Ligand Pharma Wins Equity Milestone Payment from Retrophin

Ligand Pharmaceuticals Incorporated

announced today that it has received a milestone payment of 620,000 shares of common stock in newly public partner Retrophin, Inc.The milestone arose under the previously executed license agreement for the development and commercialization of Retrophin's lead clinical candidate RE-021, formerly known as DARA (a Dual Acting Receptor Antagonist of Angiotensin and Endothelin receptors) and was triggered by the completion of Retrophin's merger with Desert Gateway, Inc. and its transition to a publicly traded company. Ligand will record milestone revenue equal to the estimated fair value of the shares received, which will be determined by an independent valuation firm. The shares issued to Ligand represent approximately 7% of Retrophin's outstanding capital stock and may be subject to certain trading restrictions. RE-021 is in development for the treatment of focal segmental glomerulosclerosis (FSGS), a rare disease that attacks the kidney's filtering system (glomeruli), causing serious scarring, progressive kidney function degeneration and rapid loss of the kidneys. FSGS is one cause of a serious condition known as Nephrotic Syndrome. An estimated 50,000 patients in the United States suffer from FSGS, with most patients diagnosed as children or young adults. Ligand believes that Retrophin expects to begin enrollment in a Phase 2 clinical trial known as “FONT-3” during the first half of 2013.