(Bloomberg) -- Private equity firm Blackstone Inc. is nearing a deal to buy Advarra Inc. from Genstar Capital in a transaction that would value the drug-research services firm at about $5 billion, according to a people with knowledge of the matter. 

A deal could be announced in the coming days, said the people, who asked not to be identified because the matter isn’t public. No final decision has been made and talks could still fall through, they added. 

Representatives for Blackstone, Genstar and Advarra declined to comment. 

Genstar acquired a majority stake in Columbia, Maryland-based Advarra from Linden Capital Partners in 2019. It had hired advisers to help it explore a potential sale of Advarra or an initial public offering, Bloomberg News reported in February. 

Advarra helps get drugs to market by reviewing clinical research to ensure trials are safe for participants and comply with regulatory requirements. The company says it supported all of the coronavirus vaccine clinical trials under the Trump administration’s Operation Warp Speed, which used government resources to fast-track vaccine development.

The company is the biggest institutional review board, or IRB, in the US and largely operates in a duopoly with Leonard Green-backed WCG. IRBs are designated under US Food and Drug Administration rules to review, approve and require changes to how trials are run.

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