* Swiss Actelion posts "stellar" results, ups forecast
* Ireland's Elan also beats expectations
* Elan gives J&J option to buy Biogen MS drug stake
* US biotechs Gilead, Genzyme, Celgene also report this week
* Actelion shares up 1.2 percent; Elan up 0.1 percent (Adds more comment; updates shares)
By Sam Cage and Padraic Halpin
ZURICH/DUBLIN, July 21 (Reuters) - European drugmakers Actelion and Elan both beat profit forecasts on Tuesday, as sales of key medicines helped shield them from the recession.
The strong results from Actelion, Europe's largest biotech company, and Irish drugmaker Elan set the stage for results from U.S. biotechs Gilead, Genzyme and Celgene.
Actelion raised its full-year outlook after its second-quarter profit beat expectations, helped by strong sales of key drug Tracleer -- results which Vontobel analyst Andrew Weiss described as "stellar".
Elan, also beat expectations, aided by a jump in sales of multiple sclerosis drug Tysabri, even though it posted a wider net loss.
The Irish company, which this month sold an 18.4 percent stake to U.S. healthcare group Johnson & Johnson, also confirmed it has given J&J an option to acquire Biogen Idec Inc's 50 percent stake in the multiple sclerosis drug Tysabri, should there be a change of control at Biogen.
Actelion is trying to cut its dependence on Tracleer for pulmonary arterial hypertension, which rakes in more than $1 billion a year, by developing it for new indications and pushing other new drugs to market.
However, it reported some delays in its promising portfolio of new medicines -- a key driver for biotech groups -- including sleep drug almorexant, which is being developed with Britain's GlaxoSmithKline.
Actelion Chief Executive Jean-Paul Clozel said the group was in talks with U.S. regulators over labelling for almorexant, a potential billion-dollar seller, which would mean a delay of eight to nine months.
Actelion shares were up 1.2 percent to 58.2 Swiss francs by 1347 GMT, versus a 1 percent rise in the DJ Stoxx European health care index. Elan shares, which jumped 9 percent on Monday following media reports that it may invest in a biologics operation in Ireland, were up 0.1 percent to 5.685 euros.
"Despite the strong financial results, we are disappointed to learn that the pipeline has experienced several delays," said Olav Zilian, an analyst at brokerage Helvea.
MS BOOST FOR ELAN
Elan's results were driven by a 30 percent jump in sales of its multiple sclerosis drug Tysabri, which the company said about 43,300 patients worldwide were taking by the end of June.
Elan and partner Biogen Idec originally predicted 100,000 patients would be taking Tysabri by the end of 2010. While they still expect to reach that figure, which would mean the drug could bring in $2 billion to $3 billion a year, they do not expect to reach it within that timeframe.
Jack Gorman, an analyst at Davy Stockbrokers, said that giving away the right on the potential blockbuster drug Tysabri, may actually be a good move for Elan.
"Looking at it another way, such a provision may indicate that J&J has more than a passing interest in the Tysabri asset -- if it was ultimately to become Elan's partner in MS, we would view this as a good result," Gorman said in a note. (Additional reporting by Paul Arnold in Zurich; Editing by Erica Billingham)