Benefit-Risk Assessment of Sirolimus in Renal Transplantation

Successful treatment of juvenile polyposis of infancy with sirolimus: a case report

BACKGROUND

Infantile Juvenile polyposis of infantile (JPI) is a rare and aggressive form of juvenile polyposis syndrome (JPS) typically diagnosed in the first year of life. It often carries a poor prognosis due to chronic gastrointestinal bleeding, protein-losing enteropathy, malnutrition and immune deficiency.

CASE PRESENTATION

We report a case of a girl initially presented with pallor at 7 months of age, which progressed to gastrointestinal bleeding and protein-losing enteropathy. Endoscopic examination, which included both upper gastrointestinal endoscopy and enteroscopy, showed diffuse polyposis. Histopathology results indicated the presence of juvenile polyps with no dysplasia in all removed polyps. Genetic testing identified a 2.1 Mb deletion on chromosome 10q23.2q23.31 involving the phosphatase and tensin homolog (PTEN) and bone morphogenetic protein receptor type IA (BMPR1A) genes. Treatment with sirolimus initiated at 10 months of age led to a reduction in the need for blood and albumin infusions, improved patient growth, and quality of life. While the frequency of endoscopic evaluations decreased with sirolimus, regular endoscopic polypectomy every 5 months remained necessary. However, discontinuation of sirolimus resulted in polyp recurrence after 2 months due to pneumonia.

CONCLUSION

This case highlights sirolimus treatment can alleviate many complications of JPI, it does not eliminate the need for aggressive polypectomy.

Rapamycin Attenuates H2O2-Induced Oxidative Stress-Related Senescence in Human Skin Fibroblasts

BACKGROUND

Oxidative stress plays an important role in the skin aging process. Rapamycin has been shown to have anti-aging effects, but its role in oxidative senescence of skin cells remains unclear. The aim of this study was to explore the effect of rapamycin on oxidative stress-induced skin cell senescence and to illustrate the mechanism.

METHODS

Primary human skin fibroblasts (HSFs) were extracted and a model of H2O2-induced oxidative senescence was constructed, and the effects of rapamycin on their value-added and migratory capacities were detected by CCK-8 and scratch assays. SA-β-gal was utilized to detect senescence, oxidatively closely related factors were also assessed. Gene and protein expressions of senescence, oxidative, and autophagy were detected by western blotting and quantitative-PCR. The data were analyzed by one-way analysis of variance.

RESULTS

Rapamycin (0.1 nmol/L for 48 h) promoted the proliferative and migration of H2O2-treated HSFs (p < 0.05), decreased senescent phenotypes SA-β-gal staining and the expression of P53, and MMP-1 proteins, and increased the expression level of COL1A-1 (p < 0.001). Rapamycin also enhanced the activities of SOD and HO-1, and effectively removed intracellular ROS, MDA levels (p < 0.05), in addition, autophagy-related proteins and genes were significantly elevated after rapamycin pretreatment (p < 0.001). Rapamycin upregulated the autophagy pathway to exert its protective effects.

CONCLUSION

Our findings indicate that rapamycin shields HSFs from H2O2-induced oxidative damage, the mechanism is related to the reduction of intracellular peroxidation and upregulation of autophagy pathway. Therefore, rapamycin has the potential to be useful in the investigation and prevention of signs of aging and oxidative stress.

Diabetic Kidney Disease in Post-Kidney Transplant Patients

Post-transplant diabetes mellitus (PTDM) is a common occurrence in post-kidney transplantation and is associated with greater mortality, allograft failure, and increased risk of infections. The primary goal in the management of PTDM is to achieve glycemic control to minimize the risk of complications while balancing the need for immunosuppression to maintain the health of the transplanted kidney. This review summarizes the effects of maintenance immunosuppression and therapeutic options among kidney transplant recipients. Patients with PTDM are at increased risk of diabetic kidney disease development; therefore, in this review, we focus on evidence supporting the use of novel antidiabetic agents and discuss their benefits and potential side effects in detail.

Evaluation of off-label rapamycin use to promote healthspan in 333 adults

Rapamycin (sirolimus) is an FDA-approved drug with immune-modulating and growth-inhibitory properties. Preclinical studies have shown that rapamycin extends lifespan and healthspan metrics in yeast, invertebrates, and rodents. Several physicians are now prescribing rapamycin off-label as a preventative therapy to maintain healthspan. Thus far, however, there is limited data available on side effects or efficacy associated with use of rapamycin in this context. To begin to address this gap in knowledge, we collected data from 333 adults with a history of off-label use of rapamycin by survey. Similar data were also collected from 172 adults who had never used rapamycin. Here, we describe the general characteristics of a patient cohort using off-label rapamycin and present initial evidence that rapamycin can be used safely in adults of normal health status.

A randomized controlled trial to evaluate efficacy and safety of early conversion to a low-dose calcineurin inhibitor combined with sirolimus in renal transplant patients

BACKGROUND

The calcineurin inhibitor (CNI)-based immune maintenance regimen that is commonly used after renal transplantation has greatly improved early graft survival after transplantation; however, the long-term prognosis of grafts has not been significantly improved. The nephrotoxicity of CNI drugs is one of the main risk factors for the poor long-term prognosis of grafts. Sirolimus (SRL) has been employed as an immunosuppressant in clinical practice for over 20 years and has been found to have no nephrotoxic effects on grafts. Presently, the regimen and timing of SRL application after renal transplantation vary, and clinical data are scarce. Multicenter prospective randomized controlled studies are particularly rare. This study aims to investigate the effects of early conversion to a low-dose CNI combined with SRL on the long-term prognosis of renal transplantation.

METHODS

Patients who receive four weeks of a standard regimen with CNI + mycophenolic acid (MPA) + glucocorticoid after renal transplantation in multiple transplant centers across China will be included in this study. At week 5, after the operation, patients in the experimental group will receive an additional administration of SRL, a reduction in the CNI drug doses, withdrawal of MPA medication, and maintenance of glucocorticoids. In addition, patients in the control group will receive the maintained standard of care. The patients' vital signs, routine blood tests, routine urine tests, blood biochemistry, serum creatinine, BK virus (BKV)/ cytomegalovirus (CMV), and trough concentrations of CNI drugs and SRL at the baseline and weeks 12, 24, 36, 48, 72, and 104 after conversion will be recorded. Patient survival, graft survival, and estimated glomerular filtration rate will be calculated, and concomitant medications and adverse events will also be recorded.

CONCLUSION

The study data will be utilized to evaluate the efficacy and safety of early conversion to low-dose CNIs combined with SRL in renal transplant patients.

