The battle to take control of ImClone Systems is heating up after the US biotechnology company claimed to have received a bigger offer than the $60 per share tabled six weeks ago.

News of the fresh bid came as ImClone’s chairman, the billionaire Carl Icahn, confirmed that a special committee had reviewed B-MS’ $4.5 billion cash offer to buy the 83% stake it does not already own, and has deemed it “inadequate”. He then went on to say that he has had “several conversations” with the chief executive of “a large pharmaceutical company”.

No names were given but Mr Icahn added that “as a result of such conversations, the pharmaceutical company has submitted a proposal, subject to due diligence, but not subject to financing”, to acquire ImClone for $70 per share in cash. The special committee has decided, subject to the execution of a confidentiality agreement, “to allow this company to conduct due diligence for a two-week period, subject to extension by mutual consent”, he added.

Mr Icahn went on to say that “no determination has been made as to whether $70 per share would be adequate.” The statement thrusts the ball firmly back in B-MS’ court, which is attempting to get further control of Erbitux (cetuximab), currently indicated for metastatic colorectal cancer and the treatment of squamous cell carcinoma of the head and neck. The two companies have a development and commercialisation pact on the drug in the USA, while Germany’s Merck KGaA holds the European rights to the drug.

Indeed there is speculation that Merck could be the mystery bidder but no firm has come forward yet. Analysts are now wondering what the upshot will be of this latest development and while a B-MS spokesperson previously told PharmaTimes World News that “we believe we have made a full and fair offer”, the general consensus is that it will take more cash than $60 to swing the deal.

Deutsche Bank analyst Barbara Ryan issued a research note saying that “in our view, this will force Bristol’s hand to offer $70 with no due diligence conditions immediately”. She believes that such a bid would win the day “and that this is a good strategic and financial deal for Bristol at that price.”