Experimental hepatitis C vaccine shows promise, researchers say
An experimental hepatitis C vaccine found to be safe will move to second-stage clinical trials.
An experimental vaccine for hepatitis C has shown promise in preliminary human safety trials, according to researchers, and may pave the way to a more affordable means of fighting the virus.
In a paper published Wednesday in the journal Science Translational Medicine, authors wrote that 15 people in Britain were given a “prime and boost” course of the experimental vaccine.
Researchers said the shots stimulated a protective response from the body’s T cells -- white blood cells that are critical to battling pathogens.
Although the vaccine caused headaches, feverishness and fatigue in some subjects, researchers said those adverse effects disappeared within two days. Overall, they said the vaccine was proved to be “safe and well tolerated.”
A larger Phase II trial will now be performed on more than 350 test subjects at UC San Francisco and Johns Hopkins Bloomberg School of Public Health, according to the National Institutes of Health.
“We won’t really know if it works -- if it is able to prevent hepatitis C infection -- until we have the results of the efficacy studies in the USA,” said Eleanor Barnes, an immunology professor at Oxford University and the paper’s senior author.
Hepatitis C is believed to affect 180 million people worldwide, and is spread through contact with infected blood. It often is associated with intravenous drug use, and can lurk in the body for years before it is detected. It is a leading cause of liver cirrhosis and can lead to liver failure and liver cancer.
New therapies for patients infected with the virus have proved effective, but they are extremely costly -- a 12-week course of medication can cost up to $84,000.
The Phase I safety trial was conducted by researchers at Oxford, Stanford University and the Italian biotechnology company Okairos, which is part of GlaxoSmithKline.
“Although new oral antivirals are available ... these are unaffordable and unavailable to most people, are least effective in patients with advanced liver disease, are associated with development of viral resistance, and do not provide protection from reinfection,” the authors wrote. “For these reasons, an effective vaccine to prevent chronic infection remains of clinical importance.”
Researchers pointed out that 1 in 4 people who suffers a first-time infection of the virus will clear it from his or her body naturally. This strongly suggests the immune system can fight off the virus with help from a vaccine.
In this case, the experimental vaccine includes an initial “prime” shot of a weakened chimpanzee cold virus that has been genetically modified to carry four proteins associated with hepatitis C. A second “boost” shot, to be given eight weeks later, contains a modified vaccinia Ankara (MVA) virus with the same four proteins.
By injecting these viral proteins into the the body, researchers hope that T cells will recognize them as potential future threats and marshal an immune cell attack on the virus.
Study authors said they were encouraged by the immune system’s response following vaccination.
“The T cell response is really high, and what’s promising is that this is a broad response,” Barnes said in a statement. “A range of different T cells are produced targeting different parts of the hepatitis C virus.”
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