Indication for mycophenolate mofetil therapy in hepatitis C patients undergoing liver transplantation

Mycophenolic acid augments interferon-stimulated gene expression and inhibits hepatitis C Virus infection in vitro and in vivo

Mycophenolic acid (MPA) is a highly effective immunosuppressant that has broad antiviral activity against different viruses and can act in synergy with interferon-α (IFN-α) on hepatitis C virus (HCV) replication. MPA is a potent inosine monophosphate dehydrogenase (IMPDH) inhibitor but the antiviral mechanisms are less understood. The aim of this study was to investigate the inhibition of HCV infection by MPA and the molecular basis for its synergy with IFN-α. The role of IMPDH and interferon-stimulated genes (ISGs) was investigated in two HCV models using gain- or loss-of-function approaches. The in vivo effect of MPA treatment was studied in NOD/SCID mice engrafted with HCV replicon cells. Potent antiviral effects of MPA at clinically relevant concentrations were observed with both the subgenomic and JFH1-derived infectious HCV models. MPA treatment in mice resulted in a specific and robust inhibition of HCV replication. Ectopic expression of an MPA-resistant IMPDH2 mutant in HCV host cells completely reversed the antiproliferative effect of MPA but only partially affected the antiviral potency. However, similar to ribavirin, MPA induced expression of multiple antiviral ISGs, including interferon regulatory factor 1 (IRF1). Cotreatment of MPA with IFN-α resulted in additive effects on ISG expression and enhanced IFN-induced luciferase reporter activity. Knockdown of IRF1, but not IFITM3, significantly attenuated the inhibition of HCV replication by MPA.

CONCLUSION

MPA exerts a potent anti-HCV effect in vitro and in mice and acts in synergy with IFN-α. MPA's antiviral activity partially depends on IMPDH but also involves stimulation of ISGs, providing a molecular basis for its synergy with IFN-α.

Flexible and individualized treatment to achieve sustained viral response for recurrent hepatitis C in liver transplant recipients

Hepatitis C recurrence after liver transplantation is universal and is a major cause of long-term graft failure. Improving the effectiveness of recurrent hepatitis C treatment is extremely important. We studied 35 anti-hepatitis C virus (HCV)-positive patients who underwent liver transplantation. Among the 35 patients, 25 patients had recurrent hepatitis C and received antiviral treatment. HCV RNA load after liver transplantation was increased by 3.68-fold. The antiviral treatment regimen comprised pegylated-interferon (180 μg) every 2 weeks and ribavirin at a dose of 200-400 mg every day. The treatment duration was flexible and individualized, and depended on viral response to treatment. The dosage of tacrolimus was decreased gradually to minimize immunocompromise. Median (interquartile) serum level of tacrolimus was 6.9 (6-8.9) ng/mL at initiation of treatment and 3.8 (3.6-5) ng/mL at the end of treatment. One patient (4.0%) was withdrawn from the study, and three patients (12%) died of infection during treatment. At end of treatment, 18 of 25 patients (72%) were negative for serum HCV RNA. After an additional 6 months following the end of treatment, 16 of the 25 patients (64%) had sustained viral response (SVR) and only two patients had HCV relapse. The 1-year, 3-year and 5-year survival rates were 91.4%, 84.5% and 84.5% for all patients and 88.0%, 82.8% and 82.8% for the 25 patients who received antiviral therapy. In conclusion, recurrent HCV infection is an important issue in liver transplantation. The flexible regimen of antiviral therapy and individualized immunosuppressive agents that was applied in this study achieved a SVR rate of 64%.

Mycophenolic acid inhibits hepatitis C virus replication and acts in synergy with cyclosporin A and interferon-alpha

BACKGROUND & AIMS

Chronic hepatitis C virus (HCV) infection is the leading indication for liver transplantation. Clinical evidence suggests that particular immunosuppressive agents can have an influence on HCV recurrence. Cyclosporine A (CsA) specifically inhibits HCV replication through blocking the viral RNA polymerase enzyme NS5B. In this study, we investigated the effect of mycophenolic acid (MPA) and other immunosuppressants on HCV replication.

