Responding to rumors on Wall Street, Icos Corp. said Thursdaythat it is discussing with Glaxo Holdings plc a collaboration todevelop drugs for inflammatory and cardiovascular diseases.

"We were concerned about speculation in the marketplaceabout a transaction coming and we wanted to clarify thesituation," said Janice LeCocq, executive vice president offinance and administration at Seattle-based Icos. "The stockhad been appreciating pretty dramatically."

Icos stock (NASDAQ:ICOS) closed Thursday at $16.38, up $2.25.The company completed an initial public offering in June at $8a share.

The companies are discussing joint development and marketingof Icos' phosphodiesterase (PDE) enzymes. No financial termshave been disclosed.

PDEs play a role in regulating the concentrations of cyclic AMPand cyclic GMP in cells. cAMP and cGMP are associated with awide variety of effects, including cardiac musclecontractility, the activation or inhibition of cells in theimmune and nervous systems, and the release of histamine andother vasoactive substances that promote inflammation.

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