Leinster's Ross Byrne and Ulster's John Cooney have also been omitted.
Simon Zebo has been left out of Ireland's 50 player training squad ahead of the Autumn internationals.
The 31-year-old, who hasn't played for his country since 2017, is eligible for selection after returning to Munster from France this summer.
There's also no place in the group for Leinster out-half Ross Byrne or Ulster scrum-half John Cooney.
Munster centre Chris Farrell says Zebo brings a freshness to their squad this season:
Ireland head-coach Andy Farrell has included Johnny Sexton, Cian Healy and Keith Earls after giving the veteran trio a break this summer.
Farrell's side will face Japan, New Zealand and Argentina in November.