METHODS

MPA and other compounds were tested in vitro using an HCV-replication model containing a luciferase reporter gene.

RESULTS

At clinically relevant concentrations (1.0-6.0 microg/mL), MPA inhibited HCV replication to approximately 75%. CsA and interferon (IFN)-alpha also showed inhibition in a dose-dependent manner. In these short-term (18 hours) experiments, MPA did not inhibit cell proliferation or induce cell death, which could have accounted for the antiviral effect. In contrast to the antiviral activity of MPA against West Nile virus, the effect of MPA on HCV replication was guanosine independent. When combined, MPA and CsA showed significant synergistic inhibition of replication, reaching maximum inhibition of approximately 90% at the highest doses. Synergistic effects were observed with suboptimal concentrations of IFN-alpha with MPA or CsA. The kinetics of HCV inhibition by MPA, CsA, and IFN-alpha were clearly distinct, with earliest effects seen with IFN-alpha. No specific inhibitory effects were observed with tacrolimus or rapamycin.

CONCLUSIONS

The immunosuppressive drug MPA is as potent as CsA as an inhibitor of HCV replication. MPA was shown to have a distinct anti-HCV mechanism of action, independent of cell proliferation and guanosine depletion.

Impact of mycophenolate mofetil versus azathioprine on early recurrence of hepatitis C after liver transplantation

The aim of this study was to evaluate the impact of mycophenolate mofetil (MMF) on incidence, delay, severity and clinical course of early recurrent hepatitis C after liver transplantation (LT). A total of 21 hepatitis C virus (HCV)-positive patients after LT were prospectively enrolled in this study. All of them received a quadruple induction cyclosporine A (CsA)-based immunosuppression, augmented by MMF (n=12) or by azathioprine (n=9, AZA). MMF tended to delay recurrent disease (50+/-35 versus 35+/-35 weeks, P=0.5) with significantly lower levels of aminotransferases (P<0.05). Furthermore, patients under MMF revealed less severe allograft fibrosis at disease recurrence (stage of fibrosis: 1.5+/-0.5 versus 2.2+/-1.2; P=0.07). But stage of fibrosis significantly increased in the MMF-group (P<0.05) during 6 months of antiviral treatment. Three patients in the MMF-group and none of the controls suffered from severe fibrosing cholestatic recurrent hepatitis C. Initial post-LT administration of MMF tended to delay recurrent hepatitis C and to limit initial HCV-related biochemical and morphological graft dysfunction. But during clinical follow-up, its immunosuppressive capabilities exceeded possible antiviral properties, finally leading to significant progression of graft fibrosis. Thus, concomitant dose reduction of other basic immunosuppressants might be useful in this clinical setting.

Peginterferon alpha-2a combination therapies in chronic hepatitis C patients who relapsed after or had a viral breakthrough on therapy with standard interferon alpha-2b plus ribavirin: a pilot study of efficacy and safety

There are no established therapeutic regimens for hepatitis C virus (HCV) patients who relapse following treatment with interferon alpha-2b and ribavirin or those who break through while on interferon alpha-2b and ribavirin. We therefore evaluated various combination therapies in HCV patients who relapsed or experienced a viral breakthrough. Patients (n = 124) were randomized to 48 weeks of treatment with once-weekly subcutaneous injections of 180 microg pegylated (peg-) interferon alpha-2a plus oral ribavirin (800-1000 mg/day), mycophenolate mofetil (2 g/day), amantadine (200 mg/day), or ribavirin and amantadine and followed for an additional 24 weeks. The sustained virologic response was higher in patients administered peginterferon alpha-2a plus ribavirin (38%) or ribavirin and amantadine (45%) than in those administered peginterferon alpha-2a plus mycophenolate mofetil (17%) or amantadine (10%). As in previous studies, patients with genotype non-1 and those with lower viral loads had better responses than those with genotype 1 and high viral loads, though the differences did not reach significance. The four treatment regimens had similar safety profiles, except that patients receiving ribavirin had greater maximal hemoglobin decreases. These findings suggest that the combination of peginterferon alpha-2a plus ribavirin or with ribavirin and amantadine is effective in some HCV patients who relapse after treatment with interferon alpha-2b plus ribavirin.

