Wasps sign Gloucester's Paul Doran-Jones and fellow prop David Langley from Cambridge, while Tom Bristow exits the club.
Gloucester confirm Carl Fearns will remain with Lyon, despite signing a deal to move to the Premiership this summer.
Edinburgh and London Irish are to meet holders Stade Francais in the Pool stage of next season's European Challenge Cup.
Leicester Tigers sign Sione Kalamafoni from Gloucester, one of four new signings at Welford Road.
Audio & Video
Gloucester chief executive Stephen Vaughan tells BBC Points West he was disappointed former head coach Laurie Fisher appeared to resign on social media.
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