Use of sirolimus and low-dose calcineurin inhibitor in lung transplant recipients with renal impairment: results of a controlled pilot study

Mammalian Target of Rapamycin Inhibitors and Kidney Function After Thoracic Transplantation: A Systematic Review and Recommendations for Management of Lung Transplant Recipients

BACKGROUND

Chronic kidney disease (CKD) after lung transplantation is common and limits the survival of transplant recipients. The calcineurin inhibitors (CNI), cyclosporine A, and tacrolimus being the cornerstone of immunosuppression are key mediators of nephrotoxicity. The mammalian target of rapamycin (mTOR) inhibitors, sirolimus and everolimus, are increasingly used in combination with reduced CNI dosage after lung transplantation.

METHODS

This systematic review examined the efficacy and safety of mTOR inhibitors after lung transplantation and explored their effect on kidney function.

RESULTS

mTOR inhibitors are often introduced to preserve kidney function. Several clinical trials have demonstrated improved kidney function and efficacy of mTOR inhibitors. The potential for kidney function improvement and preservation increases with early initiation of mTOR inhibitors and low target levels for both mTOR inhibitors and CNI. No defined stage of CKD for mTOR inhibitor initiation exists, nor does severe CKD preclude the improvement of kidney function under mTOR inhibitors. Baseline proteinuria may negatively predict the preservation and improvement of kidney function. Discontinuation rates of mTOR inhibitors due to adverse effects increase with higher target levels.

CONCLUSIONS

More evidence is needed to define the optimal immunosuppressive regimen incorporating mTOR inhibitors after lung transplantation. Not only the indication criteria for the introduction of mTOR inhibitors are needed, but also the best timing, target levels, and possibly discontinuation criteria must be defined more clearly. Current evidence supports the notion of nephroprotective potential under certain conditions.

Mammalian Target of Rapamycin Inhibitors Vs Calcineurin Inhibitors in Chronic Graft Rejection After Lung Transplantation: A Systematic Review and Meta-Analysis

BACKGROUND

The number of lung transplantations has been rising constantly. However, use of this therapeutic resource is limited by several issues that are difficult to resolve, such as chronic graft rejection and complications secondary to immunosuppression.

METHODS

This systematic review compared mammalian target of rapamycin (mTOR) inhibitor immunosuppression associated with low-dose calcineurin inhibitors with isolated calcineurin inhibitor immunosuppression on the new-onset chronic rejection development and mortality 12 months after lung transplantation. Three controlled randomized clinical trials (SHITRIT, NOCTET, and 4EVERLUNG) were selected from electronic databases.

RESULTS

Meta-analysis of the data at 12 months postintervention showed that only 4EVERLUNG assessed chronic graft rejection, with a higher incidence in the control group; however, the difference was not statistically significant (P = .197). Significant data were related to an increase in the number of adverse events (P = .0064) and improved renal function (P < .0001) in the mTOR inhibitor-based scheme. The other outcomes indicated a trend toward greater risk of death and acute graft rejection with the use of mTORs.

CONCLUSIONS

The researchers suggest considering the use of mTOR inhibitors, whose greatest benefit is felt by patients with renal dysfunction, in association with the use of calcineurin inhibitors, because of the imminent risk of death among patients with renal failure.

Estimation of Blood Sirolimus Concentration Based on Tacrolimus Concentration/Dose Normalized by Body Weight Ratio in Lung Transplant Patients

BACKGROUND

Sirolimus and tacrolimus require accurate drug dosing based on their target blood levels to produce better clinical outcomes, specifically, the avoidance of drug-induced adverse effects and the maintenance of efficacy. However, because the ideal dose of sirolimus and the schedule for measuring its blood levels are unclear in lung transplant patients, an index is required for estimating sirolimus blood concentrations. The aim of this work is to study the correlation between the trough concentration/dose normalized by body weight (C0/D) ratios of sirolimus and tacrolimus in lung transplant patients.

METHODS

Thirteen lymphangiomyomatosis patients who underwent lung transplantation and were treated with sirolimus and tacrolimus from February 2015 to July 2018 were divided into 2 groups, one receiving twice-daily (TD, n = 6) and the other once-daily (OD, n = 7) tacrolimus formulations. The correlation between the C0/D ratio of sirolimus and patient background was evaluated using Spearman's rank correlation coefficient. Correlations between sirolimus and tacrolimus C0/D ratios or doses were analyzed by single regression analysis.

