Long-term outcome of conversion to sirolimus monotherapy after liver transplant

Current Use of Immunosuppression in Liver Transplantation

Since the first successful liver transplant in 1967, immunosuppression has allowed liver transplantation to become the standard treatment of end-stage liver disease. Over the decades, the rates of rejection have decreased, and patient survival outcomes have significantly improved in large part due to the introduction and advancements of immunosuppression medications. However, the adverse effects associated with long-term immunosuppression have created new challenges facing liver transplantation and added significantly to posttransplantation morbidity. This review presents the data and rationale for immunosuppression approaches, addresses the main controversies related to immunosuppression in liver transplantation, and explores some of the newer advancements in immunosuppressive drug therapy.

Immunosuppression, Compliance, and Tolerance After Orthotopic Liver Transplantation: State of the Art

Orthotopic liver transplantation is the treatment of choice for several otherwise irreversible forms of acute and chronic liver diseases. Early implemented immunosuppressant regimens have had disappointing results with high rejection rates. However, new drugs have reduced the daily immunosuppression requirements, thereby improving graft and patient survival as well as kidney function. Liver rejection is a T-cell-driven immune response and is the active target of immunosuppressive agents. Immunosuppressants can be divided into pharmacological or biological drugs: the gold standard is the calcineurin inhibitors, steroids, mycophenolate mofetil, and mechanistic target of rapamycin inhibitors. Compliance with these agents is essential, although they can increase the risk of infections and neoplastic diseases. In some patients, graft tolerance can be achieved. Graft tolerance is defined as the absence of acute and chronic rejection in a graft, with normal function and histology in an immunosuppression-free, fully immunocompetent host, usually as the final result of a successful attempt at immunosuppression withdrawal. The occurrence of immunosuppressive-related complications has led to new protocols aimed at protecting renal function and preventing de novo cancer and dysmetabolic syndrome. The backbone of immunosuppression remains calcineurin inhibitors in association with other drugs, mainly over the short-term period. To avoid rejection and the side effects on renal dysfunction, de novo cancer, and cardiovascular syndrome, optimal long-term immunosuppressive therapy should be tailored in liver transplant recipients.

Metabolic and Renal Effects of Mammalian Target of Rapamycin Inhibitors Treatment After Liver Transplantation: Real-Life Single-Center Experience

BACKGROUND

Mammalian target of rapamycin (mTOR) inhibitors following liver transplantation (LT) are used to minimize calcineurin inhibitor (CNI)-related nephrotoxicity. Data about metabolic effects of mTOR inhibitors are still limited.

AIM

This study aims to determine the renal and metabolic effects of different mTOR inhibitor-based protocols in real-life LT patients.

METHODS

This is a retrospective cohort study of patients treated with mTOR inhibitors after LT. Demographics, treatment protocols, glomerular filtration rate (GFR), and metabolic parameters were collected over a period of 4 years. Initiation of blood pressure (BP), diabetes mellitus, and lipid medications was also noted.

RESULTS

Fifty-two LT recipients received mTOR inhibitors. GFR improved significantly (by 1.96 mL/min/year), with greater improvement in patients with baseline renal dysfunction (+13.3 mL/min vs +4.5 mL/min at 3 years). Conversion to an mTOR inhibitor during the first post-transplant year resulted in a more durable improvement in GFR (for 4 years vs only 1 year for later conversion).No significant weight gain or new-onset diabetes mellitus was observed. However, there was some increase in total cholesterol (+7 mg/dL) and blood pressure (+2 mm Hg during the third year and +8 mm Hg in the fourth years), followed by initiation of lipid-lowering and BP medications in 25% and 13% of patients, respectively.

CONCLUSIONS

Treatment with an mTOR inhibitor following LT resulted in improved kidney functions without significant negative metabolic effects such as weight gain or new-onset diabetes mellitus. This makes mTOR inhibitors a valuable immunosuppressive option in the face of the growing incidence of nonalcoholic steatohepatitis as a leading cause for LT.

Acute treatment of critical vascular stenoses with a bioabsorbable magnesium scaffold in infants with CHDs

BACKGROUND

Post-operative severe vascular stenosis and proliferating endothelial tissue lead to severe circulatory disorders and impair organ perfusion. Bioabsorbable magnesium scaffolds may help to overcome these obstructions without leaving obstructing stent material. We analyse their role in the treatment of vascular stenosis in infants.

METHODS

Since 2016, 15 magnesium scaffolds with a diameter of 3.5 mm were implanted in 9 patients aged 15 days to 7.6 years. Eight scaffolds were implanted in pulmonary venous restenoses, five in pulmonary arterial stenosis including one in-stent stenosis, one into a stenotic brachiocephalic artery, and one in a recurrent innominate vein thrombosis.

RESULTS

All patients clinically improved after the implantation of a scaffold. The magnesium scaffolds lost integrity after 30-48 days (mean 42 days). The innominate vein thrombosed early, while all other vessels remained open. Two patients died after 1.3 and 14 weeks not related to the scaffolds. Five patients needed further balloon dilations or stent implantations after the scaffold had fractured. At first recatheterisation after in mean 2.5 months, the mean minimum/maximum diameter in relation to the scaffold's original diameter was 89%/99% in the arterial implantations (n = 6) and 66%/77% in the pulmonary venous implantations.

CONCLUSIONS

The magnesium scaffolds can be used as a bridging solution to treat severe vascular stenosis in different locations. Restenosis can occur after degradation and make further interventions necessary, but neither vessel growth nor further interventions are hindered by stent material. Larger diameters may improve therapeutic options.

