Andre Savelio will join Castleford on loan for the remainder of the season.
The forward has played 42 times for Saints since making his debut against Leeds in 2014 after joining from Latchford Albion.
He makes the move to gain more game time – at his own request – as he continues his development.
A club spokesperson said: “We naturally wish Andre well in his spell over at the Tigers and will be keeping a keen eye on how he progresses.”
The loan agreement has no recall and Andre cannot play against Saints.