TRIAL REGISTRATION

Chinese Clinical Trial Registry, ChiCTR1800017277.

Rapamycin Nano-Micelle Ophthalmic Solution Reduces Corneal Allograft Rejection by Potentiating Myeloid-Derived Suppressor Cells' Function

Allograft rejection is the major cause of corneal allograft failure. Rapamycin (RAPA) has been reported as an effective and novel immunosuppressive agent for patients undergoing corneal transplantation. However, its high water insolubility and low bioavailability have strongly constrained its clinical application. In this study, we successfully developed a RAPA nano-micelle ophthalmic solution and found that corneal allograft survival in recipients treated with RAPA nano-micelle ophthalmic solution was significantly prolonged for more than 2 months, with less inflammatory infiltration, decreased production of pro-inflammatory factors, and elevated recruitment of myeloid-derived suppressor cells (MDSCs). MDSCs from mice treated with RAPA nano-micelle ophthalmic solution could significantly inhibit the proliferation of CD4⁺T cells through increased expressions of inducible nitric oxidase (iNOS) and arginase-1 (Arg-1). The activity blockade of Arg-1 and iNOS pharmacologically reversed their immunosuppressive ability. Moreover, the effects of RAPA were antagonized by the administration of anti-Gr-1 antibody or by inhibiting the activity of iNOS pharmacologically. In addition, RAPA nano-micelle also effectively alleviated allograft rejection in high-risk rabbit penetrating keratoplasty (PKP) models with corneal vascularization. Collectively, our results demonstrate that RAPA nano-micelle ophthalmic solution could improve the immunosuppressive activity of MDSCs through elevated expression of Arg-1 and iNOS, which highlights the possible therapeutic applications of RAPA against corneal allograft rejection.

A Systematic Literature Review Approach to Estimate the Therapeutic Index of Selected Immunosuppressant Drugs After Renal Transplantation

BACKGROUND

Drugs that exhibit close margins between therapeutic and toxic blood concentrations are considered to have a narrow therapeutic index (NTI). The Food and Drug Administration has proposed that NTI drugs should have more stringent bioequivalence standards for approval of generic formulations. However, many immunosuppressant drugs do not have a well-defined therapeutic index (TI).

METHODS

We sought to determine whether safety, efficacy, and pharmacokinetic data obtained from the medical literature through a comprehensive literature search could be used to estimate the TI of cyclosporine, tacrolimus, and sirolimus. In this analysis, we considered TI ≤2 as a criterion to define a drug as having an NTI.

RESULTS

Published literature indicates that cyclosporine has a TI of 2-3, which falls just short of our criteria to be classified as having an NTI. We found sirolimus and tacrolimus to have a therapeutic range of 5-12 ng/mL and of 5-20 ng/mL, respectively, but were unable to calculate the TI.

CONCLUSIONS

Although the current literature does not provide a clear indication that these drugs have an NTI, the routine use of therapeutic drug monitoring in clinical practice suggests that more stringent testing of their pharmacokinetic and pharmacodynamic properties should be performed before the approval of generic formulations.

Effects of TORC1 Inhibition during the Early and Established Phases of Polycystic Kidney Disease

The disease-modifying effects of target of rapamycin complex 1 (TORC1) inhibitors during different stages of polycystic kidney disease (PKD) are not well defined. In this study, male Lewis Polycystic Kidney Disease (LPK) rats (a genetic ortholog of human NPHP9, phenotypically characterised by diffuse distal nephron cystic growth) and Lewis controls received either vehicle (V) or sirolimus (S, 0.2 mg/kg by intraperitoneal injection 5 days per week) during the early (postnatal weeks 3 to 10) or late stages of disease (weeks 10 to 20). In early-stage disease, sirolimus reduced kidney enlargement (by 63%), slowed the rate of increase in total kidney volume (TKV) in serial MRI by 78.2% (LPK+V: 132.3±59.7 vs. LPK+S: 28.8±12.0% per week) but only partly reduced the percentage renal cyst area (by 19%) and did not affect the decline in endogenous creatinine clearance (CrCl) in LPK rats. In late-stage disease, sirolimus reduced kidney enlargement (by 22%) and the rate of increase in TKV by 71.8% (LPK+V: 13.1±6.6 vs. LPK+S: 3.7±3.7% per week) but the percentage renal cyst area was unaltered, and the CrCl only marginally better. Sirolimus reduced renal TORC1 activation but not TORC2, NF-κB DNA binding activity, CCL2 or TNFα expression, and abnormalities in cilia ultrastructure, hypertension and cardiac disease were also not improved. Thus, the relative treatment efficacy of TORC1 inhibition on kidney enlargement was consistent at all disease stages, but the absolute effect was determined by the timing of drug initiation. Furthermore, cystic microarchitecture, renal function and cardiac disease remain abnormal with TORC1 inhibition, indicating that additional approaches to normalise cellular dedifferentiation, inflammation and hypertension are required to completely arrest the progression of PKDs.

Therapeutic Drug Monitoring, Electronic Health Records, and Pharmacokinetic Modeling to Evaluate Sirolimus Drug Exposure-Response Relationships in Renal Transplant Patients

BACKGROUND

Sirolimus, an immunosuppressive agent used in renal transplantation, can prevent allograft rejection. Identification of the therapeutic index (the ratio of minimum toxic concentration to minimum therapeutic concentration) for immunosuppresants is necessary to optimize the care of patients and set standards for bioequivalence evaluation of sirolimus products. However, the therapeutic index for sirolimus has been inconsistently defined, potentially because of inconsistencies in sirolimus exposure-response relationships.

METHODS

The authors used retrospective therapeutic drug monitoring data from the electronic health records of patients treated in a tertiary health care system from 2008 to 2014 to (1) develop a population pharmacokinetic (PK) model, (2) use the model to simulate sirolimus concentrations, and (3) characterize the exposure-response relationship. Using Wilcoxon rank-sum and Fisher exact tests, the authors determined relationships between sirolimus exposure and adverse events (AEs) (anemia, leukopenia, thrombocytopenia, hyperlipidemia, and decline in renal function) and the composite efficacy end point of graft loss or rejection.

RESULTS

The developed 2-compartment population PK model showed appropriate goodness of fit. In a late-phase (>12 months), postrenal transplant population of 27 inpatients, the authors identified statistically significant relationships between 83 simulated peak and trough sirolimus concentrations and outcomes: graft loss or rejection (P = 0.018) and decline in renal function (P = 0.006), respectively.

