An evaluation of sirolimus in renal transplantation

Polymorphisms in the CYP3A5 gene significantly affect the pharmacokinetics of sirolimus after kidney transplantation

Aim: Sirolimus (SIR) is an immunosuppressant with limitations, including a narrow treatment window, multiple adverse reactions and large differences within and among individuals. Objective: The correlation between numerous SNPs and SIR in terms of trough concentration in the early stage after kidney transplantation was analyzed. Materials & methods: A retrospective cohort study involving 69 kidney transplantation recipients was designed. Blood samples were collected to extract total DNAs, and trough SIR concentrations were measured. Logistic regression was used to analyze the association between SNPs and SIR trough concentrations. Results: At 7 days, 1 month and 3 months, the mean SIR trough concentration of patients in the CYP3A5 rs4646453-CC group was significantly higher than that in the CYP3A5 rs4646453-AA and CYP3A5 rs4646453-CA groups (p < 0.001) and CYP3A5 rs15524-AA group was significantly higher than that in the CYP3A5 rs15524-AG and CYP3A5 rs15524-GG groups (p < 0.001). Conclusion: Our study indicated that both CYP3A5 rs4646453 and CYP3A5 rs15524 had a certain influence on SIR trough concentration at 7 days, 1 month and 3 months.

ODAE: Ontology-based systematic representation and analysis of drug adverse events and its usage in study of adverse events given different patient age and disease conditions

Background

Drug adverse events (AEs), or called adverse drug events (ADEs), are ranked one of the leading causes of mortality. The Ontology of Adverse Events (OAE) has been widely used for adverse event AE representation, standardization, and analysis. OAE-based ADE-specific ontologies, including ODNAE for drug-associated neuropathy-inducing AEs and OCVDAE for cardiovascular drug AEs, have also been developed and used. However, these ADE-specific ontologies do not consider the effects of other factors (e.g., age and drug-treated disease) on the outcomes of ADEs. With more ontological studies of ADEs, it is also critical to develop a general purpose ontology for representing ADEs for various types of drugs.

Results

Our survey of FDA drug package insert documents and other resources for 224 neuropathy-inducing drugs discovered that many drugs (e.g., sirolimus and linezolid) cause different AEs given patients’ age or the diseases treated by the drugs. To logically represent the complex relations among drug, drug ingredient and mechanism of action, AE, age, disease, and other related factors, an ontology design pattern was developed and applied to generate a community-driven open-source Ontology of Drug Adverse Events (ODAE). The ODAE development follows the OBO Foundry ontology development principles (e.g., openness and collaboration). Built on a generalizable ODAE design pattern and extending the OAE and NDF-RT ontology, ODAE has represented various AEs associated with the over 200 neuropathy-inducing drugs given different age and disease conditions. ODAE is now deposited in the Ontobee for browsing and queries. As a demonstration of usage, a SPARQL query of the ODAE knowledge base was developed to identify all the drugs having the mechanisms of ion channel interactions, the diseases treated with the drugs, and AEs after the treatment in adult patients. AE-specific drug class effects were also explored using ODAE and SPARQL.

Conclusion

ODAE provides a general representation of ADEs given different conditions and can be used for querying scientific questions. ODAE is also a robust knowledge base and platform for semantic and logic representation and study of ADEs of more drugs in the future.

Electronic supplementary material

The online version of this article (10.1186/s12859-019-2729-1) contains supplementary material, which is available to authorized users.

European Association of Urology Guidelines on Renal Transplantation: Update 2018

CONTEXT

The European Association of Urology (EAU) panel on renal transplantation (RT) has released an updated version of the RT guidelines.

OBJECTIVE

To present the 2018 EAU guidelines on RT.

EVIDENCE ACQUISITION

A broad and comprehensive scoping exercise was performed, encompassing all areas of RT guidelines published between January 1, 2007, and May 31, 2016. Databases covered by the search included Medline, Embase, and the Cochrane Libraries. Previous guidelines were updated, and levels of evidence and grades of recommendation were assigned.

