Lexicon Completes Phase 2 Study Of LX1033 In IBS-d

              Lexicon Completes Phase 2 Study Of LX1033 In IBS-d

PR Newswire

THE WOODLANDS, Texas, Dec. 3, 2013

THE WOODLANDS, Texas, Dec. 3, 2013 /PRNewswire/ -- Lexicon Pharmaceuticals,
Inc. (Nasdaq: LXRX) today announced top-line results from an initial Phase 2
study exploring the use of LX1033 in diarrhea-predominant irritable bowel
syndrome (IBS-d). LX1033 is an investigational drug that inhibits serotonin
synthesis in the gastrointestinal tract. Serotonin is a neurotransmitter that
has been shown to play a role in the symptoms of irritable bowel syndrome.

The primary endpoint of this study was the change in stool consistency
averaged from baseline to day 28. All treatment groups, including placebo,
showed significant improvements over time, yet differences between placebo and
LX1033 in stool consistency were not statistically significant. Further
analyses of the stool consistency data were performed adjusting for early
terminations which may have enhanced the placebo response rate. These
additional analyses of stool consistency yielded favorable results for the
LX1033 500mg three times daily dose group compared to placebo, and some of
these findings were associated with statistically significant results
(p<0.05). LX1033 reduced the production of plasma 5-HIAA (a biomarker for
serotonin synthesis) significantly more than placebo, with the greatest
reductions observed in the 500 mg three times daily dose group. This same
LX1033 dose also produced the greatest reduction in abdominal pain, an
important measure of efficacy in IBS-d. The proportion of patients showing an
abdominal pain intensity weekly response (defined as a reduction in abdominal
pain of at least 30% from baseline for at least 50% of the weeks assessed,
with no worsening from baseline in stool consistency) was 33% on placebo and
47% on LX1033 500 mg given three times daily (p<0.05). LX1033 was safe and
well tolerated in the study, with adverse events evenly distributed among
LX1033 treatment arms and placebo.

"While LX1033 showed similar improvements in stool consistency as compared to
the placebo patients who completed the study, there were positive effects on
abdominal pain in the treated group that warrant further study," said Pablo
Lapuerta, M.D., Lexicon's chief medical officer. "While this initial Phase 2a
study was underway, we completed long-term toxicology studies which would
allow us to conduct a Phase 2b study at doses informed by the current results
and with a duration of 12 weeks, a treatment period that has historically been
important to identify clinically meaningful changes as compared to placebo."

In this Phase 2 study of IBS-d, 373 patients were randomized to be treated for
28 days with either placebo or one of three different dose levels of LX1033
for 28 days, 1000 mg twice daily, 500 mg twice daily, and 500 mg three times
daily. The primary endpoint was the change from baseline in stool consistency
as evaluated by the Bristol Stool Form Scale. A key secondary endpoint was the
change from baseline in abdominal pain, and other endpoints included the
change in plasma 5-HIAA.

About Lexicon
Lexicon is a biopharmaceutical company focused on discovering breakthrough
treatments for human disease. Lexicon currently has multiple programs in
clinical development for diabetes, irritable bowel syndrome, 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. 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 Lexicon's clinical development of LX1033, characterizations of the
results of and projected timing of clinical trials of LX1033, and the
potential therapeutic and commercial potential of LX1033. The 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
LX1033 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
"Risk Factors" in Lexicon's annual report on Form 10-K for the year ended
December 31, 2012, 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

SOURCE Lexicon Pharmaceuticals, Inc.

Website: http://www.lexpharma.com
Contact: Contact for Lexicon: Alex Abuin, Ph.D., Vice President,
Communications and Alliance Management, 281/863-3213, aabuin@lexpharma.com
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