(Biotech Winners & Losers item updated for closing stock prices.)

NEW YORK ( TheStreet) -- Lexicon Pharmaceuticals ( LXRX) stock was one of the leading gainers among biotech shares Monday on a day when most names in the land of experimental medicaments were in the green.

The Nasdaq Biotechnology Index jumped 6.24 points to 930.20

Shares of Lexicon, a Houston-based outfit that's attempting to develop treatments for diabetes, irritable bowel syndrome and rheumatoid arthritis, among other diseases, gained 4% to $1.79 Monday after earlier going as high as $1.91. Volume exceeded 1.9 million shares; average daily turnover has been about 750,000 shares.

Lexicon is expected to release results of a Phase Two clinical study of its rheumatoid arthritis drug LX2931. The firm launched the 12-week study in August 2009. On Friday, the company's CEO, Arthur Sands, is scheduled to deliver a presentation at the Biotech Industry Conference in New York.

Elsewhere, Exelixis ( EXEL) shares added 21 cents, or 4.6%, to $4.81, on brisker-than-average volume. Earlier in the session, the stock hit $4.99.

Last week, the company licensed a pair of drugs still under development to Bristol-Myers Squibb ( BMY) for an initial payment of $60 million. The two companies will collaborate on developing the drugs, which could be used to treat diabetes and inflammatory illnesses, Exelixis says.

If certain milestones are hit, Exelixis said the Bristol-Myers deal could eventually result in payments of more than $500 million. Both drug programs are in preclinical trials.

Bristol-Myers in June walked away from a deal with Exelixis under which the companies were to have worked on a cancer drug. The two companies have five other licensing agreements in place.

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