EVIDENCE SYNTHESIS

It is strongly recommended to offer pure or hand-assisted laparoscopic/retroperitoneoscopic surgery as the preferential technique for living donor nephrectomy. Decisions on the acceptance of a donor organ should not be based on histological findings alone since this might lead to an unnecessarily high rate of discarded grafts. For ureterovesical anastomosis, a Lich-Gregoir-like extravesical technique protected by a ureteral stent is the preferred technique for minimisation of urinary tract complications. It is also strongly recommended to perform initial rejection prophylaxis with a combination therapy comprising a calcineurin inhibitor (preferably tacrolimus), mycophenolate, steroids, and an induction agent (either basiliximab or anti-thymocyte globulin). The long version of the guidelines is available at the EAU website (http://uroweb.org/guidelines).

CONCLUSIONS

These abridged EAU guidelines present updated information on the clinical and surgical management of RT for incorporation into clinical practice.

PATIENT SUMMARY

The European Association of Urology has released the renal transplantation guidelines. The implementation of minimally invasive surgery for organ retrieval and the latest evidence on transplant surgery as well as on immunosuppressive regimens are key factors for minimisation of rejection and achievement of long-term graft survival.

Evaluation of electrochemiluminescence immunoassays for immunosuppressive drugs on the Roche cobas e411 analyzer

Background:  Therapeutic drug monitoring of immunosuppressant drugs are used to monitor drug efficacy and toxicity and to prevent organ transplant rejection. This study evaluates the analytical performance of semi-automated electrochemiluminescence immunoassays (ECLIA) for cyclosporine (CSA), tacrolimus (TAC) and sirolimus (SRL) on the Roche cobas e 411 analyzer at a major transplant hospital to assess method suitability and limitations.

Methods: Residual whole blood samples from patients undergoing immunosuppressant therapy were used for evaluation. Imprecision, linearity, functional sensitivity, method comparisons and lot-to-lot comparisons were assessed.

Results: Total imprecision ranged from 3.3 to 7.1% for CSA, 3.9 to 9.4% for TAC, and 4.6 to 8.2% for SRL. Linearity was verified from 30.0 to 960.9 μg/L for CSA, from 1.1 to 27.1 μg/L for TAC, and from 0.5 to 32.3 µg/L for SRL. The functional sensitivity met the manufacturer’s claims and was determined to be <6.5 μg/L for CSA, 1.1 μg/L for TAC, and <0.1 µg/L for SRL (CV≤20%). Deming regression analysis of method comparisons with the ARCHITECT immunoassay yielded slopes of 0.917 (95%CI: 0.885-0.949) and r of 0.985 for CSA, 0.938 (95%CI: 0.895-0.981) and r of 0.974 for TAC, and 0.842 (0.810-1.110) and r of 0.982 for SRL. Deming regression analysis of comparisons with the LC–MS/MS method yielded slopes of 1.331 (95%CI: 1.167-1.496) and r of 0.969 for CSA, 0.924 (95%CI: 0.843-1.005) and r of 0.984 for TAC, and 0.971 (95%CI: 0.913-1.030) and r of 0.993 for SRL.

Conclusions: The cobas e 411 ECLIA for CSA, TAC, and SRL have acceptable precision, linearity, and functional sensitivity. The method comparisons correlated well with the ARCHITECT immunoassay and LC–MS/MS and is fit for therapeutic drug monitoring

Experience with belatacept rescue therapy in kidney transplant recipients

In kidney transplant recipients with chronic graft dysfunction, long-term immunosuppression with calcineurin inhibitors (CNIs) or mTOR inhibitors (mTORi) can be challenging due to adverse effects, such as nephrotoxicity and proteinuria. Seventy-nine kidney transplant recipients treated with CNI-based or mTORi-based maintenance immunosuppression who had CNI-induced nephrotoxicity or severe adverse events were switched to belatacept. Mean time from transplantation to belatacept conversion was 69.0 months. Mean estimated glomerular filtration rate (eGFR) ± standard deviation at baseline was 26.1 ± 15.0 ml/min/1.73 m² , increasing to 34.0 ± 15.2 ml/min/1.73 m² at 12 months postconversion (P < 0.0005). Renal function improvements were also seen in patients with low eGFR (<25 ml/min/1.73 m² ) or high proteinuria (>500 mg/l) at conversion. The Kaplan-Meier estimates for patient and graft survival at 12 months were 95.0% and 85.6%, respectively. The discontinuation rate due to adverse events was 7.9%. One case of post-transplant lymphoproliferative disorder occurred at 17 months postconversion. For comparison, a historical control group of 41 patients converted to mTORi-based immunosuppression because of biopsy-confirmed CNI-induced toxicity was examined; eGFR increased from 27.6 ± 7.2 ml/min/1.73 m² at baseline to 31.1 ± 11.9 ml/min/1.73 m² at 12 months (P = 0.018). Belatacept-based immunosuppression may be an alternative regimen for kidney transplant recipients with CNI- or mTORi-induced toxicity.

