at one year after LT.

Methods

Literature search

PubMed, the Cochrane Library, and ScienceDirect were searched using the terms "everolimus" and "liver transplant" or "liver transplantation" or "hepatic transplantation" or "hepatic graft" or "LT" before March 31, 2014 without language limitations.

Two reviewers (Tang CY and Shen A) independently searched articles based on titles, abstract and key words. Disagreements over articles were discussed until consensus was reached. Only published data were retrieved and included.

Inclusion and exclusion criteria

1) Study subjects included only de novo LT patients. 2) Each trial was designed to evaluate both the efficacy and safety of everolimus. 3) Follow-up time must exceed 1 year. 4) Case reports, review articles, editorials, letters, and single-arm studies were excluded. 5) Only randomized controlled trials (RCTs) were included.

Outcome of interest

The primary outcome of interest was one-year efficacy of everolimus in de novo LT patients, using renal function, treated biopsy-proven acute rejection (tBPAR), graft loss, death, and neoplasm/tumor recurrence. The secondary outcome measure was to assess the safety of everolimus in de novo LT patients.

Data extraction and quality analysis

Two reviewers (Tang CY and Shen A) independently extracted the data as follows: article authors, time of publication, trial region, number of cases, age of participants, gender of participants, route of drug administration, renal function, efficacy events and safety events. Disagreements about extraction were resolved via discussion. The two reviewers independently evaluated the quality of each study according to the Cochrane Handbook for Systematic Reviews of Interventions (http://handbook.cochrane.org/).[15]

Statistical analysis

The pooled standard mean differences (SMD), mean differences (MD), and 95% confidence intervals (CI) were reported for continuous data. Pooled relative risk (RR) and 95% CI were reported for dichotomous data. The Chi-square test-based Q statistic of RR and trials with P＜0.1 were considered heterogeneous. When P＞0.1, the DerSimonian-Laird random effects model was used to control for heterogeneity in the meta-analysis.[16]Q-based I2statistics were used to evaluate quantitative heterogeneity. Values between 0% and 25% indicated that heterogeneity might not be important. Values between 25% and 50% indicated moderate inconsistency. Values of 50% to 75% were indicated substantial heterogeneity. Values between 75% and 100% indicated considerable inconsistency. When inconsistency was detected, the reason for the heterogeneity was explored using sensitivity and subgroup analysis. A two-tailed P value of 0.05 was deemed statistically significant. All statistical calculations for this article were performed using Review Manager 5.1. These results were reported using the Cochrane Handbook for Systematic Reviews of Interventions.[15]

Results

Trial selection

Six RCTs that evaluated the efficacy and safety of everolimus in LT patients were included. Of these, four were enrolled in this review (Fig. 1).[11,12,17,18]One RCT was excluded due to recruitment of maintenance LT patients;[19]another was due to the only observation of the efficacy of everolimus in LT patients at 3 months after treatment.[20]Of the 4 studies enrolled in the present analysis, one evaluated the efficacy, safety and tolerability of the different dosage of everolimus under controlled CNIs in LT patients[17](reference 17 never mentioned "reduced CNIs". On the contrary, "steady-state administration of cyclosporine". As a matter of fact, the authorscontrolled the CNI dosage to test the safety and tolerability of everolimus at different doses); two assessed the efficacy and safety of CNI conversion to everolimus in LT patients[12,18]and one compared the efficacy and renal function between everolimus initiation with reduced-exposure tacrolimus and standard-exposure tacrolimus.[11]The baseline characteristics of included patients are detailed in Table 1 and the immunosuppression regimen is detailed in Table 2.

Fig. 1. Literature search process.

Quality of trials included in the systematic review

The method of generating a random sequence was not reported in Levy's study.[17]Three trials did not report whether or not the allocation concealment was used. Only Levy et al used a placebo-controlled double-blinded method.[17]Three studies[11,12,18]did not mention the blindness of the result evaluations. Randomization of everolimus combined with elimination of tacrolimus was terminated prematurely because of a higher rate of tBPAR in De Simone's study.[11]Levy's study[17]included three different doses of everolimus, which may have introduced bias. All four studies were found to have a high risk of bias (Table 3).

