A Phase 3 Multicenter Study to Evaluate Efficacy, Safety, and Pharmacokinetics of Upadacitinib with Open-Label Induction, Randomized, Double-Blind Maintenance and Open-Label Long- Term Extension in Pediatric Subjects with Moderately to Severely Active Ulcerative Colitis and Inadequate Response, Intolerance, or Medical Contraindications to Corticosteroids, Immunosuppressants, and/or Biologic Therapy

M14-658 is a phase 3 paediatric study to evaluate the safety of upadacitinib an oral biologic medication for children with ulcerative colitis (UC). The trial is designed in three phases starting with a placebo-controlled open-label induction phase AND a randomised, double-blind maintenance phase, this is then followed by an open-label extension (OLE) phase (period 2). Approximately 110 participants aged 2-17yrs with UC is expected to participate in this trial. Participants will have had an inadequate response, loss of response, intolerance, or medical complications with corticosteroids, immunosuppressants, and/or biologic therapy. All participants will receive open-label daily 45mg dose of upadacitinib over 8-weeks. Participants who do not achieve clinical response at the end of the 8-week induction phase in Period 1 will have the option to be transferred to the OLE Period 2 offering an 8-week extended induction treatment phase, to receive either a 30mg daily dose of upadacitinib or 15mg daily dose in a 1:1 randomisation ratio with placebo. Upadacitinib will be administered orally once daily if receiving tablet, or twice daily if receiving oral solution at Day 1 (Baseline).