HIV-HCV co-infection facing HCV protease inhibitor licensing: implications for clinicians

Reversible Covalent Inhibition─Desired Covalent Adduct Formation by Mass Action

Covalent inhibition has seen a resurgence in the last several years. Although long-plagued by concerns of off-target effects due to nonspecific reactions leading to covalent adducts, there has been success in developing covalent inhibitors, especially within the field of anticancer therapy. Covalent inhibitors can have an advantage over noncovalent inhibitors since the formation of a covalent adduct may serve as an additional mode of selectivity due to the intrinsic reactivity of the target protein that is absent in many other proteins. Unfortunately, many covalent inhibitors form irreversible adducts with off-target proteins, which can lead to considerable side-effects. By designing the inhibitor to form reversible covalent adducts, one can leverage competing on/off kinetics in complex formation by taking advantage of the law of mass action. Although covalent adducts do form with off-target proteins, the reversible nature of inhibition prevents accumulation of the off-target adduct, thus limiting side-effects. In this perspective, we outline important characteristics of reversible covalent inhibitors, including examples and a guide for inhibitor development.

Effect of HIV co-infection on adherence to a 12-week regimen of hepatitis C virus therapy with ledipasvir and sofosbuvir

OBJECTIVE

As the treatment of hepatitis C virus (HCV) infection has evolved to directly acting antiviral agents, the impact of these directly acting antiviral-only regimens on improving adherence to HCV treatment in HIV/HCV coinfected populations has not been evaluated. The study compared adherence to ledipasvir/sofosbuvir (LDV/SOF) in HCV monoinfected and HIV/HCV coinfected individuals.

DESIGN

Adherence was measured from participants in two phase 2 open-label studies (NCT01805882 and NCT01878799).

METHODS

HCV treatment-naive, genotype 1 study individuals [HCV monoinfected participants (N = 20) and HIV/HCV coinfected participants, antiretroviral untreated (N = 13) or on combination antiretroviral therapy (N = 37)] were treated with LDV (90 mg) and SOF (400 mg) administered as one tablet once daily for 12 weeks. Adherence was measured using three tools: medication event monitoring system cap, pill count, and patient report.

RESULTS

Participants were predominately African American (83%) and male (73%), with a median age of 59 years. Participants had prompt HCV viral load decline and high adherence rates (97 ± 0.5% by medication event monitoring system). Participant adherence decreased significantly from early (baseline week 4) as compared with late (weeks 8-12) in therapy in all three groups - HCV monoinfected (P = 0.01), HIV/HCV antiretroviral untreated (P = 0.02), and HIV/HCV antiretroviral treated participants (P = 0.01).

CONCLUSION

Adherence to LDV/SOF in this urban population was high and comparable between HCV monoinfected and HIV/HCV coinfected participants regardless of antiretroviral use.

Hepatitis C virus infection in the human immunodeficiency virus infected patient

Human immunodeficiency virus (HIV) and hepatitis C virus (HCV) share the same transmission routes; therefore, coinfection is frequent. An estimated 5-10 million individuals alone in the western world are infected with both viruses. The majority of people acquire HCV by injection drug use and, to a lesser extent, through blood transfusion and blood products. Recently, there has been an increase in HCV infections among men who have sex with men. In the context of effective antiretroviral treatment, liver-related deaths are now more common than Acquired Immune Deficiency Syndrome-related deaths among HIV-HCV coinfected individuals. Morbidity and mortality rates from chronic HCV infection will increase because the infection incidence peaked in the mid-1980s and because liver disease progresses slowly and is clinically silent to cirrhosis and end-stage-liver disease over a 15-20 year time period for 15%-20% of chronically infected individuals. HCV treatment has rapidly changed with the development of new direct-acting antiviral agents; therefore, cure rates have greatly improved because the new treatment regimens target different parts of the HCV life cycle. In this review, we focus on the epidemiology, diagnosis and the natural course of HCV as well as current and future strategies for HCV therapy in the context of HIV-HCV coinfection in the western world.

