Mycophenolate mofetil and sirolimus as calcineurin inhibitor-free immunosuppression for late cardiac-transplant recipients with chronic renal failure

Sirolimus potentiated angioedema: A case report and review of the literature

Introduction

In the realm of organ transplantation, particularly heart transplantation, angioedema presents a significant challenge. This clinical condition ranges from minor facial edema to life-threatening swelling of vital structures. Its multifactorial etiology involves various factors and mechanisms, including C1 esterase inhibitor deficiency, food allergen hypersensitivity, and adverse drug reactions, notably involving angiotensin-converting enzyme (ACE) inhibitors and mechanistic target of rapamycin inhibitors (mTOR-Is). We present a rare case of sirolimus potentiated angioedema in a patient with long-standing ACE inhibitor therapy.

Case

A 52-year-old male with a history of heart transplant developed severe upper and lower lip edema. The patient had been on Lisinopril without any adverse events. However, sirolimus was recently added to his drug regimen. Sirolimus potentiated angioedema was suspected.

Intervention

Intravenous methylprednisolone, famotidine, and diphenhydramine were initiated, and both lisinopril and sirolimus were discontinued. The patient showed improvement and was discharged with oral antihistamines.

Lessons

Transplant physicians should be aware of the life-threatening interaction between ACE inhibitors and mTOR-Is like sirolimus. Consideration should be given to switching from an ACE inhibitor to an angiotensin-receptor blocker when initiating patients on mTOR-Is.

Thrombotic events with proliferation signal inhibitor‒based immunosuppression in cardiac transplantation

BACKGROUND

Some literature exists potentially linking proliferation signal inhibitors (PSIs) to venous thromboembolism (VTE). We sought to determine the impact of PSIs on development of VTE in heart transplant (HT) patients while controlling for other risk factors.

METHODS

The incidence and predisposing factors of VTE were analyzed in this retrospective review of patients >18 years who underwent HT January 2000 to October 2016. Re-transplants, multiorgan transplants, or patients that expired within 30 days post-HT were excluded. VTE incidence rates are reported as number of events per 100 person-years. Cox proportional hazards models were used to assess the relationship between PSI exposure (time-varying covariate) and VTE.

RESULTS

Of 561 HT recipients, 112 received PSIs, started a median of 1.5 years post-HT. There were 102 total VTE events: 78 in PSI-naive patients during 2,547 patient-years (3.0 events per 100 person-years) vs 24 in PSI-exposed patients during 544 patient-years (4.4 events per 100 person-years). Cox proportional hazards models with PSI exposure as a time-varying covariate indicated the increased risk was statistically significant (unadjusted hazard ratio [HR] 2.14, 95% confidence interval [CI] 1.31 to 3.49, p = 0.002). A VTE history was significantly associated with increased risk of VTE post-HT (HR 1.58, 95% CI 1.07 to 2.35, p = 0.022); however, the risk remained significant when adjusting for potential confounders, including previous VTE (HR 2.0, 95% CI 1.18 to 3.38, p = 0.010).

CONCLUSIONS

Exposure to PSIs is associated with a significant increase in risk for VTE even when controlling for other risk factors. When considering the use of PSI-based immunosuppression after HT, the risk of VTE over time should be weighed against the potential benefit.

Role of FK778 Alone or in Combination with Tacrolimus or mTOR Inhibitors as an Immunomodulator of Immunofunctions: In Vitro Evaluation of T Cell Proliferation and the Expression of Lymphocyte Surface Antigens

We evaluated the in vitro capacity of FK778, alone or in combination with other immunosuppressive drugs: Tacrolimus (TRL); Sirolimus (SRL), Everolimus (EVL), to inhibit clonal expansion of T-lymphocytes and expression of lymphocyte-activation surface antigens; secondly, we compared the immunosuppressive potential of FK778 combined with TRL, SRL and EVL with the same combinations using Mycophenolic acid (MPA) as antimetabolite. Lymphocyte proliferation was assessed by 3H-Thymidine incorporation, in whole blood cultures stimulated with ConA. The effect of FK778 on alloresponse was evaluated by MLC and the expression of lymphocyte surface antigens by cytometry. FK778, TRL, SRL and EVL showed a high in vitro capacity to inhibit lymphocyte proliferation in a concentration-dependent way. Combinations of FK778 with TRL, SRL, or EVL presented an additive effect, especially FK778+TRL. Similar inhibition capacity of the clonal expansion was observed, when FK778 was combined with TRL, SRL or EVL, respecting the same combinations but using MPA instead of FK778. In addition, FK778 inhibited the expression of lymphocyte surface antigens involved in activation, co-stimulatory and apoptosis signals. In conclusion, FK778 inhibits the proliferative response induced by mitogeneic and allogeneic stimuli and the expression of surface antigens. Combinations of FK778 with TRL or mTOR inhibitors presented an additive effect and their action on T cell proliferation was similar to that of combinations with MPA. Since FK778, TRL and mTOR inhibitors present different action mechanisms and involve different cellular targets, these combinations may help prevent episodes of allorejection in organ transplants. FK778 and mTOR inhibitors may represent an alternative treatment for patients with renal failure.

