Talks between Biogen Idec and Facet Biotech over an unsolicited $493 million takeover bid have fallen through after investors were not persuaded to tender a majority of shares.

It is understood Biogen Idec may increase it’s offer, which was originally condemned by Facet chief executive Faheem Hasnain as “inadequate and did not fairly value our company”. Meanwhile, Facet is believed to be pursuing other “appropriate opportunities”.

Some analysts have suggested Bristol-Myers Squibb as a possible suitor in takeover talks.