Takeda has upped its offer to buy Shire $SHPG for a mix of stock and cash worth close to $65 billion, which is good enough for the Lexington, MA-based biotech to extend the deadline on their talks to May 8 after determining they were close to finalizing a pact.

Late Tuesday Shire reported that Takeda had upped its bid to £27.26 in new Takeda shares and £21.75 in cash, coming to £49 a share. That rings up at 0.839 new Takeda shares and $30.33 for each Shire share — or close to $65 billion, with Takeda tacking on about $2.5 billion.

From the statement Shire issued:

The Board has indicated to Takeda that it would be willing to recommend the Revised Proposal to Shire shareholders subject to satisfactory resolution of the other terms of the possible offer, including completion of reciprocal due diligence by Shire on Takeda. Accordingly, the Board will engage in discussions with Takeda in relation to these terms.

There are a few key issues that will need to be completed:

— Agreement of certain other (unspecified) terms of the revised proposal.
— Satisfactory completion of a confirmatory due diligence review by Takeda.
— The unanimous and unconditional recommendation of the board of Shire.
— And final approval by the board of Takeda.

Takeda followed with a release of its own stating:

Takeda and its Board have remained disciplined with respect to the terms of the Revised Proposal and Takeda intends to maintain its well-established dividend policy and investment grade credit rating.

A matchup with Shire would give Takeda a huge Boston/Cambridge research group — even after some presumed deep cuts in personnel — expanding on Shire’s move to concentrate its forces in Lexington and Cambridge following its Baxalta buyout. Takeda has also been gathering its R&D forces in the big Boston hub. A deal would also likely signal a further wrenching reorganization for local Shire staffers, who have been through repeated revamping under CEO Flemming Ornskov while Takeda has spent much of the past two years restructuring and cutting research.

A mega-merger like this, dwarfing a series of acquisitions in Q1, would also leave biopharma investors hunting for the next big target with 2018 shaping up as a big year for buyouts.