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(Adds GlaxoSmithKline selling 7.9 pct stake in Genmab)
By Teis Jensen
COPENHAGEN, Feb 4 (Reuters) - Positive results from a trialby biotech company Genmab of its bone marrow cancertreatment could lead to the launch of a blockbuster drug earning$3.5 billion a year, analysts said on Wednesday, sending itsshares up by over 10 percent.
But British pharmaceutical giant GlaxoSmithKline later saidafter the market closed that it would sell its 7.9 percent stakein the Danish company, which had a market value of some 26.833billion Danish crowns at the end of the day.
Genmab said the study of daratumumab, which evaluatedmultiple myeloma patients who had already had at least threedifferent lines of therapy without success, showed an overallresponse rate of 29.2 percent.
The response rate indicated Genmab's drug worked better thantwo recently approved drugs, Onyx Pharmaceuticals' Kyprolis andCelgene's Pomalyst, although these have been tested indifferent ways, Sydbank analyst Soren Lontoft Hansen said.
He said Genmab was now more likely to get U.S. Food and DrugAdministration (FDA) approval for the drug and could launch itby the end of the year.
"We believe the data is very positive and well above the FDAthreshold for approval," Danske Bank analysts said in a note."We therefore expect the study results to lead to U.S. approvalof daratumumab in the second half of 2015."
Jefferies meanwhile saw an 80 percent chance of commercialsuccess for daratumumab and annual peak revenues of $3.5 billionalthough it expected a launch in the first half of next year.
Genmab declined to comment beyond its Tuesday evening pressstatement.
Danske Bank raised its price target to 530 crowns, whileNordea raised it to 670 crowns from 450 crowns. Genmab's sharesclosed almost 11 percent up, the largest rise since August 2013,at 471 crowns.
But shortly after the Copenhagen bourse closed, GSK said itwould offer its stake to institutional investors because Genmabstopped being a core asset since the British company sold offits cancer drug portfolio.
The results of the placing are due on Thursday.
Genmab's stock has more than doubled in the last six months- including Wednesday's gains, outperforming a 10 percent risein the Danish benchmark index, and now has a marketcapitalisation of almost 24 billion crowns.
"It is because it has become more evident to the market thatdaratumumab is a very potent drug and that it is getting closerto an approval," Hansen said. ($1 = 6.5015 Danish crowns) (Editing by Susan Thomas and Greg Mahlich)