CONCLUSIONS

Use of therapeutic drug monitoring results and PK modeling permitted correlation of sirolimus concentrations with graft loss or rejection and decline in renal function. However, the method was limited in its assessment of other AEs. To better evaluate sirolimus exposure-response relationships, the method should be applied to a larger sample of newly transplanted patients with a higher propensity toward AEs or efficacy failure.

Effect of Sirolimus on Disease Progression in Patients with Autosomal Dominant Polycystic Kidney Disease and CKD Stages 3b-4

BACKGROUND AND OBJECTIVES

The effect of mammalian target of rapamycin (mTOR) inhibitors has never been tested in patients with autosomal dominant polycystic kidney disease (ADPKD) and severe renal insufficiency.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In this academic, prospective, randomized, open label, blinded end point, parallel group trial (ClinicalTrials.gov no. NCT01223755), 41 adults with ADPKD, CKD stage 3b or 4, and proteinuria ≤0.5 g/24 h were randomized between September of 2010 and March of 2012 to sirolimus (3 mg/d; serum target levels of 5-10 ng/ml) added on to conventional therapy (n=21) or conventional treatment alone (n=20). Primary outcome was GFR (iohexol plasma clearance) change at 1 and 3 years versus baseline.

RESULTS

At the 1-year preplanned interim analysis, GFR fell from 26.7±5.8 to 21.3±6.3 ml/min per 1.73 m(2) (P<0.001) and from 29.6±5.6 to 24.9±6.2 ml/min per 1.73 m(2) (P<0.001) in the sirolimus and conventional treatment groups, respectively. Albuminuria (73.8±81.8 versus 154.9±152.9 μg/min; P=0.02) and proteinuria (0.3±0.2 versus 06±0.4 g/24 h; P<0.01) increased with sirolimus. Seven patients on sirolimus versus one control had de novo proteinuria (P=0.04), ten versus three patients doubled proteinuria (P=0.02), 18 versus 11 patients had peripheral edema (P=0.04), and 14 versus six patients had upper respiratory tract infections (P=0.03). Three patients on sirolimus had angioedema, 14 patients had aphthous stomatitis, and seven patients had acne (P<0.01 for both versus controls). Two patients progressed to ESRD, and two patients withdrew because of worsening of proteinuria. These events were not observed in controls. Thus, the independent data and safety monitoring board recommend early trial termination for safety reasons. At 1 year, total kidney volume (assessed by contrast-enhanced computed tomography imaging) increased by 9.0% from 2857.7±1447.3 to 3094.6±1519.5 ml on sirolimus and 4.3% from 3123.4±1695.3 to 3222.6±1651.4 ml on conventional therapy (P=0.12). On follow-up, 37% and 7% of serum sirolimus levels fell below or exceeded the therapeutic range, respectively.

CONCLUSIONS

Finding that sirolimus was unsafe and ineffective in patients with ADPKD and renal insufficiency suggests that mTOR inhibitor therapy may be contraindicated in this context.

The antiaging activity and cerebral protection of rapamycin at micro-doses

BACKGROUND AND PURPOSE

The immunosuppressant drug rapamycin was reported to have an antiaging activity, which was attributed to the TORC1 inhibition that inhibits cell proliferation and increases autophagy. However, rapamycin also exhibits a number of harmful adverse effects. Whether rapamycin can be developed into an antiaging agent remains unclear.

METHODS AND RESULTS

We demonstrated that rapamycin at micro-doses (below the TORC1 inhibiting concentration) exhibits a cell-protective activity: (1) It protects cultured neurons against neurotoxin MPP(+) and H2O2. (2) It increases survival time of neuron in culture. (3) It maintains the nonproliferative state of cultured senescent human fibroblasts and prevents cell death induced by telomere dysfunction. (4) In animal models, it decreased the cerebral infarct sizes induced by acute ischemia and dramatically extended the life span of stroke prone spontaneously hypertensive rats (SHR-SPs).

CONCLUSION

We propose that rapamycin at micro-dose can be developed into an antiaging agent with a novel mechanism.

Immunosuppressive nano-therapeutic micelles downregulate endothelial cell inflammation and immunogenicity

In this study, we developed a stable, nontoxic novel micelle nanoparticle to attenuate responses of endothelial cell (EC) inflammation when subjected to oxidative stress, such as observed in organ transplantation. Targeted Rapamycin Micelles (TRaM) were synthesized using PEG-PE-amine and N-palmitoyl homocysteine (PHC) with further tailoring of the micelle using targeting peptides (cRGD) and labeling with far-red fluorescent dye for tracking during cellular uptake studies. Our results revealed that the TRaM was approximately 10 nm in diameter and underwent successful internalization in Human Umbilical Vein EC (HUVEC) lines. Uptake efficiency of TRaM nanoparticles was improved with the addition of a targeting moiety. In addition, our TRaM therapy was able to downregulate both mouse cardiac endothelial cell (MCEC) and HUVEC production and release of the pro-inflammatory cytokines, IL-6 and IL-8 in normal oxygen tension and hypoxic conditions. We were also able to demonstrate a dose-dependent uptake of TRaM therapy into biologic tissues ex vivo. Taken together, these data demonstrate the feasibility of targeted drug delivery in transplantation, which has the potential for conferring local immunosuppressive effects without systemic consequences while also dampening endothelial cell injury responses.

Comparison of long-term impact of immunosuppressants at therapeutic doses on hepatic function and histological changes in unilateral nephrectomized rats

Cyclosporine, tacrolimus and sirolimus are commonly used in renal transplant recipients to prevent rejection. Various adverse effects of these agents on the multiple organ system have been reported clinically. However, animal studies are necessary to determine and compare these effects on individual organ given the presence of multiple confounding factors and multi-pharmacy in clinical settings. In a physiologically and clinically relevant rat model of unilateral nephrectomy, the long-term impacts of commonly used immunosuppressants at doses equivalent to the therapeutic levels used for post-renal transplant patients on hepatic function and histological changes of the liver were examined. Cyclosporine induced significant hepatocellular injury, impairment of synthetic function of the liver, hyperbilirubinemia and cholestasis, and dyslipidemia accompanied by profound histological changes of hepatic structures on both light and electron microscopic examinations. On the other hand, neither tacrolimus nor sirolimus developed any hepatotoxic effects except for more remarkable dyslipidemia was observed in animals treated with sirolimus. Our study indicates that long-term administration of commonly used immunosuppressants has various impacts on biochemical parameters as well as histological alterations of the liver even at therapeutic levels. These data may therefore provide useful information for judicious selection of immunosuppressive agents based on different clinical settings.

