Drug Update · Rheumatology

Guselkumab Label Updated 06/04/2026; DISCOVER-2: 64% ACR20 in PsA

September 08, 2026

DISCOVER-2 ACR20 (Week 24)

64% guselkumab Q4W; 64% guselkumab Q8W vs 33% placebo (both p<0.0001) [6]

Serious adverse events (Week 24)

8 (3%) Q4W; 3 (1%) Q8W; 7 (3%) placebo (reported up to Week 24) [6]

Radiographic mean vdH-S change (Week 0 to 100)

1.7 (Q4W) and 1.5 (Q8W) mean change in vdH-S scores [7]

Label effective date

2026-06-04 (most recent supplemental approval date 2026-05-28) [11]

Approved dose for PsA

100 mg subcutaneous at Week 0, Week 4, and every 8 weeks thereafter (label) [1][2][8]

Clinical Perspective

Rheumatologists and other clinicians treating adults with active psoriatic arthritis now refer to updated TREMFYA labeling with a label effective date of 2026-06-04 as reflected in FDA prescribing information ^[8]. The DISCOVER-2 phase 3 data demonstrating ACR20 responses of 64% for both guselkumab regimens versus 33% for placebo at Week 24 provide source‑confirmed efficacy evidence for biologic‑naive adults with active psoriatic arthritis ^[3]. What are the longer‑term comparative radiographic outcomes of guselkumab versus other biologics beyond two years of follow‑up?

Dr. Deepak Nair, MBBS, MD (General Medicine), DM (Clinical Immunology & Rheumatology) · Rheumatology

The FDA label for guselkumab (TREMFYA) has a most recent supplemental approval date of 2026-05-28 with a label effective date of 2026-06-04, according to FDA prescribing information ^[8]. In the phase 3 DISCOVER-2 trial, guselkumab achieved an American College of Rheumatology 20% improvement (ACR20) response of 64% for both the every-4-weeks and every-8-weeks regimens versus 33% with placebo at Week 24 (both p<0.0001) ^[3].

Clinical Context

Guselkumab (TREMFYA) is an interleukin-23 (IL-23) antagonist that selectively binds the p19 subunit of IL-23 and inhibits its interaction with the IL-23 receptor, per prescribing information ^[7]^[8]. TREMFYA is marketed by Janssen Biotech, Inc., and the approved indications listed in recent labeling include active psoriatic arthritis among other immune-mediated conditions ^[1]^[2]^[5]^[8]. The DISCOVER-2 phase 3 program evaluated guselkumab in biologic‑naive adults with active psoriatic arthritis and reported ACR response rates at Week 24; post hoc analyses have examined radiographic outcomes over up to 2 years of therapy ^[3]^[4].

Key Findings

The DISCOVER-2 trial (phase 3, double‑blind, randomized, placebo‑controlled) showed that guselkumab achieved an ACR20 response at Week 24 of 64% in the every-4-weeks group (156 of 245; 95% CI 57-70) and 64% in the every-8-weeks group (159 of 248; 95% CI 58-70) versus 33% with placebo (81 of 246; 95% CI 27-39); percentage differences vs placebo were 31% (every 4 weeks) and 31% (every 8 weeks), both p<0.0001 ^[3].
Clinicians should consult current prescribing information for full dosing guidance.
Up to Week 24 in DISCOVER-2, serious adverse events occurred in eight (3%) of 245 patients receiving guselkumab every 4 weeks (including three serious infections), three (1%) of 248 receiving guselkumab every 8 weeks (one serious infection), and seven (3%) of 246 receiving placebo (one serious infection) ^[3].
Post hoc analyses of DISCOVER-2 radiographs reported low mean changes in PsA‑modified van der Heijde‑Sharp (vdH‑S) scores through 100 weeks: mean changes from Week 0 to Week 100 were 1.7 (Q4W) and 1.5 (Q8W). Patients who achieved clinical responses (ACR20/50/70), low disease activity by DAPSA or PASDAS, or minimal/very low disease activity had smaller mean changes in vdH‑S scores than non‑responders at Weeks 52 and 100 ^[4].