RESULTS

Significant correlations were found between the C0/D ratios of sirolimus and tacrolimus. The regression equations from the initial data of TD and OD groups at steady state were y = 1.880x + 32.636 (adjusted R = 0.743, P = 0.017) and y = 1.684x + 38.816 (adjusted R = 0.919, P < 0.001), respectively. In addition, the regression equations from all data of TD and OD groups were y = 1.883x + 4.170 (adjusted R = 0.546, P < 0.001) and y = 1.950x + 43.188 (adjusted R = 0.898, P < 0.001), respectively. A significant correlation between the dosage of sirolimus and tacrolimus was observed only in the OD group, with relatively low accuracy.

CONCLUSIONS

Blood sirolimus concentrations can be estimated using the C0/D ratio of tacrolimus, suggesting that the C0/D ratio of tacrolimus is an index of required sirolimus dosage and the frequency of blood sirolimus concentration measurements.

Immunosuppressive strategies in lung transplantation

Lung transplantation is a viable option for those with end-stage lung disease which is evidenced by the continued increase in the number of lung transplantations worldwide. However, patients and clinicians are constantly faced with acute and chronic rejection, infectious complications, drug toxicities, and malignancies throughout the lifetime of the lung transplant recipient. Conventional maintenance immunosuppression therapy consisting of a calcineurin inhibitor (CNI), anti-metabolite, and corticosteroids have become the standard regimen but newer agents and modalities continue to be developed. Here we will review induction agents, maintenance immunosuppressives, adjunctive therapies and other strategies to improve long-term outcomes.

Rapamycin: A Bacteria-Derived Immunosuppressant That Has Anti-atherosclerotic Effects and Its Clinical Application

Atherosclerosis (AS) is the leading cause of stroke and death worldwide. Although many lipid-lowering or antiplatelet medicines have been used to prevent the devastating outcomes caused by AS, the serious side effects of these medicines cannot be ignored. Moreover, these medicines are aimed at preventing end-point events rather than addressing the formation and progression of the lesion. Rapamycin (sirolimus), a fermentation product derived from soil samples, has immunosuppressive and anti-proliferation effects. It is an inhibitor of mammalian targets of rapamycin, thereby stimulating autophagy pathways. Several lines of evidence have demonstrated that rapamycin possess multiple protective effects against AS through various molecular mechanisms. Moreover, it has been used successfully as an anti-proliferation agent to prevent in-stent restenosis or vascular graft stenosis in patients with coronary artery disease. A thorough understanding of the biomedical regulatory mechanism of rapamycin in AS might reveal pathways for retarding AS. This review summarizes the current knowledge of biomedical mechanisms by which rapamycin retards AS through action on various cells (endothelial cells, macrophages, vascular smooth muscle cells, and T-cells) in early and advanced AS and describes clinical and potential clinical applications of the agent.

Long-Term Outcomes of Adult Lung Transplantation Recipients: A Single-Center Experience in South Korea

Background

Recently, the number of lung transplants in South Korea has increased. However, the long-term outcome data is limited. In this study, we aimed to investigate the long-term outcomes of adult lung transplantation recipients.

Methods

Among the patients that underwent lung transplantation at a tertiary referral center in South Korea between 2008 and 2017, adults patient who underwent deceased-donor lung transplantation with available follow-up data were enrolled. Their medical records were retrospectively reviewed.

Results

Through eligibility screening, we identified 60 adult patients that underwent lung (n=51) or heart-lung transplantation (n=9) during the observation period. Idiopathic pulmonary fibrosis (46.7%, 28/60) was the most frequent cause of lung transplantation. For all the 60 patients, the median follow-up duration for post-transplantation was 2.6 years (range, 0.01–7.6). During the post-transplantation follow-up period, 19 patients (31.7%) died at a median duration of 194 days. The survival rates were 75.5%, 67.6%, and 61.8% at 1 year, 3 years, and 5 years, respectively. Out of the 60 patients, 8 (13.3%) were diagnosed with chronic lung allograft dysfunction (CLAD), after a mean duration of 3.3±2.8 years post-transplantation. The CLAD development rate was 0%, 17.7%, and 25.8% at 1 year, 3 years, and 5 years, respectively. The most common newly developed post-transplantation comorbidity was the chronic kidney disease (CKD; 54.0%), followed by diabetes mellitus (25.9%).

Conclusion

Among the adult lung transplantation recipients at a South Korea tertiary referral center, the long-term survival rates were favorable. The proportion of patients who developed CLAD was not substantial. CKD was the most common post-transplantation comorbidity.