Alleviating neurodegeneration in Drosophila models of PolyQ diseases

Polyglutamine (polyQ) diseases are a group of neurodegenerative conditions, induced from CAG trinucleotide repeat expansion within causative gene respectively. Generation of toxic proteins, containing polyQ-expanded tract, is the key process to cause neurodegeneration. Till now, although polyQ diseases remain uncurable, numerous therapeutic strategies with great potential have been examined and have been proven to be effective against polyQ diseases, including diverse small biological molecules and many pharmacological compounds mainly through prevention on formation of aggregates and inclusions, acceleration on degradation of toxic proteins and regulation of cellular function. We review promising therapeutic strategies by using Drosophila models of polyQ diseases including HD, SCA1, SCA3 and SBMA.

What is the impact of immunosuppressive treatment on the post-transplant renal osteopathy?

Although glucocorticoid therapy is considered to be the main pathogenic factor, a consistent body of evidence suggests that other immunosuppressants might also play an important role in the development of the post-transplant renal osteopathy (PRO) through their pleiotropic pharmacological effects. Glucocorticoids seem to induce osteoclasts' activity suppressing the osteoblasts while data regarding other immunosuppressive drugs are still controversial. Mycophenolate mofetil and azathioprine appear to be neutral regarding the bone metabolism. However, the study analyzing any independent effect of antimetabolites on bone turnover has not been conducted yet. Calcineurin inhibitors (CNIs) induce trabecular bone loss in rodent, with contradictory results in renal transplant recipients. Suppression of vitamin D receptor is probably the underlying mechanism of renal calcium wasting in renal transplant recipients receiving CNI. In spite of an increased 1,25(OH)2 vitamin D level, the kidney is not able to reserve calcium, suggesting a role of vitamin D resistance that may be related to bone loss. More efforts should be invested to determine the role of CNI in PRO. In particular, data regarding the role of mammalian target of rapamycin inhibitors (mTORi), such as sirolimus and everolimus, in the PRO development are still controversial. Rapamycin markedly decreases bone longitudinal growth as well as callus formation in experimental models, but also lowers the rate of bone resorption markers and glomerular filtration in clinical studies. Everolimus potently inhibits primary mouse and human osteoclast activity as well as the osteoclast differentiation. It also prevents the ovariectomy-induced loss of cancellous bone by 60 %, an effect predominantly associated with a decreased osteoclast-mediated bone resorption, resulting in a partial preservation of the cancellous bone. At present, there is no clinical study analyzing the effect of everolimus on bone turnover in renal transplant recipients or comparing sirolimus versus everolimus impact on bone, so only general conclusions could be drawn. Hence, the use of mTORi might be useful in patients with PRO due to their possible potential to inhibit osteoclast activity which might lead to a decreased rate of bone resorption. In addition, it should be also emphasized that they might inhibit osteoblast activity which may lead to a decreased bone formation and adynamic bone disease. Further studies are urgently needed to solve these important clinical dilemmas.

Everolimus and enteric-coated mycophenolate sodium ab initio after liver transplantation: midterm results

BACKGROUND AND AIM

Everolimus (EVR) use in liver transplantation (OLT) has been prescribed with calcineurin inhibitors (CNIs), steroids, and monoclonal antibodies. The aim of our study was to evaluate the safety, feasibility, and impact on renal function of EVR ab initio, in combination with enteric-coated mycophenolate sodium (EC-MPS) without the use of induction treatment, steroids, or CNIs.

PATIENTS AND METHODS

We retrospective analyzed nine consecutive patients who underwent OLT at our institution. The initial dose of EVR (1.5 mg/d) was adjusted to achieve trough levels of 8 to 12 ng/mL. EC-MPS introduced at 1080 mg/d was maintained at the same dose over time.

RESULTS

At a mean follow-up of 21.48 (standard deviation [SD] 1.4) months from OLT, 7/9 recipients were alive with stable graft function. The 2-year patient and graft survivals were 77%. One recipient died due to cerebral hemorrhage and one, lung failure. No clinical evidence of an acute rejection episode was observed. Mean estimated glomerular filtration rate value, according to the Modification of Diet in Renal Disease formula increased from 59.5 (SD 9.89) mL/min/1.73 m(2) at OLT to 100.2 (SD 47.5) mL/min/1.73 m(2) (P = .03) after 12 months and 98.71 (SD 33.74) mL/min/1.73 m(2) (P = .03) after 24 months' follow-up.

CONCLUSION

A double immunosuppression therapy with EVR and EC-MPS ab initio seemed to be efficacions and safe, representing a valid alternative to CNIs to prevent renal failure after OLT.

An evaluation of sirolimus in renal transplantation

INTRODUCTION

Sirolimus is a powerful antiproliferative immunosuppressive drug approved for the prevention of kidney allograft rejection. By its unique mechanism of action, sirolimus provides a multitude of clinical potential and has been used effectively in different drug combinations. Extensive experience has been gained regarding the best timing of its application, side effect profile and potential benefits and limitations compared with other immunosuppressive drugs.

AREAS COVERED

The authors evaluate the recent experience with sirolimus in kidney transplantation. Pivotal randomized controlled trials were used to provide an overview with special attention to pharmacokinetic and dynamic aspects of sirolimus, its current clinical use as well as perspectives for its future role.

EXPERT OPINION

Sirolimus enriches the possibilities of immunosuppressive therapies after renal transplantation. Beneficial effects toward kidney function by allowing CNI sparing, lower incidence of malignancies and less viral infections have been suggested. Sirolimus should be used cautiously in de novo patients for reasons of wound healing. An early conversion to a sirolimus-based CNI-free regimen has shown promising results, whereas late conversion is more challenging. Finally, sirolimus-associated side effects are causing tolerability concerns and frequent discontinuations. Future research should aim to better define the therapeutic window and those patients most likely to benefit.

Rapamycin induced ultrastructural and molecular alterations in glomerular podocytes in healthy mice

BACKGROUND

In the normal kidney, rapamycin is considered to be non-nephrotoxic. In the present study, we investigated whether rapamycin is indeed non-nephrotoxic by examining the ultrastructural and molecular alterations of podocytes in healthy mice.

METHODS

Balb/c mice were given three different intraperitoneal doses of rapamycin for 1 week (dose model)-low-dose group: 1 mg/kg/day, intermediate-dose (ID) group: 1.5 mg/kg/day and high-dose (HD) group: 3 mg/kg/day; four mice in each group. An ID of rapamycin was also given for three different periods (time model): 1, 4 and 8 weeks; four mice were in each group. Mice treated with dimethyl sulphoxide served as controls. Body weight was measured weekly. Renal function was assessed by serum creatinine at the time of sacrifice. For estimation of albuminuria, 24-h urine collections were performed before treatment and weekly thereafter. Glomerular content of nephrin, podocin, Akt and Ser473-phospho-Akt was estimated by western blot and immunofluorescence. Nephrin and podocin messenger RNA (mRNA) were measured by real-time polymerase chain reaction. Mean podocyte foot process width (FPW) was measured by electron microscopy.

