Long Term Interferon for Patients Who Did Not Clear Hepatitis C Virus With Standard Treatment

The HALT-C Trial is a National Institute of Diabetes and Digestive and Kidney Diseases
sponsored, randomized clinical trial of long-term use of Peginterferon alfa-2a (pegylated
interferon) in patients who failed to respond to prior interferon treatment. All patients who
enter the trial will be treated for 6 months with Peginterferon alfa-2a and Ribavirin.
Patients who respond to this 6 month treatment will continue to be treated for an additional
6 months.

Patients who do not respond to this treatment will be eligible for the long-term maintenance
phase of this study where patients will be randomly selected to be treated with Peginterferon
alfa-2a or to discontinue treatment for 3.5 years. Patients in both arms of this study will
be followed closely with quarterly study visits.

The combination of peginterferon plus ribavirin has recently been approved by the FDA for
treatment of chronic hepatitis C. Patients who remain HCV-RNA positive after being treated
for at least 6 months with peginterferon and ribavirin outside of this study may be eligible
to directly enter the randomized portion of the HALT-C Trial.

The HALT-C study is designed to determine if continuing interferon long-term over several
years will suppress Hepatitis C virus, prevent progression to cirrhosis, prevent liver cancer
and reduce the need for liver transplantation.