Gilead Announces Update on Phase 3 Study of Oral Fixed-Dose Combination of Sofosbuvir and Ledipasvir for Genotype 1 Hepatitis C

  Gilead Announces Update on Phase 3 Study of Oral Fixed-Dose Combination of
  Sofosbuvir and Ledipasvir for Genotype 1 Hepatitis C Patients

   -- Enrollment in ION-1 Study Continues Following Planned DSMB Review --

Business Wire

FOSTER CITY, Calif. -- March 26, 2013

Gilead Sciences, Inc. (Nasdaq: GILD) today provided an update on ION-1, a
Phase 3 clinical trial evaluating a once-daily fixed-dose combination of the
nucleotide sofosbuvir and the NS5A inhibitor ledipasvir with and without
ribavirin (RBV) for 12 or 24 weeks among treatment-naïve genotype 1 patients
with hepatitis C virus (HCV) infection (n=800). A planned review by the
study's Data and Safety Monitoring Board (DSMB) of safety data from 200
patients in all four arms and of SVR4 rates (sustained virologic response four
weeks after completion of therapy) from 100 patients in the two 12-week
duration arms concludedthat the trial should continue without modification.
This recommendation is based upon the observed SVR4
ratesexceedingthepredefinedthreshold of 60 percentand the absence of
significant safety issues. Enrollment of the remaining 600 patients in ION-1
is now underway.

Sofosbuvir/ledipasvir is also being evaluated in a second Phase 3 study,
ION-2, initiated in January 2013, which is now fully enrolled. ION-2 is
evaluating sofosbuvir/ledipasvir with RBV for 12 weeks, and with and without
RBV for 24 weeks, among 400 treatment-experienced genotype 1 HCV patients.
Participants in this study failed to respond to past therapy containing
pegylated interferon (peg-IFN) or peg-IFN plus a protease inhibitor.

Sofosbuvir, ledipasvir and the sofosbuvir/ledipasvir fixed-dose combination
are investigational products and their safety and efficacy have not yet been

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 of
unfavorable longer-term results from the ION-1 study, the possibility that the
proportion of patients who maintain a sustained virologic response with longer
follow up will not be as favorable as the SVR4 rates observed in the study,
and the possibility of unfavorable results from ION-2 and other ongoing and
subsequent clinical trials involving sofosbuvir and the fixed-dose combination
of sofosbuvir/ledipasvir. In addition, Gilead may make a strategic decision to
discontinue development of sofosbuvir, ledipasvir and/or the fixed-dose
combination regimen if, for example, Gilead believes commercialization will be
difficult relative to other opportunities in its pipeline. As a result, these
compounds may never be successfully commercialized. 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 Annual Report on Form 10-K for the year ended December
31, 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

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


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