Eli Lilly and Co. has commenced its tender offer for New York-based ImClone Systems Inc., the Indianapolis-based drugmaker announced today. Lilly agreed on Oct. 6 to pay $70 a share in cash to acquire ImClone, for a total purchase price of $6.5 billion. Two of ImClone's largest shareholders-ImClone Chairman Carl Icahn and New York-based Bristol-Myers Squibb Co.-have already agreed to sell their shares to Lilly. Combined, Icahn and Bristol-Myers hold more than 30 percent of ImClone's stock. Lilly's tender offer is set to expire at midnight on Nov. 20.