Summary of LIGAND PHARMACEUTICALS INC

Item 1.01. Entry into a Material Definitive Agreement

On July 29, 2009, Ligand Pharmaceuticals Incorporated ("Ligand" or the "Company") entered into a Research Collaboration Termination Agreement (the "Termination Agreement") with N.V. Organon, a company organized under the laws of The Netherlands ("Organon"). The Termination Agreement amends certain terms with respect to ongoing research programs and provides for a wind-down period (through December 31, 2009) for such programs during which Ligand and Organon will continue their research activities and Organon will continue funding the programs. The Termination Agreement also provides for the termination, effective as of the end of the wind-down period, or December 31, 2009, of the Research Collaboration under the Collaboration and License Agreement dated February 25, 2002, as amended (the "Research Collaboration Agreement") by and between Pharmacopeia Drug Discovery, Inc. (now Pharmacopeia, LLC, a wholly owned subsidiary of Ligand) and Organon. There is no financial or other termination penalty incurred by Ligand in connection with the termination of the Research Collaboration under the Research Collaboration Agreement

Except as set forth in the Termination Agreement, the Research Collaboration Agreement remains in full force and effect. The foregoing description of the terms of the Termination Agreement does not purport to be complete and is qualified in its entirety by reference to the full text of the Termination Agreement, a copy of which the Company intends to file with its Quarterly Report on Form 10-Q for the quarter ending September 30, 2009, requesting confidential treatment for certain portions.

On July 30, 2009, Ligand issued a press release announcing the entering into of the Termination Agreement. A copy of the press release is attached as Exhibit 99.1 hereto and is incorporated herein by reference.