RESULTS

Urine albumin levels increased in the HD and 4-week groups. Renal function was modestly deteriorated in the HD group. The mean FPW increased in a dose-dependant manner at Week 1, further deteriorated at Week 4 and finally improved at Week 8. Nephrin and podocin mRNA levels showed a significant decrease at Week 1 and were restored at Week 4 and 8. Nephrin and podocin protein levels were reduced at Week 4 and recovered at Week 8. Ser473-phospho-Akt significantly increased in all rapamycin-treated groups.

CONCLUSIONS

Rapamycin induced significant ultrastructural and molecular alterations in podocytes in association with albuminuria. These alterations happened early during treatment and they tended to improve over an 8-week treatment period.

The use of sirolimus should be restricted in liver transplantation

Sirolimus and mTOR inhibitors are important additions to the therapeutic armamentarium to prevent allograft rejection, but their role in liver transplantation is evolving. De novo use of Sirolimus in the early post-transplant period has undoubtedly been influenced by the high incidence of hepatic artery thrombosis and decreased patient and graft survival leading to a black box warning. The jury remains undecided on the role of conversion from CNIs to mTOR inhibitors in those developing renal insufficiency and it must be noted that a second warning was issued by the FDA because of decreased survival in those conversion studies. Finally, the anti-atherogenic, antiviral, and anti-neoplastic effects associated with Sirolimus, which might favor their use in certain liver transplant patients, need further evaluation before firm recommendations can be made.

The food additive vanillic acid controls transgene expression in mammalian cells and mice

Trigger-inducible transcription-control devices that reversibly fine-tune transgene expression in response to molecular cues have significantly advanced the rational reprogramming of mammalian cells. When designed for use in future gene- and cell-based therapies the trigger molecules have to be carefully chosen in order to provide maximum specificity, minimal side-effects and optimal pharmacokinetics in a mammalian organism. Capitalizing on control components that enable Caulobacter crescentus to metabolize vanillic acid originating from lignin degradation that occurs in its oligotrophic freshwater habitat, we have designed synthetic devices that specifically adjust transgene expression in mammalian cells when exposed to vanillic acid. Even in mice transgene expression was robust, precise and tunable in response to vanillic acid. As a licensed food additive that is regularly consumed by humans via flavoured convenience food and specific fresh vegetable and fruits, vanillic acid can be considered as a safe trigger molecule that could be used for diet-controlled transgene expression in future gene- and cell-based therapies.

Kinetic nomograms assist individualization of drug regimens

BACKGROUND AND OBJECTIVES

Therapeutic drug monitoring is applied to a range of drugs. To predict an appropriate dosing regimen, models based on Bayesian techniques have been used. However, this approach requires a well trained professional and sophisticated software. The objectives of this study were first to develop kinetic nomograms as a useful tool to achieve individual drug blood concentrations within the therapeutic window, using few samples and in a short period of time; and second to evaluate the performance of these nomograms in dosage adjustment and compare them with the Bayesian procedure by use of simulation.

METHODS

Kinetic nomograms involve collection of concentration-time profiles following repeated administrations of a fixed identification protocol and targeting of a steady-state concentration. The profiles divide the concentration-time space into several areas, each of them corresponding to a given adjusted drug dose. Kinetic nomograms are grounded on the statistical description of the interindividual variability provided by population pharmacokinetic approaches. To use them, the assayed drug concentration in a blood sample is first located in the kinetic nomogram and then the dose corresponding to the area containing this location is read. Evaluation of performance and comparison with the traditional Bayesian procedure were done by a simulation study using the immunosuppressant drug sirolimus (rapamycin). All calculations were performed by use of Matlab software.

RESULTS

The simulation study confirmed the need for individual dosage adjustment; 71.6% of individuals underwent modification of the identification protocol of 1 mg twice daily in order to reach steady-state trough concentrations of 8 ng/mL. When the regimens were adjusted by kinetic nomograms and the Bayesian procedure, the steady-state trough concentrations of sirolimus showed low variability (coefficients of variation [CVs] of 23.4% and 24.0%, respectively) as compared with those obtained by standard recommended protocols of 4 mg once daily (CV 68.6%). The doses adjusted by kinetic nomograms and the Bayesian procedure were linearly linked and highly correlated (r = 0.96), and both provided simultaneous control of minimum and maximum drug concentrations (63.9% and 68.7% of cases between 6 and 20 ng/mL, respectively).

CONCLUSION

Kinetic nomograms allow rapid and reliable dosage adjustment after the start of drug therapy. They are interesting alternatives to the cumbersome Bayesian procedure, and they provide dosage adjustment even for drugs that exhibit large intraindividual variability. In the clinical context, kinetic nomograms render individual dosage adjustment a simplified bedside application, and they could assist population studies aiming at dose individualization.

Efficacy and Safety of Low-Dose Cyclosporine with Everolimus and Steroids in de novo Heart Transplant Patients: A Multicentre, Randomized Trial

A six-month, multicenter, randomized, open-label study was undertaken to determine whether renal function is improved using reduced-exposure cyclosporine (CsA) versus standard-exposure CsA in 199 de novo heart transplant patients receiving everolimus and steroids ± induction therapy. Mean C(2) levels were at the low end of the target range in standard-exposure patients (n = 100) and exceeded target range in reduced-exposure patients (n = 99) throughout the study. Mean serum creatinine at Month 6 (the primary endpoint) was 141.0 ± 53.1 μmol/L in standard-exposure patients versus 130.1 ± 53.7 μmol/L in reduced-exposure patients (P = 0.093). The incidence of biopsy-proven acute rejection ≥3A at Month 6 was 21.0% (21/100) in the standard-exposure group and 16.2% (16/99) in the reduced-exposure group (n.s.). Adverse events and infections were similar between treatment groups. Thus, everolimus with reduced-exposure CsA resulted in comparable efficacy compared to standard-exposure CsA. No renal function benefits were demonstrated; that is possibly related to poor adherence to reduced CsA exposure.

