Both Martin Scorsese and Steven Spielberg were attached to direct, before Bradley Cooper showed them A Star Is Born (2018).
The project got the rights to Bernstein's music instead of Cary Fukunaga's Bernstein biopic which would have starred Jake Gyllenhaal. The American.
This is Bradley Cooper and Carey Mulligan's first joint venture, but it's not the first time the pair had actually met. When Mulligan suffered a head injury during the 2018 Broadway preview of playwright Dennis Kelly's "Girls & Boys" after a heavy stage curtain struck her unexpectedly, she was accompanied to Urgent Care in Manhattan by Cooper who happened to be in the theater audience.