Guselkumab (TREMFYA®) is a fully human IgG1λ monoclonal antibody developed by Johnson & Johnson to selectively target the p19 subunit of interleukin (IL)-23, a cytokine that plays a key role in various immune-mediated inflammatory diseases. Guselkumab is approved in multiple countries worldwide, including the USA and those of the EU, for the treatment of adults with moderate-to-severe plaque psoriasis, active psoriatic arthritis, and moderately-to-severely active ulcerative colitis and Crohn's disease. In September 2025, guselkumab received its first pediatric approvals in the USA for the treatment of pediatric patients 6 years of age and older and weighing ≥ 40 kg who either have moderate-to-severe plaque psoriasis and are candidates for systemic therapy or phototherapy, or who have active psoriatic arthritis. Subsequently, guselkumab was approved in December 2025 in the EU for the treatment of moderate-to-severe plaque psoriasis in children and adolescents from the age of 6 years who are candidates for systemic therapy. Johnson & Johnson is currently undertaking phase III development of guselkumab in pediatric patients with Crohn's disease and ulcerative colitis in various countries. This article summarizes the milestones in the development of guselkumab leading to these first pediatric approvals for plaque psoriasis and psoriatic arthritis.
