Luton started the last three games - all losses - in place of the injured Gardner Minshew. The rookie passer had his worst game so far in last Sunday's 27-3 defeat to the Pittsburgh Steelers, throwing four interceptions and zero touchdowns.
Minshew is apparently nearing his return from a thumb injury. He could be active against the Browns but only in a backup role, as Marrone said he isn't comfortable with reinserting his starter without a full week of practice, per Brent Martineau of CBS47.
Glennon hasn't played this season and last started for the Chicago Bears in 2017.
The 30-year-old veteran has thrown for 5,163 yards and 36 touchdowns against 20 interceptions across 29 combined appearances (22 starts) for the Tampa Bay Buccaneers, Bears, Arizona Cardinals, and then-Oakland Raiders.