High-content chemical and RNAi screens for suppressors of neurotoxicity in a Huntington's disease model

To identify Huntington's Disease therapeutics, we conducted high-content small molecule and RNAi suppressor screens using a Drosophila primary neural culture Huntingtin model. Drosophila primary neurons offer a sensitive readout for neurotoxicty, as their neurites develop dysmorphic features in the presence of mutant polyglutamine-expanded Huntingtin compared to nonpathogenic Huntingtin. By tracking the subcellular distribution of mRFP-tagged pathogenic Huntingtin and assaying neurite branch morphology via live-imaging, we identified suppressors that could reduce Huntingtin aggregation and/or prevent the formation of dystrophic neurites. The custom algorithms we used to quantify neurite morphologies in complex cultures provide a useful tool for future high-content screening approaches focused on neurodegenerative disease models. Compounds previously found to be effective aggregation inhibitors in mammalian systems were also effective in Drosophila primary cultures, suggesting translational capacity between these models. However, we did not observe a direct correlation between the ability of a compound or gene knockdown to suppress aggregate formation and its ability to rescue dysmorphic neurites. Only a subset of aggregation inhibitors could revert dysmorphic cellular profiles. We identified lkb1, an upstream kinase in the mTOR/Insulin pathway, and four novel drugs, Camptothecin, OH-Camptothecin, 18β-Glycyrrhetinic acid, and Carbenoxolone, that were strong suppressors of mutant Huntingtin-induced neurotoxicity. Huntingtin neurotoxicity suppressors identified through our screen also restored viability in an in vivo Drosophila Huntington's Disease model, making them attractive candidates for further therapeutic evaluation.

Everolimus-based, calcineurin-inhibitor-free regimen in recipients of de-novo kidney transplants: an open-label, randomised, controlled trial

BACKGROUND

Non-nephrotoxic immunosuppressive strategies that allow reduction of calcineurin-inhibitor exposure without compromising safety or efficacy remain a goal in kidney transplantation. Immunosuppression based on the mammalian-target-of-rapamycin inhibitor everolimus was assessed as a strategy for elimination of calcineurin-inhibitor exposure and optimisation of renal-graft function while maintaining efficacy.

METHODS

In the ZEUS multicentre, open-label study, 503 patients (aged 18-65 years) who had received de-novo kidney transplants were enrolled. After initial treatment with ciclosporin, based on trough concentrations, and enteric-coated mycophenolate sodium (1440 mg/day, orally), corticosteroids (≥5 mg/day prednisolone or equivalent, orally), and basiliximab induction (20 mg, intravenously, on day 0 [2 h before transplantation], and on day 4), 300 (60%) patients were randomly assigned at 4·5 months in a 1:1 ratio to undergo calcineurin-inhibitor elimination (everolimus-based regimen that was based on trough concentrations [6-10 ng/mL] and enteric-coated mycophenolate sodium [1440 mg/day] with corticosteroids), or continue standard ciclosporin-based treatment. Randomisation was done by use of a central, validated system that automated the random assignment of treatment groups to randomisation numbers. The primary objective was to show better renal function (glomerular filtration rate [GFR]; Nankivell formula) with the calcineurin-inhibitor-free everolimus regimen at 12 months after transplantation. Analysis was by intention to treat. This study is registered with ClinicalTrials.gov, number NCT00154310.

FINDINGS

118 (76%) of 155 everolimus-treated patients and 117 (81%) of 145 ciclosporin-treated patients completed treatment with study drug up to 12 months after transplantation. At this timepoint, the everolimus regimen was associated with a significant improvement in GFR versus the ciclosporin regimen (71·8 mL/min per 1·73 m(2) vs 61·9 mL/min per 1·73 m(2), respectively; mean difference 9·8 mL/min per 1·73 m(2), 95% CI -12·2 to -7·5). Rates of biopsy-proven acute rejection were higher in the everolimus group than in the ciclosporin group after randomisation (15 [10%] of 154 vs five [3%] of 146; p = 0·036), but similar for the full study period (23 [15%] vs 22 [15%]). Compared with the ciclosporin regimen, higher mean lipid concentrations, slightly increased urinary protein excretion, and lower haemoglobin concentrations were noted with the everolimus regimen; thrombocytopenia, aphthous stomatitis, and diarrhoea also occurred more often in the everolimus group. A higher incidence of hyperuricaemia was noted with ciclosporin.

INTERPRETATION

Early elimination of calcineurin inhibitor by use of everolimus-based immunosuppression improved renal function at 12 months while maintaining efficacy and safety, indicating that this strategy may facilitate improved long-term outcomes in selected patients.

FUNDING

Novartis Pharma.

Proteinuria after conversion to sirolimus in kidney transplant recipients: impact of pre-existing proteinuria, graft function, and angiotensin-converting enzyme inhibitors/angiotensin-receptor antagonists

BACKGROUND

Proteinuria is a known side effect of therapy with sirolimus. The effect of angiotensin-converting enzyme inhibitors or angiotensin-receptor blockers (ACEI/ARB ) on sirolimus-associated proteinuria has not yet been assessed.

PATIENTS AND METHODS

A retrospective cohort study of renal transplant patients treated with sirolimus (n = 55) was performed.

RESULTS

Of 55 patients, 24 (44%) had no proteinuria (<0.15 g/d) prior to conversion. Of 24 patients, 11 (46%) showed de novo proteinuria >0.15 g/d after 12 months, only 2 developed proteinuria > 1 g/d. The total number of proteinuria >1 g/d after 12 months including patients with pre-existing proteinuria >1 g/d (n = 3) was seven of 55 patients (13%). Multivariate regression analysis revealed pre-existing proteinuria > 0.15 g/d and reduced glomerular filtration rate as independent predictors for the development of proteinuria after conversion to sirolimus.

CONCLUSION

Reduced glomerular filtration rate and pre-existing proteinuria but not therapy with ACEI/ARB are independent predictors for proteinuria after conversion to sirolimus. Treatment with ACEI/ARB did not reduce pre-existing proteinuria after conversion except in single cases with severe proteinuria.

Calcineurin inhibitor-free immunosuppression in pediatric renal transplantation: a viable option?

