Pfizer Submits SNDA to Expand Potential Market for Lasofoxifene; Triggers Ligand Royalty Buy-Out Option from Salk and Expands Potential Ligand Royalty Revenue

SAN DIEGO, CA -- Feb. 3, 2005 -- Ligand Pharmaceuticals Incorporated (Nasdaq: LGND) announced today that Pfizer has confirmed a December 2004 FDA filing of a supplemental NDA for the use of lasofoxifene for the treatment of vaginal atrophy. This follows an August 2004 NDA filing by Pfizer for use of lasofoxifene in the prevention of osteoporosis. Lasofoxifene is a selective estrogen receptor modulator (SERM) and the first of Ligand’s royalty-bearing products to get to the NDA submission stage. Lasofoxifene is also being developed by Pfizer for the treatment of osteoporosis.


According to an estimate published in the May 15, 2000 issue of American Family Physician, from ten to 40 per cent of postmenopausal women have symptoms of vaginal atrophy including dryness, burning, itching and soreness. This often leads to an increased susceptibility to urinary and vaginal infections and to a decrease in sexual activity and associated emotional distress. Census figures show that more than 42 million American women are age 50 or older, the approximate age when menopause begins.

According to the National Osteoporosis Foundation, eight million American women have osteoporosis and almost 27 million women are estimated to have osteopenia (low bone mass), placing them at increased risk for osteoporosis.

"If approved for this additional indication, lasofoxifene could provide an important new therapeutic option to improve the urogenital health and quality of life for postmenopausal women in this often overlooked and under-diagnosed condition" said Andres Negro-Vilar, M.D. PhD, Ligand’s executive vice president of research and development and chief scientific officer. "A clinical trial presented at the October 2004 meeting of the North American Menopause Society by D. Portman et al. shows that lasofoxifene but not raloxifene (Evista(R)) significantly improves the clinical symptoms of vaginal atrophy compared to placebo and is the first SERM to demonstrate these positive effects. A second study by G. Bachmann et al. confirmed the improvements in vaginal atrophy by lasofoxifene compared to placebo"

Under the terms of the agreement between Ligand and Pfizer, Ligand is entitled to receive an additional milestone upon the first FDA approval of lasofoxifene and, if marketed, royalty payments equal to 6% of net sales of lasofoxifene worldwide for any indication.

As a result of the supplemental lasofoxifene NDA filing, Ligand has exercised an option to pay the Salk Institute $1.12 million to buy out royalty payments due on future sales of the product in this additional indication. In March of 2004 Ligand exercised a previous option and paid Salk $1.12 million to buy out royalty payments due on total sales of lasofoxifene for the prevention of osteoporosis.

Ligand has sold to Royalty Pharma the rights to a total of 3.0125% of net sales of lasofoxifene and each of the other two SERM products for a period of ten years following first commercial sale of each product. Ligand retains an approximately equal portion of lasofoxifene and other SERM’s net sales going forward and for periods that may exceed ten years. The royalty rates owed to Royalty Pharma may be reduced by one third if SERM product sales exceed certain thresholds across all indications.

"We are very pleased with the supplemental NDA filing for lasofoxifene in this exciting, new, large-market indication as the first of three SERM products which, if successful, could significantly expand our royalty revenue" said Paul V. Maier, Ligand’s senior vice president and chief financial officer. "It also underscores the maturation of our portfolio of milestone and royalty-bearing drugs in human development. We believe Wyeth will proceed to NDA filing for bazedoxifene, our second SERM, for prevention of osteoporosis in the first half of 2006 and for combination bazedoxifene CE, our third SERM, in 2007. These drugs and several others in the diabetes, cardiovascular disease and contraception fields provide an exciting major opportunity for milestone and royalty revenues to complement our growing specialty pain and oncology business revenues and increase shareholder value"

About Ligand

Ligand discovers, develops and markets new drugs that address critical unmet medical needs of patients in the areas of cancer, pain, skin diseases, men’s and women’s hormone-related diseases, osteoporosis, metabolic disorders, and cardiovascular and inflammatory diseases. Ligand’s proprietary drug discovery and development programs are based on its leadership position in gene transcription technology, primarily related to Intracellular Receptors (IRs) and Signal Transducers and Activators of Transcription (STATs). For more information, go to www.ligand.com.

Caution Regarding Forward-Looking Statements

This news release contains certain forward-looking statements by Ligand that involve risks and uncertainties and reflect the company’s judgment as of the date of this release. These statements include those related to royalty revenue, milestones, product approval, product development and potential for our milestone and royalty-bearing drugs, growing revenues and increasing shareholder value. Actual events or results may differ from expectations. There can be no assurance that development of lasofoxifene or other products will be successful, that any of the mentioned products will receive regulatory approvals, that Ligand will receive royalties or milestones from the continued development or commercialization of lasofoxifene or any partnered compounds, that any of the collaborative drug programs mentioned will result in approved drugs or drugs that achieve commercial success, that our revenue will continue to grow nor that shareholder value will increase. Additional information concerning these and other risk factors affecting Ligand’s business can be found in prior press releases as well as in Ligand’s public periodic filings with the Securities and Exchange Commission, available at www.ligand.com. Ligand disclaims any intent or obligation to update these forward-looking statements beyond the date of this release. This caution is made under the safe harbor provisions of the Private Securities Litigation Reform Act of 1995.

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Abe Wischnia

Senior Director of Investor Relations

Ligand Pharmaceuticals Incorporated

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