DeGale is the reigning IBF super-middleweight champion but had to travel to Boston to win that belt and has competed on the other side of the Atlantic in each of his three defences since.
Truax meanwhile is getting his second shot at a world title, having taken on Daniel Jacobs for the WBA middleweight strap in 2015, losing by TKO in the final round.
He has since lost one other fight, stopped by Anthony Dirrell in the first round last year, to give him a record of 28-3-2.
DeGale is a heavy favourite to hang onto his belt but will want to make a statement to the British public and show George Groves what he can expect if they do book a rematch in 2018.
But they will both have to wait for the undercard to unfold before getting in the ring – Lee Selby is the main other attraction, defending his featherweight title against the unbeaten Eduardo Ramirez.
DeGale vs Truax undercard
James DeGale vs Caleb Truax (IBF world super-middleweight championship)
Lee Selby vs Eduardo Ramirez (IBF world featherweight championship)
Anthony Yarde vs Nikola Sjekloca (WBO European light-heavyweight championship)
Joe Mullender vs Lee Churcher
Johnny Garton vs TBA
Daniel Dubois vs Dorian Darch
Archie Sharp vs Rafael Castillo
Craig Evans vs TBA
Sanjeev Sahota vs TBA
Hamza Sheeraz vs TBA
Umar Sadiq vs TBA
Harvey Horn vs Denis Bartos
Ben Smith vs TBA