A team of researchers from Saint Louis University (SLU) in Missouri recently published a study advancing a new technique to predict if a patient infected with the hepatitis C virus (HCV) will respond to treatment. HCV can cause liver cancer, cirrhosis, end stage liver disease and ultimately liver failure. Such a test is needed because current therapies are costly, cause severe side effects and have a high failure rate.
Led by principal investigator Rajeev Aurora, PhD, professor in the molecular microbiology and immunology department, the team examined the genetic makeup of HCV to discern patterns that might reveal which patients would respond to therapy. Although a combination therapy of pegylated interferon and ribavirin is the standard treatment for patients with chronic HCV, nearly 50% do not respond.
However, even patients who do respond to treatment often suffer from debilitating side effects that can last the duration of the treatment—either 24 or 48 weeks. Interferon side effects include severe flulike symptoms, irritability, depression, skin rash, fatigue and insomnia. Ribavirin can cause anemia, skin rash and itching, nasal congestion, fatigue and birth defects. Another disadvantage of this combination therapy is the prohibitive cost of both drugs.
These considerable drawbacks provide the impetus for the development of an accurate, preliminary therapy response predictor. “If you can identify those patients who aren’t going to respond anyways because they’ve got a strain that is highly resistant to the drug, then you just don’t treat those patients and you save them $20,000 to $30,000 in medical bills just from drugs alone--not to mention the side effects,” said John E. Tavis, PhD, professor of molecular and microbiology at SLU, during a phone interview. He is a member of the study team.
The SLU team analyzed the ribonucleic acid (RNA) chains of HCV from 94 patients in the Virahep C Study Group, looking for indicators of treatment success or failure. Employing a mathematical formula, they uncovered a pattern of changes called “covariance networks.” The patterns, according to investigators, proved to be viable predictors. “What we found will allow a doctor to predict whether or not a medication will work in a patient,” added Tavis in a statement.
The two pegylated interferon brands available in the U.S. are Pegasys,®
Roche Holding AG’s product, which may be taken alone, but is often used in combination with the company’s ribavirin product COPEGUS®; and Schering-Plough Corporation’s Pegintron™, which is often prescribed with its ribavirin therapy, REBETOL®. There are several other HCV drug therapies in development, but they are in the clinical trials stage.
The study, “Genome-wide hepatitis C virus amino acid covariance networks can predict response to antiviral therapy in humans,” was published online on December 22, 2008 in The Journal of Clinical Investigation.
Source: Reuters, December 23, 2008