Successful use in lung transplantation of an immunosuppressive regimen aimed at reducing target blood levels of sirolimus and tacrolimus

Sirolimus Long-Term Tolerability and Impact on Kidney Function in Lung Transplantation: A Single-Center Experience

BACKGROUND

After lung transplant, 2 common complications are calcineurin inhibitor (CNI) induced nephrotoxicity and bronchiolitis obliterans syndrome. The objective of this study was to investigate the long-term effects of sirolimus conversion after lung transplantation.

METHODS

This was a retrospective cohort study of patients who had undergone lung transplantation at a single center from June 2003 to December 2016. We compared patients converted to a sirolimus-based regimen to those maintained on our standard tacrolimus-based regimen. Kidney function, pulmonary function, and immunosuppression concentrations were compared between the groups. Additionally, indications, toxicity monitoring parameters, and discontinuation rates for sirolimus were collected.

RESULTS

During the study period, 176 of the 205 patients who underwent lung transplants were converted to a sirolimus-containing regimen (86%). The most common reason for sirolimus initiation was impairment of kidney function or CNI-associated neurotoxicity. Sirolimus was initiated at a median of 150 days post-transplantation and continued for a medium time of 5.02 (2.27-7.85) years. Of those patients converted to sirolimus, 39 (22%) had sirolimus subsequently discontinued secondary to an adverse event. No difference in pulmonary function was found between the groups at 1- and 3-years post-transplantation. In the sirolimus group, the median estimated glomerular filtration rate improved by 8.6 mL/min/1.73 m2 at 3 months post-conversion (P < .001), which was maintained at both 1 and 3 years (P = .014 and .025, respectively).

CONCLUSION

Sirolimus is a viable immunosuppressant option after lung transplant, which successfully allows for the reduction or withdrawal of the CNI, resulting in sustained improvement in kidney function.

Translation suppression underlies the restrained COVID-19 mRNA vaccine response in the high-risk immunocompromised group

Background

Immunocompromised (IC) patients show diminished immune response to COVID-19 mRNA vaccines (Co-mV). To date, there is no ‘empirical’ evidence to link the perturbation of translation, a rate-limiting step for mRNA vaccine efficiency (VE), to the dampened response of Co-mV.

Materials and methods

Impact of immunosuppressants (ISs), tacrolimus (T), mycophenolate (M), rapamycin/sirolimus (S), and their combinations on Pfizer Co-mV translation were determined by the Spike (Sp) protein expression following Co-mV transfection in HEK293 cells. In vivo impact of ISs on SARS-CoV-2 spike specific antigen (SpAg) and associated antibody levels (IgGSp) in serum were assessed in Balb/c mice after two doses (2D) of the Pfizer vaccine. Spike Ag and IgGSp levels were assessed in 259 IC patients and 50 healthy controls (HC) who received 2D of Pfizer or Moderna Co-mV as well as in 67 immunosuppressed solid organ transplant (SOT) patients and 843 non-transplanted (NT) subjects following three doses (3D) of Co-mV. Higher Co-mV concentrations and transient drug holidays were evaluated.

Results

We observed significantly lower IgGSP response in IC patients (p&lt;0.0001) compared to their matched controls in 2D and 3D Co-mV groups. IC patients on M or S showed a profound dampening of IgGSP response relative to those that were not on these drugs. M and S, when used individually or in combination, significantly attenuated the Co-mV-induced Sp expression, whereas T did not exert significant influence. Sirolimus combo pretreatment in vivo significantly attenuated the Co-mV induced IgMSp and IgGSp production, which correlated with a decreasing trend in the early levels (after day 1) of Co-mV induced Sp immunogen levels. Neither higher Co-mV concentrations (6μg) nor withholding S for 1-day could overcome the inhibition of Sp protein levels. Interestingly, 3-days S holiday or using T alone rescued Sp levels in vitro.

Conclusions

This is the first study to demonstrate that ISs, sirolimus and mycophenolate inhibited Co-mV-induced Sp protein synthesis via translation repression. Selective use of tacrolimus or drug holiday of sirolimus can be a potential means to rescue translation-dependent Sp protein production. These findings lay a strong foundation for guiding future studies aimed at improving Co-mV responses in high-risk IC patients.

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.

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.

Survival Associated With Sirolimus Plus Tacrolimus Maintenance Without Induction Therapy Compared With Standard Immunosuppression After Lung Transplant

Importance

Median survival after lung transplant is less than 6 years. Standard maintenance therapy typically includes tacrolimus and an antimetabolite (mycophenolate mofetil or azathioprine). Replacing the antimetabolite with sirolimus after postoperative wound healing may improve long-term survival due to antifibrotic, antiproliferative, and antiaging effects of sirolimus.

Objectives

To compare survival between patients receiving sirolimus plus tacrolimus vs mycophenolate mofetil plus tacrolimus (the most common maintenance therapy) and to identify the combination of induction and maintenance therapy associated with the highest survival.