Kidney Dysfunction After Vascularized Composite Allotransplantation

BACKGROUND

Kidney dysfunction is a major complication after nonrenal solid organ transplants. Transplantation of vascularized composite allografts (VCA) has yielded successful midterm outcomes despite high rates of acute rejection and greater requirements of immunosuppression. Whether this translates in higher risks of kidney complications is unknown.

METHODS

Ninety-nine recipients of facial or extremity transplants from the Brigham and Women's Hospital (BWH) and the International Registry on Hand and Composite Tissue Transplantation (IR) were reviewed. We assessed immunosuppression, markers of renal function over time, as well as pretransplant and posttransplant renal risk factors.

RESULTS

Data were obtained from 10 patients from BWH (age at transplant, 42.5 ± 13.8 years) and 89 patients (37.8 ± 11.5 years) from IR. A significant rise in creatinine levels (BWH, P = 0.0195; IR, P < 0.0001) and drop in estimated glomerular filtration rate (GFR) within the first year posttransplant was observed. The BWH and IR patients lost a mean of 22 mL/min GFR and 60 mL/min estimated GFR in the first year, respectively. This decrease occurred mostly in the first 6 months posttransplant (BWH). Pretransplant creatinine levels were not restored in either cohort. A mixed linear model identified multiple variables correlating with renal dysfunction, particularly tacrolimus trough levels.

CONCLUSIONS

Kidney dysfunction represents a major complication posttransplantation in VCA recipients early on. Strategies to mitigate this complication, such as reducing calcineurin inhibitor trough levels or using alternative immunosuppressive agents, may improve long-term patient outcomes. Standardizing laboratory and data collection of kidney parameters and risk factors in VCA patients will be critical for better understanding of this complication.

New frontiers in immunosuppression

Immunosuppressive therapy is arguably the most important component of medical care after lung transplantation. The goal of immunosuppression is to prevent acute and chronic rejection while maximizing patient survival and long-term allograft function. However, the benefits of immunosuppressive therapy must be balanced against the side effects and major toxicities of these medications. Immunosuppressive agents can be classified as induction agents, maintenance therapies, treatments for acute rejection and chronic rejection and antibody directed therapies. Although induction therapy remains an area of controversy in lung transplantation, it is still used in the majority of transplant centers. On the other hand, maintenance immunosuppression is less contentious; but, unfortunately, since the creation of three-drug combination therapy, including a glucocorticoid, calcineurin inhibitor and anti-metabolite, there have been relatively modest improvements in chronic maintenance immunosuppressive regimens. The presence of HLA antibodies in transplant candidates and development of de novo antibodies after transplantation remain a major therapeutic challenge before and after lung transplantation. In this chapter we review the medications used for induction and maintenance immunosuppression along with their efficacy and side effect profiles. We also review strategies and evidence for HLA desensitization prior to lung transplantation and management of de novo antibody formation after transplant. Finally, we review immune tolerance and the future of lung transplantation to limit the toxicities of conventional immunosuppressive therapy.

Individualizing immunosuppression in lung transplantation

Immunosuppression management after lung transplantation continues to evolve, with an increasing number of agents available for use in various combinations allowing for more choice and individualization of immunosuppressive therapy. Therapeutic developments have led to improved outcomes including lower acute rejection rates and improved survival. However, a one size fits all approach for any immunosuppressive strategy may not be best suited to the individual patient and ultimately patient specific factors must be considered when designing the immunosuppressive regimen. Recipient factors including age, race, co-morbidities, immunologic risk, genetic polymorphisms, concomitant and previous pharmacotherapy, and overall immunosuppression burden should be considered. There are several significant drug-drug interactions with select immunosuppressive agents utilized in lung transplant pharmacotherapy that must be considered when choosing and devising a dosing strategy for an individual immunosuppressive agent. Herein, considerations for immunosuppression management in the individual patient will be reviewed.

Prevention of chronic rejection after lung transplantation

Long-term survival after lung transplantation (LTx) is limited by chronic rejection (CR). Therapeutic strategies for CR have been largely unsuccessful, making prevention of CR an important and challenging therapeutic approach. In the current review, we will discuss current clinical evidence regarding prevention of CR after LTx.

