26 Mar, 2012
Source: Australian Doctor
Author: Nyssa Skilton
Unexpectedly severe side effects are hampering the roll-out of two highly promising drugs for hepatitis C, an expert says, amid ongoing setbacks in securing PBS listings.
Both telaprevir (Incivo) and boceprevir (Victrelis) were approved by the Therapeutic Goods Administration for the treatment of genotype 1 HCV in February this year - becoming the first new treatment options in more than a decade.
The drugs - described as "breakthroughs" in a long-stagnant therapeutic area - are taken orally and have significantly higher cure rates and potentially halve the treatment time of current therapies.
However, Professor Robert Batey, clinical director of the viral hepatitis program at the Australasian Society for HIV Medicine, said there was now an emerging belief among specialists that the new drugs were "not as brilliant as we thought they were".
"We've all been hyped up to wait for these drugs but the reality is they're coming with significant side-effect profiles," Professor Batey said.
Boceprevir was linked with increased rates of anaemia, while telaprevir could cause severe rash and perianal discomfort in a small proportion of patients, he said.
Both agents must be administered alongside standard peginterferon-ribavirin therapy, and can cut the treatment duration down to just 24 weeks, from the usual 48-week regimen.
They have so far been denied PBS listings amid uncertainty about their cost effectiveness and likely uptake. Both are available to limited numbers of patients through early access programs.
Professor Batey expected another generation of hepatitis C drugs could be available in Australia in the next 5-7 years, and would not require co-administration with interferon-based regimens.
"Unless you've got severe disease, you''re probably going to want to wait for the next generation of drugs, because they're going to be even more effective and have fewer side effects," he said.
However, Professor Geoff McCaughan, director of the University of Sydney's AW Morrow Gastroenterology and Liver Centre, maintained that telaprevir and boceprevir were a big step forward from current therapy.
"The significant advances are that there's been a 50% increase in the cure rate, and that 50% of patients with both these drugs have therapies reduced from 12 months to six months," he said.
Professor McCaughan said significant side effects such as anaemia and rash had been documented from clinical trials of both drugs, and cautioned against "paying too much attention" to anecdotal reports.
He noted telaprevir offered the shortest course of protease inhibitor therapy - 12 weeks compared with 24 or 48 weeks - potentially limiting the extent of side-effects experienced.
The TGA in January approved boceprevir for use in genotype 1 HCV patients, and this month granted the same approval to telaprevir.
However PBS listing has remained a hurdle for both drugs: the Pharmaceutical Benefits Advisory Committee rejected telaprevir at its November meeting, having previously rejected boceprevir. The PBAC has just reviewed boceprevir for a second time, but is now understood to have deferred the decision.
Boceprevir manufacturer MSD said the drug was an important new option in HCV treatment, particularly for patients with genotype 1.
"It is important to recognise the significant impact HCV has on its sufferers which can include cirrhosis, liver cancer and mortality," a company spokesman said.
Professor McCaughan has served on advisory boards for the manufacturers of both boceprevir and telaprevir.
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