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The hepatitis C virus (HCV) is
the most common chronic blood-borne infection in the United States,
with about 2.7 million people
being infected, according to
an editorial in the New England Journal of Medicine. In addition,
most of those infected go undiagnosed, since it usually produces
no symptoms.
Now, two new studies have shown that a new, modified form of interferon,
the currently preferred therapy of mainstream medicine for hepatitis
C, is more effective than ordinary interferon.
Standard interferon is usually given in combination with the drug
ribavirin, but the treatment provides long-lasting
benefits to fewer than 20% of patients who receive it
and can cause serious side effects.
Since regular interferon does not remain in the body for long,
it is usually taken three times a week. But a process called
pegylation produces peginterferon alfa-2a, which stays in the body
longer so patients only have to take it once a week.
Pegylation is a process by which a molecule of the polymer polyethyleneglycol
(PEG) is joined to the drug. The purpose is to alter the metabolism
and excretion of the active agent in order to reduce the frequency
of doses.
"In patients with chronic hepatitis
C, a regimen of peginterferon alfa-2a given once weekly is more
effective than a regimen of interferon alfa-2a given three times
weekly" researchers conclude.
In the second study, researchers report that peginterferon alfa-2a
is more effective than ordinary interferon in patients with HCV
who have already developed cirrhosis or some scarring of the liver.
Normally, anti-HCV treatment can cause extremely serious side effects
in people who have already developed liver scarring.
Both studies were funded by F. Hoffmann-LaRoche, the Swiss company
that makes peginterferon alfa-2a, which is not currently approved
for use in the US.
In an accompanying editorial, Drs. Daniel F. Schafer and Michael
F. Sorrell, of the University of Nebraska Medical Center in Omaha,
note that peginterferon alfa-2a may be a promising treatment for
HCV. However, they note that a higher percentage of Americans than
in the studies are infected with a strain of HCV that is more resistant
to treatment. Whereas 75% of infected persons in the US carry a
variant of HCV that is more resistant to interferon alfa therapy,
only 62% and 56% percent of the patients in the two just-published
trials had this strain of the virus.
The NEJM editorialist notes:
Combination therapy with interferon alfa and ribavirin
is now considered the treatment of choice for chronic hepatitis
C. Even this therapy is none too good, however: more than
half the patients who receive treatment will continue to have viremia
once treatment is stopped ... . The complex and shifting balance
between host and virus has driven hepatologists to adopt the language
of oncologists. Instead of "cure," we have "response"
(loss of measurable levels of virus in the blood during therapy)
and "sustained response" (loss of measurable levels of
virus 24 weeks after the completion of therapy). Clinical trials
focus on a variety of end points, including biochemical, virologic,
and histologic responses. This cautious terminology is necessary
for a disease with a variable natural history and a rate of progression
that is measured in decades.
The New England Journal of Medicine
December 7, 2000; 343: 1666-1680, 1723-1724
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