Should patients with chronic hepatitis C infection be transplanted?

Chronic hepatitis C (HCV) infection affects more than 170 million people throughout the world and 2 to 3 million Americans. End-stage liver disease secondary to chronic HCV infection is the most frequent indication for liver transplantation in this country. Currently, the gold standard for treatment for immunocompetent patients is a combination of peginterferon (PEG-IFN) and ribavirin for 6 to 12 months depending on the genotype. This treatment achieves a sustained virological response (SVR) in 54% to 61% of patients overall. Almost 50% of patients do not respond or have recurrences posttreatment and progress in over 10 to 20 years into chronic liver disease and its complications. Liver transplantation is the only therapeutic modality that impacts on quality of life and survival of these patients. However, recurrence of HCV in the new allograft is universal with accelerated progression to cirrhosis in 5 to 10 years. Response to treatment is usually low (20% to 30%), and associated with significant side effects and depression. A significant percentage of patients with recurrent HCV after transplantation require retransplantation to control the complications of end-stage liver disease. Other solid organ transplants recipients already HCV-positive, or infected at the time of transplantation from blood transfusions or an infected graft, develop accelerated, progressive liver disease facilitated by the adverse effects of immunosuppression in addition to HCV replication. To prevent morbidity, mortality, and high costs related to the consequences of HCV infection, all solid organ transplant candidates should be tested for HCV infection and treated appropriately with PEG-IFN and ribavirin prior to transplantation.

A prospective cross-over study comparing the effect of mycophenolate versus azathioprine on allograft function and viral load in liver transplant recipients with recurrent chronic HCV infection

It has been suggested that Mycophenolate Mofetil (MMF) may have an antiviral effect in patients with recurrent HCV infection post-liver transplantation. We conducted a prospective cross-over study in liver transplant recipients with recurrent chronic HCV infection to examine whether substitution of azathioprine (AZA) with MMF would reduce HCV load and improve allograft function. Thirteen long standing HCV liver transplant recipients receiving AZA were enrolled in a 9-month prospective cross-over study. In the initial 3 months lead-in period, baseline viral loads and biochemistry were recorded. Following this, MMF was substituted for AZA at a dose of 1 gm twice/day for a period of 3 months after which patients were switched back to AZA and observed for a further 3 months. Viral loads, biochemical allograft function, and adverse effects were closely monitored during the study period. Thirteen patients (12 males and 1 female) were enrolled. The mean age was 54 (+/-8) years and the mean time from transplantation was 68 (+/-35) months. Baseline mean viral load was 0.74 x 10(6)(+/-0.47 x 10(6)) messenger RNA (mRNA) copies/ml. By the end of the MMF treatment period, the mean viral load increased to a level of 1.64 x 10(6) (+/-1.3 x 10(6)) mRNA copies/ml (P = 0.026) compared to baseline. The increase in viral load however was not associated with an increase in ALT level. In a cohort of 13 HCV liver transplant recipients with recurrent chronic HCV infection, substitution of azathioprine with MMF did not lead to a decrease in viral load.

Mycophenolate mofetil in combination with recombinant interferon alfa-2a in interferon-nonresponder patients with chronic hepatitis C

BACKGROUND/AIMS

Since ribavirin was able to improve the antiviral efficacy of interferon alfa in patients with chronic hepatitis C, several other adjuncts have been studied. It has been shown that mycophenolate mofetil (MMF) is a more potent inhibitor of the inosine 5'-monophosphate-dehydrogenase (IMPDH) than ribavirin. The present study is a pilot study evaluating the efficacy and safety of combination therapy with interferon alfa-2a and MMF in interferon alfa nonresponder patients.

METHODS

Thirty-eight adult patients with chronic hepatitis C who did not respond to a previous interferon alfa monotherapy were enrolled to receive 6 million units of interferon alfa-2a tiw in combination with MMF (1 week 500 mg/day, 1 week 1000 mg/day, 22 weeks 2000 mg/day).

