Aug 2 (Reuters) - UK drugmaker AstraZeneca has been exploring a deal to combine with U.S. rival Bristol Myers Squibb, the Financial Times reported on Sunday, citing people familiar with the matter. The ‌deal could create one of the world's biggest pharmaceutical companies with a combined value of nearly $400 ‌billion. AstraZeneca declined to comment, while Bristol Myers did not immediately respond to a Reuters request for comment. Combining with Bristol Myers, whose shares are up around 44% over ​the ​last year, could draw attention from antitrust regulators. In 2019, Bristol Myers bought Celgene for about $80 billion, acquiring its flagship blood cancer drug Revlimid, which became Bristol's top-selling product.