Efficacy

Renal function

Some studies used creatinine clearance (CrCl; Cockcroft-Gault) to evaluate renal function;[12,17]others used glomerular filtration rate (GFR; modification of diet in renal disease formula) or both.[11,12,18]The pooled SMD was reported in this way. Meta-analyses demonstrated that everolimus-based treatment significantly improves renal function one year after treatment (SMD: 0.35; 95% CI: 0.13-0.57; P＜0.01), but substantial heterogeneity was observed (I2=52%; Fig. 2). However, sensitivity analysis confirmed stability in this set of results.

Subgroup analysis demonstrated that everolimus initiation with reduced CNIs significantly improved the CrCl (MD: 5.13; 95% CI: 0.42-9.84; P=0.03; I2=0%) at one year[11,17]compared with standard exposure of CNIs (Fig. 3). Everolimus initiation with CNIs elimination also significantly improved GFR by 10.42 mL/min/1.73 m2(MD: 10.42; 95% CI: 3.44-17.41; P＜0.01; I2=69%; Fig. 3).[11,12,18]Heterogeneity may be attributed mainly to Masetti's study, for which cyclosporine in the control group was elevated gradually.[18]

tBPAR, graft loss, death and neoplasms/tumor recurrence

Everolimus combined reduced CNIs in de novo LT decreased the risk of tBPAR one year after treatment.[11,17]However, everolimus initiation with elimination of CNIs increased the risk of tBPAR.[11,12,18]Neither everolimus combined with CNIs reduction nor everolimus initiation with CNIs elimination was associated with more risk of graft loss and death one year after treatment compared to the control group. All included studies reported relevant data regarding neoplasms/tumor recurrence and our analysis confirmed that everolimus decreased the risk of neoplasms/tumor recurrence one year after transplantation although it has no statistical significance (Table 4).

Safety

Not all trials provided a complete report about everolimus side effects.[17,18]Meta-analyses confirmed that everolimus significantly increased the risk of adverse events and discontinuation of therapy (Tables 4 and 5).

Table 1. Baseline characteristics of included studies

Table 2. Immunosuppression regimens of included studies

Table 3. Quality of the RCTs included in this systematic review

Table 4. Meta-analyses of primary outcomes at one year after treatment

Fig. 2. Meta-analysis of RCTs comparing the overall mean change in renal function of everolimus to that of the control group at one year.

Fig. 3. Meta-analysis of RCTs comparing the mean change in renal function of the everolimus+reduced CNIs group or everolimus+ eliminated CNIs group to that of the control group at one year.

Table 5. Meta-analyses of adverse events in the included trials

Discussion

One study including 36 849 LT patients suggested that the cumulative incidence of chronic renal failure was -20% three years after transplantation and this was associated with a 4-fold increase in the risk of death.[21]One major contributor to renal dysfunction in LT recipients was CNIs.[22]Because CNIs are the backbone of immunosuppressive treatment of LT, better regimens must be formulated to reduce this risk.[1]

The present systematic review demonstrated that everolimus-based immunosuppression can significantly improve renal function one year after treatment and it does not increase the risk of graft loss or death. Also, everolimus combined with reduced CNIs improves renal function at one year without an increased risk of graft loss or death and these benefits were long-lasting. Saliba's group remarked that combination treatment improves GFR of LT patients three years post transplantation.[10,13]This systemic review showed that everolimus plus reduced-dose CNIs decrease the risk of tBPAR by 44%. This may be a synergistic effect of everolimus and CNIs.[23,24]Experimental studies demonstrated that everolimus and cyclosporine have synergistic effect on corneal and kidney transplantations in immunosuppression in rats.[23,24]

