Guselkumab

What it is and how it works

Mechanism of Action Guselkumab is a human monoclonal IgG1λ antibody that selectively binds to the p19 subunit of interleukin 23 (IL-23) and inhibits its interaction with the IL-23 receptor. IL-23 is a naturally occurring cytokine that is involved in normal inflammatory and immune responses. Guselkumab inhibits the release of proinflammatory cytokines and chemokines.

Mechanism class: Interleukin-23 Antagonists

Indications

is an interleukin-23 antagonist indicated for the treatment of: adults and pediatric patients 6 years of age and older who also weigh at least 40 kg with moderate-to-severe plaque psoriasis and who are candidates for systemic therapy or phototherapy. adults and pediatric patients 6 years of age and older who also weigh at least 40 kg with active psoriatic arthritis. adults with moderately to severely active ulcerative colitis. adults with moderately to severely active Crohn's disease. Plaque Psoriasis TREMFYA is indicated for the treatment of adults and pediatric patients 6 years of age and older who also weigh at least 40 kg with moderate-to-severe plaque psoriasis and who are candidates for systemic therapy or phototherapy. Psoriatic Arthritis TREMFYA is indicated for the treatment of adults and pediatric patients 6 years of age and older who also weigh at least 40 kg with active psoriatic arthritis. Ulcerative Colitis TREMFYA is indicated for the treatment of adult patients with moderately to severely active ulcerative colitis.

Dosage and administration (summary)

For the treatment of ulcerative colitis or Crohn's disease: Obtain liver enzymes and bilirubin levels prior to initiating treatment with TREMFYA. ( 2.1 , 5.4 ). For the treatment of plaque psoriasis or psoriatic arthritis, if clinically indicated, evaluate liver enzymes and bilirubin at baseline prior to initiating treatment with TREMFYA ( 2.1 , 5.4 ). Complete all age-appropriate vaccinations as recommended by current immunization guidelines prior to treatment initiation. Recommended Dosage Plaque Psoriasis Adults 100 mg administered by subcutaneous injection at Week 0, Week 4, and every 8 weeks thereafter.

Contraindications

is contraindicated in patients with a history of serious hypersensitivity reaction to guselkumab or to any of the excipients . History of serious hypersensitivity reactions to guselkumab or to any of the excipients.

Warnings and precautions

Hypersensitivity Reactions : Serious hypersensitivity reactions, including anaphylaxis, may occur. Infections : TREMFYA may increase the risk of infections. Do not initiate treatment with TREMFYA in patients with clinically important active infection until the infection resolves or is adequately treated. If such an infection develops, discontinue TREMFYA until the infection resolves. Tuberculosis (TB) : Evaluate for TB prior to initiating treatment with TREMFYA. Monitor patients for signs and symptoms of active TB during and after treatment with TREMFYA.

Pregnancy

Pregnancy Pregnancy Exposure Registry There is a pregnancy registry that monitors pregnancy outcomes in women exposed to TREMFYA during pregnancy. Patients should be encouraged to enroll in the registry by visiting www.mothertobaby.org/ongoing-study/tremfya-guselkumab, by calling 1-877-311-8972, or emailing MotherToBaby@health.ucsd.edu.

Storage and supply

Storage and Handling TREMFYA is sterile and preservative-free. Discard any unused portion. Store in a refrigerator between 2 ºC to 8 ºC (36 ºF to 46 ºF). Store in original carton until time of use. Protect from light until use. Do not freeze. Do not shake. Not made with natural rubber latex.

Source: Guselkumab (Tremfya) — US FDA prescribing information, 2026-06-04, DailyMed. Summarised and shortened; the full label governs. Iranian registration, indications and labelling may differ.