NATAP: TDF Prodrug Starts Phase 2 (GS-7340)

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Subject: NATAP: TDF Prodrug Starts Phase 2 (GS-7340)Gilead Initiates Phase 2 Clinical Trial Evaluating GS-7340, A Low-Dose Novel Prodrug of Tenofovir for the Treatment of HIV

-- Phase 2 Study Will Examine GS-7340 as Part of a New Once-Daily,

Single-Tablet Regimen --

FOSTER CITY, Calif.--(BUSINESS WIRE)--Jan. 24, 2012--

Gilead Sciences, Inc. (Nasdaq: GILD) today announced the initiation of a

Phase 2 clinical trial evaluating GS-7340 for the treatment of HIV-1

infection in treatment-naíve adults. GS-7340 is a novel prodrug of

tenofovir, the active agent in Viread® (tenofovir disoproxil

fumarate). In previous studies, GS-7340 has demonstrated the ability to

provide greater antiviral efficacy at a dose that is ten times lower

than Viread.

"The advancement of GS-7340 into this Phase 2 study is an important

milestone in Gilead's efforts to develop the next generation of

best-in-class therapies for HIV," said Norbert Bischofberger, PhD,

Executive Vice President, Research and Development and Chief Scientific

Officer, Gilead Sciences. "Because it can be used once-daily at

one-tenth the dose of Viread, which is a much lower dose compared to

other currently available anti-HIV compounds, GS-7340 could enable the

development of a new range of single-tablet regimens for HIV that

optimize clinical efficacy, safety and tolerability for patients."

The Phase 2 study will evaluate GS-7340 as part of a once-daily,

co-formulated single-tablet regimen that will also contain the boosting

agent cobicistat, the integrase inhibitor elvitegravir, and Emtriva®

(emtricitabine). The GS-7340-containing single-tablet regimen will be

compared to Gilead's Quad single-tablet regimen, which contains Viread

and Emtriva (as Truvada®), elvitegravir and cobicistat, and

is currently under review for marketing approval by U.S. and European

regulatory agencies.

Gilead plans to initiate a second Phase 2 trial for GS-7340 later in

2012 that will assess GS-7340 as part of another single-tablet regimen

containing cobicistat, Emtriva and Tibotec Pharmaceuticals' protease

inhibitor Prezista® (darunavir). Gilead announced an

agreement with Tibotec to develop this single-tablet regimen on November

15, 2011.

Viread was approved for HIV treatment in 2001 and has accumulated more

than 4.4 million patient years of clinical experience to date.

About the GS-7340 Phase 2 Study

The Phase 2 study is a randomized, double-blind 48-week clinical trial

among HIV-1 infected adults with HIV RNA levels (viral load) greater

than or equal to 5,000 copies/mL and CD4 cell counts greater than 50

cells/mm3. A total of 150 patients will be randomized (2:1)

to receive a once-daily tablet containing GS-7340 10 mg/cobicistat 150

mg/elvitegravir 150 mg/emtricitabine 200 mg (n=100) or the Quad

(tenofovir disoproxil fumarate 300 mg/cobicistat 150 mg/elvitegravir 150

mg/emtricitabine 200 mg) (n=50). The HIV virus of participants must be

sensitive to both tenofovir and emtricitabine, prior use of

antiretrovirals is not allowed and participants must have adequate renal

function (defined as an estimated glomerular filtration rate of greater

than or equal to 70 mL/min, according to the Cockcroft-Gault formula).

The primary endpoint will be the proportion of patients with viral load

less than 50 copies/mL at 24 weeks of treatment as determined by the

FDA-defined snapshot analysis. Secondary endpoints will include the

proportion of patients who achieve viral load of less than 50 copies/mL

at 48 weeks of therapy, and change from baseline in HIV-1 RNA and in

CD4+ cell count to Weeks 24 and 48. After week 48, patients will

continue to take their blinded study drug until treatment assignments

have been unblinded, at which point all will be given the option to

participate in an open-label rollover extension and receive the

GS-7340-based single-tablet regimen.

Additional information about the study can be found at www.clinicaltrials.gov.

About GS-7340

GS-7340 is a novel prodrug of tenofovir, the active agent in the

company's HIV drug Viread. Like Viread, GS-7340 is a nucleotide reverse

transcriptase inhibitor (NtRTI). Phase 2a dose-ranging studies have

identified a dose that is ten times lower than Viread and provides

greater antiviral efficacy. The smaller milligram size of GS-7340 may

enable the development of new fixed-dose combinations and single-tablet

regimens for HIV therapy that are not feasible with Viread.

About Cobicistat

Cobicistat is a potent mechanism-based inhibitor of cytochrome P450 3A

(CYP3A), an enzyme that metabolizes drugs in the body. Gilead is

evaluating cobicistat in three separate pivotal Phase 3 studies, both as

a stand-alone boosting agent for protease inhibitors, as well as part of

the Quad regimen. Gilead has exclusive rights to develop cobicistat

worldwide, except for Japan, where JT is licensed to develop and

commercialize the product.

About Elvitegravir

As an integrase inhibitor, elvitegravir interferes with HIV replication

by blocking the ability of the virus to integrate into the genetic

material of human cells. Elvitegravir was licensed by Gilead from Japan

Tobacco Inc. (JT) in March 2005. Under the terms of Gilead’s agreement

with JT, Gilead has exclusive rights to develop and commercialize

elvitegravir in all countries of the world, excluding Japan, where JT

retains rights.

About Quad

The Quad is a single-tablet regimen that contains elvitegravir,

cobicistat, emtricitabine and tenofovir disoproxil fumarate. In October

2011, Gilead submitted a New Drug Application to the U.S. FDA for the

Quad for the treatment of HIV among treatment-naïve patients.

GS-7340, cobicistat, elvitegravir and the Quad 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 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 risks

related to our ability to enroll patients in the Phase 2 clinical trial

of a single-tablet regimen containing elvitegravir, cobicistat,

emtricitabine and GS-7340, our ability to initiate the Phase 2 trial of

a single-tablet regiment containing cobicistat, emtricitabine, darunavir

and GS-7340, the possibility of unfavorable results of this or other

clinical trials involving GS-7340, the need to modify or delay the

clinical trials or to perform additional trials and the risk of failing

to obtain U.S. Food and Drug Administration and other regulatory body

approvals for GS-7340 and single-tablet regimens containing GS-7340,

including the Quad. As a result, GS-7340 may never be successfully

commercialized. Further, we may make a strategic decision to discontinue

development of GS-7340 if, for example, we believe commercialization

will be difficult relative to other opportunities in our 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, 2011,

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.

U.S. full prescribing information for Viread is available at www.Viread.com.U.S.

full prescribing information for Truvada is available at www.Truvada.com.U.S.

full prescribing information for Emtriva is available at www.GileadHIV.com.Viread,

Truvada and Emtriva are registered trademarks of Gilead Sciences, Inc.

For more information on Gilead Sciences, please visit the company's

website at www.gilead.com

or call Gilead Public Affairs at 1-800-GILEAD-5 or 1-650-574-3000.

Source: Gilead Sciences, Inc.

Gilead Sciences, Inc. Hubbard, 650-522-5715 (Investors)

Rau, 650-522-5635 (Media)