Directing acting antivirals pre-transplant
With the introduction of first generation direct acting antivirals telaprevir and boceprevir (NS3/4A protease inhibitors) in 2011, much interest focused upon their applicability in treatment experienced populations with advanced fibrosis. However, phase III studies did not include a large number of cirrhotics.64,65 Recently, results from the Compassionate Use of Protease Inhibitors in Viral C Cirrhosis (CUPIC) cohort evaluating the effectiveness of first generation protease inhibitor with Peg-IFN and RBV in treatment experienced HCV genotype 1 patients with cirrhosis were reported.66 In 511 patients who did not respond to a prior course of Peg-IFN and RBV, telaprevir (n = 299) or boceprevir (n = 212) was used for 48 weeks. Among the telaprevir treated cohort, 74.2% of previous relapsers, 40.0% of partial responders, and 19.4% of null responders achieved SVR12. Among the boceprevir cohort, 53.9% of relapsers, 38.3% of partial responders, and none of the null responders achieved SVR12. While efficacy was certainly improved with addition of a first generation protease inhibitor, issues of tolerability remained. Severe adverse events occurred in 49.9% of cases, including liver decompensation and death in 2.2%. On multivariate analysis, baseline parameters, including prior null response and serum albumin level < 35 g/L, and platelet count ≤ 100,000), predicted serious adverse events and use was cautioned in patients with these factors.
Towards the end of 2013, two additional agents were added to the HCV armamentarium: simeprevir, a second generation once daily NS3/4A inhibitor, and sofusbuvir, an NS5B polymerase inhibitor of HCV.67,68 Clinical studies that led to Food and Drug Administration (FDA) approval for sofosbuvir demonstrated relatively high efficacy and safety in patients with cirrhosis.69 Both agents are approved as agents in combination with either Peg-IFN or RBV. As previously mentioned, there has been a rise in transplant listings for HCC related to HCV cirrhosis, and HCC may develop in those with well compensated cirrhosis (i.e., low native Model for End-Stage Liver Disease (MELD). Such a patient population with relatively well compensated cirrhosis listed for orthotopic liver transplant by virtue of concomitant HCC represented an excellent opportunity to evaluate second generation DAA efficacy prior to transplant in preventing post-transplant recurrence. Curry et al. recently reported results from a Phase 2, open-label study investigating use of sofosbuvir plus RBV for up to 48 weeks in patients with HCV listed for liver transplant with HCC.70 Patients with chronic HCV infection of any genotype listed for liver transplantation for HCC received up to 48 weeks of sofosbuvir (400 mg/day) and RBV (1000–1200 mg/day) before transplantation. Overall, sofosbuvir and RBV therapy was safe with well compensated cirrhosis and prevented post-transplant HCV recurrence in 64% of patients who had HCV RNA < 25 IU/mL prior to transplant. The number of consecutive days with HCV RNA target not detected prior to transplant appeared to be the strongest predictor of post-transplant HCV recurrence. Certainly, as new agents are developed, their applicability will be tested in cirrhotic populations to further optimize efficacy and minimize serious adverse events (Table 1).
Table 1Summary of Treatment Trials Pre-Transplant: Recent studies have evaluated the effectiveness of pegylated interferon (Peg-IFN) and ribavirin (RBV) in conjunction with newer direct acting antiviral agents including: sofosbuvir (SOF), simeprevir (SMV) and ledipasvir (LED). Identification of increasingly tolerable regimens prior to transplant able to achieve high SVR12 or reliable post transplant virologic response (pTVR) are in development.
