Sunday July 29, 2012
WHILE current knowledge about hepatitis C (HCV) is growing by leaps and bounds, doctors are still grappling with the most effective way to treat HCV, which consists of at least six genotypes.
A genotype refers to the genetic make-up of an organism or group of organisms with reference to a single trait, set of traits, or an entire complex of traits.
HCV genotype 1 (G1) is the most common genotype encountered (consisting of up to 60% of cases in the United States, Europe and Japan), but unfortunately, it is also the hardest to treat.
“The G1 usually does not respond well to treatment, and patients need a longer duration of treatment. For example, the response rate for those with G1 is at 40-50% at best, while those with G3 can be as high as 80%,” said Dr Tan Soek Siam, a consultant hepatologist who heads the Department of Hepatology and Hepatology Service at Selayang Hospital, Selangor.
Currently, the most widely used drugs are a combination of pegylated interferon (injection) and ribavirin (tablet form).
The benchmark for hepatitis C treatment to be declared a success is that the HCV (or specifically, bits of viral genetic material called ribonucleic acid, or RNA) must no longer be detectable in the blood six months after completion of treatment, a phenomenon otherwise known as sustained viral response (SVR).
Since the liver has a certain level of regenerative ability, achieving SVR as quickly as possible is important as some liver damage could be reversed if the cause of the damage is removed early enough.
After SVR is reached and depending on the degree of damage from the virus, the risk of liver cancer is reduced.
Conventional treatment (a combination of pegylated interferon and ribavirin, otherwise known as peg/riba) doesn’t necessarily eliminate the hepatitis C virus from the liver, though the regime can certainly suppress the virus to undetectable levels for an extended period of time.
Studies have shown that with a six-month SVR, relapse occurred in 1-2% of the patients. In other words, for every 100 people who attained SVR after completing treatment, the virus made a comback in two of them (for whatever reason, the virus was able to continue replicating).
Adults with G1 hepatitis C and stable liver problems who have not been treated before, or who have failed previous treatments, can now be considered for a new drug called boceprevir.
“Boceprevir is a HCV protease inhibitor that targets the virus directly. It is a first generation direct-acting anti-viral that was developed based on current knowledge of the HCV life cycle. It kills the virus by inhibiting viral replication,” said Dr Tan. “We dare say it is a cure for HCV, and that is something we cannot say for other forms of treatment for chronic diseases.”
Nonetheless, boceprevir is not a stand-alone therapy, and must not be used on its own. According to Merck, boceprevir, when used in combination with peg/riba, offers a greater chance of success compared to treatments based on peg/riba alone.
In Malaysia, three patients are now on a regime of boceprevir, courtesy of a “compassionate programme” offered by Merck.