Vertex Pharmaceuticals has posted some highly promising late-stage data which shows that 75% of patients with chronic hepatitis C not on any drug were cured following treatment based on the firm’s investigational antiviral telaprevir.

In the first of three Phase III trials, 1095 patients with HCV were randomised to receive 12 weeks of telaprevir plus pegylated-interferon and ribavirin (the current standard of care), followed by treatment with the latter two drugs. Some 75% of the patients in the 12-week telaprevir group achieved sustained viral response (SVR or viral cure) six months after treatment stopped, while 69% achieved SVR after receiving an eight-week telaprevir-based combination regimen, followed by treatment with pegylated-interferon and ribavirin alone.

Vertex chief medical officer Robert Kauffman called the data “groundbreaking”, noting that the majority received only 24 weeks of therapy, “marking what we believe may be a potentially dramatic improvement in the future treatment of HCV”. He added that fewer than half of people with genotype 1 hepatitis C achieve a viral cure with currently approved therapies.

One slight problem, however, were the adverse events, of which anemia, rash, pruritus and nausea occurred more frequently in the telaprevir-based treatment arms than in the control arm. Datamonitor analyst Hedwig Kresse noted that “the rash is somewhat of a problem, but not as critical as side effects observed for some of telaprevir’s competitors”, such as the anaemia reported for Merck & Co’s investigational drug boceprevir.

She added that “telaprevir will be a very welcome addition to HCV treatment, particularly in the hard-to-treat population of genotype 1 patients, non- or partial responders to standard therapy”. The drug is being developed in collaboration with Johnson & Johnson’s Tibotec Pharaceuticals and Japan’s Mitsubishi Tanabe Pharma.