Effects of mTOR and calcineurin inhibitors combined therapy in Epstein-Barr virus positive and negative Burkitt lymphoma cells

Post-transplant lymphoproliferative disorder is a severe complication in solid organ transplant recipients, which is highly associated with Epstein-Barr virus infection in pediatric patients and occasionally presents as Burkitt- or Burkitt-like lymphoma. The mammalian target of rapamycin (mTOR) pathway has been described as a possible antitumor target whose inhibition may influence lymphoma development and proliferation after pediatric transplantation. We treated Epstein-Barr virus positive (Raji and Daudi) and negative (Ramos) human Burkitt lymphoma derived cells with mTOR inhibitor everolimus alone and in combination with clinically relevant immunosuppressive calcineurin inhibitors (tacrolimus or cyclosporin A). Cell proliferation, toxicity, and mitochondrial metabolic activity were analyzed. The effect on mTOR Complex 1 downstream targets p70 S6 kinase, eukaryotic initiation factor 4G, and S6 ribosomal protein activation was also investigated. We observed that treatment with everolimus alone significantly decreased Burkitt lymphoma cell proliferation and mitochondrial metabolic activity. Everolimus in combination with cyclosporin A had a stronger suppressive effect in Epstein-Barr virus negative but not in Epstein-Barr virus positive cells. In contrast, tacrolimus completely abolished the everolimus-mediated suppressive effects. Moreover, we showed a significant decrease in activation of mTOR Complex 1 downstream targets after treatment with everolimus that was attenuated when combined with tacrolimus, but not with cyclosporin A. For the first time we showed the competitive effect between everolimus and tacrolimus when used as combination therapy on Burkitt lymphoma derived cells. Thus, according to our in vitro data, the combination of calcineurin inhibitor cyclosporin A with everolimus is preferred to the combination of tacrolimus and everolimus.

Sirolimus conversion after heart transplant: risk factors for acute rejection and predictors of renal function response

In a randomized, comparative study of cardiac transplant patients with mild-to-moderate renal insufficiency, conversion from calcineurin inhibitors (CNIs) to sirolimus improved renal function at 1 year versus continuing CNIs, with an attendant risk of biopsy-confirmed acute rejection (BCAR). Post hoc analyses were conducted to identify predictors of BCAR and GFR improvement associated with conversion. Patients with proteinuria >500 mg/day were excluded. Univariate and multivariate regression analyses tested 13 parameters for BCAR and six for GFR improvement. In 57 sirolimus-treated patients, mean daily mycophenolate mofetil (MMF) dose was lower in those with versus without BCAR (1000 vs. 1420 mg; p = 0.014). Receiver operating characteristic analysis identified MMF dose ≤1000 mg/day as the optimal cutoff to predict BCAR. Multivariate analysis confirmed low MMF dose (odds ratio: 9.94; p = 0.007) and non-white race (odds ratio: 15.3; p = 0.06) were independently associated with BCAR. GFR improvement was evaluated in intent-to-treat patients (n = 116). Significant interaction was detected between treatment effect and preexisting diabetes status (univariate p = 0.077; multivariate p = 0.022), indicating greater beneficial effect of sirolimus in those without preexisting diabetes. These findings suggest that sirolimus is more effective in improving GFR in patients without preexisting diabetes, and adequate MMF doses are needed for sirolimus conversion.

Tacrolimus with mycophenolate mofetil or sirolimus compared with calcineurin inhibitor-free immunosuppression (sirolimus/mycophenolate mofetil) after heart transplantation: 5-year results

BACKGROUND

Despite improvements in immunosuppressive therapy, the most advantageous combination for cardiac transplant recipients has not been established. This randomized controlled trial was performed to evaluate the efficacy and safety of 3 immunosuppressive protocols.

METHODS

Between 2003 and 2005, 78 de novo cardiac transplant recipients were randomized 2:2:1 to receive steroids and tacrolimus plus mycophenolate mofetil (TAC/MMF; n = 34), TAC and sirolimus (TAC/SRL; n = 29), or SRL and MMF (SRL/MMF) plus anti-thymocyte globulin (ATG; n = 15). Steroids were withdrawn after 6 months.

RESULTS

The 5-year survival was 85.3% for TAC/MMF, 93.1% for TAC/SRL, and 86.7% for SRL/MMF (p = 0.31 for TAC/MMF vs TAC/SIR; p = 0.47 for TAC/MMF vs SIR/MMF and p = 0.86 for TAC/SIR vs SIR/MMF). Despite the use of ATG, patients in the SRL/MMF group revealed numerically fewer freedom from acute rejection episodes: TAC/MMF, 82.4%; TAC/SRL, 85.2%; SRL/MMF, 73.3% (p = 0.33). Mean creatinine at 5 years revealed preservation of renal function in the SRL/MMF vs the TAC/MMF group (p = 0.045): TAC/MMF, 1.70±0.91 mg/dl; TAC/SRL, 1.44±0.65 mg/dl; and SRL/MMF, 1.25±0.46 mg/dl. Freedom from cardiac allograft vasculopathy was improved in the SRL/MMF group (93.3%) compared with TAC/MMF (73.5%) and TAC/SRL (80.8%) groups, reaching no statistical significance. Freedom from cytomegalovirus infection was TAC/MMF, 72.2%; TAC/SRL, 89.7%; and SRL/MMF, 86.7%. There was a trend toward improved freedom from cytomegalovirus infection with TAC/SRL vs TAC/MMF (p = 0.076). More frequent discontinuations of study medication occurred in SRL-based immunosuppression protocols (TAC/SRL vs TAC/MMF, p = 0.034; SRL/MMF vs TAC/MMF, p = 0.003).