RESULTS

An interim analysis of 29 patients after 12 weeks of therapy showed that only one patient had negative hepatitis C virus-RNA at this time point. There was no significant reduction of the viral load during therapy. Due to inefficacy the study was discontinued.

CONCLUSIONS

Combination therapy of interferon alfa-2a and MMF is ineffective in improving virological response rates in nonresponder patients with chronic hepatitis C. These data suggest that inhibition of the IMPDH seems not to be the major mechanism of ribavirin in enhancing the antiviral effect of interferon alfa in chronic hepatitis C.

Treatment of recurrent hepatitis C

1. Treatment of established recurrent hepatitis C with interferon-alpha monotherapy does not achieve sustained virologic response (SVR). 2. Treatment of established recurrent hepatitis C with combination interferon plus ribavirin achieves SVR rates of 17% to 27%, but dropout rates approach 30%. 3. Pretransplant prophylaxis against recurrent hepatitis C with combination interferon plus ribavirin is poorly tolerated in patients with decompensated hepatitis C cirrhosis. 4. Posttransplant prophylaxis with combination interferon plus ribavirin prevents both recurrent viremia and hepatitis in 15% to 20% of patients, but dropout rates approach 50%. 5. Hepatitis C virus genotype is the best predictor of response to antiviral prophylaxis and treatment of recurrent hepatitis C. 6. Interferon-alpha therapy is not associated with an increased risk of allograft rejection in liver transplant recipients. 7. Ribavirin therapy is associated with increased hemolysis in liver transplant recipients. 8. Preliminary data suggest pegylated interferon monotherapy will have similar efficacy but better tolerability than combination interferon plus ribavirin. 9. In a recent study, posttransplant immunoprophylaxis with polyclonal hepatitis C immunoglobulin had no effect on recurrent viremia or hepatitis.

Management of chronic viral hepatitis before and after renal transplantation

Hepatitis C virus (HCV) infection is present in 2-50% of renal transplant recipients and patients receiving hemodialysis. Renal transplantation confers an overall survival benefit in HCV positive (HCV+) hemodialysis patients, with similar 5-year patient and graft survival to those without HCV infection. However, longer-term studies have reported increased liver-related mortality in HCV-infected recipients. Unfortunately, attempts to eradicate HCV infection before transplant have been disappointing. Interferon is poorly tolerated in-patients with end-stage renal disease and ribavirin is contraindicated because reduced renal clearance results in severe hemolysis. Antiviral therapy following renal transplantation is also poorly tolerated, because of interferon-induced rejection and graft loss. Although the prevalence of hepatitis B virus (HBV) infection has declined in hemodialysis patients and renal transplant recipients since the introduction of routine vaccination and other infection control measures, it remains high within countries with endemic HBV infection (especially Asia-Pacific and Africa). Renal transplantation is associated with reduced survival in HBsAg+ hemodialysis patients. Unlike interferon, lamivudine is a safe and effective antiviral HBV treatment both before and after renal transplantation. Lamivudine therapy commenced at transplantation should prevent early posttransplant reactivation and subsequent progression to cirrhosis and late liver failure. This preemptive therapy should also eradicate early liver failure from fibrosing cholestatic hepatitis. Because cessation of treatment may lead to severe lamivudine-withdrawal hepatitis, most patients require long-term therapy. The development of lamivudine-resistance will be accelerated by immunosuppression and may result in severe hepatitis flares with decompensation. Regular monitoring with liver function tests and HBV DNA measurements should enable early detection and rescue with adefovir. Chronic HCV and HBV infections are important causes of morbidity and mortality in renal transplant recipients. The best predictor for liver mortality is advanced liver disease at the time of transplant, and liver biopsy should be considered in all potential HBsAg+ or HCV+ renal transplant candidates without clinical or radiologic evidence of cirrhosis. Established cirrhosis with active viral infection should be considered a relative contraindication to isolated renal transplantation.

