Ardea Biosciences's MEK Inhibitor, RDEA119, Demonstrates Synergy with Other Anti-Cancer Agents in Multiple Tumor Types

Ardea Biosciences Presents Preclinical Data on its Lead MEK Inhibitor, RDEA119, Demonstrating Synergy with Other Anti-Cancer Agents in Multiple Tumor Types

October 24, 2008--SAN DIEGO--(BUSINESS WIRE)--Ardea Biosciences, Inc. (Nasdaq: RDEA) announced today that it presented preclinical data on its lead mitogen-activated ERK kinase (MEK) inhibitor at the 20th European Organisation for Research and Treatment of Cancer (EORTC) -- National Cancer Institute (NCI) -- American Association for Cancer Research (AACR) symposium on 'Molecular Targets and Cancer Therapeutics' in Geneva, Switzerland.

In preclinical studies, RDEA119 has demonstrated synergistic activity when used in combination with multiple anti-cancer agents in a wide range of tumor cell lines. Additionally, RDEA119 has demonstrated the ability to produce significant tumor cell death when administered in combination with sorafenib (Nexavar®; Onyx Pharmaceuticals, Bayer HealthCare) in cancer cells that had developed resistance to sorafenib.

Doses being evaluated in an ongoing Phase 1 study of RDEA119 as a single agent in patients with advanced cancer have achieved systemic exposure consistent with active doses in animal models of human tumors, without drug-related toxicity. A Phase 1/2 study in combination with Nexavar in patients with advanced cancer has been recently initiated.

"The preclinical data presented today formed the rationale for our Phase 1/2 study of RDEA119 in combination with Nexavar," commented Barry D. Quart, PharmD, Ardea's president and chief executive officer. "RDEA119's potential to enhance the activity of current cancer therapies and its broad activity against both K-ras and B-raf mutations makes RDEA119 a very promising product candidate to improve the current standard-of-care across multiple cancer indications. We are pleased with the progress that we have made with RDEA119 thus far and look forward to working with a partner in the future to bring this important potential therapy to patients."

The poster is available on the Company website (http://www.ardeabio.com) under the title, "RDEA119: A Potent and Highly Selective MEK Inhibitor for the Treatment of Cancer."

About RDEA119

RDEA119, a non-ATP competitive, highly-selective MEK inhibitor for the treatment of inflammatory diseases and cancer is the Company's lead compound from its MEK inhibitor research and development program. RDEA119 has shown potential as a potent inhibitor of MEK, which is believed to play an important role in inflammation, as well as cancer cell proliferation, apoptosis and metastasis. Preclinical and clinical results suggest that RDEA119 has favorable properties, including oral dosing, excellent selectivity and limited retention in the brain, which, in turn, may result in a reduced risk of central nervous system (CNS) side effects.

About Nexavar

Nexavar, a small-molecule drug, is being developed and marketed by Onyx Pharmaceuticals, Inc., in collaboration with Bayer HealthCare Pharmaceuticals, Inc. Nexavar is currently approved for the treatment of unresectable hepatocellular carcinoma and advanced renal cell carcinoma.

About Ardea Biosciences, Inc.

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, gout, cancer and inflammatory diseases. We have five product candidates in clinical trials and others in preclinical development and discovery. Our most advanced product candidate is RDEA806, a non-nucleoside reverse transcriptase inhibitor (NNRTI), which has successfully completed a Phase 2a study for the treatment of patients with 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 for clinical development. RDEA594, our lead product candidate for the treatment of hyperuricemia and gout, is being evaluated in a Phase 1 clinical trial 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 1/2 study in combination with sorafenib (Nexavar®; Onyx Pharmaceuticals, Bayer HealthCare) and as a single agent in a Phase 1 study, both in advanced cancer patients, and have completed 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 for clinical development.

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 plans and goals, the expected properties and benefits of RDEA806, RDEA427, RDEA594, RDEA119, RDEA436 and our other compounds, and the timing and results of our 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, costs associated with our drug discovery and development programs, and risks related to the outcome of our 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.