Lexicon Files Investigational New Drug Application For LX2931 As A Potential Treatment For Rheumatoid Arthritis

Lexicon
Pharmaceuticals, Inc. (Nasdaq: LXRX) announced that it has submitted
an investigational new drug (IND) application to the U.S. Food and Drug
Administration (FDA) for LX2931, an oral drug candidate for rheumatoid
arthritis and other autoimmune conditions. The initial Phase 1 clinical
trial of LX2931 is planned as a double-blind, randomized,
placebo-controlled, ascending single-dose study in healthy volunteers,
designed to evaluate the safety, tolerability, and pharmacokinetics of
LX2931. Lexicon expects to initiate clinical trials with LX2931 following
FDA review.


"As an orally-delivered modulator of lymphocyte activity, we believe
LX2931 has potential to be an important new therapy for rheumatoid
arthritis and other autoimmune disorders," said Philip M. Brown, M.D.,
J.D., vice president of clinical development at Lexicon. "We can now add
immunology to the list of therapeutic areas with clinical-stage compounds
from Lexicon's drug discovery pipeline."



Rheumatoid arthritis is an autoimmune disorder characterized by
stiffness, pain, swelling, and limitation of motion in multiple joints.
More than 2 million Americans suffer from rheumatoid arthritis, which, if
left untreated, can result in disfigurement and disability from
irreversible joint damage. According to the National Institutes of Health
(NIH), autoimmune disorders affect between 14.7 and 23.5 million people in
the United States.



LX2931 was developed at Lexicon as an inhibitor of a key enzyme in the
sphingolipid pathway, which controls lymphocyte circulation and trafficking
to peripheral sites in the body during an inflammatory response. As with
Lexicon's other clinical and preclinical programs, the LX2931 target enzyme
was identified through Lexicon's gene knockout program, Genome5000(TM).
Knockout mice lacking this enzyme had a significantly decreased number of
circulating lymphocytes and were resistant to inflammation in a wide range
of assays modeling processes involved in the development of arthritis and
other autoimmune conditions. Because inappropriate activation of
lymphocytes is associated with autoimmune disorders, including rheumatoid
arthritis, reduction of lymphocyte buildup at sites of disease activity
holds promise as a new therapeutic mechanism. Preclinical studies with
LX2931 showed a robust and reproducible reduction of inflammation in animal
models of arthritis. Additionally, LX2931-treated animals showed a rapid,
dose-dependent reduction in peripheral lymphocyte counts.



About Lexicon



Lexicon is a biopharmaceutical company focused on the discovery and
development of breakthrough treatments for human disease. Lexicon currently
has development programs underway for such areas of major unmet medical
need as irritable bowel syndrome, cognitive disorders, and autoimmune
diseases. The company has used its proprietary gene knockout technology to
discover more than 100 promising drug targets and create an extensive
pipeline of clinical and preclinical programs in the therapeutic areas of
diabetes and obesity, cardiovascular disease, psychiatric and neurological
disorders, cancer, immune system disorders and ophthalmic disease.
Lexicon's drug discovery system has been so productive that Lexicon plans
to move ten drug candidates into human clinical trials by the end of 2010.
This strategic initiative is referred to as the 10to10 program. To advance
the development and commercialization of its programs, Lexicon is working
both independently and through collaborators including Bristol-Myers Squibb
Company, Genentech, Inc. and N.V. Organon. For additional information about
Lexicon and its programs, please visit lexpharma.
















Safe Harbor Statement



This press release contains "forward-looking statements," including
statements relating to Lexicon's clinical development of LX2931 and the
potential therapeutic and commercial potential of LX2931. 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 LX2931 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, 2006, 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.


Lexicon Pharmaceuticals, Inc.

lexpharma