CONCLUSIONS

The 3 strategies yield no survival advantage at 5 years, with higher numeric rates of rejection and adverse effects in the calcineurin inhibitor-free arm. A trend was observed in favor of freedom from cardiac allograft vasculopathy and preservation of renal function in the calcineurin inhibitor-free arm. However, the clinical relevance on outcomes is unclear because only few patients were receiving the assigned treatment protocols.

Rejection after conversion to a proliferation signal inhibitor in chronic heart transplantation

We sought to determine the incidence, risk factors, and consequences of acute rejection (AR) after conversion from a calcineurin inhibitor (CNI) to a proliferation signal inhibitor (PSI) in maintenance heart transplantation. Relevant clinical data were retrospectively obtained for 284 long-term heart transplant recipients from nine centers in whom CNIs were replaced with a PSI (sirolimus or everolimus) between October 2001 and March 2009. The rejection rate at one yr was 8.3%, stabilizing to 2% per year thereafter. The incidence rate after conversion (4.9 per 100 patient-years) was significantly higher than that observed on CNI therapy in the pre-conversion period (2.2 per 100 patient-years). By multivariate analysis, rejection risk was associated with a history of late AR prior to PSI conversion, early conversion (<5 yr) after transplantation and age <50 yr at the time of conversion. Use of mycophenolate mofetil was a protective factor. Post-conversion rejection did not significantly influence the evolution of left ventricular ejection fraction, renal function, or mortality during further follow-up. Conversion to a CNI-free immunosuppression based on a PSI results in an increased risk of AR. Awareness of the clinical determinants of post-conversion rejection could help to refine the current PSI conversion strategies.

Randomized controlled trial of sirolimus conversion in cardiac transplant recipients with renal insufficiency

This randomized, comparative, multinational phase 3b/4 study of patients 1-8 years postcardiac transplantation (mean 3.9 years) evaluated the effect of conversion from a calcineurin inhibitor (CNI) to sirolimus on renal function in patients with renal insufficiency. In total, 116 patients on CNI therapy with GFR 40-90 mL/min/1.73 m(2) were randomized (1:1) to sirolimus (n = 57) or CNI (n = 59). Intent-to-treat analysis showed the 1-year adjusted mean change from baseline in creatinine clearance (Cockcroft-Gault) was significantly higher with sirolimus versus CNI treatment (+3.0 vs. -1.4 mL/min/1.73 m(2) , respectively; p = 0.004). By on-therapy analysis, values were +4.7 and -2.1, respectively (p < 0.001). Acute rejection (AR) rates were numerically higher in the sirolimus group; 1 AR with hemodynamic compromise occurred in each group. A significantly higher treatment discontinuation rate due to adverse events (AEs; 33.3% vs. 0%; p < 0.001) occurred in the sirolimus group. Most common treatment-emergent AEs significantly higher in the sirolimus group were diarrhea (28.1%), rash (28.1%) and infection (47.4%). Conversion to sirolimus from CNI therapy improved renal function in cardiac transplant recipients with renal impairment, but was associated with an attendant AR risk and higher discontinuation rate attributable to AEs.

Mammalian target of rapamycin (mTOR) inhibitors: potential uses and a review of haematological adverse effects

Mammalian target of rapamycin (mTOR) inhibitors (mTORis) constitute a relatively new category of immunosuppressive and antineoplastic drugs. These share a unique mechanism of action that is focused on the inhibition of the mTOR. Their clinical applications have recently expanded significantly to cover a wide spectrum of immune and non-immune-mediated disorders, including, apart from solid organ transplantation, various solid organ and haematological malignancies, rheumatological and auto-immune diseases such as rheumatoid arthritis, systemic lupus erythematosus, fibrotic conditions, e.g. pulmonary and hepatic fibrosis, and even metabolic problems such as diabetes mellitus and obesity. The most challenging and frequent adverse effects of the mTORis are the haematological ones, especially anaemia, leukopenia and thrombocytopenia. A unique characteristic of mTORi-induced anaemia is concurrent marked microcytosis. Recently, mechanisms have been proposed to explain the microcytic appearance of this anaemia; these include globin production defect, erythropoietin resistance, chronic inflammation, dysregulation of cellular iron metabolism and hepcidin-mediated iron homeostasis interference. As the differential diagnosis of microcytic anaemia includes pure iron deficiency, functional iron deficiency and haemoglobinopathies, characterization of the anaemia requires significant investigation, time and costs. Therefore, understanding of the likely interaction between mTORis and patients is valuable in clinical practice. Moreover, this could expand the drugs' therapeutic applications to other disorders, and suggest novel targets for further research.