Management of recurrent hepatitis C after liver transplantation

Hepatitis C virus (HCV) reinfection is almost universal in patients transplanted for HCV-related cirrhosis. The medium-term survival after orthotopic liver transplantation (OLT) is similar to other transplanted patients, but the long-term survival remains uncertain. The prevention and an effective treatment of progressive liver disease are the primary aims in HCV recurrence. Interferon and ribavirin, as monotherapy or in combination, have been tried to treat or prevent HCV recurrence. Preliminary studies suggest a better chance of initial HCV clearance and better results in preventing HCV recurrence with combination therapy. IFN or ribavirin, as monotherapy, may normalize liver enzymes, but only gives rise to a transient virological response, without histological improvement. Combination IFN and ribavirin may be able to prevent progression of HCV-related graft disease, but indications and duration of treatment need further evaluation. No clear association between type and dose of immunosuppressive and outcome of post-transplant HCV recurrence has been found. Strategies to minimize the effects of immunosuppressive drugs include dose reduction of all agents and the selective discontinuation of individual agents. Initial immunosuppression with a single drug may inhibit or delay the severe fibrosis, and further investigation with a single immunosuppressive regimen to evaluate the outcome of recurrent hepatitis C should be performed. The recent evidence that mycophenolate may have an antiviral effect needs a clinical confirmation. Retransplantation survival is better with early retransplantation, and for indications not directly related to viral recurrence.

Modern immunosuppression

The current treatment of posttransplant lymphoproliferative disease (PTLD) includes prophylaxis at the time of transplant, decreasing or stopping immunosuppresion and initiation of antiviral therapy in patients with polymerase chain reaction or clinical evidence of PTLD, and judicial reintroduction of immunosuppression in patients who have cleared their PTLD and have begun to have rejection. The pharmacology, pharmacokinetics, notable side effects, and toxicities of the immunosuppressive agents are described in this article. At the conclusion of each section the author's current practice with these agents and treatment strategies are described.

Liver transplantation for hepatitis C virus related cirrhosis

Hepatitis C virus (HCV) related chronic liver disease is now the leading cause for liver transplantation in many centres. Virological recurrence is inevitable following liver transplantation. Excellent patient and graft survival are seen in the short-term, equivalent to that in patients transplanted for other causes of liver disease. However, histological evidence of disease recurrence or hepatitis is present in over half the patients within a year of transplantation, although a small percentage develop progressive cholestatic hepatitis with graft loss within a year. Cirrhosis can develop in the first year after transplantation and 28% of patients have evidence of cirrhosis by 5 years. There is little agreement over the factors that predict the recurrence of disease, development of cirrhosis within the graft and graft or patient survival. Graft loss due to HCV occurs in up to 9% at 5 years and the long-term prognosis may not be comparable to groups transplanted for other diseases. Patients with hepatocellular carcinoma may benefit from liver transplantation if the tumour is small and without vascular invasion. There are, as yet, no clear guidelines regarding the best combination of immunosuppressants in patients with HCV but viral clearance has been achieved with the use of interferon and ribavirin therapy post-operatively.

Impact of immunoadsorption on xenogeneic extracorporeal pig liver perfusion: assessment of organ function during autologous reperfusion

The shortage of liver grafts has resulted in an intensive search for alternative strategies of liver support in acute liver failure. Extracorporeal perfusion of pig livers (ECLP) is not a new concept, but recent improvements in cardiopulmonary bypass technology and new knowledge about xenogeneic immunologic mechanisms have made it a potential therapeutic modality. In previous suboptimal experimental and clinical models, no statements about the beneficial effect of long-lasting periods of ECLP were made. The aim of this study was to evaluate the capacity of pig liver for metabolic regeneration after xenogeneic ECLP under largely physiologic conditions. To delay hyperacute rejection (HAR), we utilized immunoadsorption (IA) of naturally preformed xenogeneic antibodies (XNAbs). This led to a stable xenogeneic ECLP for 45 min. However, IA was not able to prevent completely organ damage or loss of function resulting from insufficient autologous reperfusion. The inability to regenerate during autologous reperfusion provides a new measure of the function of a xenogeneic perfused pig liver. In addition, our results implicate that patients with fulminant liver failure will benefit from short perfusions with several fresh organs rather than from long perfusion with a single pig liver.