The 23-year-old, who can play either as a winger or an attacking midfielder, is reported to have a release clause of €25 million (£21.61m).
Brandt has previously said that he is happy at Leverkusen and is not interested in a move either to one of the club's Bundesliga rivals or to the Premier League.
However, much could depend on whether his club qualify for next season's Champions League.
Bayer Leverkusen are currently fifth, level on points with fourth-placed Borussia Mönchengladbach in the final Champions League spot, and just two behind on goal difference with one game each remaining this Saturday.