Mammalian target of rapamycin (mTOR) inhibitors: potential uses and a review of haematological adverse effects

Mammalian target of rapamycin (mTOR) inhibitors (mTORis) constitute a relatively new category of immunosuppressive and antineoplastic drugs. These share a unique mechanism of action that is focused on the inhibition of the mTOR. Their clinical applications have recently expanded significantly to cover a wide spectrum of immune and non-immune-mediated disorders, including, apart from solid organ transplantation, various solid organ and haematological malignancies, rheumatological and auto-immune diseases such as rheumatoid arthritis, systemic lupus erythematosus, fibrotic conditions, e.g. pulmonary and hepatic fibrosis, and even metabolic problems such as diabetes mellitus and obesity. The most challenging and frequent adverse effects of the mTORis are the haematological ones, especially anaemia, leukopenia and thrombocytopenia. A unique characteristic of mTORi-induced anaemia is concurrent marked microcytosis. Recently, mechanisms have been proposed to explain the microcytic appearance of this anaemia; these include globin production defect, erythropoietin resistance, chronic inflammation, dysregulation of cellular iron metabolism and hepcidin-mediated iron homeostasis interference. As the differential diagnosis of microcytic anaemia includes pure iron deficiency, functional iron deficiency and haemoglobinopathies, characterization of the anaemia requires significant investigation, time and costs. Therefore, understanding of the likely interaction between mTORis and patients is valuable in clinical practice. Moreover, this could expand the drugs' therapeutic applications to other disorders, and suggest novel targets for further research.

Proliferation signal inhibitors and post-transplant malignancies in heart transplantation: practical clinical management questions

Although malignancy is a major threat to long-term survival of heart transplant (HT) recipients, clear strategies to manage immunosuppression in these patients are lacking. Several lines of evidences support the hypothesis of an anticancer effect of proliferation signal inhibitors (PSIs: mammalian target of rapamycin [mTOR] inhibitors) in HT recipients. This property may arise from PSI's ability to replace immunosuppressive therapies that promote cancer progression, such as calcineurin inhibitors or azathioprine, and/or through their direct biological actions in preventing tumor development and progression. Given the lack of randomized studies specifically exploring these issues in the transplant setting, a collaborative group reviewed current literature and personal clinical experience to reach a consensus aimed to provide practical guidance for the clinical conduct in HT recipients with malignancy, or at high risk of malignancy, with a special focus on advice relevant to potential role of PSIs.

Current outcome of heart transplantation: a 10-year single centre perspective and review

BACKGROUND

Heart transplantation (HTx), the gold standard therapy for advanced heart failure, is limited by donor availability; alternative therapies are now becoming available.

AIM

We examined the outcome of HTx with current immunosuppressive and adjunctive therapy.

DESIGN AND METHODS

We analysed the outcome of 399 consecutive patients who underwent transplantation at our centre (1995-2007). Prior to HTx 23% (98) required inotropic support, 8.5% (34) an intra-aortic balloon pump and 11% (43) a ventricular assist device.

RESULTS

Actuarial patient survival was 86% at 30 days, 79% at 1 year and 62% at 10 years. Survival was similar regardless of the heart failure severity, P=0.22. The cumulative incidence of allograft vasculopathy, Costanzo grade≥2, was 7% at 5 years and 23% by 10 years with an 11% cumulative probability of requiring a percutaneous coronary intervention by 10 years. Allograft function was preserved with a mean±SD left ventricular ejection fraction of 73±7% at 1 year and 74±8% at 10 years. The cumulative incidence of malignancy by 10 years was 27% (skin malignancy 13% and post transplant lymphoproliferative diseases 10%). The cumulative incidence of developing chronic kidney disease (CKD) with an estimated glomerular filtration rate≤45 ml/min/1.73 m2 was 42% at 1 year, 62% at 5 years and 72% at 10 years and of requiring long-term renal replacement therapy was 10.6% at 10 years.

CONCLUSION

HTx provided good medium-term survival for patients with advanced heart failure, independent of its severity. The incidence of allograft vasculopathy was lower than reported previously but malignancy and CKD remain cause for concern.

Clinical recommendations for the use of everolimus in heart transplantation

Proliferation signal inhibitors (PSIs), everolimus (EVL), and sirolimus are a group of immunosuppressor agents indicated for the prevention of acute rejection in adult heart transplant recipients. Proliferation signal inhibitors have a mechanism of action with both immunosuppressive and antiproliferative effects, representing an especially interesting treatment option for the prevention and management of some specific conditions in heart transplant population, such as graft vasculopathy or malignancies. Proliferation signal inhibitors have been observed to work synergistically with calcineurin inhibitors (CNIs). Data from clinical trials and from the growing clinical experience show that when administered concomitantly with CNIs, PSIs allow significant dose reductions of the latter without loss of efficacy, a fact that has been associated with stabilization or significant improvement in renal function in patients with CNI-induced nephrotoxicity. The purpose of this article was to review the current knowledge of the role of PSIs in heart transplantation to provide recommendations for the proper use of EVL in cardiac transplant recipients, including indications, treatment regimens, monitoring, and management of the adverse events.

Everolimus with reduced calcineurin inhibitor in thoracic transplant recipients with renal dysfunction: a multicenter, randomized trial

BACKGROUND

The proliferation signal inhibitor everolimus offers the potential to reduce calcineurin inhibitor (CNI) exposure and alleviate CNI-related nephrotoxicity. Randomized trials in maintenance thoracic transplant patients are lacking.

