A Study to Assess the Pharmacokinetics, Effectiveness and Safety of Afimkibart for Induction and Maintenance Therapy in Children With Moderately to Severely Active Crohn's Disease

This phase III, double-blind, multi-center treat-through study will evaluate the efficacy and safety of Afimkibart (also known as RO7790121) in children with moderately to severely active Crohn's Disease (CD).

Inclusion Criteria: * Body weight \>= 10 kilogram (kg) * Active CD confirmed by endoscopy (ileocolonoscopy) * Moderately to severely active CD, defined as a Pediatric Crohn's Disease Activity Index (PCDAI) score \>= 30, and Simple Endoscopic Score Crohn's Disease (SES-CD) \>=6 (or \>=4 for isolated ileal disease) confirmed through centrally-read ileocolonoscopy * Inadequate response, loss of response, and/or intolerance to at least one of the following conventional therapies (aminosalicylates, corticosteroids and/or immunosuppressants) or advanced therapies (including anti-tumor necrosis factor, anti-interleukin, anti-integrin, or Janus Kinase (JAK) inhibitors) Exclusion Criteria: * Monogenic disorder pertaining to infant onset Inflammatory Bowel Disease (IBD) * History of \>= 3 bowel resections: \> 2 missing segments of the following five segments: terminal ileum, right colon, transverse colon, sigmoid and left colon, and rectum * Current diagnosis of ulcerative colitis (UC), abdominal/intraabdominal/perianal fistula and/or abscess, indeterminant colitis, IBD-unclassified, microscopic colitis, ischemic colitis, infectious colitis, radiation colitis, or active diverticular disease. * Symptomatic bowel strictures, fulminant colitis, or toxic megacolon * Presence of abdominal or perianal abscess * Current diagnosis or suspicion of primary sclerosing cholangitis