New agents for the treatment of hepatitis C in patients co-infected with HIV

Pilot trials evaluating the efficacy and safety of the first licensed hepatitis C virus (HCV) protease inhibitors (PIs), boceprevir (BOC) and telaprevir (TVR), for the treatment of genotype 1 infection in HCV/HIV co-infected patients revealed similar results as in HCV mono-infected patients. HCV liver disease progresses more rapidly in co-infected patients, particularly with advanced immunodeficiency. Therefore, HCV treatment in HIV is of great importance. However, dual therapy with pegylated interferon (PegIFN) and ribavirin (RBV) has been associated with lower cure rates and increased toxicities in co-infected subjects, thereby limiting overall HCV therapy uptake. The availability of HCV PIs opens new perspectives for HCV cure in co-infected patients, with a 70% sustained virologic response (SVR) rate in HCV treatment-naïve patients. Despite these impressive advances, the use of the new treatment options has been low, reflecting the complex issues with modern triple HCV therapy. Indeed pill burden, adverse events (AEs), drug-drug interactions (DDIs) and high costs complicate HCV therapy in HIV. So far, studies have shown no tolerability differences in mono- and co-infected patients with the early stages of liver fibrosis. Regarding DDIs between HVC PIs and antiretroviral drugs, TVR can be safely administered with efavirenz (with dose adjustment of TVR), etravirine (ETR), rilpivirine, boosted atazanavir (ATV/r) and raltegravir (RAL), while BOC can be safely administered with ETR, RAL and potentially ATV/r for treatment-naïve patients under careful monitoring. Currently, the great number of HCV molecules under development is promising substantially improved treatment paradigms with shorter treatment durations, fewer AEs, less DDIs, once-daily administration and even interferon-free regimens. The decision to treat now with the available HCV PIs or defer therapy until the second generation of HCV direct acting antivirals become available should be based on liver fibrosis staging and fibrosis progression during follow up. More data are urgently needed regarding the efficacy of triple therapy in HIV/HCV co-infected patients who previously failed PegIFN/RBV therapy as well as in patients with more advanced fibrosis stages.

Advances in the treatment of hepatitis B virus/hepatitis C virus coinfection

INTRODUCTION

Patients with chronic hepatitis B virus (HBV)/hepatitis C virus (HCV) coinfection are at a high risk of developing liver cirrhosis and hepatocellular carcinoma, and consequently, warrant effective treatment.

AREAS COVERED

Effective treatment should eradicate HCV infection and inhibit HBV replication but without serious adverse reactions. Careful evaluation of disease progression, predominance of one virus over another, comorbidities and concomitant hepatitis delta virus and/or HIV infection are essential for better therapy choices. In the case of HCV predominance, Peg-interferon plus ribavirin with or without a first-generation directly acting antiviral (DAA) should be the first choice, but future treatments will be DAA-based and interferon-free. In the case of HBV predominance, tenofovir or entecavir should be part of treatment. Patients should be closely monitored for early identification and treatment of HCV or HBV reactivation.

EXPERT OPINION

High potency and high genetic barrier nucleos(t)ide analogues to inhibit HBV replication have been used for years, with no urgency for new drugs. Several DAAs for interferon-free therapy for HCV eradication will be available in the near future. We hope that the high cost of these drugs will not be a limitation to their use in developing countries. Further investigation of HBV/HCV interaction is needed before and during the administration of new therapies.

Efficacy of lead-in silibinin and subsequent triple therapy in difficult-to-treat HIV/hepatitis C virus-coinfected patients

OBJECTIVES

The efficacy of current hepatitis C virus (HCV) triple therapy, including a protease inhibitor, is limited in HIV/HCV-coinfected patients with advanced liver fibrosis and nonresponse to previous peginterferon-ribavirin. These patients have a low chance (only 30%) of achieving a sustained virological response (SVR) during triple therapy and cannot wait for next-generation anti-HCV drugs. In a pilot study, we investigated the efficacy of a lead-in therapy with silibinin before triple therapy in difficult-to-treat patients.

METHODS

Inclusion criteria were HIV/HCV coinfection with advanced liver fibrosis and documented failure of previous peginterferon-ribavirin treatment. Intervention was lead-in therapy with intravenous silibinin 20 mg/kg/day for 14 days. Subsequently, peginterferon-ribavirin combined with telaprevir was initiated for 12 weeks, followed by peginterferon-ribavirin dual therapy until week 48 after initiation of triple therapy. The outcome measurements were HCV RNA after silibinin lead-in, at weeks 2, 4 and 12 of triple therapy, and SVR at week 24 after the end of treatment.

RESULTS

We examined six HIV/HCV-coinfected patients (four infected with genotype 1a). All had fibrosis grade METAVIR ≥F3 and were on fully suppressive antiretroviral therapy. Mean HCV RNA decline after silibinin therapy was 2.6 log10 IU/mL (range 2-3 log10 IU/mL). Five of the six patients were virologically suppressed at weeks 2 and 4, and all six at week 12 of triple therapy. One experienced a viral breakthrough thereafter. Four of five patients (80%) showed an SVR 24. One patient had an SVR 12 but has not yet reached week 24.

