The letters have started flying again from Amylin and dissident shareholders as the battle for control of the board heats up before a crucial proxy vote next week.

The company’s annual meeting of stockholders will be held next week and the pressure on Amylin’s board being applied by major investors Carl Icahn and Eastbourne Capital has increased. The two dissidents recently joined forces to present a slate of prospective nominees that would replace the current directors who stand accused of failing to maximise the commercial value of Amylin’s assets, namely the diabetes blockbuster Byetta (exenatide).

Eastbourne issued a number of releases yesterday, with the last noting that a fourth independent proxy advisory firm, Egan Jones, is backing two of its nominees, plus one of Mr Icahn’s choices. The other firms supporting a pretty similar stance are RiskMetrics Group, Glass Lewis & Co and Proxy Governance.

Earlier in the day, Eastbourne had said it believes that the incumbent board “could, if it chose, bring the election contest to an amicable conclusion” by offering Amylin shareholders the opportunity to support a unified slate made up of Eastbourne, Icahn and company nominees. However it has been informed that the board “has determined not to accept Eastbourne's proposed resolution”.

Eastbourne founder Richard Barry said in a letter to Amylin that “it will be disappointing if, rather than welcoming new, eminently capable, shareholder-sponsored directors, you choose to continue a proxy contest and draw valuable resources and time away from addressing the issues facing the company”. He added that “as time is short, we sincerely hope that you will respond quickly and privately”.

The board did indeed respond quickly and issued its own statement saying that "after significant efforts and consultation with numerous shareholders, Amylin has been unable to achieve a settlement with Eastbourne and Carl Icahn which is in the best interests of all shareholders. The firm added that “of course, we continue to remain open to new ideas and perspectives”.

The board backed its track record, saying that it has “executed on its strategy and is now poised to capitalise on its market position with the highly anticipated launch of exenatide once-weekly in 2010”. With no similar drug on the market, “we believe it has the potential to transform the treatment of diabetes”, the company added.

The meeting is scheduled to be held on May 27, leaving plenty of time for more frank exchanges between the two factions.