Actelion boosted by delay to potential competitor

ZURICH, June 18 (Reuters) - Shares in Swiss biotech company Actelion Ltd. ATLN.S were boosted on Monday after U.S. regulators declined to approve a potential competitor to its flagship Tracleer drug for life-threatening lung disease. Encysive Pharmaceuticals Inc. ENCY.O said on Friday the Food and Drug Administration had declined to approve its pulmonary arterial hypertension (PAH) treatment Thelin, saying in a third approvable letter that the drug did not demonstrate the required effectiveness.

"We had not expected Thelin to be approved, but were surprised that the FDA questioned efficacy," said Kepler Equities analyst Denise Anderson. "Eventual U.S. approval therefore seems very unlikely."

Actelion shares were 4.3 percent higher at 59.50 Swiss francs by 0739 GMT.

The FDA also approved another PAH treatment, Letairis from Gilead Sciences Inc. (GILD.O), which will compete with Tracleer.

"The battle begins," Lehman Brothers said in a note. "Gilead is launching Letairis this week, with both doses priced at parity to Tracleer.

"We believe Actelion's shares may be range-bound in the coming months, prior to the market gaining visibility on Letairis' impact," Lehman said.

((Reporting by Sam Cage, editing by Greg Mahlich; e-mail: zurich.newsroom@reuters.com Reuters Messaging: sam.cage.reuters.com@reuters.net; telephone: +41 (0) 44 631 7457)) Keywords: ACTELION SHARES/

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