New Drug Applications

Promacta

eltrombopag

Treatment for Idiopathic (Immune) Thrombocytopenic Purpura

Ligand Earns $1 Million Milestone Payment as GlaxoSmithKline Submits New Drug Application for Promacta (eltrombopag)

SAN DIEGO--(BUSINESS WIRE)--Dec 20, 2007 - Ligand Pharmaceuticals Incorporated (the Company or Ligand) today announced that it has earned from GlaxoSmithKline (GSK) a milestone payment of $1 million as a result of GSK's submission of a New Drug Application (NDA) for Promacta (eltrombopag). If approved, Promacta would be the first oral platelet growth factor therapy for the short-term treatment of previously treated patients with chronic idiopathic thrombocytopenic purpura (ITP) to increase platelet counts and reduce or prevent bleeding. Chronic ITP is a disorder marked by increased platelet destruction and/or inadequate platelet production in the blood, which causes an increased risk of bruising and bleeding. Promacta is an investigational, once-daily oral treatment that induces the proliferation and differentiation of cells in the bone marrow to produce platelets.

The milestone payment arises from a drug discovery alliance with GSK to focus on the discovery of small-molecule TPO mimetics. Under the terms of the collaboration, Ligand is eligible to receive an additional milestone payment of $2 million upon approval of Promacta by the U.S. Food and Drug Administration (FDA), as well as royalty payments on any future sales of the drug.

"We are very pleased with GSK's progress with Promacta. Their team has done an excellent job executing its clinical activities, and they have obtained encouraging results. This milestone reinforces our belief in Ligand's science and technology that has yielded the first oral TPO receptor agonist," said John L. Higgins, President and Chief Executive Officer of Ligand Pharmaceuticals. "Our collaborations with pharmaceutical industry leaders such as GSK are representative of Ligand's commitment to leverage its technology and research capabilities to create value for shareholders."

Ligand and GlaxoSmithKline Collaboration

The GSK-Ligand collaboration began in 1997 to utilize Ligand's expertise and technology to discover small-molecule drugs to control hematopoieses and treat patients with cancer, anemia or platelet deficiencies. The research phase of the collaboration ended in 2001. GSK is responsible for the registration and worldwide marketing of Promacta.

About Ligand Pharmaceuticals

Ligand discovers and develops new drugs that address critical unmet medical needs of patients in the areas of thrombocytopenia, hepatitis C, cancer, hormone-related diseases, osteoporosis 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.

Caution Regarding Forward-Looking Statements
This news release contains forward-looking statements by Ligand that involve risks and uncertainties and reflect Ligand's judgment as of the date of this release. These statements include those related to future action by the FDA for the recently submitted NDA; the promise of Promacta (eltrombopag) future regulatory approvals; increases in shareholder value; and future milestone and royalty payments. Actual events or results may differ from our expectations. There can be no assurance GlaxoSmithKline, or any of our other partners will continue clinical development of any compound(s); that clinical development will be successful; that future clinical trial data will be favorable or that such trials will confirm any improvements over other products or lack of negative impacts; that drugs will receive required regulatory approvals or that they will be commercially successful therapies, provide new options or be successfully marketed; that our partner portfolio will continue to mature, that our business will continue to grow or that shareholder value will increase, that the FDA will accept any filing, or that any future milestone or royalty payments will be received. Our stock price could be harmed if any of these events or trends fails to occur, is delayed or otherwise differs from expectations. Additional information concerning these and other risk factors affecting Ligand's business can be found on 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.

Contact

Ligand Pharmaceuticals Incorporated
John L. Higgins, President and CEO or
Erika Luib, Investor Relations
858-550-7896
or
Lippert/Heilshorn & Associates
Don Markley, 310-691-7100
dmarkley@lhai.com

Related Articles:

Ligand Partner GlaxoSmithKline Receives FDA Extended Priority Review for Promacta NDA - June 23, 2008

Promacta (eltrombopag) Receives Unanimous Recommendation by FDA Advisory Panel - May 30, 2008

FDA Grants Priority Review for Promacta (eltrombopag) - March 3, 2008

GlaxoSmithKline Files for FDA Approval of Promacta (eltrombopag) to be the First Oral Platelet Growth Factor for Rare Blood Disorder - December 20, 2007