Ligand Earns $1 Million Milestone Payment as GlaxoSmithKline Advances Development of 501516; PPAR Modulator Offers Potential to Treat Dyslipidemias

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SAN DIEGO--()--June 4, 2003--Ligand Pharmaceuticals (Nasdaq: LGND) has earned a $1.0 million milestone payment from GlaxoSmithKline (NYSE: GSK) as a result of GSK's decision to continue Phase I development of 501516, a novel peroxisome proliferation activated receptor (PPAR) modulator for the treatment of dyslipidemias.

Dyslipidemias include elevated LDL (bad) cholesterol, low HDL (good) cholesterol and/or elevated triglycerides, all of which increase the risk of cardiovascular disease, the leading cause of death in the United States. Although widely used drugs such as statins lower LDL cholesterol effectively, they are less efficacious at improving other lipid profiles.

PPARs are a subfamily of intracellular receptors that regulate lipid and glucose homeostasis. They play a key role in fat tissue stores and metabolism, as well as enhancing cellular responses to insulin.

"We are very pleased that GSK has decided to continue development of 501516, which may represent an important advance in the treatment of dyslipidemias and associated cardiovascular disorders," said Andres Negro-Vilar, M.D., Ph.D., Ligand's executive vice president for research and development and chief scientific officer.

Under the recently amended terms of the research and development agreement between Ligand and GSK, GSK is responsible for the development and registration of 501516, and may pay Ligand milestone payments of up $12 million as the product moves through the development process. GSK has exclusive worldwide marketing rights to 501516, and will pay Ligand up to double-digit royalties on potential product sales. If GSK decides not to proceed with development of 501516, Ligand will retain the right to develop and commercialize the product.

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 that involve risks and uncertainties and reflect Ligand's judgment as of the date of this release. These statements include those related to research productivity and discoveries, clinical development, and milestone and royalty payments. Actual events or results may differ from our expectations. There can be no assurance that new drug compounds will be discovered, that clinical development will be successful, that drugs will receive required regulatory approvals, that future milestones or royalties will be earned, or that the drugs will be successfully developed or commercialized. Additional information concerning these and other risk factors affecting Ligand's business can be found in the company's prior press releases as well as in public periodic filings with the Securities and Exchange Commission, available via 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.

Contacts

Ligand Pharmaceuticals Incorporated
Michael J. Watts, 858/550-7850
Director, investor relations and
corporate communications

Contacts

Ligand Pharmaceuticals Incorporated
Michael J. Watts, 858/550-7850
Director, investor relations and
corporate communications