Originally published April 26.
This article was updated on April 27 to include information about Merck's protease inhibitor Victrelis.
Quest Diagnostics last week launched its AccuType IL28B test for helping doctors predict which patient are likely to respond to peginterferon alpha-based therapy for hepatitis C virus infection.
AccuType IL28B was developed under a global non-exclusive license agreement with Schering-Plough, which merged with Merck in late 2009. Under the terms of the deal, Schering licensed to Quest patent rights claiming interleukin 28B genetic markers linked to patient response to peginterferon alpha-based HCV therapy.
In introducing its Accutype test, Quest will compete with the Laboratory Corporation of America, which in July 2010 launched its own IL28 genotyping test.
Similar to LabCorp's test, Quest's assay gauges the presence of SNPs in IL28B, which are found in people with the most common HCV infection, HCV genotype 1. In previous studies, HCV patients with the homozygous IL28B rs12979860 C/C allele have been most likely to spontaneously clear HCV and appear to have the best response to interferon-based therapy. People with T/T alleles are least likely to have a good response to interferon treatment and heterozygous patients have an average response.
"Our AccuType IL28B test will give physicians greater insights for treating individual patients infected with the most common form of HCV using standard antiviral therapies," Rick Pesano, medical director of infectious diseases at Quest, said in a statement. The company added that non-genetic factors such as age and gender could also affect a person's response to interferon-based treatments.
Pesano added that Quest may eventually extend the indication for the AccuType IL28B test to predict response to alternative HCV therapies, such as protease inhibitors that are currently under review by the US Food and Drug Administration. Currently, the company is selling the laboratory-developed test to US healthcare providers and to drug companies interested in using it in clinical trials.
It's unclear whether Quest's test is being used by drug firms developing HCV protease inhibitors. The company did not respond to questions for this article.
On April 27, the FDA's Antiviral Drugs Advisory Committee unanimously recommended that the agency approve Merck's protease inhibitor for HCV genotype 1 infections Victrelis (boceprevir) in combination with current standard therapy.
On April 28, the same advisory will discuss Vertex's new drug application for its HCV protease inhibitor telaprevir. Vertex is proposing that the drug be indicated as a treatment of chronic HCV genotype 1 infection, and given in combination with peginterferon alpha and ribavirin to adult patients with "compensated liver disease who are previously untreated or who have failed previous therapy." Patients with "compensated liver disease," have livers that are damaged but are still functioning.
Quest is hoping that with this test, physicians can improve outcomes for HCV patients, many of whom have lackluster response to peginterferon alpha-based therapy or experience side effects that cause them to discontinue treatment.
Standard treatment for HCV is a combination interferon-ribavirin therapy given to the patient over several months. Patients who take this treatment commonly experience side effects, such as fatigue, depression and nausea, and as a result, between 10 percent and 14 percent discontinue treatment, Quest estimates. In addition, according to reports, 50 percent of patients fail to eradicate the HCV virus, even after a full course of therapy.
Based on statistics from the US Centers for Disease Control and Prevention, 3.2 million people in the US have chronic HCV infections, and between 8,000 and 10,000 people die each year from the blood-borne infection, which can lead to liver cancer or liver cirrhosis if untreated.
AccuType IL28B is the newest addition to Quest Diagnostics' existing HCV test menu, including hepatic function tests that gauge HCV exposure and identify abnormal liver function; Heptimax, a viral RNA quantitative test that monitors viral load during treatment; HCV genotyping that helps doctors assess treatment duration and success; and HepaScore, a test to help physicians identify and stage liver fibrosis.