Roles of mTOR complexes in the kidney: implications for renal disease and transplantation

The mTOR pathway has a central role in the regulation of cell metabolism, growth and proliferation. Studies involving selective gene targeting of mTOR complexes (mTORC1 and mTORC2) in renal cell populations and/or pharmacologic mTOR inhibition have revealed important roles of mTOR in podocyte homeostasis and tubular transport. Important advances have also been made in understanding the role of mTOR in renal injury, polycystic kidney disease and glomerular diseases, including diabetic nephropathy. Novel insights into the roles of mTORC1 and mTORC2 in the regulation of immune cell homeostasis and function are helping to improve understanding of the complex effects of mTOR targeting on immune responses, including those that impact both de novo renal disease and renal allograft outcomes. Extensive experience in clinical renal transplantation has resulted in successful conversion of patients from calcineurin inhibitors to mTOR inhibitors at various times post-transplantation, with excellent long-term graft function. Widespread use of this practice has, however, been limited owing to mTOR-inhibitor- related toxicities. Unique attributes of mTOR inhibitors include reduced rates of squamous cell carcinoma and cytomegalovirus infection compared to other regimens. As understanding of the mechanisms by which mTORC1 and mTORC2 drive the pathogenesis of renal disease progresses, clinical studies of mTOR pathway targeting will enable testing of evolving hypotheses.

New perspectives on mTOR inhibitors (rapamycin, rapalogs and TORKinibs) in transplantation

The macrolide rapamycin and its analogues (rapalogs) constitute the first generation of mammalian target of rapamycin (mTOR) inhibitors. Since the introduction of rapamycin as an immunosuppressant, there has been extensive progress in understanding its complex mechanisms of action. New insights into the function of mTOR in different immune cell types, vascular endothelial cells and neoplastic cells have opened new opportunities and challenges regarding mTOR as a pharmacological target. Currently, the two known mTOR complexes, mTOR complex (mTORC) 1 and mTORC2, are the subject of intense investigation, and the introduction of second-generation dual mTORC kinase inhibitors (TORKinibs) and gene knockout mice is helping to uncover the distinct roles of these complexes in different cell types. While the pharmacological profiling of rapalogs is advanced, much less is known about the properties of TORKinibs. A potential benefit of mTOR inhibition in transplantation is improved protection against transplant-associated viral infections compared with standard calcineurin inhibitor-based immunosuppression. Preclinical and clinical data also underscore the potentially favourable antitumour effects of mTOR inhibitors in regard to transplant-associated malignancies and as a novel treatment option for various other cancers. Many aspects of the mechanisms of action of mTOR inhibitors and their clinical implications remain unknown. In this brief review we discuss new findings and perspectives of mTOR inhibitors in transplantation.

Drug target molecules to guide immunosuppression

The individual and interindividual variability of response to immunosuppressants combined with the prevailing concept of lifelong immunosuppression following any organ transplantation motivates the search for methods to further individualize such therapy. Traditional therapeutic drug monitoring, adapting dose according to concentrations in blood, targets the pharmacokinetic variability. It has been increasingly recognized, however, that there is also a considerable variability in the response to a given concentration. Attempts to overcome this variability in response include the efforts to identify relevant targets and methods for pharmacodynamic monitoring. For several of the currently used immunosuppressants there is experimental data suggesting markers that are relevant as indicators for individual monitoring of the effects of these drugs. There are also some clinical data to support these approaches; however what is generally missing, are studies that in a prospective manner demonstrates the benefits and effects on outcome. The monitoring of antithymocyte globulin by lymphocyte subset counts is actually the only well established example of pharmacodynamic monitoring. For drugs such as MPA and mTOR inhibitors, there are candidates such as IMPDH activity expression and p70SK6 phosphorylation status, respectively. The monitoring of CNIs using assays for NFAT RGE, either alone or combined with concentration measurements, is already well documented. Even here, some further investigations relating to the categories of organ transplant, combination of immunosuppressants etc. will be requested. Although some further standardization of the assay is warranted and there is a need for specific recommendations of target levels and how to adjust dose, the NFAT RGE approach to pharmacodynamic monitoring of CNIs may be close to implementation in clinical routine.