CONCLUSIONS

A lead-in with silibinin before triple therapy is highly effective and increases the probability of HCV treatment success in difficult-to-treat HIV/HCV-coinfected patients with advanced liver fibrosis and previous failure of peginterferon-ribavirin.

The cost-effectiveness of improved hepatitis C virus therapies in HIV/hepatitis C virus coinfected patients

OBJECTIVES

To evaluate the effectiveness and cost-effectiveness of strategies to treat hepatitis C virus (HCV) in HIV/HCV coinfected patients in the United States.

PARTICIPANTS

Simulated cohort of HIV/HCV genotype 1 coinfected, noncirrhotic, HCV treatment-naive individuals enrolled in US HIV guideline-concordant care.

DESIGN/INTERVENTIONS

Monte Carlo simulation comparing five strategies: no treatment; dual therapy with pegylated-interferon (PEG) and ribavirin (RBV); 'PEG/RBV trial' in which all patients initiate dual therapy and switch to triple therapy upon failure; 'IL28B triage' in which patients initiate either dual therapy or triple therapy based on their IL28B allele type; and PEG/RBV and telaprevir (TPV) triple therapy. Sensitivity analyses varied efficacies and costs and included a scenario with interferon (IFN)-free therapy.

MAIN MEASURES

Sustained virologic response (SVR), life expectancy, discounted quality-adjusted life expectancy (QALE), lifetime medical costs, and incremental cost-effectiveness ratios (ICERs) in $/quality-adjusted life years (QALY) gained.

RESULTS

'PEG/RBV trial,' 'IL28B triage,' and 'triple therapy' each provided 72% SVR and extended QALE compared with 'dual therapy' by 1.12, 1.14, and 1.15 QALY, respectively. The ICER of 'PEG/RBV trial' compared with 'dual therapy' was $37 500/QALY. 'IL28B triage' and 'triple therapy' provided little benefit compared with 'PEG/RBV trial,' and both had ICERs exceeding $300 000/QALY. In sensitivity analyses, IFN-free treatment attaining 90% SVR had an ICER less than $100 000/QALY compared with 'PEG/RBV trial' when its cost was $109 000 or less (125% of the cost of PEG/RBV/TVR).

CONCLUSION

HCV protease inhibitors are most efficiently used in HIV/HCV coinfection after a trial of PEG/RBV, sparing protease inhibitors for those who attain rapid virologic response and SVR. The cost-effectiveness of IFN-free regimens for HIV/HCV coinfection will depend on the cost of these therapies.

Anti-viral treatment and cancer control

Hepatitis B virus (HBV), hepatitis C virus (HCV), human papillomavirus (HPV), and Epstein-Barr virus (EBV) contribute to about 10-15 % global burden of human cancers. Conventional chemotherapy or molecular target therapies have been used to treat virus-associated cancers. However, a more proactive approach would be the use of antiviral treatment to suppress or eliminate viral infections to prevent the occurrence of cancer in the first place. Antiviral treatments against chronic HBV and HCV infections have achieved this goal, with significant reduction in the incidence of hepatocellular carcinoma in treated patients. Antiviral treatments for EBV, Kaposi's sarcoma-associated herpesvirus (KSHV), and human T-cell lymphotropic virus type 1 (HTLV-1) had limited success in treating refractory EBV-associated lymphoma and post-transplant lymphoproliferative disorder, KSHV-associated Kaposi's sarcoma in AIDS patients, and HTLV-1-associated acute, chronic, and smoldering subtypes of adult T-cell lymphoma, respectively. Therapeutic HPV vaccine and RNA-interference-based therapies for treating HPV-associated cervical cancers also showed some encouraging results. Taken together, antiviral therapies have yielded promising results in cancer prevention and treatment. More large-scale studies are necessary to confirm the efficacy of antiviral therapy. Further investigation for more effective and convenient antiviral regimens warrants more attention.

Managing HIV/hepatitis C co-infection in the era of direct acting antivirals

Morbidity and mortality from co-morbid hepatitis C (HCV) infection in HIV co-infected patients are increasing; hence, the management of hepatitis co-infection in HIV is now one of the most important clinical challenges. Therefore, the development of direct acting antivirals (DAAs) for treatment of HCV has been eagerly awaited to hopefully improve HCV treatment outcome in co-infected individuals. Indeed, the availability of the first HCV protease inhibitors (PI) boceprevir and telaprevir for HCV genotype 1 patients has changed the gold standard of treating hepatitis C allowing for substantially improved HCV cure rates under triple HCV-PI/pegylated interferon/ribavirin therapy. Moreover, numerous other new DAAs are currently being studied in co-infected patient populations, also exploring shorter treatment durations and interferon-free treatment approaches promising much easier and better tolerated treatment regimens in the near future. Nevertheless, numerous challenges remain, including choice of patients to treat, potential for drug-drug interactions and overlapping toxicities between HIV and HCV therapy. The dramatically improved rates of HCV cure under new triple therapy, however, warrant evaluation of these new treatment options for all co-infected patients.