A study of 240 LT patients confirmed that transition from CNIs to everolimus increases GFR by 4.2 mL/min with a low risk of tBPAR.[25]However, our systematic review suggested that everolimus combined with early withdrawal of CNIs increased the risk of tBPAR by 77% compared with controls, even though everolimus treatment improved renal function. Similar results were observed in renal transplantation patients.[26]This may be attributed to the fact that the mean time of the introduction of everolimus in Saliba's study (mean: 4.9±5.2 years post transplantation) was later than that in the trials included in the present review.[25]In the reviewed studies everolimus treatment began within 30 days after the transplant procedure and CNI treatment was terminated earlier. However, re-starting CNI treatment immediately after tBPAR detection did not increase the overall risk of graft loss or death.[11,12,18]Saliba's group also reported that the mean change of GFR was significantly different depending on whether everolimus treatment began dur-ing or after the first year after transplantation (12.5 vs 5.5 mL/min).[25]Therefore, after a certain time, everolimus treatments do not improve renal function because this improvement has already occurred due to the reduction of CNI dose.[19]

Renal function in the everolimus group is better than that in the controls, this may be explained mainly by minimization of exposure to CNIs.[7,18,19,25]One RCT suggested that low doses of cyclosporine are associated with significantly better renal function in kidney transplantation patients than in those who received full doses of cyclosporine at one year.[27]Everolimus may also have contributed to improve renal function. Experimental studies suggested that everolimus can significantly improve glomerular hypertrophy in diabetic mice and therefore, everolimus improves renal function.[28]Most importantly, everolimus allows dose reduction or elimination of CNIs not only in LT, but also after transplantation of other solid organs. Everolimus combined with reduced CNIs also improves post-transplantation renal function while preserving graft function in kidney,[29-31]thoracic,[32]and heart transplantations.[33]

The present systematic review confirmed that everolimus inhibits tumor recurrence. Everolimus decreased the risk of tumor recurrence by 40%, similar to that of sirolimus (odds ratio: 0.42; 95% CI: 0.21-0.83).[34]Both drugs inhibit the mTOR serine/threonine kinase by binding to 12-kDa immunophilin FK506-binding protein (FKBP12) to prevent tumors,[35]and each can inhibit angiogenesis by blocking the PI3K-Akt-mTOR signaling pathway and preventing fibrosis by inhibiting the mTOR/p70S6k/procollagen 1 pathway.[24]

The present systematic review revealed serious side effects in everolimus-treated patients compared to controls (RR: 1.25; 95% CI: 1.10-1.42; P=0.0007). The risk of drug discontinuation was 2-fold greater in everolimus-treated patients than that in controls but lower than that in sirolimus group (RR: 1.98 vs 3.61).[36]This may be attributed to everolimus's short half-life (28 hours vs sirolimus's 60 hours), greater solubility, greater bioavailability, and weaker binding affinity to FKBP12.[14]

Everolimus increases the risk of leukopenia likely due to the inhibition of cell proliferation by blocking the cell from the G1 to S phase.[4]Everolimus also increases the risk of bacterial infection,[17,18,37]perhaps due to the deterioration of immune function associated with leukopenia. However, even serious infections did not affect the overall patient survival.[11,12,17-19]Everolimus increases low-density lipoprotein cholesterol. Although the importance of dyslipidemia caused by everolimus is unknown,[38]this dyslipidemia should be managed. Another side effect of everolimus is proteinuria, the possible mechanism is that everolimus inhibits the secretion of vascular endothelial growth factor (VEGF) and blocks its signaling pathway.[40]Patients with proteinuria can be treated with angiotensin-converting enzyme inhibitors or angiotensin receptor blockers.[41]The peripheral edema caused by everolimus may be explained by decreased plasma osmolality because of proteinuria that causes interstitial fluid reflux disorder and edema.