METHODS

In a 12-month, open-labeled, multicenter study, maintenance thoracic transplant patients (glomerular filtration rate > or =20 mL/min/1.73m and <90 mL/min/1.73 m) >1 year posttransplant were randomized to continue their current CNI-based immunosuppression or start everolimus with predefined CNI exposure reduction.

RESULTS

Two hundred eighty-two patients were randomized (140 everolimus, 142 controls; 190 heart, 92 lung transplants). From baseline to month 12, mean cyclosporine and tacrolimus trough levels in the everolimus cohort decreased by 57% and 56%, respectively. The primary endpoint, mean change in measured glomerular filtration rate from baseline to month 12, was 4.6 mL/min with everolimus and -0.5 mL/min in controls (P<0.0001). Everolimus-treated heart and lung transplant patients in the lowest tertile for time posttransplant exhibited mean increases of 7.8 mL/min and 4.9 mL/min, respectively. Biopsy-proven treated acute rejection occurred in six everolimus and four control heart transplant patients (P=0.54). In total, 138 everolimus patients (98.6%) and 127 control patients (89.4%) experienced one or more adverse event (P=0.002). Serious adverse events occurred in 66 everolimus patients (46.8%) and 44 controls (31.0%) (P=0.02).

CONCLUSION

Introduction of everolimus with CNI reduction offers a significant improvement in renal function in maintenance heart and lung transplant recipients. The greatest benefit is observed in patients with a shorter time since transplantation.

Impact of different long-term maintenance immunosuppressive therapy strategies on patients' outcome after heart transplantation

The introduction of cyclosporine in the early 1980s meant a decisive improvement in post-transplant outcomes for all solid-organ transplants and, in particular, it allowed heart transplantation to emerge as a viable therapeutic option for patients with end-stage cardiac failure. Many factors, including recipient and donor selection, organ preservation and the technical aspects of the transplant itself, influence post-operative outcomes following heart transplantation but the continued need to treat the recipient's immune response plays a key role in determining long-term outcomes. Thereby interactions between immunosuppressive drugs used in different combinations play an important role in patients' outcome. After more than two decades, significant controversy still exists as to the best immunosuppressive regimen for long-term maintenance. During the 1990s and 2000s, newer immunosuppressive medications, specifically, tacrolimus, mycophenolate mofetil, sirolimus, everolimus and the IL-2 receptor blockers (daclizumab and basiliximab), were introduced that allow the clinician several options to try to minimize side effects and maximize the desired therapeutic effects. The side effects involve direct organ toxicity (e.g. renal and hepatic dysfunction), metabolic disturbances, (e.g. diabetes, hyperlipidemia and hypertension), neurotoxicity, and several other significant adverse events, such as cholestasis and myelosuppression. Newer immunosuppressive drugs can impair wound healing, induce lung toxicity and produce various cytopenic states. Steroids continue to plague patients with their well-known side effects. This article reviews the current data on the benefits and risks of the various therapeutic regimens available, which are analyzed under three main themes: calcineurin inhibitor based therapies, calcineurin minimization protocols and calcineurin free regimens.

Pharmacokinetic optimization of immunosuppressive therapy in thoracic transplantation: part II

Part I of this article, which appeared in the previous issue of the Journal, reviewed calcineurin inhibitors--ciclosporin and tacrolimus. In part II, we review the pharmacokinetics and therapeutic drug monitoring of mycophenolate and mammalian target of rapamycin inhibitors--sirolimus and everolimus--in thoracic transplantation, and we provide an overall discussion and suggest various areas for future study.

Usefulness of sirolimus as rescue therapy in heart transplant recipients with renal failure: analysis of the Spanish Multicenter Observational Study (RAPACOR)

BACKGROUND

Chronic renal failure is a common complication of heart transplantation. Sirolimus (SRL) is an immunosuppressive drug that, unlike calcineurin inhibitors (CNIs), is not associated with nephrotoxicity.

METHODS

We collected efficacy and safety data from a Spanish registry of heart transplant recipients who were switched from a CNI to SRL due to renal failure. Patients were included if the serum creatinine level before switching was >1.5 mg/dL and/or the estimated creatinine clearance level was below 50 mL/min.

RESULTS

Ninety-seven patients started SRL due to renal impairment. When SRL was started, CNIs were progressively tapered and in some cases withdrawn. Mean baseline creatinine level was 2.5 mg/dL and mean creatinine clearance level was 39 mL/min. Only 1 episode of acute rejection was observed in a patient receiving SRL plus cyclosporine (CsA) but the eventual allograft function remained stable. Compared with baseline, a significant improvement in renal function was observed at 6 months among patients who stopped CNIs before the third month after SRL was started, although not among those who continued taking CNIs. Upon multivariate analysis, no predictors of response were observed. SRL was withdrawn in 18% of patients due to adverse events.

CONCLUSIONS

Switching to SRL was safe in heart allograft recipients, improving renal function among those previously receiving a CNI. Renal function improves if CNIs are withdrawn soon after starting SRL.