The introduction, in the mid-1980s, of calcineurin inhibitors - namely ciclosporin (cyclosporine) and later tacrolimus - has significantly improved short-term renal graft survival by lowering acute rejection rates in both adult and pediatric kidney transplantation. Nonetheless, long-term transplant survival is still not satisfactory, with calcineurin inhibitor-induced chronic nephrotoxicity being one of the main causes of progressive nephron loss and declining renal transplant function. Hence, different immunosuppressant regimens have been proposed to avoid or ameliorate calcineurin inhibitor-induced nephrotoxicity. These comprise the use of non-depleting or depleting antibodies for calcineurin inhibitor minimization, calcineurin inhibitor avoidance, or calcineurin inhibitor withdrawal from mycophenolate mofetil-based immunosuppressant protocols. De novo use of a mammalian target of rapamycin (mTOR) inhibitor (sirolimus or everolimus) or conversion from a calcineurin inhibitor to an mTOR inhibitor may constitute another therapeutic option to avoid or reduce calcineurin inhibitor-induced nephrotoxicity. To date, complete calcineurin inhibitor avoidance seems to be inappropriate because other relatively potent immunosuppressant agents such as lymphocyte-depleting antibodies are needed for rejection prophylaxis, which are frequently accompanied by a higher incidence of infections and an unacceptably high acute rejection rate under calcineurin inhibitor avoidance. In some studies, calcineurin inhibitor withdrawal in adult and pediatric kidney allograft recipients with stable or declining transplant function has been associated with an amelioration of renal function; however, this is attained at the cost of a higher acute rejection rate in 10-20% of patients. It has been frequently stressed that conversion from a calcineurin inhibitor-based regimen to an mTOR inhibitor-based immunosuppressant regimen should be performed early (e.g. 3 or 6 months post-transplant) in patients with well-preserved renal transplant function without significant proteinuria in order to prevent, or at least limit, calcineurin inhibitor-induced tissue damage and provide long-term benefit. It should be borne in mind though that the use of an mTOR inhibitor carries the risk of potential adverse events such as aggravation of proteinuria, hyperlipidemia, myelosuppression, and hypergonadotropic hypogonadism. Even though everolimus may be better tolerated than sirolimus, studies on everolimus for calcineurin inhibitor-free immunosuppression in the pediatric kidney transplant patient population are lacking. At present, the safest therapeutic strategy for pediatric renal allograft recipients with chronic calcineurin inhibitor-induced nephrotoxicity appears to be a mycophenolate mofetil-based regimen with low-dose calcineurin inhibitor therapy and corticosteroids; available published data show that dual immunosuppression with mycophenolate mofetil and corticosteroids, as well as an mTOR inhibitor plus mycophenolate mofetil plus corticosteroid-based regimens, are associated with an increased risk of acute rejection episodes. In individual patients with evidenced chronic allograft dysfunction and over-immunosuppression leading to recurrent infections, dual maintenance immunosuppression with mycophenolate mofetil and corticosteroids may be appropriate. As stated in the annual report issued by the North American Pediatric Renal Trials and Collaborative Studies (NAPRTCS) Registry, currently the most popular immunosuppressant protocol consists of a calcineurin inhibitor combined with mycophenolate mofetil and corticosteroids: 59.1% and 53.2% of patients with a functioning graft receive a calcineurin inhibitor plus mycophenolate mofetil plus corticosteroid-based immunosuppression at 1 and 5 years post-transplant, respectively. 91.4% and 87.8% of patients are administered a calcineurin inhibitor-containing regimen 1 and/or 5 years after transplantation, respectively. Undoubtedly, the use of calcineurin inhibitor-free immunosuppressant regimens with or without antibody induction, plus an mTOR inhibitor and mycophenolate mofetil, requires more comprehensive long-term investigations to determine whether acceptable rejection rates and conservation of renal function can be achieved.

Reduction of cyclosporine following the introduction of everolimus in maintenance heart transplant recipients: a pilot study

Data are scarce concerning the calcineurin inhibitor dose reduction required following introduction of everolimus in maintenance heart transplant recipients to maintain stable renal function. In a 48-week, multicenter, single-arm pilot study in heart transplant patients >12 months post-transplant, everolimus was started at 1.5 mg/day (subsequently adjusted to target C(0) 5-10 ng/ml). Mycophenolate mofetil or azathioprine was discontinued on the same day and cyclosporine (CsA) dose was reduced by 25%, with a further 25% reduction each time calculated glomerular filtration rate (cGFR) decreased to <75% of baseline. Of 36 patients enrolled, 25 were receiving everolimus at week 48. From baseline to week 48, there was a mean decrease of 44.5%, 50.9% and 44.6% in CsA dose, C(0) and C(2), respectively. Mean cGFR was 68.9 +/- 14.5 ml/min at baseline and 61.6 +/- 11.5 ml/min at week 48 (P = 0.018). The prespecified criterion for stable renal function was met, i.e. a mean decrease <or=25% of cGFR from baseline. Two patients experienced biopsy-proven acute rejection Grade 3A (5.6%). Between baseline and week 48, there were significant increases in total cholesterol, LDL cholesterol and triglycerides, and small but significant elevations in liver enzymes. This 1-year pilot study suggests that CsA dose reduction of ca. 40% after initiation of everolimus was associated with a decrease in cGFR, however, based on the prespecified criteria stable renal function was attained.

Allogeneic hematopoietic stem-cell transplantation for sickle cell disease

BACKGROUND

Myeloablative allogeneic hematopoietic stem-cell transplantation is curative in children with sickle cell disease, but in adults the procedure is unduly toxic. Graft rejection and graft-versus-host disease (GVHD) are additional barriers to its success. We performed nonmyeloablative stem-cell transplantation in adults with sickle cell disease.

METHODS

Ten adults (age range, 16 to 45 years) with severe sickle cell disease underwent nonmyeloablative transplantation with CD34+ peripheral-blood stem cells, mobilized by granulocyte colony-stimulating factor (G-CSF), which were obtained from HLA-matched siblings. The patients received 300 cGy of total-body irradiation plus alemtuzumab before transplantation, and sirolimus was administered afterward.

RESULTS

All 10 patients were alive at a median follow-up of 30 months after transplantation (range, 15 to 54). Nine patients had long-term, stable donor lymphohematopoietic engraftment at levels that sufficed to reverse the sickle cell disease phenotype. Mean (+/-SE) donor-recipient chimerism for T cells (CD3+) and myeloid cells (CD14+15+) was 53.3+/-8.6% and 83.3+/-10.3%, respectively, in the nine patients whose grafts were successful. Hemoglobin values before transplantation and at the last follow-up assessment were 9.0+/-0.3 and 12.6+/-0.5 g per deciliter, respectively. Serious adverse events included the narcotic-withdrawal syndrome and sirolimus-associated pneumonitis and arthralgia. Neither acute nor chronic GVHD developed in any patient.

CONCLUSIONS

A protocol for nonmyeloablative allogeneic hematopoietic stem-cell transplantation that includes total-body irradiation and treatment with alemtuzumab and sirolimus can achieve stable, mixed donor-recipient chimerism and reverse the sickle cell phenotype. (ClinicalTrials.gov number, NCT00061568.)

