Lexicon Pharmaceuticals Announces First Patient Screened in Pivotal Phase 3 Clinical Trial of Sotagliflozin

The Woodlands, Texas, March 25, 2015 - Lexicon Pharmaceuticals, Inc. (Nasdaq: LXRX), a biopharmaceutical company focused on developing breakthrough treatments for human disease, today announced that it has commenced screening in its first pivotal Phase 3 clinical trial of sotagliflozin for type 1 diabetes.

"We are pleased to achieve this important milestone in sotagliflozin's Phase 3 development on schedule," said Lonnel Coats, Lexicon's president and chief executive officer. "We believe this first-in-class, dual SGLT1 and SGLT2 inhibitor has the potential to provide unique benefits to individuals with type 1 diabetes."

Lexicon will be conducting two pivotal Phase 3 clinical trials of sotagliflozin, one in North America and another primarily in Europe. Each pivotal trial is a randomized, double-blind, placebo-controlled, parallel-group, multicenter study to evaluate the efficacy, safety and tolerability of sotagliflozin in adult patients with type 1 diabetes. Two dose levels of sotagliflozin, 200mg and 400mg once daily, will be tested along with placebo. The primary efficacy endpoint under evaluation will be reduction of A1C versus placebo on optimized insulin treatment at 24 weeks, with secondary endpoints including percentage of patients achieving A1C levels of less than 7%, reduction in meal-time, or bolus, insulin use and weight loss. Additional information on the North American study can be found at www.clinicaltrials.gov by using the identifier NCT02384941.

About Lexicon
Lexicon is a biopharmaceutical company focused on developing breakthrough treatments for human disease. Lexicon has clinical-stage drug programs for diabetes, carcinoid syndrome, and other indications, all of which were discovered by Lexicon's research team. Lexicon has used its proprietary gene knockout technology to identify more than 100 promising drug targets. For additional information about Lexicon and its programs, please visit www.lexpharma.com.

Safe Harbor Statement
This press release contains "forward-looking statements," including statements relating to Lexicon's clinical development of sotagliflozin (LX4211), including characterizations of the results of and projected timing of clinical trials and the potential therapeutic and commercial potential of sotagliflozin. In addition, this press release also contains forward-looking statements relating to Lexicon's growth and future operating results, discovery and development of products, strategic alliances and intellectual property, as well as other matters that are not historical facts or information. All forward-looking statements are based on management's current assumptions and expectations and involve risks, uncertainties and other important factors, specifically including those relating to Lexicon's ability to meet its capital requirements, successfully conduct clinical development of sotagliflozin and preclinical and clinical development of its other potential drug candidates, obtain necessary regulatory approvals, achieve its operational objectives, obtain patent protection for its discoveries and establish strategic alliances, as well as additional factors relating to manufacturing, intellectual property rights, and the therapeutic or commercial value of its drug candidates, that may cause Lexicon's actual results to be materially different from any future results expressed or implied by such forward-looking statements. Information identifying such important factors is contained under "Risk Factors" in Lexicon's annual report on Form 10-K for the year ended December 31, 2014, as filed with the Securities and Exchange Commission. Lexicon undertakes no obligation to update or revise any such forward-looking statements, whether as a result of new information, future events or otherwise.

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