The 30-year-old is set to return to Arsene Wenger's side in July after his performances failed to impress the Brazilian club's coach Vanderlei Luxemburgo
Having made just eight Premier League appearances for Arsene Wenger's side, the 30-year-old was sent out on loan with the Brazilian club in February.
But Santos' performances have failed to convince Gremio coach Vanderlei Luxemburgo and the defender even failed to make the squad for the club's fixture against Nautico on Sunday.
"We hired André for the Libertadores and his contract ends in July," said the Gremio's football advisor Marcos Chitolina.
"To renew, that would be too expensive for Gremio. He's a very expensive player."