The 24-year-old prop has played 50 games since joining the club in the summer of 2014 from Buenos Aires-based San Cirano.
Lancuba has not added to his five international caps during his spell in Jersey, with his last Pumas appearance against Brazil in May 2013.
He may not play again in a Jersey shirt having been injured in a recent match against London Scottish.
He is the second prop this week to confirm he is leaving the islanders after Sam Lockwood agreed a summer move to Newcastle.
Argentina forward Ignacio Lancuba is to leave Jersey at the end of the season.