guselkumab
Tremfya (guselkumab) is a monoclonal antibody from Janssen that selectively blocks interleukin-23, a driver of psoriatic inflammation. It clears skin in plaque psoriasis and treats psoriatic arthritis, in adults and children from six years.
This page is based on FDA prescribing information and the EMA medicine record for guselkumab, cross-checked with DailyMed and the National Cancer Institute dictionary; the mechanism is explained in plain language, and analogies are used only where they stay accurate.
How it works
Explains what the medicine does in the body, not dosing, side effects, or safety.
An analogy
Psoriasis is a fire kept burning by a bellows called IL-23, which pumps immune cells into overdrive in the skin and joints. Guselkumab clamps the bellows shut. Without the extra air, the inflammatory fire dies down, plaques fade and swollen joints settle.
In simple terms
In psoriasis, the immune system mistakenly keeps skin cells inflamed and multiplying too fast. A signalling protein called IL-23 helps maintain that inflammation. Guselkumab binds IL-23 and prevents it from activating immune cells. With the signal blocked, red scaly plaques clear, and in psoriatic arthritis the same action reduces joint inflammation and damage.
In depth
Guselkumab is a fully human IgG1-lambda monoclonal antibody that binds the p19 subunit unique to IL-23, blocking its interaction with the IL-23 receptor and downstream JAK-STAT signalling in Th17 cells. Selectivity for IL-23 over the p40 subunit shared with IL-12 preserves IL-12-mediated immunity. The long half-life supports dosing every eight weeks after induction, and trials show high rates of skin clearance and sustained joint responses.
See it in motion
A schematic animation of the mechanism — simplified for clarity, not drawn to scale.
How guselkumab clamps the IL-23 bellows shut in psoriasis
- Psoriasis is a fire kept burning by a bellows called IL-23, which pumps immune cells into overdrive in the skin and joints.
- Guselkumab is a fully human IgG1-lambda monoclonal antibody that binds the p19 subunit unique to IL-23, blocking its interaction with the IL-23 receptor and downstream JAK-STAT signalling in Th17 cells.
- Selectivity for IL-23 over the p40 subunit shared with IL-12 preserves IL-12-mediated immunity.
- The long half-life supports dosing every eight weeks after induction, and trials show high rates of skin clearance and sustained joint responses.
Target: Interleukin-23 (IL-23, p19 subunit)
A cytokine that sustains the inflammatory loop in psoriasis and psoriatic arthritis; blocking its p19 subunit calms the immune cascade without disturbing the related IL-12 pathway.
Approved uses
Approved uses differ by country and change over time. Always follow your local prescribing information.
Approved uses in United States
FDA- Treatment of adults and children 6 years and older weighing at least 40 kg with moderate-to-severe plaque psoriasis who are candidates for systemic therapy or phototherapy
- Treatment of adults and children 6 years and older weighing at least 40 kg with active psoriatic arthritis
Approved uses in European Union
EMA- Treatment of moderate to severe plaque psoriasis in adults who are candidates for systemic therapy
- Treatment of moderate to severe plaque psoriasis in children and adolescents from 6 years of age who are candidates for systemic therapy
Official sources
The statements on this page trace back to these records.
- Tremfya (guselkumab) — Summary of product characteristics and package leaflet, English version
European Medicines Agency
- DailyMed: Tremfya (guselkumab) label
DailyMed, U.S. National Library of Medicine
- U.S. Food and Drug Administration: guselkumab prescribing information
U.S. Food and Drug Administration
- National Cancer Institute: guselkumab
National Cancer Institute
This page explains how the medicine works — it isn’t the patient leaflet. For anything that applies to you, read the leaflet that came with your medicine or ask your pharmacist.
MedUnfold provides educational content and is not medical advice. Always follow your local prescribing information and healthcare professional.