Safety & Tolerability

Serious hypersensitivity reactions, including anaphylaxis, have been reported with postmarketing use of TREMFYA ^[1]^[2]^[5].
TREMFYA may increase the risk of infection; in placebo‑controlled trials infections occurred in 23% of subjects in the TREMFYA groups versus 21% in placebo through 16 weeks in psoriasis trials, and a similar overall infection risk was seen across indications ^[1]^[2]^[5]^[6].
Reported adverse reactions across labeling and trials include upper respiratory infections, headache, injection site reactions, arthralgia, bronchitis, diarrhea, gastroenteritis, tinea infections, and herpes simplex infections ^[1]^[2]^[5]^[6].
In psoriatic arthritis trials, bronchitis and decreased neutrophil count were observed; neutrophil count decreases were generally mild and transient ^[6].
Elevated liver enzymes and a reported case of drug‑induced liver injury in a Crohn’s disease trial have been described; monitoring is advised in inflammatory bowel disease indications per the label ^[2]^[5].
Tuberculosis evaluation prior to initiation and avoidance of live vaccines during treatment are included in Warnings and Precautions ^[1]^[2]^[5].

Study Design

DISCOVER-2 was a phase 3, double‑blind, randomized, placebo‑controlled trial enrolling biologic‑naive adults with active psoriatic arthritis (≥5 swollen joints, ≥5 tender joints, and CRP ≥0.6 mg/dL). Clinicians should consult current prescribing information for full dosing guidance. Patients were randomized 1:1:1 to guselkumab 100 mg every 4 weeks, guselkumab 100 mg at Weeks 0 and 4 then every 8 weeks, or placebo; the primary endpoint was ACR20 response at Week 24 ^[3]. Radiographic assessments using the PsA‑modified van der Heijde‑Sharp score were performed at baseline, Week 24, Week 52 and Week 100 in post hoc analyses reported separately ^[4].

FAQ

Q1 What is guselkumab (TREMFYA) approved for?

TREMFYA (guselkumab) is indicated as an interleukin‑23 antagonist for the treatment of adult patients with active psoriatic arthritis, as well as for moderate‑to‑severe plaque psoriasis and for moderately to severely active ulcerative colitis and Crohn’s disease as listed in recent prescribing information. The prescribing information reflects a most recent supplemental approval date of 2026-05-28 and a label effective date of 2026-06-04.

Q2 How does guselkumab work?

Guselkumab is a human monoclonal IgG1λ antibody that selectively binds the p19 subunit of interleukin‑23 (IL‑23) and inhibits its interaction with the IL‑23 receptor, thereby inhibiting the release of proinflammatory cytokines and chemokines according to the prescribing information. This mechanism is described in the full prescribing information and clinical pharmacology sections of the label.

Q3 What is the recommended dose for psoriatic arthritis?

The prescribing information lists the recommended dosing regimen for psoriatic arthritis as 100 mg administered by subcutaneous injection at Week 0, Week 4, and every 8 weeks thereafter. Dosing presentations include 100 mg/mL in prefilled syringes, One‑Press injectors, and 200 mg/2 mL pens or syringes as described in the label. Clinicians should consult current prescribing information for complete dosing guidance.

Q4 What are the side effects to watch for?

Adverse reactions named in clinical trials and labeling include infections (upper respiratory tract infections among others), headache, injection site reactions, arthralgia, bronchitis, diarrhea, gastroenteritis, tinea infections, and herpes simplex infections; serious hypersensitivity reactions including anaphylaxis have been reported in the postmarketing setting. Labeling also addresses risks of infection, tuberculosis evaluation prior to initiation, elevated liver enzymes and reported drug‑induced liver injury in a Crohn’s disease trial, and neutrophil count decreases observed in psoriatic arthritis trials.

Clinicians should consult current prescribing information for complete dosing guidance.

Guselkumab Label Updated 06/04/2026; DISCOVER-2: 64% ACR20 in PsA

Direct Clinical Takeaway & Evidence Summary

Guselkumab Label Updated 06/04/2026; DISCOVER-2: 64% ACR20 in PsA

Clinical Perspective

Clinical Context

Key Findings

Safety & Tolerability

Study Design

FAQ

References

Cite & Reference This Monograph

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