James McAvoy has been forced to leave Summit and Mandate’s Untitled comedy due to undisclosed personal reasons and has been replaced by Joseph Gordon-Levitt.

Gordon-Levitt, riding high following star turns in 500 Days Of Summer and recent Sundance premiere Hesher, will now star opposite Seth Rogen.

Jonathan Levine will commence shooting next week in Vancouver after the original start date was pushed back from February.

Oscar nominee Anna Kendrick, Bryce Dallas Howard, Anjelica Huston and Philip Baker Hall also star in the tale of life, love and death.

Will Reiser wrote the screenplay and Rogen, Evan Goldberg and Ben Karlin are producing. Reiser is serving as executive producer along with Mandate Pictures president Nathan Kahane.

Summit’s president of production Erik Feig and senior vice-president of acquisitions and co-productions Michael Schaefer will oversee the project for the studio.  Nicole Brown will oversee for Mandate Pictures. Lionsgate is handling international sales.

Gordon-Levitt is represented by CAA.