|Hepatitis B--Courtesy of U.S. National Library of Medicine|
Gilead Sciences ($GILD) is working on a small molecule to treat hepatitis B, a contagious liver disease that often begins as an acute infection but can turn into a chronic disease in some patients. The inflammatory illness affects an estimated 800,000 to 1.4 million people in the U.S. If left untreated, hepatitis B infection can damage the liver, causing cirrhosis and liver cancer.
Research published in the May issue of Gastroenterology by scientists at Gilead and the Texas Biomedical Research Institute showed that Gilead's immune modulator GS-9620 helped control the virus in chimpanzees. In the study, conducted at Texas Biomed's Southwest National Primate Research Center in San Antonio, researchers administered GS-9620--which targets a receptor on immune cells--to chimps three times a week for four weeks at 1 mg/kg and, after a one-week break, for four weeks at 2 mg/kg. GS-9620 reduced both the virus levels and the number of infected liver cells in chimpanzees chronically infected with the hepatitis B virus.
"This GS-9620 therapy represents the first conceptually new treatment for HBV in more than a decade, and combining it with the existing antiviral therapy could be transformative in dealing with this disease," study co-author Robert Lanford of Texas Biomed said in a previous statement.
The Gilead drug works by binding a receptor called Toll-like receptor 7, which is found in immune cells. Normally, Toll-like receptor 7 recognizes invading viruses and kicks the immune system into gear to stop viral replication using both arms of the immune system--the innate immune response and the adaptive immune response.
The preclinical work is notable because chimpanzees are the only species other than humans that can be infected by HBV and hence provide a good basis for safety and effectiveness in humans. Researchers previously had success when testing the drug in woodchucks with a virus similar to human hepatitis B.
Current treatment for hep B targets the virus and works to suppress viral replication and delay the progression of liver disease, but the medication must be taken over the course of a lifetime, and the therapy does not provide a cure. What's most encouraging about the preclinical work is that GS-9620 continued to suppress virus levels for months after therapy was stopped, a sign that the drug could have long-term benefits in humans.
Michele Rest, a spokesperson for Gilead, told FierceBiotechResearch in an email that the company has started testing GS-9620 in hepatitis B in Phase I studies. Gilead is also evaluating GS-4774, a therapeutic vaccine for hepatitis B, in Phase I studies.
Gilead drug clears hep B virus in chimpanzees