A survey of hepatitis C treatment clinical practice patterns using the newly approved protease inhibitors

GOALS

To describe current hepatitis C virus (HCV) treatment practices in the United States and identify physician characteristics associated with the use of first generation direct-acting antivirals (DAAs).

BACKGROUND

HCV treatment practice patterns have not been assessed after the introduction of DAA, which are now considered standard of care for most HCV genotype 1 patients.

STUDY

We sampled nationally representative physicians treating HCV patients with DAAs through a web-based survey. Stepwise multivariate logistic regression was performed to identify physician characteristics associated with the use of DAAs in 4 clinical vignettes (early stage fibrosis, prior null response, human immunodeficiency virus (HIV) co-infection, and post-liver transplantation).

RESULTS

Of 1658 deliverable emails, 337 (20.3%) clinicians responded. Fifty percent of providers recommended DAA therapy for treatment-naive patients with early stage fibrosis, whereas 49% of providers would await new therapies. For prior null responders with significant fibrosis, 74% would attempt retreatment using DAAs and 26% would await new therapies. Off-label use of DAAs was recommended by 69% of providers for patients with HIV infection and 48% of providers for post-liver transplant patients. Academic affiliation was significantly associated with higher rates of off-label use in both HIV and post-liver transplant patients.

CONCLUSIONS

Despite more potent and less toxic therapies on the horizon, many physicians recommended DAAs in treatment-naive patients with early stage fibrosis. Providers also frequently recommended DAAs for off-label uses, such as treating post-liver transplant patients and those coinfected with HIV.

Liver abnormalities in the immunosuppressed

The immunosuppressed state may arise due to medical illness or drug therapy, which can result in a diverse array of liver derangements. This article discusses the commonly-encountered immunosuppressed conditions and the associated specific liver diseases. Due to the frequency of blood-borne viral disease globally, viral hepatitis (hepatitis B and C) during chemotherapy, transplantation and the increasingly utilised biological therapies for autoimmune disorders is discussed. An overview of human immunodeficiency virus co-infection with hepatitis B and C is provided. This article aims to highlight the variety of liver diseases which can occur in clinically relevant, particularly iatrogenic, immunosuppressed conditions, and summarise learning and practice points for clinicians. Recognition and prevention of viral liver disease is crucial and early involvement of experts prior to administration of immunosuppressive therapy is advised.

Telaprevir in HIV/HCV-coinfected patients: a new standard with a short half-life

The licensing of the first HCV protease inhibitors will lead to a dramatic increase in cure rates for patients with chronic genotype 1 hepatitis C. The addition of a third drug, such as telaprevir, to the standard treatment with pegylated interferon and ribavirin has become the new standard of care in the western world. While a shortening of the treatment duration is often possible, side effects are likely to increase with these products. The experience with telaprevir in HIV/HCV-coinfected patients is limited to one Phase II trial. Nevertheless, HIV-positive patients are in urgent need for new treatment options, as they often have more aggressive liver disease and lower reponse rates with the current standard treatments. These initial results are very promising, and HIV/HCV-coinfected patients seem to now have equal response rates as monoinfected patients, as long as drug–drug interactions remain under control.

Temporal changes and regional differences in treatment uptake of hepatitis C therapy in EuroSIDA

OBJECTIVES

All HIV/hepatitis C virus (HCV)-coinfected patients with chronic HCV infection and ≥ F2 fibrosis should be considered for HCV therapy. This study aimed to determine the rate of HCV treatment uptake among coinfected patients in Europe.

METHODS

EuroSIDA patients with viraemic HCV infection were included in the study. Poisson regression was used to identify temporal changes and regional differences in HCV treatment uptake.