It is noteworthy that cyclosporine and tacrolimus were coadministered with everolimus in different trials, but no study focused on the difference between the two combination strategies. Early study[42]demonstrated that cyclosporine can increase everolimus blood levels by 2.7-fold, so that cyclosporine reduction may decrease the levels of everolimus in the blood. However, everolimus exposure is not affected when tacrolimus blood levels are down-titrated within range of 1.5-7 ng/mL.[43]This may indicate that tacrolimus may be more suitable for immunosuppressive treatment than cyclosporine when coadministerd with everolimus. Further studies are warranted.

Although the present study demonstrated that everolimus had an efficacy and safety profile in adult liver transplantation, it has several drawbacks that should be acknowledged. First, renal function measurement was not uniform; however, sensitivity analysis confirmed stable results. Moreover, subgroup analyses confirmed stable conclusions. Second, one trial arm in De Simone's et al's study[11]ended early because of profound adverse events. This may cause random bias, but the baseline characteristics of the included patients were similar to the controls.[11]Third, many studies are not placebo-controlled trials which may cause performance bias. However, regular monitoring of the drug blood levels may have made the placebo-controlled method difficult to conduct. Fourth, the small number of included trials may have introduced publication bias.[44,45]Several ongoing studies (NCT01888432, NCT01551212, NCT01625377, etc.) may diminish this bias in future meta-analyses.[24]Fifth, only published data were extracted, and some data were extracted indirectly using a formula. This may have decreased the accuracy of the results, but these methods are permitted by the Cochrane Collaborative Group when raw data are not available.[15]Sixth, many of the studies included here only evaluated the efficacy and safety of everolimus one year after treatment rather than at other time points. Long-term effects need further study. Finally, this article only addressed the efficacy and safety of everolimus in adult LT recipients. There is still a lack of robust data about everolimus efficacy and safety in pediatric LT recipients, although Nielsen's study has produced promising results.[46]Ongoing trials (NCT01598987, CRAD001H2305, etc.) may eventuallybe informative in this regard.

In conclusion, early introduction of everolimus in de novo LT patients (within 30 days after transplantation) can significantly improve renal function one year after treatment. Everolimus combined with reduced doses of CNIs may decrease tBPAR at one year. However, the everolimus initiation with eliminated CNIs increased the rate of acute rejection. Everolimus also decreases the risk of neoplasms and tumor recurrence after LT at one year. Everolimus is associated with a higher risk of infections, leukopenia, hypercholesterolemia, proteinuria, and peripheral edema.

Contributors: TCY and SA put forward this idea, extracted the data, carried out statistical analysis of this study, and wrote the manuscript. WXF and LR searched the literature, extracted the data, carried out the critical appraisal of included studies. LQD and DHJ performed the statistical analysis and edited figures of this paper. WYZ and WZJ revised this article. TCY and SA contributed equally to this paper. WZJ is the guarantor.

Funding: This study was supported by grants from the National Nature Science Foundation of China (81171562), the Chongqing Medical Research Project (2011-2-081), the Frontier and Applied Basic Research Project of Chongqing (cstc2013yykfA0093) and the Science and Technology Talent Cultivation Project of Chongqing (Young Talents of New Product Innovation) (cstc2013kjrcqnrc10006).

Ethical approval: Not needed.

Competing interest: No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article.

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Accepted after revision June 29, 2015

10.1016/S1499-3872(15)60419-2

Author Affiliations: Department of Pharmacy (Tang CY) and Department of Hepatobiliary Surgery (Wei XF, Liu R and Wu ZJ), First Affiliated Hospital of Chongqing Medical University, Chongqing 404100, China; Department of Hepatobiliary Surgery (Shen A, Li QD and Deng HJ) and Department of Radiotherapy (Wu YZ), Chongqing Cancer Institute, Chongqing 400030, China

Zhong-Jun Wu, MD, PhD, Department of Hepatobiliary Surgery, First Affiliated Hospital of Chongqing Medical University, Chongqing 404100, China (Fax: +86-23-68711487; Email: wzjtcy@126.com)

© 2015, Hepatobiliary Pancreat Dis Int. All rights reserved.

Published online September 17, 2015.

November 20, 2014