You are here
Study Shows Adding Peginterferon Alfa-2a Doubles Efficacy of Conventional Interferon
PEGASYS given for six months at the same 180 ug dose as in hepatitis C, showed a combined end point of HBeAg loss, HBV DNA below 500,000 copies/ml and normalisation of ALT, of 28% compared to 12% for conventional interferon (Roferon(r) A: 4.5 MIU).
The Phase II study assessed the efficacy of PEGASYS in patients with difficult-to-treat HBeAg-positive CHB, which was defined as high pre-treatment HBV DNA (high levels of replicating virus in the patient's liver) and low pre-treatment ALT (indicating a weak natural response from the patients immune system to HBV). These factors are considered predictors of a poor response to HBV therapy. As in hepatitis C, where genotype 1 is considered difficult to treat, there is also evidence that those infected by the HBV genotype C virus respond less well to treatment.
"Until now, there was only a slim chance that these hepatitis B patients could be cured of their disease," said Professor Graham Cooksley, the lead investigator of the study and Senior Principal Research Fellow, Clinical Research Centre, Royal Brisbane Hospital, Australia. "These monotherapy results are extremely positive and demonstrate the same kind of efficacy in hepatitis B as we saw with genotype 1 patients in hepatitis C. PEGASYS works very well in those with the most treatment-resistant disease."
PEGASYS fared better than conventional interferon in every efficacy parameter measured. The efficacy parameters were:
- HBeAg loss (loss of viral protein indicates that viral replication has stopped)
- HBV DNA below 500, 000 copies/ml (a level that indicates the virus is being effectively controlled)
- normalisation of ALT (normal ALT enzyme level reflects normal function of the liver)
When all of the response criteria noted above are met, this is described as a "combined response."
Results in difficult-to-treat HBV Disease
- In patients with low pre-treatment ALT (0- 2 x upper limit of normal), the combined response was achieved in 27% of patients treated with PEGASYS compared to 11% of patients treated with conventional interferon.
- In patients with high pre-treatment HBV DNA (> log 8.5 HBV DNA), the combined response was achieved in20% of patients on Pegasys compared to 14% of patients treated with conventional interferon.
- In patients with HBV genotype C, the combined response was achieved by 21% of PEGASYS patients compared to 6% of interferon patients.
The 194 patients in the study were treated with either conventional interferon three times weekly or PEGASYS (at 90 ug, 180 ug or 270 ug) once weekly for a 24-week-period, and were then observed with no further treatment over the subsequent 24 weeks.
In addition to this research effort, there are two phase III studies approaching completion. These studies explore the benefit of a longer duration of treatment (48 weeks) where it is postulated that even higher response rates may be achieved based on data with conventional interferon. These studies, which use the same 180 ug dose, will also explore the efficacy of combining of PEGASYS with lamivudine, a nucleoside analogue.
New Hope for HBV Sufferers
Currently, lamivudine, adefovir dipovoxil and conventional interferon alfa are the sole agents approved for the treatment of hepatitis B. However, these agents have clear limitations in terms of overall efficacy and about 20 per cent of patients treated with lamivudine develop resistance to the drug within one year of therapy. In addition, the majority of patients treated with lamivudine are required to continue therapy indefinitely. PEGASYS overcomes the limitations of current therapies; delivering higher efficacy within a defined treatment duration. Importantly, the hepatitis B virus is unlikely to develop resistance to PEGASYS.
About Hepatitis B
Hepatitis B is a blood-born virus that attacks the liver and is the most common serious liver infection in the world. The Hepatitis B virus is highly contagious and is relatively easy to transmit from one infected individual to another. It is 100 times more infectious than the HIV virus.
Despite a highly effective vaccine, More than two billion people have been infected by HBV and 350 million people have chronic infection, which can be easily transmitted by blood-to-blood contact, during birth, sex, and by sharing needles. For those chronically infected with HBV, treatment is the only option. Hepatitis B is the ninth leading cause of death in the world; left unchecked, it can cause liver cancer and death.
PEGASYS, a new generation hepatitis C therapy that is different by design, provides significant benefit over conventional interferon therapy in patients infected with HCV of all genotypes. The benefits of PEGASYS are derived from its new generation large 40 kilodalton branched-chain polyethylene glycol (PEG) construction, which allows for constant viral suppression. PEGASYS also distributes more readily to the liver (the primary site of infection) than conventional interferon. PEGASYS is the only pegylated interferon available as a ready-to-administer solution. Each weekly subcutaneous injection contains 180mcg of pegylated interferon alfa-2a which is the recommended dose for all patients, regardless of body weight.
PEGASYS has been approved for the treatment of chronic hepatitis C in more than 70 countries, including the European Union and the United States. The most recent approvals for PEGASYS have occurred in China and New Zealand.