RESULTS

A total of 1984 patients were included in the study, with a median follow-up time of 168 months [interquartile range (IQR) 121-204 months]. To date, 501 (25.3%) HIV/HCV-coinfected patients have received HCV therapy. Treatment incidence rose from 0.33 [95% confidence interval (CI) 0.16-0.50] per 100 person-years of follow-up (PYFU) in 1998 to 5.93 (95% CI 4.49-7.38) in 2007, falling to 3.78 (95% CI 2.50-5.07) in 2009. After adjustment, CD4 cell count > 350 cells/μL [incidence rate ratio (IRR) 1.33 (95% CI 1.06-1.67) vs. CD4 count 200-350 cells/μL] and ≥F2 liver fibrosis [IRR 1.60 (95% CI 1.14-2.25; P = 0.0065) vs. < F2 fibrosis] were predictors of anti-HCV treatment initiation. However, 22% of patients who remain untreated for HCV, with fibrosis data available, had ≥F2 fibrosis and should have been considered for treatment, while only 36% of treated patients had ≥F2 fibrosis.

CONCLUSIONS

Although treatment incidence for HCV has increased, there remain a large proportion of patients indicated for treatment who have yet to be treated.

Triple combination therapy for hepatitis C with telaprevir exhibits greater early antiviral activity than with boceprevir

BACKGROUND

Achievement of early viral suppression is important in patients with chronic HCV infection treated with telaprevir (TLV) or boceprevir (BOC) to avoid selection of drug resistance and attain cure. No head-to-head studies comparing TLV and BOC have been performed so far.

METHODS

All consecutive individuals who initiated triple HCV therapy with TLV or BOC outside clinical trials at three European clinics were evaluated. Rapid virological response (RVR) was defined as unquantifiable HCV RNA (<25 IU/ml) at week 4 for TLV and at week 8 for BOC (4 weeks after lead-in).

RESULTS

A total of 106 patients were evaluated, 33 treated with BOC and 73 with TLV. Median age, gender, body mass index, baseline HCV RNA, HCV subtype 1a (45% versus 42%) and IL28B-CC alleles (29% versus 23%) did not differ significantly in BOC and TLV groups, respectively. HIV coinfection was more prevalent in patients on TLV than BOC (24% versus 44%). Conversely, more patients on BOC than TLV had previously failed pegylated interferon plus ribavirin (82% versus 64%). RVR was achieved by 82% of patients on TLV versus 59% on BOC (P=0.001). Multivariate logistic regression analysis confirmed that TLV use was the strongest predictor of RVR (OR 3.54 [95% CI 1.23, 10.24]; P=0.02), others being HCV subtype 1b versus 1a (OR 3.26 [95% CI 1.17, 9.09]; P=0.02) and low baseline HCV RNA (OR 0.41 [95% CI 0.16, 1.03]; P=0.06). Prior interferon exposure, HIV coinfection or absence of advanced liver fibrosis did not influence the likelihood of RVR.

CONCLUSIONS

Compared to BOC, triple therapy with TLV produces greater RVR rates. TLV might be a better option in more difficult-to-cure patients, such as those with high baseline HCV RNA and/or HCV 1a subtype. HIV coinfection does not influence early HCV RNA responses.

Increasing Hepatitis C treatment uptake among HIV-infected patients using an HIV primary care model

Background

Access to Hepatitis C (HCV) care is low among HIV-infected individuals, highlighting the need for new models to deliver care for this population.

Methods

Retrospective cohort analysis that compared the number of HIV patients who initiated HCV therapy: hepatology (2005–2008) vs. HIV primary care model (2008–2011). Logistic-regression modeling was used to ascertain factors associated with HCV therapy initiation and achievement of sustained viral response (SVR).

Results

Of 196 and 163 patients that were enrolled in the HIV primary care and hepatology models, 48 and 26 were treated for HCV, respectively (p = 0.043). The HIV/HCV-patient referral rate did not differ during the two study periods (0.10 vs. 0.12/patient-yr, p = 0.18). In unadjusted analysis, predictors (p < 0.05) of HCV treatment initiation included referral to the HIV primary care model (OR: 1.7), a CD4+ count ≥400/mm3 (OR: 1.8) and alanine aminotranferase level ≥63U/L (OR: 1.9). Prior psychiatric medication use correlated negatively with HCV treatment initiation (OR: 0.6, p = 0.045). In adjusted analysis the strongest predictor of HCV treatment initiation was CD4+ count (≥400/mm3, OR: 2.1, p = 0.01). There was no significant difference in either clinic model (primary care vs. hepatology) in the rates of treatment discontinuation due to adverse events (29% vs. 16%), loss to follow-up (8 vs. 8%), or HCV SVR (44 vs. 35%).

Conclusions

Using a HIV primary care model increased the number of HIV patients who initiate HCV therapy with comparable outcomes to a hepatology model.