Study | Agents | Patients(n) | Virologic response (%)(SVR 12/pTVR) | Adverseevents (%) | Influentialpredictors |
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Everson et al.,63 2013 | Peg-IFN alfa2b & RBV (with dose escalation) | 59 | 22% GT 129% GT 2/3 | 68-Serious | Duration of treatment >16 weeks |
Hezode et al.,66 2014 | Peg-IFN alfa 2b & RBV with Telaprevir or Boceprevir | 511299-Telaprevir212-Boceprevir | SVR12/Agent/Previous historyTelaprevir74.2/relapsers40/partial responders19.4/null respondersBoceprevir53.9/relapsers38.3/partial responders0/null responders | 49.9-Serious | Response to prior therapyAlbumin <35 g/LPlts<100,000 |
Curry et al.,70 2013 | Sofosbuvir & RBV | 61 | 64% | 18-Serious | Number of days with HCV RNA below lower limit of detection |
Lawitz et al.,84 2014 | Simeprevir & Sofosbuvir +/− RBV | 87 | SVR12/Duration/Agent93/12 weeks/SOF + SMV93/12 weeks/SOF + SMV + RBV100/24 weeks SOF + SMV93/24 weeks/SOF +SMV + RBV | 4.6-Serious | ? Q80K polymorphism |
Afdahl et al.,85 2014 | Ledipasvir & Sofosbuvir+/− RBV | 440 total treated(88 Cirrhotic) | SVR12/Duration/Agent86/12 weeks/SOF + LED82/12 weeks/SOF + LED + RBV99/24 weeks SOF + LED99/24 weeks/SOF + LED + RBV | 0-Serious67-90% mild to moderatedepending on regimen/duration | ? NS5A resistance at baseline |
Treatment of recurrence post-transplant
Given the difficulty in treating cirrhotic populations prior to transplant, much attention has focused on treatment post-transplant. In this context, two approaches have been examined: 1) a pre-emptive approach where antiviral therapy is used in the first weeks following transplantation and 2) a histologic, recurrence-based approach for patients with established hepatitis. Early post transplantation therapy administered during the first 2–7 weeks post-transplantation before there is clinical evidence of liver damage has been evaluated.71 The results have been disappointing overall in terms of antiviral efficacy and tolerability. With PegIFN based therapy, SVR rates of about 20% have been documented, ranging from 18 to 39% (5–33% in genotype 1 and 14–100% in genotypes 2/3).71 About 30% of patients discontinue treatment, and dose reductions are required in 70% secondary to side effects, such as bacterial infections, hematological toxicity, and rejections (0–26%).72
The most widely used strategy involves the initiation of antiviral therapy once histologic consequences of HCV recurrence are detected on allograft biopsy. With PEG-IFN and RBV, the previous standard of care, studies estimate SVR at a rate of 30%.73,74 Transplanted patients were particularly predisposed to hematologic toxicities, especially anemia (60–80%), necessitating careful and frequent RBV dose adjustments.
In addition, patients with recurrent HCV infection treated with Peg-IFN (PEG) after liver transplantation can develop severe immune-mediated graft dysfunction (IGD) characterized by plasma cell hepatitis or rejection. A recent multicenter case-control study of 52 liver transplant recipients with hepatitis C assessed the incidence of, risk factors for, and outcomes of PEG-IGD.75 Overall incidence of PEG-IGD during a 10-year study period was 7.2%. Variables associated with increased mortality included acute rejection as the PEG-IGD sub-type and lack of a SVR. Variables associated with graft failure included a high level of alkaline phosphatase at PEG initiation and lack of a SVR.
Directing antivirals post-transplant
Interferon based therapy post-transplantation is fraught with a number of issues, including: comparative lack of efficacy, infection, anemia, and immune mediated graft dysfunction. However, similar to the case of their applicability immediately prior to transplant, much interest has focused on their efficacy in treatment of recurrence. A major limitation with first generation DAAs (telaprevir and boceprevir) are interactions with calcineurin inhibitors cyclosporine (CsA) and tacrolimus (Tac), the cornerstones of immunosuppression post liver transplant. Boceprevir and telaprevir are potent inhibitors of cytochrome P450 3A4. In a study of healthy volunteers, boceprevir was shown to increase the area under the curve of CsA and Tac by 2.7 and of 17, respectively.76 In another study, the concomitant administration of a calcinuerin inhibitor with telaprevir in healthy volunteers increased CsA and Tac exposures approximately 4.6-fold and 70-fold, respectively.77
Recently, interim results from Europe evaluating the efficacy of telaprevir in conjunction with Peg-IFN and RBV post-transplant have been presented.78 Patients receiving calcineurin based immunosuppression (6 months to 10 years after LT), with fibrosis stage F0-F3, received telaprevir, Peg-IFN, and RBV for 12 weeks and Peg-IFN and RBV for an additional 36 weeks. The study included 74 post-transplant patients, and at week 12, 40 (80%) patients on tacrolimus and 21 (87.5%) on cyclosporine achieved undetectable HCV RNA. Common adverse events included anemia, pruritus, and rash. These results show improved efficacy with first generation DAAs and, importantly, manageable levels of immunosuppression with close monitoring.
A US based retrospective cohort study of 81 patients with genotype 1 HCV treated with boceprevir (10%) or telaprevir (90%) plus Peg-IFN and RBV was performed with SVR12 as the primary endpoint.79 The intent-to-treat SVR12 rate was 63% in this post-transplant cohort. Patients with extended rapid virologic response (undetectable HCV RNA at 4 and 12 weeks after starting boceprevir or telaprevir) had higher rates of SVR12 compared to all other patients (85% vs. 15%). Similar to the European study, adverse effects were common; 21% of patients experienced hemoglobin <8 g/dL, and 57% required blood transfusions during the first 16weeks. Twenty seven percent were hospitalized, and 9% died.
In another investigation of 37 liver recipients with advanced HCV recurrence (either ≥ F2 fibrosis [n=31] or fibrosing cholestatic hepatitis [n=6]) treated with Peg-IFN, RBV, and first generation DAA, SVR12 was observed in 20% (1/5) and 71% (5/7) of patients in telaprevir and boceprevir groups, respectively (p=0.24).80 Treatment was discontinued in 16 patients (treatment failures (n=11), serious adverse events (n=5)).