Microsphere-Based Rapamycin Delivery, Systemic Versus Local Administration in a Rat Model of Renal Ischemia/Reperfusion Injury

Purpose

The increasing prevalence and treatment costs of kidney diseases call for innovative therapeutic strategies that prevent disease progression at an early stage. We studied a novel method of subcapsular injection of monodisperse microspheres, to use as a local delivery system of drugs to the kidney.

Methods

We generated placebo- and rapamycin monodisperse microspheres to investigate subcapsular delivery of drugs. Using a rat model of acute kidney injury, subcapsular injection of placebo and rapamycin monodisperse microspheres (monospheres) was compared to subcutaneous injection, mimicking systemic administration.

Results

We did not find any adverse effects related to the delivery method. Irrespective of the injection site, a similar low dose of rapamycin was present in the circulation. However, only local intrarenal delivery of rapamycin from monospheres led to decreased macrophage infiltration and a significantly lower amount of myofibroblasts in the kidney, where systemic administration did not. Local delivery of rapamycin did cause a transient increase in the deposition of collagen I, but not of collagen III.

Conclusions

We conclude that therapeutic effects can be increased when rapamycin is delivered subcapsularly by monospheres, which, combined with low systemic concentrations, may lead to an effective intrarenal delivery method.

Electronic supplementary material

The online version of this article (doi:10.1007/s11095-015-1700-8) contains supplementary material, which is available to authorized users.

The need for minimization strategies: current problems of immunosuppression

New immunosuppressants and the better use of immunosuppressant combination therapy have led to significant improvements in renal allograft outcomes over the last decades. Yet, despite dramatic reduction in rejection rates and improvement in 1-year graft survival, long-term graft attrition rates remained rather constant. Current immunosuppressant combinations are frequently leading to overimmunosuppression and are increasing cardiovascular risk. Importantly, calcineurin inhibitors are nephrotoxic, contribute to cardiovascular risk and chronic allograft dysfunction. Furthermore, immunosuppressant-associated toxicities aggravate immune-mediated nephron injury and side effects lead to nonadherence, an identified important reason for late acute and chronic antibody-mediated rejections. The frequent development of a chronic humoral response indicates rather insufficient immunosuppression of current combinations than simple under-immunosuppression. While there is no evidence that increasing immunosuppressive doses will improve outcomes or reduce de novo HLA-antibody formation, there is clear evidence that adequate minimization strategies will reduce side effect burden. Because of low rejection risk, but frequent side effects, drug minimization is particularly relevant for the many maintenance patients. In summary, new therapeutic strategies need to be developed from adequately powered clinical trials for reduction of the many side effects of immunosuppressants. Such evidence-based and time-dependent immunosuppressive minimization strategies are needed to achieve better long-term outcomes in the future.

Renal function to 5 years after late conversion of kidney transplant patients to everolimus: a randomized trial

BACKGROUND

Few trials have investigated late preemptive conversion of kidney transplant patients from a calcineurin inhibitor (CNI) to an mTOR inhibitor.

METHODS

In an open-label, 12-month, prospective, randomized, parallel-group study, maintenance kidney transplant patients (>6 months post-transplant) either switched from CNI to everolimus or continued their current CNI regimen. Patients who completed the core study were followed to 5 years post-randomization.

RESULTS

Of 93 randomized patients, 78 completed the core study and 67 attended the final 60-month study visit. Mean time post-transplant at baseline was 82.6 months and 70.5 months in the everolimus and CNI groups, respectively. At month 60, adjusted mean eGFR (Nankivell) was 63.0 (95% CI 57.8, 68.2) mL/min/1.73 m(2) in the everolimus group versus 57.9 (95% CI 52.6, 63.1) mL/min/1.73 m(2) in the CNI group, a difference of 5.1 (95% CI -0.6, 10.8) mL/min/1.73 m(2) (p = 0.076). Among patients who remained on randomized study drug at month 60, mean eGFR (Nankivell) was 71.6 (95% CI 64.2, 79.0) mL/min/1.73 m(2) in everolimus-treated patients (n = 21) versus 60.6 (95% CI 55.1, 66.1) mL/min/1.73 m(2) in CNI-treated patients (n = 29) (mean difference 11.0; 95% CI 3.6, 18.5 mL/min/1.73 m(2); p = 0.005). No cases of BPAR occurred from randomization to month 60 in either group. Graft loss occurred in three everolimus-treated patients and one CNI-treated patient. No unexpected safety concerns were observed in either group.

