A cure for hepatitis C should soon be possible for most patients with the virus, an expert predicts, but unless treatment uptake skyrockets, many will miss out.
Infectious diseases physician Associate Professor Joe Torresi from Melbourne's Austin Hospital Department of Infectious Diseases says emerging treatments could boost overall cure rates to as high as 95%.
Torresi will speak at the Australasian Society for Infectious Diseases annual meeting being held in Darwin this week.
"Combination antiviral therapy of pegylated interferon-a and ribavirin has become the standard of care for patients with chronic hepatitis C, and it is now possible to achieve high cure rates with this therapy," he says.
"However with the advent of direct acting antivirals and various immunotherapeutic approaches it should become possible in the future to achieve a cure in almost all patients infected with hepatitis C."
Torresi says cure rates depend on the strain or genotype. In Australia half of those infected have genotype 1, and one-third have genotypes 2 or 3, with the rest type 4 or other strains.
Treatment for 24 weeks achieves cure, defined as sustained virological response or SVR, in up to 85% of type 2 and 3 cases, while 48 weeks treatment cures between 40 and 50% of type 1 cases. But type 1 patients who have a rapid response four weeks into therapy have a cure rate up to 80% and for types 2 and 3, it is 95%.
Torresi says direct acting antivirals target a different part of the virus, preventing replication, but are not yet commercially available.
"They will probably be added to existing treatments for genotype 1 infected patients. Clinical trials [funded by drug companies] for two of them - Telaprevir and Boceprivir - found they boost SVR in those with type 1 from between 40% and 50% to 60% and 70%," he says.
"Many different types of these treatments are being developed including immunotherapetic treatments such as vaccines and drugs to block the entry of the virus into liver cells.
"Using a number of different classes of drugs in combination we hope would cure almost all of those infected and lift genotype 1 cure rates to those of genotype 2 and 3.
"If direct acting antivirals do translate to a 20% to 25% increase in SVR for genotype 1 patients, as indicated in initial clinical trials, we can expect to cure 75% to 95% of patients with hepatitis C overall."
The Austin Hospital is currently conducting clinical trials of combination therapies for hepatitis, which involves Torresi as co-investigator, along with a number of specialist gastroenterologists and hepatologists. He says he has no connection to the drug companies and does not receive funding from them.
Low treatment rates
Physician and epidemiologist Dr Benjamin Cowie from the Victorian Infectious Diseases Service, who will also speak at the conference, says without a substantial increase in the proportion of those infected receiving treatment, mortality will continue to escalate.
According to a new report by the National Centre in HIV Epidemiology and Clinical Research, only 10% of those with hepatitis C in Australia have received treatment, and just 2% are currently undergoing therapy.
A separate report, the 3rd National Hepatitis C Strategy 2010-2013 endorsed by the Federal Government, says while 284,000 Australians have been exposed to hepatitis C, some have been cured or spontaneously cleared the virus. Of the remaining 212,000 who currently have chronic hepatitis C, between 40,000 and 50,000 are undiagnosed cases.
It adds, only 3500 a year are undergoing treatment, despite 10,000 new infections and 330 deaths occurring annually, a number which is expected to start rising sharply.
Despite the numbers, the strategy also highlights the improvements in treating hepatitis.
"It is possible the new agents will be approved, potentially shorten treatment duration and improve response rates," says the report.
Cowie agrees that in the future it may be possible to cure most cases.
"It could happen soon because the rate of change in therapies for hepatitis C and B has been profound," he says. "A substantial proportion of those infected [with hepatitis C] can't tolerate existing drugs or they don't clear the virus. But indications are some of the new agents may enhance abilities to cure the virus."
He says one in four spontaneously clear the virus after infection but most develop chronic hepatitis, which if untreated may progress to potentially fatal cirrhosis, liver cancer or liver failure.
Cowie says side-effects and 'clinic waits' may deter some from seeking treatment. Torresi believes many think it is a death sentence, but once clinicians counsel patients about their treatment and the chance of cure, they generally stick with it.
Hepatitis C is a blood borne virus, mainly transmitted by sharing drug injecting equipment.
Transmission can also occur via non-sterile tattooing and body piercing, unsterile medical or dental procedures, from mother to infant during delivery, via needlestick injuries or exposure to blood or blood product.