New therapies against HCV: expected risks and challenges associated with their use in the liver transplant setting

Hepatitis C Virus-Associated Extrahepatic Manifestations in Lung and Heart and Antiviral Therapy-Related Cardiopulmonary Toxicity

Besides liver cirrhosis and hepatocellular carcinoma, chronic hepatitis C virus (HCV) infection is associated with many extrahepatic manifestations (EHMs). HCV exhibits lymphotropism that is responsible for various EHM. An important characteristic of HCV is escape from the immune system, which enables it to produce chronic infections and autoimmune disorders along with accumulation of circulating immune complexes. These EHMs have large spectrum, because they affect many organs such as heart, lungs, kidney, brain, thyroid, and skin. HCV-related cardiac and pulmonary manifestations include myocarditis, cardiomyopathies, cardiovascular diseases (i.e., Stroke, ischemic heart disease), chronic obstructive pulmonary disease, idiopathic pulmonary fibrosis, asthma, and interstitial lung diseases. This review discusses etiology and pathogenesis of HCV-associated cardiac and pulmonary manifestations and how different genes, immune system, indirectly linked factors (mixed cryoglobulinemia), liver cirrhosis, and antiviral treatment are involved in HCV-related heart and lung diseases, however, their exact mechanism is not clear.

Management of HCV in the liver transplant setting

Hepatitis C-related cirrhosis is the main indication for liver transplantation. In the absence of viral eradication, viral recurrence leads to recurrent HCV disease and progression to advanced graft disease in many recipients, particularly those transplanted with subobtimal grafts. Viral eradication is associated with improved outcome whether used pre- or post-transplantation. In the new era of interferon-free regimes, this is now safe and feasible in most transplant candidates and transplant recipients. There are questions that remain unanswered, such as defining the point of no return where clinical improvement does not follow viral eradication or management of treatment failures.

Drug-drug interactions with oral anti-HCV agents and idiosyncratic hepatotoxicity in the liver transplant setting

Studies of boceprevir and telaprevir based antiviral therapy in liver transplant (LT) recipients with hepatitis C genotype 1 infection have demonstrated dramatic increases in tacrolimus, cyclosporine, and mTOR inhibitor exposure. In addition to empiric dose reductions, daily monitoring of immunosuppressant blood levels is required when initiating as well as discontinuing the protease inhibitors to maximize patient safety. Although improved suppression of HCV replication is anticipated, 20 to 40% of treated subjects have required early treatment discontinuation due to various adverse events including anemia (100%), infection (30%), nephrotoxicity (20%) and rejection (5 to 10%). Simeprevir and faldaprevir will likely have improved efficacy and safety profiles but potential drug interactions with other OATP1B1 substrates and unconjugated hyperbilirubinemia are expected. In contrast, sofosbuvir and daclatasvir based antiviral therapy are not expected to lead to clinically significant drug-drug interactions in LT recipients but confirmatory studies are needed. Liver transplant recipients may also be at increased risk of developing drug induced liver injury (DILI). Establishing a diagnosis of DILI in the transplant setting is very difficult with the variable latency, laboratory features and histopathological manifestations of hepatotoxicity associated with a given drug, the need to exclude competing causes of allograft injury, and the lack of an objective and verifiable confirmatory test. Nonetheless, a heightened awareness of the possibility of DILI is warranted in light of the large number of medications used in LT recipients and the potential adverse impact that DILI may have on patient outcomes.

Impact of donor and recipient single nucleotide polymorphisms of IL28B rs8099917 in living donor liver transplantation for hepatitis C

Single nucleotide polymorphisms of interleukin-28B (IL28B) rs8099917 are reported to be associated with virologic clearance in interferon-and ribavirin -based treatment for hepatitis C virus (HCV)-infected patients. We examined virologic response in accordance with IL28B polymorphisms in our living donor liver transplantation series under a preemptive interferon and RBV treatment approach. Adequate DNA samples from both the recipient and donor for the study of single nucleotide polymorphisms of IL28B were available from 96 cases and were the subjects of the present study. Various clinical factors related with virologic response including early virologic response (EVR) and sustained virologic response (SVR) were examined. Totally 51% presented with EVR and 44% achieved SVR. Presence of the major allele (TT) in either the recipient or the donor corresponded to SVR of 53% and 48%. Presence of the minor allele (TG or GG) corresponded to SVR of 26% and 32%. Multivariate analysis revealed that genotype of HCV or EVR, but not IL28B polymorphisms in either the recipient or donor, was an independent factor for achieving SVR. When virologic response to treatment was incorporated into analysis, the impact of IL28B polymorphism on virological clearance remained relative to other factors and was not significantly independent.

Management of HCV transplant patients with triple therapy

Hepatitis C virus (HCV) infection is one of the leading causes of end-stage liver disease and the main indication for liver transplantation (LT) in most countries. All patients who undergo LT with detectable serum HCV RNA experience graft reinfection. Between 20 and 30% of patients have developed cirrhosis at 5 years post-LT. The outcome of transplant patients with cirrhosis on the graft is severe, with a rate of decompensation at 1 year of approximately 40%. To date, retransplantation is the only option in patients with decompensated liver disease. Until 2011, standard antiviral therapy with pegylated interferon (PEG-IFN) and ribavirin (RBV), was the only effective therapy. Obtaining a sustained virological response (SVR) in patients with LT greatly improves overall and graft survival but this only occurs in 30% of transplanted patients. Direct acting antivirals (DAAs) such as protease inhibitors (PI), polymerase or other non-structural proteins inhibitors represent a new era in HCV associated liver disease. Although their use in the field of LT will certainly be essential there are some limitations because of safety and tolerance. One limitation is the potential interaction with calcineurin inhibitors. We describe the results of triple therapy with boceprevir (BOC) or telaprevir (TVR) for efficacy and safety and comment on future therapeutic strategies in liver transplant recipients.

Pretransplant and posttransplant treatment of hepatitis C virus infection with protease inhibitors

PURPOSE OF REVIEW

Considering the impact of recurrent hepatitis C after liver transplantation on patient and graft survival, we examine the current and potential use of protease inhibitors in the prevention and treatment of recurrent hepatitis C.

RECENT FINDINGS

In genotype-1-infected patients in the waiting list, triple therapy with boceprevir or telaprevir should be considered in compensated cirrhotics. However, tolerability of therapy is low, and side effects are frequent and potentially life-threatening. In posttransplant hepatitis C, available data suggest that triple therapy substantially increases the virological response. Interactions of protease inhibitors with immunosuppressants are considerable, especially between tacrolimus and telaprevir. Anemia seems to be particularly frequent with triple therapy after liver transplantation. Interferon (IFN)-free regimens seem to achieve a high antiviral effect with an excellent safety profile and will probably replace the current IFN-based treatments in a few years from now.

SUMMARY

Antiviral therapy with protease inhibitors will substantially increase the number of patients achieving sustained hepatitis C virus eradication, either before or after liver transplantation. However, side effects and drug-drug interactions will possibly hamper their applicability in both settings; thus, a careful selection and management of patients will be crucial. In the near future, combination of direct-acting antivirals will allow shorter, safer, and more effective IFN-free regimens.