Lady Gaga discussed this subject while explaining how the movie inspired her new album Harlequin, which collects reimagined covers that she and Phoenix sing in Joker, as well as two original songs. The singer-songwriter and star of movies like A Star is Born and House of Gucci started off by telling EW:

As Joker 2 nears its release, director Todd Phillips has opened up about the future of Lady Gaga’s Harley Quinn. During a red carpet event, Phillips discussed the possibility of a standalone film for Gaga’s Harleen Quinzel.

Joaquin Phoenix's Joker gets a partner in both romance and crime in the new movie Joker: Folie à Deux. The movie introduces Lady Gaga as a new incarnation of Harley Quinn, though director Todd Phillips is suggesting that fans should not get their hopes up about seeing the character getting her own spinoff film.