Northampton Saints flanker Calum Clark and Leicester Tigers lock Ed Slater have both been ruled out of England's tour to Uruguay and Argentina.
Clark has been ruled out with an ankle injury, while Slater has also been declared unavailable due to a recurrence of a triceps injury.
England coach Stuart Lancaster told reporters at a press conference: "It's unfortunate for both Calum and Ed that they won't be able to join up with England this summer but I'm sure they will be back and pushing for places next season.
"Kearnan did well in a good team performance against the Barbarians and now has a great chance to continue his progress with us on tour.
"It means we travel with one player less than originally selected but we have lots of options in the second row and back row to cover for that."
London Wasps' Kearnan Myall has been added to the squad.