Immunosuppression in lung transplantation

Lung transplantation can be a life-saving procedure for those with end-stage lung diseases. Unfortunately, long term graft and patient survival are limited by both acute and chronic allograft rejection, with a median survival of just over 6 years. Immunosuppressive regimens are employed to reduce the rate of rejection, and while protocols vary from center to center, conventional maintenance therapy consists of triple drug therapy with a calcineurin inhibitor (cyclosporine or tacrolimus), antiproliferative agents [azathioprine (AZA), mycophenolate, sirolimus (srl), everolimus (evl)], and corticosteroids (CS). Roughly 50% of lung transplant centers also utilize induction therapy, with polyclonal antibody preparations [equine or rabbit anti-thymocyte globulin (ATG)], interleukin 2 receptor antagonists (IL2RAs) (daclizumab or basiliximab), or alemtuzumab. This review summarizes these agents and the data surrounding their use in lung transplantation, as well as additional common and novel therapies in lung transplantation. Despite the progression of the management of lung transplant recipients, they continue to be at high risk of treatment-related complications, and poor graft and patient survival. Randomized clinical trials are needed to allow for the development of better agents, regimens and techniques to address above mentioned issues and reduce morbidity and mortality among lung transplant recipients.

Immunosuppression and allograft rejection following lung transplantation: evidence to date

The enduring success of lung transplantation is built on the use of immunosuppressive drugs to stop the immune system from rejecting the newly transplanted lung allograft. Most patients receive a triple-drug maintenance immunosuppressive regimen consisting of a calcineurin inhibitor, an antiproliferative and corticosteroids. Induction therapy with either an antilymphocyte monoclonal or an interleukin-2 receptor antagonist are prescribed by many centres aiming to achieve rapid inhibition of recently activated and potentially alloreactive T lymphocytes. Despite this generic approach acute rejection episodes remain common, mandating further fine-tuning and augmentation of the immunosuppressive regimen. While there has been a trend away from cyclosporine and azathioprine towards a preference for tacrolimus and mycophenolate mofetil, this has not translated into significant protection from the development of chronic lung allograft dysfunction, the main barrier to the long-term success of lung transplantation. This article reviews the problem of lung allograft rejection and the evidence for immunosuppressive regimens used both in the short- and long-term in patients undergoing lung transplantation.

Effects of prophylactic use of sirolimus on bronchiolitis obliterans syndrome development in lung transplant recipients

BACKGROUND

Sirolimus (SIR) has been shown to stabilize the lung function in lung transplant recipients with bronchiolitis obliterans syndrome (BOS). However, there is no long-term data on the prophylactic use of SIR in lung transplant recipients. This retrospective study examines the effects of SIR in the prevention of BOS.

METHODS

From 1999 to 2009, 24 lung transplant recipients whose maintenance immunosuppression regimen consisted of tacrolimus (Tac), mycophenolate mofetil (MMF) or azathioprine (AZA), and prednisone (Pred), were switched to Tac, SIR, and Pred at 1 year after transplantation. From these 24 patients, 5 developed side effects that necessitated the cessation of SIR within 1 year, while 19 patients tolerated long-term use of SIR. The clinical outcomes of these 19 patients (SIR group) were compared with 22 lung transplant recipients whose immunosuppression regimen consisted of Tac, MMF or AZA, and Pred from the time of transplant (MMF group). Survival rates and freedom from BOS were calculated by the Kaplan-Meier method.

RESULTS

The SIR group had a lower incidence of BOS and viral infection (p = 0.05), and higher survival rates (p = 0.004). The SIR group had lower levels of Tac and received less Pred. The incidences of acute rejection, carcinoma, hypertension, and diabetes were similar between both groups.

CONCLUSIONS

Results from this study suggest that conversion to SIR 1 year after lung transplantation improves survival and decreases the development of BOS. Randomized studies with higher number of patients are needed to determine the prophylactic efficacy of sirolimus in preventing the development of BOS.

Graft rejection: pharmacogenetic analysis or drug anamnesis?

AIMS

A 23-year-old Caucasian woman, with cystic fibrosis, bilateral lung-transplantation and immunosuppressive therapy with prednisolone, tacrolimus and sirolimus, presented with clinical symptoms of a chronic transplant rejection.

METHODS

Since constant sufficient blood level of tacrolimus and sirolimus had never been achieved, a genetic analysis was carried out to clarify drug metabolism.

RESULTS

The genetic analysis for polymorphisms of cytochrome P450 (CYP) 3A4,5,7 revealed no sequence alterations in the CYP 3A4,5,7 gene. Thus, drug intake was scrutinized in detail, disclosing a missing interval between the intake of both immunosuppressive agents. After a correct drug intake the woman's condition ameliorated and the blood levels reached normal range.

CONCLUSIONS

This case report highlights the crucial importance of basic medical skills like an accurate and dainty drug anamnesis before high tech approaches were applied.

