Injectable-drug users make up the largest group of those infected with… (Victoria Sayer Pearson )
In findings that may represent a breakthrough in the treatment of hepatitis C infection, researchers have reported that weekly injections of an experimental medication that denies the virus a foothold in the liver substantially drove down subjects' viral loads after five weeks of treatment. Fourteen weeks after the injections ended, researchers found that five of 18 infected subjects getting the medication's higher doses showed no detectable trace of infection.
The new study describes a treatment approach that could outsmart the hepatitis C virus's penchant for developing resistance to existing drugs and "provide curative therapy to a large proportion" of the 170 million people in the world who are infected with the virus, wrote Harvard University physician Dr. Judy Lieberman and Dr. Peter Sarnow of Stanford University.
The treatment, called miravirsen, does so by targeting the "Achilles' heel" that is common to all of the hepatitis C virus' diverse strains--their universal need to colonize certain bits of protein that turn genes on and off in the liver. Miravirsen is an antisense oligonucleotide: It enters the liver cells and binds tightly to those messenger proteins the hepatitis C virus needs to survive and replicate. By denying the virus its host, miravirsen could leave the virus homeless.
Even the wiliest strains of the virus would be locked out of the sanctuary they need to develop resistance to protease inhibitors such as teleprevir and boceprevir. And that, in turn, could free hepatitis C patients from the need to take interferon and ribavirin, which come with such side effects as fatigue, flu-like symptoms, anxiety, depression, diarrhea and nausea.
But the safety of using miravirsen for long periods at high doses remains a question for further research, Lieberman and Sarnow wrote: As it happens, miravirsen targets a bit of genetic material that helps suppress the development of fatty liver, liver fibrosis and liver tumors, all of which are side effects of hepatitis C infection as well.
Such safety concerns might limit the sweeping promise of miravirsen to cure hepatitis C infection in all its forms, Lieberman and Sarnow said. But even then, it could become part of a cocktail of antiviral medications that, collectively, could hold such infections in check. And on the plus side, they noted, miravirsen appeared to have the effect of lowering cholesterol in subjects -- a particular advantage because hepatitis C sufferers taking protease inhibitors cannot take cholesterol-lowering statin drugs.
The new research, as well as Lieberman and Sarnow's assessments of its promise, were published Wednesday on the New England Journal of Medicine's website.