- Offer raised to 55 pounds a share- Pfizer calls on Astra to begin substantive engagement- 'Time for constructive engagement is running out'Pfizer has sweetened its offer for AstraZeneca again in what is thought to be a last-ditch attempt to take over the UK pharmaceutical rival.The US group has lifted its cash-and-shares bid to £55 a share, up from the previous £50-a-share offer made on May 2nd and a lower initial proposal of £46.61 a share in January.The new offer, which raised the cash element, is thought to value AstraZeneca at around £69bn. This is a 24% higher than the initial January proposal and a 34% premium to AstraZeneca's all-time closing high reached in April.Pfizer said this is a "final proposal" and would not be increasing it any further, as it called on AstraZeneca shareholders to urge the latter's board to begin "substantive engagement"."Pfizer will not make a hostile offer directly to AstraZeneca shareholders and will only announce an offer with the recommendation of the AstraZeneca board."Under the new proposal, Pfizer and AstraZeneca shareholders would own 74% and 26% of the new enlarged company, respectively."We believe our proposal is compelling for AstraZeneca's shareholders and that a Pfizer-AstraZeneca combination is in the best interests of all stakeholders," said Pfizer's Chairman and Chief Executive Ian Read."Following a conversation with AstraZeneca earlier today, we do not believe that the AstraZeneca board is currently prepared to recommend a deal at a reasonable price. We remain ready to engage in a meaningful dialogue but time for constructive engagement is running out."BC