Arena Pharmaceuticals (ARNA) Initiates Phase 1 Clinical Trial of APD811 for Pulmonary Arterial Hypertension

SAN DIEGO, Dec. 10, 2010 /PRNewswire-FirstCall/ — Arena Pharmaceuticals, Inc. (Nasdaq: ARNA) announced today the initiation of dosing in a Phase 1 clinical trial of APD811, a novel oral drug candidate discovered by Arena that targets the prostacyclin receptor for the treatment of pulmonary arterial hypertension, or PAH.

“An orally bioavailable prostacyclin receptor agonist could improve the standard of care for patients with PAH, a life-threatening disorder,” said William R. Shanahan, M.D., Arena’s Senior Vice President and Chief Medical Officer. “APD811 is a non-prostanoid compound; in preclinical studies, the oral uptake, half life and efficacy characteristics suggest that it could offer improved administration over current prostacyclin receptor therapies.”

This randomized, double-blind and placebo-controlled Phase 1 trial is planned to enroll up to 72 healthy adult volunteers and will evaluate the safety, tolerability and pharmacokinetics of single-ascending doses of APD811.

“While our primary focus is on achieving FDA approval of lorcaserin for weight management, we see value in advancing our promising earlier-stage compounds that may also address underserved medical needs,” said Jack Lief, Arena’s President and Chief Executive Officer. “With a measured investment, we aim to establish a favorable pharmacokinetic and preliminary safety profile for APD811 in this trial.”

About Pulmonary Arterial Hypertension (PAH)

PAH is a progressive, life-threatening disorder characterized by increased pressure in the arteries that carry blood from the heart to the lungs. The increased pressure puts a strain on the heart, which can lead to limited physical activity and a reduced life expectancy. Over time, the heart muscle weakens and can no longer pump blood efficiently. If PAH is not treated, the heart will eventually fail. Data from the National Institutes of Health Registry indicate that without treatment, patients in the United States with PAH have a median survival time of approximately three years from diagnosis.

About APD811

APD811, a potent and selective agonist (or activator) of the prostacyclin receptor, is Arena’s internally discovered drug candidate for the treatment of PAH. Prostacyclin receptor agonists, through regulation of vascular smooth muscle tone, improve mortality and exercise tolerance in PAH patients and are among the treatments administered as standard of care for advanced PAH. Currently available prostacyclin receptor agonists belong to the prostanoid class of molecules and these products need to be administered frequently or continuously through intravenous, subcutaneous or inhaled routes. Arena believes that APD811, as a non-prostanoid prostacyclin agonist, has the potential to improve the standard of care for PAH by providing an oral form of administration with clinical benefits similar to currently available prostacyclin receptor agonists.

About Arena Pharmaceuticals

Arena is a clinical-stage biopharmaceutical company focused on discovering, developing and commercializing oral drugs that target G protein-coupled receptors, an important class of validated drug targets, in four major therapeutic areas: cardiovascular, central nervous system, inflammatory and metabolic diseases. Arena’s most advanced drug candidate, lorcaserin, is intended for weight management. Arena’s wholly owned subsidiary, Arena Pharmaceuticals GmbH, has granted Eisai Inc. exclusive rights to market and distribute lorcaserin in the United States following FDA approval of the New Drug Application for lorcaserin.

Arena Pharmaceuticals(R) and Arena(R) are registered service marks of the company.

Forward-Looking Statements

Certain statements in this press release are forward-looking statements that involve a number of risks and uncertainties. Such forward-looking statements include statements about the advancement, therapeutic indication and use, safety, efficacy, tolerability, and mechanism of action of APD811; the potential of APD811 and orally bioavailable prostacyclin receptor agonists in general, including with regard to improving treatment; the protocol, design, scope, enrollment, potential results and other aspects of the Phase 1 clinical trial for APD811; Arena’s earlier-stage compounds and related value and potential; Arena’s focus on the approval of lorcaserin; the potential therapeutic indication and use, FDA approval and commercialization of lorcaserin; the Eisai collaboration and potential activities thereunder; and Arena’s aim, focus, goals, strategy, research and development programs, and ability to develop compounds and commercialize drugs. For such statements, Arena claims the protection of the Private Securities Litigation Reform Act of 1995. Actual events or results may differ materially from Arena’s expectations. Factors that could cause actual results to differ materially from the forward-looking statements include, but are not limited to, the following: there was a small safety margin from the no observed adverse effect level to significant adverse events in preclinical studies of APD811, and APD811 could have an unacceptable safety and efficacy profile in humans; the risk that regulatory authorities may not find data and other information related to Arena’s clinical trials and other studies meet safety or efficacy requirements or are otherwise sufficient for regulatory approval; the timing of regulatory review and approval is uncertain; Arena’s response to the complete response letter for the lorcaserin NDA may not be submitted in a timely manner or the information provided in such response may not satisfy the FDA; the FDA may request additional information prior to approval of the lorcaserin NDA; unexpected new data; risks related to commercializing new products; Arena’s ability to obtain and defend its patents; the timing, success and cost of Arena’s research and development programs; results of clinical trials and other studies are subject to different interpretations and may not be predictive of future results; clinical trials and other studies may not proceed at the time or in the manner Arena or others expect or at all; Arena’s ability to obtain adequate funds; risks related to relying on collaborative agreements; the timing and receipt of payments and fees, if any, from collaborators; and satisfactory resolution of pending and any future litigation or other disagreements with others. Additional factors that could cause actual results to differ materially from those stated or implied by Arena’s forward-looking statements are disclosed in Arena’s filings with the Securities and Exchange Commission. These forward-looking statements represent Arena’s judgment as of the time of this release. Arena disclaims any intent or obligation to update these forward-looking statements, other than as may be required under applicable law.