Emerging data with second generation DAAs shows promise in the post-transplant population regarding efficacy and tolerability. Preliminary results presented at AASLD 2013 showed that in a population of transplant recipients with HCV recurrence (predominately genotype 1) treated with sofosbuvir (400 mg daily) along with RBV (400 mg daily) with dose escalation based on hemoglobin, 77% of patients achieved SVR 4 and all patients demonstrated HCV RNA below the lower limit of detection 4 weeks after treatment.81 Treatment was well tolerated and no interactions with immunosuppressive agents were observed. In addition, recent data from the sofosbuvir compassionate use program for patients with severe recurrent hepatitis C, including fibrosing cholestatic hepatitis following liver transplantation, showed higher rates of SVR12 (62%) than standard therapies in this context, improved liver function tests, and improved clinical outcomes82 (Table 2).
Table 2Summary of Treatment Trials Post-Transplant: Recent studies have evaluated the effectiveness of pegylated interferon (Peg-IFN) and ribavirin (RBV) in conjunction with newer direct acting antiviral agents including post-transplant
Study | Agents | Patients(n) | SVR 12(%) (n where applicable) | Adverse events |
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Forns et al.,78 2014(interim analysis) | Peg-IFN alfa 2b & RBV & Telaprevir | 74 | 59.6% (19/32) | 11%-serious60%-anemia |
Burton et al.,79 2014 | Peg-IFN alfa 2b & RBV & Telaprevir or Boceprevir | 81(10% boceprevir/90%telaprevir) | 63% | Common21% Hgb<8g/dL57% requiring transfusions9% liver related death |
Coilly et al.,80 2014 | Peg-IFN alfa 2b & RBV & Telaprevir or Boceprevir | 37Boceprevir (n=18)Telaprevir (n=19 | 71% (5/7) Boceprevir20% (1/5) Telaprevir | Common16 discontinuations92%-anemia |
Charlton et al.,81 2013(abstract) | Sofosbuvir & RBV | 40 | SVR 4–77% | 15%-serious |
Forns et al.,82 2014(abstract) | Sofosbuvir & RBV | 104 | 62% | 48%-serious |
Kwo et al.,86 2014(abstract) | ABT-450/r/ABT-267 + ABT-333 + Ribavirin | 34 | 96.2% | 5.8%-serious17.6%-anemia |
Recently, the use of sofosbuvir and simeprevir in combination has been examined.83 At EASL 2014: Cohort 2 of the COSMOS trial consisting of those with advanced fibrosis (F3-F4) showed overall SVR rates of over 90% with a 12 week regimen not containing RBV.84 Phase III clinical studies evaluating the combination of sofosbuvir and simeprevir are currently underway.
In the upcoming months, further regimens will be added to the HCV armamentarium. It is expected that newer approved regimens with agents such as ledipasvir (NS5A inhibitor) will have sufficient data to make recommendations for usage in those with cirrhosis and possibly on the road to liver transplant.85 In addition, studies for the aforementioned agents are being conducted in post-transplant populations. In another recent study of a regimen containing ABT-450/r/ABT-267 along with ABT-333 and RBV in liver transplant recipients with genotype 1 recurrence, 96% of patients achieved an SVR12 with 24 weeks of therapy.86 An unprecedented number of treatment regimens are on the horizon.
The American Association for Liver Diseases (AASLD) and Infectious Disease Society of America (IDSA) have published recommendations regarding treatment of HCV recurrence in the allograft.87 Here is a new recommended treatment option for treatment naïve patients with genotype 1 recurrence in the allograft includes: sofosbuvir (400 mg) plus simeprevir (150 mg), with or without RBV (initial dose 600 mg/day, increased monthly by 200 mg/day as tolerated to weight-based dose of 1,000 mg [<75 kg] to 1200 mg [>75 kg]), for 12 weeks to 24 weeks. Another alternate regimen for treatment naïve patients with genotype 1 HCV in the allograft liver, including those with compensated cirrhosis, is as follows: sofosbuvir (400 mg) and RBV (initial dose 600 mg/day, increased monthly by 200 mg/day as tolerated to weight-based dose of 1000 mg [<75 kg] to 1200 mg [>75 kg]) with or without Peg-IFN (in the absence of contraindication to its use), for 24 weeks in patients with compensated allograft HCV genotype 1 infection. A recommended regimen for treatment-naïve patients with HCV genotype 2 or 3 in the allograft liver, including those with compensated cirrhosis, is as follows: sofosbuvir (400 mg) and RBV (initial dose 600 mg/day, increased monthly by 200 mg/day as tolerated to weight-based dosages) with consideration of the patient's creatinine clearance value and hemoglobin level for 24 weeks. These guidelines are dynamic and are expected to be revised as new agents become approved and clinical experience grows.