Recent Trends in the Treatment of Chronic Hepatitis C
Published Online: April 16, 2014
Sara C. Erickson, PharmD; Wenyi Qiu, MS; Crystal R. Maas-Patel, PharmD; Sharon M. Wang, PharmD, MS; and Bimal V. Patel, PharmD, MS
Since the discovery of the hepatitis C virus (HCV) in 1989, the chronically infected population has experienced dynamic change. The prevalence of chronic HCV infection in the United States has decreased over the past decades, with the most recent estimate at approximately 2.7 million people (or 1%) of those 6 years and older.1 The decline corresponds with the increase in HCV-associated deaths and decreased transmission rather than from an increase in treatment success.1,2 Increasing access to more effective and affordable treatments is a major public health concern.
Chronic HCV infection remains largely undertreated, with only 13% to 18% of infected individuals having received treatment.3,4 The largest barrier to treatment is that many infections remain undiagnosed, with fewer than half of all HCV-infected individuals being aware of their infection.5 Other barriers to treatment include contraindications or perceived contraindications by prescribers, lack of access to prescribers with HCV expertise, and patient barriers (eg, the asymptomatic nature of the infection, fear of medication side effects, and concerns regarding treatment duration, cost, and effectiveness).6,7 Patients and prescribers have postponed treatment in hopes of more effective and more tolerable treatments on the horizon.8
After developing chronic HCV infection, 60% to 70% will progress to chronic liver disease; 5% to 20% will develop cirrhosis; and 1% to 5% will die from cirrhosis or liver cancer.9 However, these sequelae take decades to develop, and for most patients, there is no urgency for treatment. Treatment is recommended for individuals with existing liver disease or fi brosis, but may be delayed for those with less severe disease.10
As the majority of patients are believed to have acquired their infection between the 1960s and the 1980s, the proportion of newly diagnosed patients with mature infection requiring immediate treatment is steadily on the rise.11 Chronic infection is more often found among individuals over age 50 years. Approximately 81% of individuals with HCV infection were born between 1945 and 1965.1 In 2012, the Centers for Disease Control and Prevention issued guidance that all persons born in this time frame should be screened for HCV at least once, regardless of risk factors.12 With increased screening, more individuals are likely to be diagnosed and receive treatment in coming years.
The goal of therapy is to eradicate HCV infection, and with it to prevent liver cirrhosis, liver failure, hepatocellular carcinoma (HCC), and death.10 The eradication of HCV is determined by a highly sensitive assay in which circulating HCV RNA is undetectable at 12 or 24 weeks after completion of treatment—known as sustained virologic response (SVR). SVR at 24 weeks has been shown to provide a durable response and is associated with improvement in liver fibrosis, reduced risk of liver-related morbidity and mortality (including liver failure, liver transplantation, and HCC), and reduced risk of all-cause mortality, even in advanced cases.13-19 In 2013, undetectable serum HCV RNA at 12 weeks after the end of treatment was found to be concordant with testing after 24 weeks, and has become the new standard of care and end point used in clinical trials.20,21
Genotype 1 is the most common HCV genotype in the United States, comprising approximately 70% of all cases. It is also the most difficult to treat, requiring prolonged therapy. Beginning in 2001, pegylated interferon plus ribavirin was the standard-of-care treatment for all genotypes. A 48-week regimen with pegylated interferon and ribavirin for genotypes 1, 4, 5, and 6 typically resulted in SVR rates of 40% to 50% (Figure 1). In clinical trials, treatment-naïve patients with HCV genotypes 2 and 3 treated with pegylated interferon plus ribavirin for 24 weeks often obtained SVR rates of 70% to 80%.
The SVR rates achieved in clinical trials may not always be realized due to suboptimal patient adherence in the general population.22,23 Severe side effects often negatively impact patient adherence to therapy.24 Pegylated interferon products have a black box warning of fatal or life-threatening neuropsychiatric, autoimmune, ischemic, and infectious disorders. The side effects of pegylated interferon that often cause the most frequent complaints from patients are the flu-like symptoms, which must be tolerated for up to 48 weeks. Ribavirin also has serious side effects, including anemia, which can worsen heart disease, and teratogenicity.
In 2011, 2 direct-acting antiviral (DAA) non-structural (NS) 3/4A protease inhibitors, boceprevir and telaprevir, were approved to treat genotype-1 HCV. SVR was achieved for an additional 25% to 31% of treatment-naïve patients treated with boceprevir or telaprevir plus pegylated interferon and ribavirin compared with standard dual therapy.25,26 Boceprevir and telaprevir require complex treatment response–guided regimens, carry signifi - cant pill burdens, and have greater incidence of severe side effects such as cytopenias and skin reactions.25-28 Boceprevir and telaprevir are both substrates and inhibitors of P-glycoprotein and cytochrome P450 3A4, which can cause significant drug interactions. In one cohort study, potential drug interactions that required dose adjustments or medication changes were found in half the population initiating boceprevir or telaprevir.29
In late 2013, 2 additional oral DAAs were approved. Simeprevir, a third NS3/4A protease inhibitor, was approved for use in conjunction with pegylated interferon and ribavirin to treat HCV genotype 1. Advantages of simeprevir over first-generation NS3/4A protease inhibitors include once-daily dosing, slightly improved SVR rates, and an improved side effect profile. Overall, 80% of patients achieved SVR; however, among patients with genotype 1a, 58% of patients achieved SVR with the NS3 Q80K polymorphism compared with 84% of patients without the polymorphism.30 It is recommended, but not required, that patients be screened for the NS3 Q80K polymorphism prior to initiating regimens including simeprevir.
PDF is available on the last page.