Gilead Announces Sustained Virologic Response Rate of 78% From Phase 3 Study of Sofosbuvir for Genotype 2/3 Hepatitis C Infected

  Gilead Announces Sustained Virologic Response Rate of 78% From Phase 3 Study
  of Sofosbuvir for Genotype 2/3 Hepatitis C Infected Patients

-- POSITRON Demonstrates Efficacy of a 12-Week All-Oral Regimen of Sofosbuvir
Plus Ribavirin for Chronic Hepatitis C Patients who are Unable or Unwilling to
                              Take Interferon --

Business Wire

FOSTER CITY, Calif. -- November 27, 2012

Gilead Sciences (Nasdaq:GILD) today announced topline results from the Phase 3
POSITRON study examining a 12-week course of once-daily sofosbuvir plus
ribavirin (RBV) in patients with genotype 2 or 3 chronic hepatitis C virus
(HCV) infection who are not candidates to take interferon (IFN). The study
found that 78 percent of patients (n=161/207) remained HCV RNA undetectable 12
weeks after completing therapy (SVR12). The safety profile of sofosbuvir was
similar to that observed in previous studies, and there were few treatment
discontinuations due to adverse events.

POSITRON is the first of three Phase 3 studies to be completed that are
evaluating sofosbuvir therapy in HCV genotype 2 or 3 infected patient
populations.

“Achieving a sustained virologic response in three quarters of patients is an
impressive result for a sofosbuvir-based, all-oral treatment in a group of
individuals for which no suitable alternative therapy exists. These patients
by definition had previously declined interferon-based therapy, were
ineligible to receive interferon, or were interferon intolerant,” said Norbert
Bischofberger, PhD, Executive Vice President of Research and Development and
Chief Scientific Officer, Gilead Sciences. “We look forward to sharing data
from additional Phase 3 studies in early 2013, and expect to submit our first
regulatory filings for sofosbuvir by mid-2013.”

In POSITRON, HCV genotype 2 or 3 patients who were interferon intolerant,
interferon ineligible or unwilling to take interferon were randomized (3:1) to
receive 12 weeks of either sofosbuvir 400 mg once daily plus weight-based RBV
twice daily (n=207) or matching placebo (n=71). Of the 207 patients randomized
to the sofosbuvir/RBV arm, 15 percent had compensated cirrhosis (more advanced
liver disease) and 53 percent were infected with genotype 2. SVR12 rates were
93 percent in genotype 2 and 61 percent in genotype 3. In the small percentage
of patients with cirrhosis at baseline who received sofosbuvir/RBV, 61 percent
achieved SVR12. All patients receiving sofosbuvir/RBV became HCV RNA negative
on treatment and relapse accounted for all virologic failures. No patient in
the placebo group achieved an SVR12. The most common adverse events reported
in greater than 10 percent of patients in the study were fatigue, nausea,
headache, insomnia, pruritis and anemia.

Full data from the study will be submitted for presentation at a future
scientific conference.

The Phase 3 clinical trial program for sofosbuvir includes two additional
studies evaluating 12 and 16 weeks of therapy with sofosbuvir plus RBV in HCV
genotype 2 and 3 infected patients. A fourth Phase 3 clinical trial is
evaluating sofosbuvir combined with RBV and peg-IFN among patients with HCV
genotypes 1, 4, 5 and 6. Pending the results, these studies will support
initial regulatory filings in mid-2013 for an all-oral therapy with sofosbuvir
plus RBV among genotype 2/3 treatment-naïve, treatment-experienced and
interferon-intolerant patients, and for sofosbuvir in combination with RBV and
peg-IFN among treatment-naïve patients with HCV genotypes 1, 4, 5 and 6.

About Sofosbuvir

Sofosbuvir (formerly referred to as GS-7977) is a once-daily nucleotide analog
polymerase inhibitor for the treatment of HCV infection. Sofosbuvir is being
evaluated as part of multiple therapeutic regimens, including the programs
outlined above in combination with RBV and peg-IFN. Additionally, sofosbuvir
is being studied as a once-daily fixed-dose combination containing sofosbuvir
and the NS5A inhibitor GS-5885, with the added goal of creating a potent,
tolerable and convenient all-oral treatment for genotype 1 infected HCV
patients that may eliminate the need for interferon and/or RBV.

Sofosbuvir and GS-5885 are investigational products and their safety and
efficacy have not yet been established.

About Gilead Sciences

Gilead Sciences is a biopharmaceutical company that discovers, develops and
commercializes innovative therapeutics in areas of unmet medical need. The
company’s mission is to advance the care of patients suffering from
life-threatening diseases worldwide. Headquartered in Foster City, California,
Gilead has operations in North America, Europe and Asia Pacific.

Forward-Looking Statement

This press release includes forward-looking statements within the meaning of
the Private Securities Litigation Reform Act of 1995 that are subject to
risks, uncertainties and other factors, including the possibility that the
proportion of patients who maintain a sustained virologic response with longer
follow up will not be as favorable as the sustained virologic response rates
reported in this press release and the possibility of unfavorable results from
additional clinical trials involving sofosbuvir and the fixed-dose combination
of sofosbuvir and GS-5885. As a result, sofosbuvir and GS-5885 as single
agents or as a fixed-dose combination may never be successfully
commercialized. Further, Gilead may make a strategic decision to discontinue
development of the compounds or the fixed-dose combination regimen if, for
example, Gilead believes commercialization will be difficult relative to other
opportunities in its pipeline. These risks, uncertainties and other factors
could cause actual results to differ materially from those referred to in the
forward-looking statements. The reader is cautioned not to rely on these
forward-looking statements. These and other risks are described in detail in
Gilead’s Quarterly Report on Form 10-Q for the quarter ended September 30,
2012, as filed with the U.S. Securities and Exchange Commission. All
forward-looking statements are based on information currently available to
Gilead, and Gilead assumes no obligation to update any such forward-looking
statements.

For more information on Gilead Sciences, please visit the company’s website at
  www.gilead.com, follow Gilead on Twitter (@GileadSciences) or call Gilead
             Public Affairs at 1-800-GILEAD-5 or 1-650-574-3000.

Contact:

Gilead Sciences
Patrick O’Brien, 650-522-1936 (Investors)
Cara Miller, 650-522-1616 (Media)
 
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