Anthony Walker, 21, who has made five appearances so far, has been given a new two-year deal taking him to the end of 2015.
Fellow forward Jordan Hand, 19, who made his Super League debut against Wakefield in March, has signed a 12-month extension.
Saints coach Nathan Brown said: "Both are young home-grown players who have come through the system.
"They are natural players, not manufactured, and have come through a good system. They have had a good education from a young age and understand the game very well.
"As long as they train very hard in the years down the track, they should develop into good long-term players for the club."
- Sports & Recreation
- Jordan Hand