Gilead Sciences Submits Marketing Authorisation Application for Aztreonam Lysine 75 mg Powder for Nebuliser Solution, a Potential New Treatment for Cystic Fibrosis, to European Medicines Agency

Gilead Sciences, Inc. (Nasdaq:GILD) today announced the submission
of a Marketing Authorisation Application (MAA) for marketing approval
of aztreonam lysine 75 mg powder for nebuliser solution (aztreonam
lysine) in the European Union. The MAA will be reviewed by the
Committee for Medicinal Products for Human Use (CHMP), subject to
validation by the European Medicines Agency (EMEA). Review of the MAA
will be conducted by the EMEA under the centralized licensing
procedure, which, when finalized, provides one marketing authorization
in all member states of the European Union. Aztreonam lysine is an
investigational therapy in development for people with cystic fibrosis
(CF) who have pulmonary Pseudomonas aeruginosa (P. aeruginosa)
infection. Aztreonam lysine 75 mg powder for nebuliser solution is
administered using an eFlow(R) Nebuliser (PARI GmbH).

The MAA is supported by data from two Phase III clinical studies
(AIR-CF1 and AIR-CF2) and interim data from an ongoing open-label
extension study (AIR-CF3) of patients who participated in AIR-CF1 or
AIR-CF2.

"Chronic pseudomonal airway infection represents the single
greatest cause of morbidity and mortality for people with cystic
fibrosis, and with a limited number of inhaled antibiotics, there
remains a significant unmet medical need," said A. Bruce Montgomery,
MD, Senior Vice President, Head of Respiratory Therapeutics, Gilead
Sciences. "The submission of this MAA in the European Union further
underscores Gilead´s commitment to advancing therapies for patients
with this life-threatening disease."

Aztreonam lysine 75 mg powder for nebuliser solution is an
investigational therapy and has not yet been determined safe or
efficacious in humans.

About Aztreonam Lysine 75 mg Powder for Nebuliser Solution

Aztreonam lysine 75 mg powder for nebuliser solution is an
antibiotic candidate currently being studied in an ongoing Phase III
open label trial for people with cystic fibrosis who have pulmonary P.
aeruginosa. Aztreonam has potent activity against Gram-negative
bacteria such as P. aeruginosa. Aztreonam formulated with arginine
is a U.S. Food Drug and Administration (FDA)-approved agent for
intravenous administration. Aztreonam lysine is a proprietary
formulation of aztreonam developed specifically for inhalation and has
been designated with orphan drug status in the United States and
Europe.

In the United States, the investigational product is referred to
as aztreonam lysine for inhalation. Gilead submitted its U.S. New Drug
Application for aztreonam lysine for inhalation to the FDA on November
16, 2007. The FDA has established a target review date, under the
Prescription Drug User Fee Act, of September 16, 2008. Gilead
submitted its application in Australia on November 30, 2007.

About the AIR-CF Phase III Program

The Phase III AIR-CF clinical program was designed to determine
the safety and efficacy of aztreonam lysine for use in people with
cystic fibrosis who have pulmonary P. aeruginosa. In each of these
studies, aztreonam lysine was administered by the PARI eFlow
Electronic Nebulizer.

AIR-CF1 was a double-blind, randomized, placebo-controlled study
designed to assess the safety and efficacy of a 28-day treatment
course of aztreonam lysine in people with cystic fibrosis who have
pulmonary P. aeruginosa. The primary endpoint was the change at day 28
from baseline in respiratory symptoms as assessed by the Cystic
Fibrosis Questionnaire-Revised (CFQ-R). This study enrolled 164
patients who were randomized to receive 28 days of treatment with
aztreonam lysine or volume-matched placebo administered three times
daily. Results from this study were presented at the 21st Annual North
American Cystic Fibrosis Conference (NACFC) in Anaheim, California on
October 4, 2007.

AIR-CF2 was a randomized, double-blind, placebo-controlled study
designed to assess the safety and efficacy of a 28-day treatment
course with aztreonam lysine following a 28-day treatment course of
tobramycin inhalation solution in people with cystic fibrosis who have
pulmonary P. aeruginosa. Patients were randomized to receive 28 days
of treatment with 75 mg of aztreonam lysine or volume-matched placebo
each administered two times or three times daily. Patients were
followed for an overall study period of 126 days, with 56 days of
observation after receiving aztreonam lysine therapy or placebo.
Results from this study were presented at the Cystic Fibrosis
Therapeutics Development Network conference in Seattle, Washington on
April 19, 2007 and at the European Cystic Fibrosis Society (ECFS)
Conference in Belek, Turkey on June 14, 2007.

AIR-CF3 is an open-label, multi-center study of patients who
participated in the AIR-CF1 or AIR-CF2 studies. The primary objective
of the study is to evaluate the safety of repeated exposure to
aztreonam lysine in people with cystic fibrosis. Patients will receive
treatment with aztreonam lysine with the same dosing regimen they
received in AIR-CF1 or AIR-CF2. This trial is ongoing. Limited interim
data from this study were presented in a plenary session at NACFC on
October 5, 2007.

About PARI Pharma and eFlow(R) Nebuliser

Aztreonam lysine 75 mg powder for nebuliser solution is delivered
by an eFlow(R) Nebuliser, developed by PARI Pharma GmbH. eFlow is a
portable nebuliser that enables aerosolization of liquid medications
via a vibrating, perforated membrane. PARI Pharma also contributed to
the development and optimization of the drug formulation (aztreonam
lysine 75 mg powder for nebuliser solution) for delivery via eFlow.
Based on PARI´s 100-year history working with aerosols, PARI Pharma is
dedicated to advancing inhalation therapies by developing innovative
delivery platforms and new pharmaceutical formulations that work
together to improve patient care.

About Cystic Fibrosis

Today, more than 70,000 people worldwide have cystic fibrosis.
Cystic fibrosis is a chronic, debilitating genetic disease. A major
characteristic of cystic fibrosis is production of abnormally thick,
sticky mucus in the lungs that traps bacteria and predisposes people
with cystic fibrosis to lung infections, which damage their lungs.
Pulmonary infection with gram-negative bacteria, particularly
pulmonary P. aeruginosa, represents the single greatest cause of
morbidity and mortality among people with cystic fibrosis. Currently
there is no known cure for cystic fibrosis, and the goal of cystic
fibrosis therapy is to control symptoms and prevent further lung
damage.

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 Australia.

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
risk that the EMEA, FDA or other regulatory agencies may not approve
aztreonam lysine 75 mg powder for nebuliser solution for treatment of
people with cystic fibrosis (CF) who have pulmonary P. aeruginosa
infection, and any marketing approval, if granted, may have
significant limitations on its use. 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, 2007 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, please call the Gilead Public
Affairs Department at 1-800-GILEAD-5 (1-800-445-3235) or visit
www.gilead.com.