To see how difficult it can be even for Mr Icahn to get his way, look to the saga at Biogen Idec, another American biotech firm in which the gadfly billionaire owns a stake.

• 就算伊汉出马，此道也绝非易事，只要看看另一家美国生物科技公司BiogenIdec的坎坷经历就可见一斑。