Mycophenolate mofetil and calcineurin-inhibitor reduction: recent progress

Mycophenolate mofetil (MMF) in combination with calcineurin inhibitors (CNIs) has greatly contributed to acute rejection rate reduction. Because of its immunosuppressive potency it was initially thought that MMF would help in reducing/avoiding CNI-related nephrotoxicity. Elective avoidance of CNI in induction and maintenance MMF-based immunosuppression has resulted in an increased risk for acute and chronic rejection. A recent meta-analysis suggests that CNI elimination in patients on MMF with progressive renal dysfunction is associated with a better outcome, although more data are needed to support any recommendation. So far, the more conservative approach involving CNI minimization with MMF has been associated with amelioration of renal function and low risk for rejection, providing an adequate risk/benefit balance. However, MMF with belatacept might pave the way for CNI-free induction and maintenance immunosuppression. Meanwhile, the assessment of immunological risk by new monitoring tools could be a prerequisite to further implement such CNI sparing strategies.

Pharmacokinetic optimization of immunosuppressive therapy in thoracic transplantation: part I

Although immunosuppressive treatments and therapeutic drug monitoring (TDM) have significantly contributed to the increased success of thoracic transplantation, there is currently no consensus on the best immunosuppressive strategies. Maintenance therapy typically consists of a triple-drug regimen including corticosteroids, a calcineurin inhibitor (ciclosporin or tacrolimus) and either a purine synthesis antagonist (mycophenolate mofetil or azathioprine) or a mammalian target of rapamycin inhibitor (sirolimus or everolimus). The incidence of acute and chronic rejection and of mortality after thoracic transplantation is still high compared with other types of solid organ transplantation. The high allogenicity and immunogenicity of the lungs justify the use of higher doses of immunosuppressants, putting lung transplant recipients at a higher risk of drug-induced toxicities. All immunosuppressants are characterized by large intra- and interindividual variability of their pharmacokinetics and by a narrow therapeutic index. It is essential to know their pharmacokinetic properties and to use them for treatment individualization through TDM in order to improve the treatment outcome. Unlike the kidneys and the liver, the heart and the lungs are not directly involved in drug metabolism and elimination, which may be the cause of pharmacokinetic differences between patients from all of these transplant groups. TDM is mandatory for most immunosuppressants and has become an integral part of immunosuppressive drug therapy. It is usually based on trough concentration (C(0)) monitoring, but other TDM tools include the area under the concentration-time curve (AUC) over the (12-hour) dosage interval or the AUC over the first 4 hours post-dose, as well as other single concentration-time points such as the concentration at 2 hours. Given the peculiarities of thoracic transplantation, a review of the pharmacokinetics and TDM of the main immunosuppressants used in thoracic transplantation is presented in this article. Even more so than in other solid organ transplant populations, their pharmacokinetics are characterized by wide intra- and interindividual variability in thoracic transplant recipients. The pharmacokinetics of ciclosporin in heart and lung transplant recipients have been explored in a number of studies, but less is known about the pharmacokinetics of mycophenolate mofetil and tacrolimus in these populations, and there are hardly any studies on the pharmacokinetics of sirolimus and everolimus. Given the increased use of these molecules in thoracic transplant recipients, their pharmacokinetics deserve to be explored in depth. There are very few data, some of which are conflicting, on the practices and outcomes of TDM of immunosuppressants after thoracic transplantation. The development of sophisticated TDM tools dedicated to thoracic transplantation are awaited in order to accurately evaluate the patients' exposure to drugs in general and, in particular, to immunosuppressants. Finally, large cohort TDM studies need to be conducted in thoracic transplant patients in order to identify the most predictive exposure indices and their target values, and to validate the clinical usefulness of improved TDM in these conditions. In part I of the article, we review the pharmacokinetics and TDM of calcineurin inhibitors. In part II, we will review the pharmacokinetics and TDM of mycophenolate and mammalian target of rapamycin inhibitors, and provide an overall discussion along with perspectives.

Progression of renal dysfunction in cardiac transplantation after the introduction of everolimus in the immunosuppressive regime

The aim of this study was to analyze, in heart transplant patients, if renal function improvement after cyclosporine replacement by everolimus persists at the middle term and its predictors. We studied prospectively 56 patients in whom conversion was consecutively made. Forty-five patients completed the follow-up period. Significant improvement was observed at 6 and 12 months in plasma creatinine levels (1.92+/-0.7 vs. 1.67+/-0.6 and 1.69+/-0.6 mg/dL; P=0.047) and glomerular filtration rate (43.9+/-17 vs. 52.5+/-23 and 51.3+/-22.3 mL/min; P=0.004). Glomerular filtration rate increased in 32 patients (71%). Baseline characteristics comparison showed a lower percentage of patients with smoking history and new onset diabetes in responders group, but only previous smoking was shown as independent factor (Exp B: 0.083; 95% confidence interval: 0.010-0.793; P=0.024). No differences regarding age, gender, body mass index, disease leading to transplantation, time between transplantation and replacement, cardiovascular risk factors, lipid levels, and hematologic parameters were found.

