OREXIGEN™ Therapeutics Announces European Patent Office Allows Composition and Use Claims for its Patent on Contrave™ to Treat Obesity

Business Wire, Feb 28, 2008

--Clears the Way for Possible Development of Contrave in Europe--

SAN DIEGO -- Orexigen(TM) Therapeutics, Inc. (Nasdaq: OREX), a biopharmaceutical company focused on the treatment of central nervous system disorders, including obesity, today announced that the European Patent Office has issued a Decision to Grant a Patent covering compositions and uses of bupropion and naltrexone for affecting weight loss. These two drugs are the active constituents in Contrave[TM], Orexigen's lead product candidate for the treatment of obesity. This development is an important milestone toward an eventual patent validation in individual European countries. This patent, once issued, would provide exclusive rights on this combination in those countries until 2024.

This is the latest in a series of decisions strengthening Orexigen's intellectual property portfolio. A notice allowing the corresponding U.S. patent was received from the United States Patent Office (USPTO) in January, and a notice of allowance from the USPTO was received earlier this month for zonisamide to treat obesity. Zonisamide is a key ingredient in Empatic[TM], which is in the later stages of Phase II clinical development.

"This patent, upon issuance, both strengthens and broadens the scope of our intellectual property position for this novel, proprietary drug combination," said Orexigen President and CEO, Gary Tollefson, M.D., Ph.D. "We view this decision as further validation of our intellectual property and one which now opens the door for our consideration of a European development strategy with Contrave."

The Decision to Grant the European patent was received in writing by the Company and will take effect when it is published, which is expected to occur on March 12th.

Contrave is a proprietary fixed dose combination of bupropion SR and the Company's novel formulation of naltrexone SR in a single tablet. Orexigen chose these two constituent drugs based on preclinical data that suggested that they could both initiate and sustain weight loss. The Contrave Phase IIb clinical trial at 48 weeks demonstrated weight loss from baseline body weight, absent a significant diet or exercise intervention, that ranged from 8.0% to 10.7% across three Contrave dosage groups among patients who completed the trial. Four Phase III clinical trials of Contrave are now underway and are expected to be completed by mid-2009 with the filing of a New Drug Application (NDA) with the FDA projected for late 2009.

About Orexigen Therapeutics

Orexigen(TM) Therapeutics, Inc. is a biopharmaceutical company focused on the development of pharmaceutical product candidates for the treatment of central nervous system disorders, including obesity. Orexigen's lead combination product candidates targeted for obesity are Contrave[TM], which is in Phase III clinical trials, and Empatic[TM], which is in the later stages of Phase II clinical development.

Forward-Looking Statements

Orexigen cautions you that statements included in this press release that are not a description of historical facts are forward-looking statements. Words such as "believes," "anticipates," "plans," "expects," "indicates," "will," "intends," "potential," "suggests," "assuming," "designed" and similar expressions are intended to identify forward-looking statements. These statements are based on Orexigen's current beliefs and expectations. These forward-looking statements include statements regarding the development of Contrave[TM] in Europe, the publishing of a European patent covering SR compositions of bupropion and naltrexone combined in a single dosage form, the timing of the completion of the Company's Contrave Phase III clinical trials and the timing of its submission of an NDA with the FDA. The inclusion of forward-looking statements should not be regarded as a representation by Orexigen that any of its plans will be achieved. Actual results may differ from those set forth in this release due to the risk and uncertainties inherent in Orexigen's business, including, without limitation: the progress and timing of the Company's Contrave clinical trials or the development of Contrave; the potential for adverse safety findings relating to Contrave to delay or prevent regulatory filings; and its licensors may not be able to obtain, maintain and successfully enforce adequate patent and other intellectual property protection of its product candidates; and other risks described in Orexigen's filings with the Securities and Exchange Commission (SEC). You are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date hereof, and Orexigen undertakes no obligation to revise or update this news release to reflect events or circumstances after the date hereof. All forward-looking statements are qualified in their entirety by this cautionary statement. This caution is made under the safe harbor provisions of Section 21E of the Private Securities Litigation Reform Act of 1995.