In a statement released on Tuesday morning, AstraZeneca said clearance from the European Commission marked "an important step towards completion".
"We are now another step closer to closing the acquisition and combining the two companies to create a leader in immunology and precision medicines," said Marc Dunoyer, CFO and executive director of AstraZeneca. "We continue to progress towards the completion of the acquisition during this quarter."
AstraZeneca shares ticked a third of a percent higher in London and Alexion shares were unchanged in the pre-market in New York.
The takeover has already been approved by regulators in the United States, Japan and other countries globally, but is still awaiting clearance from the UK.
The UK's Competition Markets Authority said in May that it is examining the deal after potential antitrust concerns were raised. The watchdog has until 21 July to launch an in-depth inquiry.
The proposed acquisition, first announced in December 2020, will improve AstraZeneca's scientific presence in immunology. The deal will add five approved medicines and a pipeline of 11 new potential drugs.
AstraZeneca said that rare diseases represent a high-growth disease area with rapid innovation and significant unmet medical needs. Demand for medicines to treat rare diseases is forecasted to grow by a low double-digit percentage in the future.
Shareholders of both companies overwhelmingly supported the acquisition in a vote on 11 May 2021.
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