"He's a brilliant player and he's a world-class player," England scrumhalf Danny Care, who was not named in Eddie Jones' squad, told BBC's Rugby Union Weekly. "He's a guy who gives you an unbelievable amount of energy every defensive and attacking play, he's in your face, he's someone teams do not want to play against.
"He's a big loss for England. I hope he's back as soon as possible but there will be other players who can step up to the plate." Itoje, who could return for England's final two matches against Italy and Scotland next month, was replaced by fellow Saracen Nick Isiekwe.
Jones also picked uncapped players Jack Singleton, Ben Earl, Dan Robson and Ollie Thorley in the 35-man squad. Full squad:
Forwards Jack Clifford (Harlequins), Dan Cole (Leicester Tigers), Luke Cowan-Dickie (Exeter Chiefs), Tom Curry (Sale Sharks), Ben Earl (Saracens), Ellis Genge (Leicester Tigers), Jamie George (Saracens), Nathan Hughes (Wasps), Nick Isiekwe (Saracens), George Kruis (Saracens), Joe Launchbury (Wasps), Courtney Lawes (Northampton Saints), Ben Moon (Exeter Chiefs), Brad Shields (Wasps), Kyle Sinckler (Harlequins), Jack Singleton (Worcester Warriors), Billy Vunipola (Saracens), Mako Vunipola (Saracens), Harry Williams (Exeter Chiefs), Mark Wilson (Newcastle Falcons).
Backs Chris Ashton (Sale Sharks), Mike Brown (Harlequins), Joe Cokanasiga (Bath Rugby), Elliot Daly (Wasps), Ollie Devoto (Exeter Chiefs), Owen Farrell (Saracens) captain, George Ford (Leicester Tigers), Jonny May (Leicester Tigers), Jack Nowell (Exeter Chiefs), Dan Robson (Wasps), Henry Slade (Exeter Chiefs), Ben Te’o (Worcester Warriors), Ollie Thorley (Gloucester Rugby), Manu Tuilagi (Leicester Tigers), Ben Youngs (Leicester Tigers). (Reporting by Hardik Vyas in Bengaluru, editing by Pritha Sarkar)