Lexicon Presents Positive Outcome in IBS Patients Treated With LX1031 and Data Supporting Mechanism of Action

THE WOODLANDS, Texas, May 5 /PRNewswire-FirstCall/ -- Lexicon Pharmaceuticals, Inc. (Nasdaq: LXRX), a biopharmaceutical company focused on discovering and developing breakthrough treatments for human disease, presented results from its positive Phase 2 clinical study with LX1031 in patients with non-constipating irritable bowel syndrome (IBS) at Digestive Disease Week (DDW) 2010 in New Orleans, Louisiana.

LX1031 is an oral, serotonin synthesis inhibitor that acts locally in the gastrointestinal tract targeting tryptophan hydroxylase (TPH), an enzyme necessary for the production of serotonin. LX1031 is the first TPH inhibitor to be evaluated in human clinical trials for the treatment of IBS.  Results from the randomized, placebo-controlled study of 155 patients with non-constipating IBS showed that patients who received LX1031 (1,000 mg four times a day) for 28 days experienced significant improvement (p<0.05) in global assessment of relief of IBS pain and discomfort over the four-week dosing period as compared to placebo.  Corresponding to the improvements in global assessment, significant improvements also occurred in stool consistency.  It was noted that an increased clinical response correlated with a reduction in serotonin synthesis as reflected by measures of urinary 5-HIAA.  LX1031 was well tolerated, with no notable differences in adverse events observed between placebo and either treatment group.  

To validate the mechanism of action of LX1031, treated patients were categorized based on whether or not they reached a threshold of 15% reduction in urinary 5-HIAA, a biomarker of serotonin synthesis. The resulting analysis showed that the 5-HIAA biomarker could distinguish patients who responded to the investigational drug LX1031 across multiple clinically-relevant measures. After four weeks of receiving 1,000 mg of LX1031 four times daily, 73% of patients who reached the biomarker reduction threshold reported experiencing adequate relief of their IBS pain and discomfort as compared to only 11% of patients not meeting the biomarker response threshold (p<0.01). These results illustrate the potential utility of an objective biochemical marker in the management of patients with IBS. In addition, the data suggest the ability to identify patients who are most likely to benefit from therapy with LX1031.

"These findings are especially important in IBS, which has been lacking an objective biochemical marker. The 5-HIAA biomarker correlation with clinical response in this study validates the mechanism of action of LX1031," said Dr. Philip Brown, senior vice president of clinical development at Lexicon. "We intend to integrate measures of 5-HIAA in future clinical development of LX1031, which could reduce variability and improve response rates."

About LX1031

Clinical development of LX1031 is being funded through a product development collaboration with Symphony Capital Partners, L.P. and its co-investors.

For more information on this program, and to access the presentations, please visit www.lexpharma.com.

About Lexicon

Lexicon is a biopharmaceutical company focused on discovering and developing breakthrough treatments for human disease.  Lexicon currently has four drug candidates in mid-stage development for diabetes, irritable bowel syndrome, carcinoid syndrome and rheumatoid arthritis, 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.  Lexicon has focused drug discovery efforts on these biologically-validated targets to create its extensive pipeline of clinical and preclinical programs.  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 the potential utility of urinary 5-HIAA as a biochemical marker in the management of patients with IBS, including its potential use in identifying patients who are most likely to benefit from therapy with LX1031, Lexicon's intent to integrate measures of 5-HIAA and other matters relating to the future clinical development of LX1031, including effects on variability and response rates, validation of the mechanism of action of LX1031, and the potential therapeutic and commercial potential of LX1031. 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 successfully conduct clinical development of LX1031 and preclinical and clinical development of its other potential drug candidates, advance additional candidates into preclinical and clinical development, 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 "Factors Affecting Forward-Looking Statements" and "Risk Factors" in Lexicon's annual report on Form 10-K for the year ended December 31, 2009, 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.

SOURCE Lexicon Pharmaceuticals, Inc.