Mycophenolate and sirolimus as calcineurin inhibitor-free immunosuppression improves renal function better than calcineurin inhibitor-reduction in late cardiac transplant recipients with chronic renal failure

BACKGROUND

Calcineurin-inhibitor-(CNI)-induced renal failure is one major cause of morbidity in cardiac transplantation (HTx). In this prospective, randomized, multicenter trial, the impact of immunosuppressive conversion toward CNI-free (mycophenolate mofetil [MMF] and sirolimus) or a CNI-reduced immunosuppressive regimen on renal function, efficacy, and safety was evaluated.

METHODS

Since 2004, 63 HTx-patients (0.5-18.4 years after HTx) with CNI-based immunosuppression and reduced creatinine clearance less than 60 mL/min (39+/-15 mL/min) were included in this trial. Patients in the CNI-free-Group (group 1) were converted to sirolimus that was started with 2 mg/day until target trough levels (8-14 ng/mL) were achieved. Subsequently, CNIs were withdrawn. In CNI-reduction-Group (group 2), CNI target trough levels were reduced by 40%. In both groups MMF was continued and trough level adjusted (1.5-4 microg/mL).

RESULTS

Patients demographics and survival (mean follow-up time: 16.7+/-9 months) was equal (100%). Renal function improved significantly after complete CNI withdrawal while remaining unchanged with CNI-reduction (Creatinine clearance after 12 months: 53+/-24 mg/dL [group 1] vs. 38+/-20 mg/dL [group 2], P=0.01). End-stage renal failure (hemodialysis) was avoided by CNI-withdrawal and occurred only after CNI reduction (n=6; P=0.01). Acute rejection episodes were more common in group 2 (4 vs. 2). Graft function remained stable (echocardiography) within both groups. Adverse events were more common in group 1 (65%) than in group 2 (n=40%) and were responsible for discontinuation in 4 and 0 cases, respectively.

CONCLUSIONS

Conversion toward a CNI-free immunosuppression (Mycophenolate, sirolimus) is superior to CNI-reduced immunosuppression in improving renal failure in late HTx-recipients. However, this benefit is relativized by the increased incidence and severity of sirolimus/MMF-associated side effects.

Everolimus: an update on the mechanism of action, pharmacokinetics and recent clinical trials

BACKGROUND

A growing body of evidence suggests that everolimus might offer effective immunosuppressive activity together with antiproliferative effects that may address some of the unmet needs in the long-term therapeutic management of the post-transplant patient.

OBJECTIVE

To summarize the emerging evidence for employing everolimus-based immunosuppression.

METHODS

A systematic review was conducted of the Medline, Embase and Renal Health Library (Cochrane Collaboration) databases, and of the summary publications from international transplant meetings and congresses during 2000-2008.

RESULTS

This article summarizes this analysis, with special focus on the pharmacokinetic characteristics of everolimus and on the results of its use in renal transplantation. Some data has also been included about the efficacy of the drug in other solid organ transplantation and in tumours.

CONCLUSIONS

Everolimus is an immunosuppressant drug with proven efficacy in transplantation. When used in combination with cyclosporin, better results are obtained in renal function with low cyclosporin doses. Adverse events related to this drug are frequent and lead to moderate dropout rates.

Renal histopathological lesions after lung transplantation in patients with cystic fibrosis

We have analyzed the evolution of renal status beyond the perioperative period in patients with cystic fibrosis (CF) undergoing lung transplantation and presented histological analysis of 15 patients biopsied for an episode of accelerated renal function loss (RFL). Episodes of accelerated RFL after the perioperative period occurred in 32.5% of patients and significantly raised the risk of end-stage renal disease (ESRD) (p < 0.001). The histologic lesions associated with these episodes differed according to the time of onset. Early onset (10 cases) was associated with tubulointerstitial lesions in the form of oxalate nephropathy (50%) and/or a pigmented tubulopathy (80%). This latter was correlated with treatment with antiviral agents (p = 0.002) and aminoside and glycopeptide antibiotics (p = 0.03) administered in the month preceding biopsy. Lesions in late episodes of accelerated RFL (5 cases) were principally vascular: arteriosclerosis and arteriolosclerosis (p = 0.007, p = 0.00002), correlated with diabetic glomerulosclerosis or focal segmental glomerulosclerosis in the absence of prominent diabetic changes. Specific calcineurin-inhibitor nephrotoxicity was present in 93.3% of biopsies associated with thrombotic microangiopathy in 46.7% of cases. The identification of specific etiologies of progressive kidney disease in patients with CF after lung transplantation should permit more effective post-transplant care of these patients.

Development of proteinuria after switch to sirolimus-based immunosuppression in long-term cardiac transplant patients

Calcineurin-inhibitor therapy can lead to renal dysfunction in heart transplantation patients. The novel immunosuppressive (IS) drug sirolmus (Srl) lacks nephrotoxic effects; however, proteinuria associated with Srl has been reported following renal transplantation. In cardiac transplantation, the incidence of proteinuria associated with Srl is unknown. In this study, long-term cardiac transplant patients were switched from cyclosporine to Srl-based IS. Concomitant IS consisted of mycophenolate mofetil +/- steroids. Proteinuria increased significantly from a median of 0.13 g/day (range 0-5.7) preswitch to 0.23 g/day (0-9.88) at 24 months postswitch (p = 0.0024). Before the switch, 11.5% of patients had high-grade proteinuria (>1.0 g/day); this increased to 22.9% postswitch (p = 0.006). ACE inhibitor and angiotensin-releasing blocker (ARB) therapy reduced proteinuria development. Patients without proteinuria had increased renal function (median 42.5 vs. 64.1, p = 0.25), whereas patients who developed high-grade proteinuria showed decreased renal function at the end of follow-up (median 39.6 vs. 29.2, p = 0.125). Thus, proteinuria may develop in cardiac transplant patients after switch to Srl, which may have an adverse effect on renal function in these patients. Srl should be used with ACEi/ARB therapy and patients monitored for proteinuria and increased renal dysfunction.

