Tenofovir Works as Well as Adefovir for Chronic Hepatitis B
On
June 6, 2007, Gilead Sciences announced that its nucleotide analog tenofovir
(Viread) was as effective as adefovir (Hepsera)
for the treatment of chronic hepatitis B virus (HBV)
infection. Adefovir is currently approved as a treatment for hepatitis B.
Tenofovir is approved as a treatment for HIV, but not for HBV; it is also a component
of the fixed-dose combination pills Truvada
(tenofovir/emtricitabine) and Atripla
(tenofovir/emtricitabine/efavirenz).
Below
is an excerpt from Gilead's press release announcing the results from Study 102:
Phase
III Study Evaluating Gilead's Viread for the Treatment of Chronic Hepatitis B
Virus Meets Primary Endpoint
FOSTER
CITY, Calif. -- (BUSINESS WIRE) -- June 6, 2007 -- Gilead Sciences, Inc. (Nasdaq:GILD)
today announced that Study 102, a Phase III clinical trial evaluating the company's
once-daily anti-HIV drug Viread (tenofovir disoproxil fumarate or tenofovir DF)
300 mg as a potential treatment for chronic hepatitis B virus (HBV) infection,
met its primary efficacy endpoint.
The study shows that Viread is non-inferior
to the company's once-daily antiviral drug Hepsera (adefovir dipivoxil) among
patients with HBeAg-negative/anti-HBe positive (presumed pre-core mutant) chronic
HBV infection. The primary efficacy endpoint, the proportion of patients with
a complete response at week 48, was defined by serum HBV DNA levels below 400
copies/mL and histologic improvement characterized by at least a two point reduction
in the Knodell necroinflammatory score (a measure of necro-inflammation -- an
inflammatory process in the liver including or leading to death of liver cells)
with no concurrent worsening of fibrosis (scarring of liver tissue).
At
48 weeks, 70.8 percent of patients in the Viread arm (n=250) had a complete response
compared to 48.8 percent in the Hepsera arm (n=125; p less than 0.001). The most
commonly observed treatment-emergent adverse events of moderate intensity or higher
were abdominal pain, back pain, headache, respiratory infections, creatinine phosphokinase,
and transaminase elevations. The incidence of these events was comparable between
the Viread and Hepsera arms of the study. In addition, the incidence of grade
3 or 4 laboratory abnormalities was comparable between the two arms. Full study
results will be submitted for presentation at an upcoming scientific meeting.
"Chronic
hepatitis B remains a serious disease that impacts more than one million people
in the United States and an estimated 400 million people worldwide," said
Franck Rousseau, MD, Vice President, Clinical Research, Gilead Sciences. "We
believe Viread has the potential to be an important treatment option for patients
with chronic hepatitis B and look forward to sharing detailed data from this study
at a scientific conference later this year."
Study 102 is one of two
Phase III pivotal studies evaluating the efficacy, safety, and tolerability of
Viread for the treatment of chronic hepatitis B. The second study (Study 103),
a 48-week trial among patients with hepatitis B "e" antigen (HBeAg)-positive
chronic hepatitis B, is expected to be complete later this year.
The active
ingredient in Viread, tenofovir DF, is currently the most prescribed molecule
in the United States for combination HIV therapy. Viread received approval as
an anti-HIV medication from the U.S. Food and Drug Administration (FDA) in October
2001 and from the European Commission in February 2002. Viread is not approved
as a treatment for chronic hepatitis B, and data from this analysis have not been
reviewed by the FDA.
Study Design
Study 102 is a multi-center,
randomized, double-blind Phase III clinical trial that compares the efficacy,
safety and tolerability of Viread and Hepsera over 48-weeks among patients with
HBeAg-negative/anti-HBe positive (presumed pre-core mutant) chronic hepatitis
B. Three hundred and seventy-five patients were randomized in a 2:1 ratio to receive
either tenofovir DF (300 mg once daily; n=250) or Hepsera (10 mg once daily; n=125).
Source Gilead
Sciences (via BusinessWire). Phase III Study Evaluating Gilead's Viread for the
Treatment of Chronic Hepatitis B Virus Meets Primary Endpoint. Press release.
June 6, 2007.