CONCLUSION

Late preemptive conversion of maintenance kidney transplant patients from CNI to everolimus may be associated with improved long-term renal function and preserves immunosuppressive efficacy. Patient numbers were low, but these findings merit further investigation.

Emerging therapeutic strategies for eosinophilic esophagitis

OPINION STATEMENT

Eosinophilic esophagitis (EoE) is recognized as an increasingly common cause of chronic and recurrent esophageal symptoms that significantly impact quality of life and may occasionally result in severe complications in both pediatric and adult patients. The disease is triggered and maintained by exposure to food antigens in most patients, with an additional role proposed for airborne allergens. Different diet-based approaches focused on restricting potentially offending foods have proven to be effective long-term therapies for EoE. Dietary therapy is thus an attractive, yet challenging treatment option that should be considered for all pediatric and adult EoE patients. However, limitations related to food restriction, patient willingness to undergo repeated endoscopies and biopsies, and the variable results of allergy testing imply that dietary management is for the most part currently restricted to highly motivated healthcare providers treating highly motivated patients reluctant to utilize drug-based therapy on a chronic basis. Pharmacological therapies for EoE mainly comprise swallowed topical steroids, especially fluticasone propionate and budesonide, which were originally developed to treat bronchial asthma and are now extensively used "off label" in EoE patients. In fact, topical steroids currently constitute the prevailing therapeutic option and will probably continue to do so in the near future; indeed, several randomized clinical trials are currently underway to test these drugs for approval as the first pharmacological agents for EoE patients. Immunomodulators and several anti-allergic agents must be further assessed as therapeutic alternatives for refractory cases or patients with complications. Endoscopic dilation represents the third pillar in the therapeutic management of EoE patients, since they frequently present reductions in the esophageal caliber as a result of collagen deposition and a progressive fibrous remodeling process promoted by chronic eosinophilic infiltration. Dilation provides at least temporary symptom relief with similar complication rates to esophageal strictures from a different origin. However, although repeated endoscopic dilation has sometimes been used as the sole therapy for EoE, it best constitutes an adjuvant therapy along with dietary or pharmacological-based interventions, especially since dilation has no effect on the underlying esophageal inflammation. Current therapeutic management of EoE varies widely, with physician experience being a major explanatory factor. New evidence from ongoing research on EoE should thus seek to define a common treatment algorithm to optimize EoE patient management.

[Allogeneic kidney transplantation. Preoperative, perioperative and postoperative management]

Allogeneic renal transplantation is the best treatment for many patients with chronic renal failure and end-stage kidney disease. Especially the health-related quality of life markedly improves after renal transplantation and the side effects of dialysis treatment as well as the progression of organ and tissue deterioration related to renal failure which are not treated effectively by dialysis are greatly reduced. To achieve good results of renal transplantation, however, the best possible preoperative as well as perioperative and postoperative conditions have to be established and patients on waiting lists need to be well prepared. Interdisciplinary patient care is needed before and after renal transplantation in order to achieve durable and long-term success of renal transplantation.

Severe rhabdomyolysis associated with concurrent use of simvastatin and sirolimus after cisplatin-based chemotherapy in a kidney transplant recipient

OBJECTIVES

Cardiovascular disease is the most common cause of sickness and death for long-term kidney transplant recipients, and dyslipidemia is an important risk factor for developing cardiovascular disease. Lipid-lowering strategies, with the use of statins, have been shown to reduce the cardiovascular risks related to dyslipidemia, but concomitant use of 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors and immunosuppressive agents may increase the risk of rhabdomyolysis owing to a drug-drug interaction. We report a case of simvastatin-induced rhabdomyolysis and acute kidney injury triggered by addition of sirolimus and cisplatin-based chemotherapy to a kidney transplant recipient who had previously tolerated chronic statin therapy.