Multidisciplinary insights on clinical guidance for the use of proliferation signal inhibitors in heart transplantation

Proliferation signal or mammalian target-of-rapamycin inhibitors (PSI/mTOR inhibitors), everolimus and sirolimus, provide attractive options for use in heart transplantation because they are immunosuppressive and anti-proliferative. PSI/mTOR inhibitors work synergistically with calcineurin inhibitors (CNIs) and thus permit the minimization of CNIs without compromising efficacy. This approach is advantageous for the majority of heart transplant recipients and might provide particular benefit in specific cases, such as patients with cardiac allograft vasculopathy, malignancies and renal dysfunction, or in patients intolerant to other immunosuppressive agents. Drawing on the expertise of transplant cardiologists, cardiac surgeons and nephrologists, we addressed the assessment of renal function; management of adverse events associated with this class of drugs; and clinical guidance, specifically for the use of everolimus, including patient selection, indications for treatment and practicalities of drug initiation and monitoring.

Conversion to sirolimus as primary immunosuppression attenuates the progression of allograft vasculopathy after cardiac transplantation

BACKGROUND

We investigated the potential of conversion to sirolimus (SRL) as a primary immunosuppressant in attenuating cardiac allograft vasculopathy progression.

METHODS AND RESULTS

Twenty-nine cardiac transplant recipients were converted to SRL 3.8+/-3.4 years after transplantation with complete calcineurin inhibitor (CNI) withdrawal. Secondary immunosuppressants (azathioprine or mycophenolate) and steroids remained unchanged. Forty patients (controls) 4.8+/-4.0 years from transplantation were maintained on CNIs. Three-dimensional intravascular ultrasound studies were performed at baseline and 12.1+/-2.6 months later. Mean plaque (media and intima) volume (PV) and plaque index (PI) (PV/vessel volume percent) increased significantly in the CNI group (1.28+/-2.86 mm(3)/mm, P=0.004; and 6+/-8%, P=0.0001) but not in the SRL group (0.1+/-1.13 mm(3)/mm, P=0.63; and 0.1+/-8%, P=0.94). In patients enrolled within 2 years after transplantation, the increases in PV (0.06+/-1.06 versus 1.77+/-1.65 mm(3)/mm; P=0.0081) and PI (0+/-9% versus 10+/-8%; P=0.0145) were smaller in the SRL group (n=11) than in the CNI (n=12) group. In patients enrolled >/=2 years after transplantation, the increase in PI was less in the SRL group compared with the CNI group (0.1+/-6.5% versus 5+/-8%; P=0.033), but changes in PV did not differ significantly. Treatment with azathioprine or mycophenolate did not affect PV or PI in either the SRL group (PV: 0.22+/-0.66 versus 0.05+/-1.45 mm(3)/mm, P=0.46; PI: 1.5+/-6% versus -1.6+/-8.5%, P=0.29) or the CNI group (PV: 1.42+/-1.39 versus 1.06+/-2.28 mm(3)/mm, P=0.49; PI: 7.8+/-8.7% versus 4.8+/-7.3%, P=0.23).

CONCLUSIONS

Substituting CNI with SRL as primary immunosuppression attenuates cardiac allograft vasculopathy progression.

Impact on Renal Function of the Use of Sirolimus in Cardiac Transplantation

INTRODUCTION

During the last few years sirolimus has been introduced as an alternative to preserve renal function in transplant recipients receiving calcineurin inhibitors.

MATERIALS AND METHODS

We reviewed our results on the use of sirolimus in cardiac transplant recipients.

RESULTS

Twenty-seven patients with an average age of 63 years received sirolimus. The average time after transplantation was 73.4 +/- 58.9 months and the average follow-up was 31.7 +/- 18.01 months. Sirolimus was prescribed in 37% of cases due to chronic renal failure (CRF), 14.8% because of cardiac allograft vasculopathy (CAV), 11.1% for tumors, 22.2% de novo, 7.4% for CRF and tumor, and 7.4% for CRF and CAV. Among the patients with CRF (n = 14), there were 5 (35%) on dialysis at the moment of starting the treatment and 1 was retired from dialysis. The other 4 (28.5%) patients had to be treated with dialysis after starting the treatment. In all, 42.8% of the patients with nephropathy maintained stable renal function or improved. Among the 17 (63%) patients who did not require dialysis, there was no significant change in renal function after 6 months or 1, 2, and 3 years follow-up.

CONCLUSIONS

The use of sirolimus in cardiac transplantation maintains stable renal function in the majority of patients in the medium term.