Design, Setting, and Participants

This cohort study of US recipients of lung transplants from January 1, 2003, through August 31, 2016, analyzed United Network for Organ Sharing (UNOS) data from January 1 through September 13, 2018. Because initiation of sirolimus therapy is usually delayed 3 to 12 months after lung transplant, primary analyses were based on patients alive and free of chronic rejection and malignant disease at 1 year in all groups, whereas sensitivity analyses used appropriate methods to include all patients from transplant time. Regression models adjusted for available potential confounders, including transplant center performance.

Exposures

Cell cycle inhibitor maintenance therapies, including sirolimus (n = 219), mycophenolate mofetil (n = 5782), mycophenolate sodium (n = 408), azathioprine (n = 2556), and concurrent sirolimus plus mycophenolate mofetil (n = 54), were compared within a tacrolimus-based regimen. Combinations of each induction (basiliximab, daclizumab, antithymocyte globulin, alemtuzumab, or none) and maintenance (tacrolimus plus sirolimus, mycophenolate mofetil, or azathioprine) therapy were also compared.

Main Outcomes and Measures

Survival was the primary outcome; chronic rejection incidence and subsequent mortality were secondary outcomes.

Results

Among this population of 9019 patients (median age, 57 years [interquartile range {IQR}, 46-63 years]; 5194 men [57.6%]), sirolimus plus tacrolimus was associated with better survival than mycophenolate mofetil plus tacrolimus (median, 8.9 years [IQR, 4.4-12.7 years] vs 7.1 years [IQR, 3.6-12.1 years]; adjusted hazard ratio [aHR], 0.71; 95% CI, 0.56-0.89; P = .003). Chronic rejection incidence (aHR, 0.75; 95% CI, 0.61-0.92) and mortality after chronic rejection (aHR, 0.52; 95% CI, 0.31-0.81) were lower with sirolimus plus tacrolimus. Compared with mycophenolate mofetil plus tacrolimus, survival differences for sirolimus plus mycophenolate mofetil plus tacrolimus (aHR, 1.14; 95% CI, 0.79-1.65), mycophenolate sodium plus tacrolimus (aHR, 0.95; 95% CI, 0.77-1.17), and azathioprine plus tacrolimus (aHR, 0.93; 95% CI, 0.84-1.02) were not significant. The induction-maintenance combination with the highest survival was sirolimus plus tacrolimus without induction therapy (median survival, 10.7 years [IQR, 7.3-12.7 years]; aHR, 0.48; 95% CI, 0.31-0.76; P = .002) compared with mycophenolate mofetil plus tacrolimus with induction therapy (median survival, 7.4 years [IQR, 3.9-12.6 years]).

Conclusions and Relevance

Sirolimus plus tacrolimus was associated with improved patient survival after lung transplant compared with mycophenolate mofetil plus tacrolimus; no antibody induction therapy with sirolimus plus tacrolimus was associated with maximal survival.

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.

Recommendations on the use of everolimus in lung transplantation

The antiproliferative effect of everolimus provides a therapeutic option in the immunosuppression therapy of lung transplantation, by reducing both the risk of acute rejection and the process of progressive fibrosis that determines chronic graft rejection. However, few data on the use of everolimus in lung transplantation have been published to date, and the specific indications of the drug, along with the most adequate time for its introduction or dosing, have not been defined yet. The aim of this article is to propose recommendations for the use of everolimus in lung transplant recipients, including indications, dosing schedules and the use of concomitant immunosuppression. This consensus document has been developed by experts of all the Spanish lung transplant groups from the review of the existing literature and the clinical experience.

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.

Sirolimus treatment for recurrent lymphangioleiomyomatosis after lung transplantation

Pulmonary lymphangioleiomyomatosis is a rare disease that generally progresses to respiratory failure. We experienced a patient who had recurring lymphangioleiomyomatosis in the transplanted lungs. A chest computed tomographic scan showed a progressing emphysematous change. The patient had a subclinical extent of pan-circumferential stricture at the distal site of the left bronchial anastomosis. We treated the patient with sirolimus for three years. Chest computed tomography showed no sign of exacerbation during the late 3 years, whereas pulmonary function test revealed a slight increase after the use of sirolimus. Bronchial stricture also disappeared almost completely. This is the first reported case with sirolimus treatment for post-transplant recurrent lymphangioleiomyomatosis.

Tacrolimus-induced lung injury in a rheumatoid arthritis patient with interstitial pneumonitis

A 74-year-old woman was experiencing rheumatoid arthritis complicated with interstitial pneumonitis (IP), and tacrolimus treatment was started. She presented with dyspnea. Chest X-ray and computed tomography (CT) showed ground-glass opacity and IP. Although tacrolimus was stopped, she died of respiratory failure. At autopsy, both the upper and lower lung fields showed usual IP and the organizing stage of diffuse alveolar damage. The former is common, but the latter is uncommon, suggesting tacrolimus may cause severe alveolar damage.

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.