Safety of mTOR inhibitors in adult solid organ transplantation

INTRODUCTION

Mammalian target of rapamycin (mTOR) inhibitors (sirolimus and everolimus) are a class of immunosuppressive drugs approved for solid organ transplantation (SOT). By inhibiting the ubiquitous mTOR pathway, they present a peculiar safety profile. The increased incidence of serious adverse events in early studies halted the enthusiasm as a kidney sparing alternative to calcineurin inhibitors (CNI).

AREAS COVERED

Herein we review mTOR inhibitors safety profile for adult organ transplantation, ranging from acute side effects, such as lymphoceles, delayed wound healing, or cytopenias, to long-term ones which increase morbidity and mortality, such as cancer risk and metabolic profile. Infection, proteinuria, and cutaneous safety profiles are also addressed.

EXPERT OPINION

In the authors' opinion, mTOR inhibitors are a safe alternative to standard immunosuppression therapy with CNI and mycophenolate/azathioprine. Mild adverse events can be easily managed with an increased awareness and close monitoring of trough levels. Most serious side effects are dose- and organ-dependent. In kidney and heart transplantation mTOR inhibitors may be safely used as either low-dose de novo or through early-conversion. In the liver, conversion 4 weeks post-transplantation may reduce long-term chronic kidney disease secondary to calcineurin nephrotoxicity, without increasing hepatic artery/portal vein thrombosis.

A retrospective 15-year review: survival advantage after switching to sirolimus in hepatitis C virus infected liver graft recipients

BACKGROUND

The use of sirolimus-based immune suppression in liver transplantation, particularly in hepatitis C virus (HCV)-infected recipients, remains contentious. There is some evidence that sirolimus retards hepatic fibrosis, is renal sparing and may be of benefit in preventing hepatocellular carcinoma (HCC) recurrence. Sirolimus has not been adopted by many transplant centres because of persistent concerns regarding an increased risk of hepatic artery thrombosis, graft loss and death with de novo sirolimus.

AIM

To review the impact of switching to sirolimus monotherapy in HCV-infected liver recipients with respect to survival, graft loss and hepatic fibrosis.

METHODS

A retrospective review of 190 patients from a single centre undergoing first liver transplantation for HCV over 15 years. 113 patients were switched from calcineurin inhibitor (CNI)-based therapy to low-dose sirolimus monotherapy at a median of 15 months after transplantation for HCV-related fibrosis (72%), renal impairment (14%) or high-risk HCC (5%).

RESULTS

Patients switched to sirolimus had improved survival (P < 0.001) and slower progression to cirrhosis (P = 0.001). In patients with HCC (n = 91), sirolimus duration rather than strategy was an independent predictor of survival (P = 0.001) and extended time to HCC recurrence (33 vs. 16 months). Patients switched for renal dysfunction showed improvement in serum creatinine (140-108 μmol/L, P = 0.001). Those remaining on CNI-therapy were more likely to develop post-transplant diabetes (P = 0.03).

CONCLUSION

These data suggest selective switching to low-dose sirolimus monotherapy in HCV-positive liver recipients improves clinical outcome.

The Role of mTOR Inhibitors in Liver Transplantation: Reviewing the Evidence

Despite the success of liver transplantation, long-term complications remain, including de novo malignancies, metabolic syndrome, and the recurrence of hepatitis C virus (HCV) and hepatocellular carcinoma (HCC). The current mainstay of treatment, calcineurin inhibitors (CNIs), can also worsen posttransplant renal dysfunction, neurotoxicity, and diabetes. Clearly there is a need for better immunosuppressive agents that maintain similar rates of efficacy and renal function whilst minimizing adverse effects. The mammalian target of rapamycin (mTOR) inhibitors with a mechanism of action that is different from other immunosuppressive agents has the potential to address some of these issues. In this review we surveyed the literature for reports of the use of mTOR inhibitors in adult liver transplantation with respect to renal function, efficacy, safety, neurological symptoms, de novo tumors, and the recurrence of HCC and HCV. The results of our review indicate that mTOR inhibitors are associated with efficacy comparable to CNIs while having benefits on renal function in liver transplantation. We also consider newer dosing schedules that may limit side effects. Finally, we discuss evidence that mTOR inhibitors may have benefits in the oncology setting and in relation to HCV-related allograft fibrosis, metabolic syndrome, and neurotoxicity.

Lipid metabolism and oxidative stress in children after liver transplantation treated with sirolimus

Lipid disturbances are one of the most frequent side effects of SRL; however, clinical consequences are not known. The aim of the study was to evaluate the risk of AS in children after LTx treated with SRL. In 17 children with median age 13.2 yr (1.9-17.9) who received SRL on average for 4.1 yr (s.d. ± 2.9) we measured and compared with age-matched healthy control group (n = 45) lipid parameters and markers of AS: ADMA, oxyLDL, GSH, GPx, TC, TG, HDL cholesterol, LDL cholesterol, VLDL cholesterol, ApoAI, ApoB, ApoE, lipoprotein (a) (Lp(a)). We found no major differences in cholesterol, cholesterol in lipoprotein fractions and TG concentrations between patients receiving SRL and the control group. ApoE was markedly increased in the study group (19.1 g/L [±1.8]) when compared to controls (9.8 [±3.9]). ApoA1 was decreased in the study group: 1.30 g/L (±0.2) vs. 1.45 (±0.25), p = 0.04. ApoB and Lpa concentrations were similar in both groups. There were differences in oxidative stress markers: GSH 743 (±66.2) mol/mL vs. 780 (±48.2), p = 0.02 and GPx 32.8 (±5.5) U/gHb vs. 34.3(±2.6), p = 0.01. Markers of AS: ADMA did not differ between groups and oxidized LDLc was significantly lower in SRL group: 190 mU/mL (±113) vs. 237 (±107) in control, p < 0.05. SRL does not significantly disturb lipid metabolism and oxidative status in children after LTx.