Horton recently suffered a setback in his rehab for a right lat strain and isn't expected to return from Triple-A Iowa's 60-day injured list this season, Tim Stebbins of MLB.com reports.
Though Horton is expected to resume throwing before Iowa's season comes to an end Sept. 22, the 22-year-old right-hander won't have enough time to get ramped up for a return to game action. The setback is a tough development for Horton, who is one of the Cubs' top pitching prospects and looked like a candidate to make his MLB debut at some point in 2024 before suffering the lat injury in late May. Over his nine starts with Double-A Tennessee and Iowa this season, Horton compiled a 4.46 ERA, 1.25 WHIP and 40:13 K:BB over 34.1 innings.