Analysis of USRDS: incidence and risk factors for Pneumocystis jiroveci pneumonia

BACKGROUND

To investigate the effect of modern immunosuppression on the incidence, risk factors, morbidity, and mortality of Pneumocystis pneumonia (PCP) in recipients of kidney transplants.

METHODS

We conducted a retrospective cohort study of 32,757 Medicare primary transplant recipients in the United States Renal Data System from January 1, 2000 through July 31, 2004. PCP infection was defined by Medicare claims using International Classification of Disease, 9th Revision codes. The incidence of PCP infections, graft loss, and death were measured.

RESULTS

There were a total of 142 cases (cumulative incidence 0.4%) of PCP after kidney transplantation during the study period. By using multivariate analysis with Cox regression, expanded criteria donor, donation after cardiac death, and earlier year of transplant were associated with development of PCP disease. Induction immunosuppression and acute rejections were not associated with risk for PCP infections. However, based on adjusted hazard ratio (AHR), maintenance immunosuppression regimens containing the combination of tacrolimus and sirolimus (AHR 3.60, confidence interval [CI] 2.03-6.39), Neoral and mycophenolate mofetil (AHR 2.09, CI 1.31-3.31), and sirolimus and mycophenolate mofetil (AHR 2.77, CI 1.40-5.47), were associated with development of PCP. As a time dependent variable, PCP was associated with an increased risk of both graft loss and death.

CONCLUSION

PCP infections are rare in the modern era of prophylaxis; however, these infections are a serious risk factor for graft loss and patient death, in particular, in patients who are on sirolimus as part of the immunosuppressive regimen. The median time to development of PCP after transplant was 0.80+/-0.95 years, suggesting a longer period of PCP prophylaxis.

The use of everolimus in renal-transplant patients

Despite advances in immunosuppressive therapy, long-term renal-transplantation outcomes have not significantly improved over the last decade. The nephrotoxicity of calcineurin inhibitors (CNIs) is an important cause of chronic allograft nephropathy (CAN), the major driver of long-term graft loss. Everolimus is a proliferation signal inhibitor with a mechanism of action that is distinct from CNIs. The efficacy and tolerability of everolimus in renal-transplant recipients have been established in a wide range of clinical trials. Importantly, synergism between everolimus and the CNI cyclosporine (CsA) permits CsA dose reduction, enabling nephrotoxicity to be minimized without compromising efficacy. Currently, everolimus is being investigated in regimens where reduced exposure CNIs are used from the initial post-transplant period to improve renal function and prevent CAN. By inhibiting the proliferation of smooth muscle cells, everolimus may itself delay the progression or development of CAN. Although everolimus is associated with specific side effects, these can generally be managed. By targeting the main causes of short- and long-term graft loss, everolimus has a key role to play in renal transplantation, which is being explored further in a number of ongoing Phase III–IV trials.

Calcineurin inhibitor sparing in renal transplantation

Although calcineurin inhibitors (CNIs) are effective at preventing acute rejection, their long-term use is associated with nephrotoxicity that may compromise long-term renal allograft survival. Consequently, there is considerable interest in identifying immunosuppressive regimens that permit reduced exposure to CNIs while maintaining adequate immunosuppression. Introducing such strategies early after transplantation may mean that the development of CNI-associated nephrotoxicity could be minimized or prevented. Several CNI-sparing regimens have shown at least comparable efficacy with standard-dose CNI regimens. In particular, a regimen of mycophenolate mofetil (MMF), corticosteroids, interleukin-2 receptor antagonist induction, and low-dose tacrolimus from the time of transplantation provided superior renal function and a lower acute rejection rate than the same regimen but with low-dose cyclosporine or low-dose sirolimus, or standard-dose cyclosporine, MMF, and corticosteroids. The use of low-dose cyclosporine does not seem to eliminate nephrotoxicity in de novo renal transplant recipients. The early withdrawal of CNIs from MMF-based regimens generally improves renal function but has been associated with an increased risk of acute rejection, in particular when the levels of mycophenolic acid were not adjusted to maintain the same total level of immunosuppression. Research aiming to achieve the "best" balance of efficacy and toxicity of available immunosuppressive regimens continues.

Sirolimus is associated with new-onset diabetes in kidney transplant recipients

New-onset diabetes (NOD) is associated with transplant failure. A few single-center studies have suggested that sirolimus is associated with NOD, but this is not well established. With the use of data from the United States Renal Data System, this study evaluated the association between sirolimus use at the time of transplantation and NOD among 20,124 adult recipients of a first kidney transplant without diabetes. Compared with patients treated with cyclosporine and either mycophenolate mofetil orazathioprine, sirolimus-treated patients were at increased risk for NOD, whether it was used in combination with cyclosporine (adjusted hazard ratio [HR] 1.61; 95% confidence interval [CI] 1.36 to 1.90),tacrolimus (adjusted HR 1.66; 95% CI 1.42 to 1.93), or an antimetabolite (mycophenolate mofetil orazathioprine; adjusted HR 1.36; 95% CI 1.09 to 1.69). Similar results were obtained in a subgroup analysis that included the 16,861 patients who did not have their immunosuppressive regimen changed throughout the first posttransplantation year. In conclusion, sirolimus is independently associated with NOD. Given the negative impact of NOD on posttransplantation outcomes, these findings should be confirmed in prospective studies or in meta-analyses of existing trials that involved sirolimus.

Early, abrupt conversion of de novo renal transplant patients from cyclosporine to everolimus: results of a pilot study

In a single-center study, 20 kidney transplant patients without prior rejection were abruptly converted from cyclosporine to everolimus at seven wk post-transplant. All patients received basiliximab induction with maintenance enteric-coated mycophenolate sodium and corticosteroids. Biopsy-proven acute rejection had occurred in three of 20 patients (15.0%) by the end of week seven post-conversion. All episodes were mild and reversible, with subsequent recovery of renal function. Calculated glomerular filtration rate (GFR) improved significantly (51 +/- 11 mL/min at time of conversion, 58 +/- 12 mL/min at week seven post-conversion, 57 +/- 17 mL/min at month six post-conversion; p = 0.001). No patient developed proteinuria in the nephrotic range. Twenty-two adverse events were reported in 10 patients, three of which had a suspected relationship to everolimus. Mean leukocyte and platelet count decreased significantly, and triglyceride level increased. This study suggests that kidney transplant patients without prior rejection can be converted abruptly from cyclosporine to everolimus at seven wk post-transplant, resulting in significantly improved renal function with no apparent increase, in risk of rejection and good tolerability.