Renal disease in recipients of nonrenal solid organ transplantation

Worldwide, more than 250,000 individuals who have received a liver, heart, lung, or intestinal transplant are living longer. Twenty percent to 25% of these recipients experience perioperative acute renal failure, with 10% to 15% requiring renal replacement therapy. Chronic kidney disease (CKD) is also highly prevalent, affecting 30% to 50% of the nonrenal organ transplant population with an annual end-stage renal disease risk of 1.5% to 2.0%. Both acute renal failure and CKD contribute to increased morbidity and premature mortality. The dominant causative factor for renal disorders seen in nonrenal transplant recipients are the calcineurin inhibitors (CNI) and rapamycin analogues, which singly or in combination lead to a variety of nephrotoxic injury. However, 25% to 30% of nonrenal transplant recipients with CKD have other conditions such as hypertension, focal segmental glomerulosclerosis, diabetes mellitus, and hepatitis C infection as the principal underlying cause. Management strategies for renal disease in the nonrenal transplant recipients include the following: (1) delayed introduction of CNI after graft implantation, (2) withdrawal or minimization of long-term CNI therapy, (3) timely use of an appropriate dialysis modality, and (4) expeditious introduction of supportive measures such as anemia management, phosphate binding therapy, and dietary modification. Compared with maintenance dialysis, kidney transplantation reduces long-term mortality by 60% to 70% in nonrenal transplant recipients with end-stage renal disease.

Use of sirolimus in solid organ transplantation

Sirolimus is a mammalian target of rapamycin (mTOR) inhibitor that inhibits cell cycle progression and has proven to be a potent immunosuppressive agent for use in solid organ transplant recipients. The drug was initially studied as an adjunct to ciclosporin (cyclosporine) to prevent acute rejection in kidney transplant recipients. Subsequent studies have shown efficacy when combined with a variety of other immunosuppressive agents. The most common adverse effects of sirolimus are hyperlipidaemia and myelosuppression. The drug has unique antiatherogenic and antineoplastic properties, and may promote immunological tolerance and reduce the incidence of chronic allograft nephropathy. Although sirolimus is relatively non-nephrotoxic when administered as monotherapy, it pharmacodynamically enhances the toxicity of calcineurin inhibitors. Ironically, the drug has been used to facilitate calcineurin inhibitor-free protocols designed to preserve renal function after solid organ transplantation. Whether sirolimus can be used safely over the long term with low doses of calcineurin inhibitors requires further study. The use of sirolimus as a corticosteroid-sparing agent also remains to be proven in controlled trials. Postmarketing studies have revealed a number of unforeseen adverse effects including impaired wound healing and possibly proteinuria, oedema, pneumonitis and thrombotic microangiopathy. Overall, sirolimus is a powerful agent when used judiciously with other available immunosuppressants. As is true for all immunosuppressive drugs available for treatment of solid organ transplant recipients, the efficacy of the drug must be balanced against its considerable adverse effects.

Initial Single-Center Experience With Sirolimus After Lung Transplantation

BACKGROUND

Standard immunosuppression after lung transplantation includes calcineurin inhibitors, mycophenolate mofetil, and steroids. Long-term survivors of lung transplantation are often confronted with chronic kidney disease, by definition related to the intake of calcineurin inhibitors. Sirolimus has been increasingly proposed as an alternative immunosuppressive agent due to its absence of nephrotoxicity, which could be used in selected patients.

METHODS

We prospectively administered sirolimus as an alternative to calcineurin inhibitors in 10 lung transplantation recipients with persistent drug nephrotoxicity. They were switched from tacrolimus to sirolimus. Four patients also had bronchiolitis obliterans syndrome. The conversion scheme consisted of an immediate stop of tacrolimus and an 6 to 8-mg loading dose of sirolimus, followed by 4 mg/d. After 5 days, the sirolimus dose was adjusted to maintain trough levels between 12 and 18 ng/mL or 6 and 12 ng/mL for combined sirolimus and tacrolimus. Patients were monitored for renal and graft function as well as clinical status.

RESULTS

A significant decrease in creatinine was observed after 1 week of treatment (P = .011). Azotemia decreased after 1 month, remaining stable (P < .01). Pulmonary function tests did not show significant modification from before sirolimus, inception in patients with or without bronchiolitis obliterans syndrome. There were seven infections. One patient died of complications related to bronchiolitis obliterans.

CONCLUSION

Sirolimus was a useful alternative immunosuppressant, allowing significant tacrolimus withdrawal in transplant recipients with renal impairment. Sirolimus administration allowed recovery of renal function with low morbidity; it was useful for rescue of chronic renal impairment after lung transplantation.