Ardea Biosciences, Inc. Identifies Lead Development Candidate for Gout, RDEA594

SAN DIEGO, May 19 /PRNewswire-FirstCall/ -- Ardea Biosciences, Inc. today announced the identification of its lead development candidate for the treatment of patients with gout, RDEA594. Gout is a painful and debilitating disease that is caused by abnormally elevated levels of uric acid in the blood stream. RDEA594 is a major metabolite in both humans and animals of RDEA806, the Company's lead human immunodeficiency virus (HIV) development candidate. RDEA594 does not have significant antiviral activity, but is believed to be responsible for essentially all of the uric acid lowering effects seen with RDEA806. Robust uric acid-lowering effects have been observed following administration of RDEA806 in Phase 1 and Phase 2 clinical trials that included over 100 subjects.

Based on extensive in vitro and in vivo experiments, the Company believes it has elucidated the mechanism by which RDEA594 lowers serum uric acid levels. RDEA594 exhibits a concentration-dependent inhibitory effect on the URAT1 transporter-mediated uptake of uric acid ex vivo and increases uric acid excretion in animal models. These effects are believed to result in the lowering of serum uric acid observed with RDEA806. URAT1 is a specific urate transporter expressed in the kidney responsible for regulation of uric acid levels, and is a validated target for treatment of hyperuricemia and gout.

"Gout represents a major medical challenge in the United States and throughout the world, with millions of people affected by this debilitating condition," said Barry D. Quart, PharmD, Ardea Biosciences' President and CEO. "With the designation of RDEA594 as our clinical candidate for the treatment of gout, we now expect to have five novel candidates in clinical testing during the second half of 2008, positioning us with the potential to have a broad-based, late-stage pipeline in 2009. This finding also allows us to focus our future development efforts with RDEA806 on the treatment of HIV."

The Company plans to initiate a Phase 1 clinical study of RDEA594 in the second half of this year. As previously announced, the Company also plans to conduct a Phase 2 proof-of-concept clinical study in patients with gout, to confirm RDEA594's activity in the target population using its prodrug, RDEA806. This study is on track to be initiated in the second quarter of this year.

About Gout

An estimated 3-5 million people in the United States suffer from gout, which is the most common form of inflammatory arthritis in men over 40. Gout, also known as metabolic arthritis, is a painful and debilitating disease caused by abnormally elevated levels of uric acid in the blood stream. These abnormally elevated levels lead to the deposition of uric acid crystals in and around the connective tissue of the joints and in the kidneys, leading to inflammation, the formation of disfiguring nodules (tophi), intermittent attacks of severe pain (acute flares), and kidney damage (nephropathy). While gout is a treatable condition, there are limited treatment options, and a number of adverse effects are associated with current therapies. No new therapies have been approved by the FDA for the treatment of hyperuricemia associated with gout in the past 40 years.

About RDEA594

RDEA594 is a development candidate that has potential for treating gout patients with hyperuricemia. RDEA594 is a metabolite of RDEA806, a non-nucleoside reverse transcriptase inhibitor (NNRTI) in development for the treatment of HIV. In Phase 1 studies with RDEA806 in healthy volunteers, increased urinary excretion of uric acid was observed in the first 24 hours after dosing, with statistically significant, exposure-dependent, decreases in serum uric acid of 35% to 50% observed following 10-14 days of dosing. RDEA594 exhibits a concentration-dependent inhibitory effect on the URAT1-mediated uptake of uric acid ex vivo and is believed to be the active moiety responsible for the uric acid-lowering effects of RDEA806. Approximately 90% of hyperuricemic patients are considered to be under-excretors of uric acid, so increasing excretion may provide the most physiologically appropriate treatment. RDEA594 does not have significant antiviral activity.

About Ardea Biosciences

Ardea Biosciences, Inc., of San Diego, California, is a biotechnology company focused on the discovery and development of small-molecule therapeutics for the treatment of HIV, cancer and inflammatory diseases, including gout. We have four drug candidates in clinical trials and others in preclinical development and discovery. Our most advanced development candidate is RDEA806, a non-nucleoside reverse transcriptase inhibitor (NNRTI), which is in a Phase 2a study for the treatment of HIV. We have evaluated our second-generation NNRTI for the treatment of HIV, RDEA427, in a human micro-dose pharmacokinetic study and have selected it as a development candidate. RDEA594, our lead development candidate for the treatment of gout, is in preclinical development and is believed to be an inhibitor of the URAT1 transporter in the kidney, which is responsible for regulation of uric acid levels. We are evaluating our lead MEK inhibitor, RDEA119, in a Phase 1 study in advanced cancer patients, as well as in a Phase 1 study in normal healthy volunteers as a precursor to trials in patients with inflammatory diseases. Lastly, we have evaluated our second-generation MEK inhibitor for the treatment of cancer and inflammatory diseases, RDEA436, in a human micro-dose pharmacokinetic study and have selected it as a development candidate.

Statements contained in this press release regarding matters that are not historical facts are "forward-looking statements" within the meaning of the Private Securities Litigation Reform Act of 1995. Because such statements are subject to risks and uncertainties, actual results may differ materially from those expressed or implied by such forward-looking statements. Such statements include, but are not limited to, statements regarding our goals, including the expected properties and benefits of RDEA806, RDEA427, RDEA594, RDEA119, RDEA436 and our other compounds and the results of preclinical, clinical and other studies. Risks that contribute to the uncertain nature of the forward-looking statements include: risks related to the outcome of preclinical and clinical studies, risks related to regulatory approvals, delays in commencement of preclinical and clinical studies, and costs associated with internal development and business development activities. These and other risks and uncertainties are described more fully in our most recently filed SEC documents, including our Annual Report on Form 10-K and our Quarterly Reports on Form 10-Q, under the headings "Risk Factors." All forward-looking statements contained in this press release speak only as of the date on which they were made. We undertake no obligation to update such statements to reflect events that occur or circumstances that exist after the date on which they were made.

CONTACT: Edie DeVine of WeissComm Partners, +1-415-946-1081, for Ardea
Biosciences, Inc.

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