The primary objective is to evaluate the efficacy and dose response of 3 different dose regimens of TEV-48574 in adult participants with IBD (moderate to severe Ulcerative Colitis (UC) or Crohn's Disease (CD)) as assessed by induction of clinical remission (UC) and endoscopic response (CD). Secondary objectives: -To evaluate the efficacy and dose response of the 3 different dose regimens as assessed by multiple standard measures. -To evaluate the safety and tolerability of the 3 different dose regimens. -To evaluate the immunogenicity of the 3 different dose regimens. The study will consist of a screening period of up to 6 weeks (42 days), a 14-week treatment period, and a 4-week follow-up period.