Guselkumab Shows Sustained 48-Week Protection Against Joint Damage in PsA

Guselkumab (Tremfya; Johnson & Johnson) continued to reduce signs and symptoms of active psoriatic arthritis (PsA) and sustained inhibition of structural joint damage through 48 weeks, according to new phase 3b APEX (NCT04882098) study results.¹

Presented at the Inflammatory Skin Disease Summit 2025, the findings reinforce guselkumab’s role in slowing radiographic progression, improving clinical response, and supporting its potential label expansion for adults with active PsA.

"Psoriatic arthritis is a chronic condition where joint damage can begin early and progress quickly if left untreated," said Christopher Ritchlin, MD, MPH, University of Rochester Medical Center and APEX study investigator, in a statement. "The APEX study results show that guselkumab can inhibit this process, even once it has begun, making it a valuable treatment option for both initiating treatment early and for patients who already show signs of joint damage."

The APEX study is a multicenter, randomized, double-blind, placebo-controlled trial designed to evaluate guselkumab in biologic-naïve patients with active PsA who had an inadequate response to standard therapies such as conventional synthetic disease-modifying antirheumatic drugs, apremilast, or nonsteroidal anti-inflammatory drugs.² The trial includes a 24-week double-blind, placebo-controlled phase followed by a 24-week active treatment period.

Patients who choose to continue into the long-term extension will receive an additional 2 years of active treatment before the final safety follow-up.

In the ongoing trial, participants were separated into 3 treatment groups in a 5:7:7 ratio.³ Participants received subcutaneous guselkumab 100 mg every 4 weeks (Q4W), guselkumab 100 mg at weeks 0 and 4 followed by every 8 weeks (Q8W), or placebo every 4 weeks. The primary endpoint at Week 24 was the proportion of patients achieving an American College of Rheumatology (ACR)20 response, and the major secondary endpoint was the least squares mean change from baseline in total PsA-modified van der Heijde-Sharp (vdH-S) score. Both endpoints were multiplicity-controlled for comparisons between each guselkumab regimen and placebo.

Among 1020 participants, significantly higher proportions of those receiving guselkumab every 4 weeks (66.6%) or every 8 weeks (68.3%) achieved AR20 at week 24 compared with placebo (47.0%; both P < .001). Baseline mean total van der Heijde-Shar scores were similar across groups (26.7-27.7), and both dosing regimens showed markedly lower rates of radiographic progression at week 24, with least squares mean changes of 0.55 every 4 weeks (Q4W) and 0.54 (Q8W) vs 1.35 for placebo (P = .002 and P < .001, respectively).

Safety outcomes were consistent with the established profile, with adverse events reported in 38.2% (Q4W), 42.5% (Q8W), and 37.3% (placebo) of participants and no new safety signals identified.

These findings support guselkumab’s potential as a first-line therapy for biologic-naïve patients and strengthen Johnson & Johnson’s supplemental FDA submission to expand the label for inhibiting progression of structural damage in PsA.

"These long-term data show [guselkumab] has set a new benchmark as the only IL-23 inhibitor proven to inhibit structural damage in active psoriatic arthritis, which can develop in up to 30% of people living with psoriasis," said Leonard Dragone, MD, PhD, vice president, Rheumatology and Autoantibody Disease Area Leader, Johnson & Johnson Innovative Medicine, in a statement.¹ "Its durable efficacy and established safety make [guselkumab] an attractive first-line treatment option for patients with psoriatic disease."

References

1. New long-term data reinforces Tremfya (guselkumab) as the only IL-23 inhibitor proven to substantially inhibit structural joint damage in active psoriatic arthritis. Johnson & Johnson. News release. November 17, 2025. Accessed November 17, 2025. https://www.prnewswire.com/news-releases/new-long-term-data-reinforces-tremfya-guselkumab-as-the-only-il-23-inhibitor-proven-to-substantially-inhibit-structural-joint-damage-in-active-psoriatic-arthritis-302616074.html

2. Johnson & Johnson files with US FDA to include new evidence in Tremfya (guselkumab) label as the only IL-23 inhibitor to demonstrate significant inhibition of joint structural damage in active psoriatic arthritis. Johnson & Johnson. News release. July 29, 2025. Accessed November 17, 2025. https://www.jnj.com/media-center/press-releases/johnson-johnson-files-with-u-s-fda-to-include-new-evidence-in-tremfya-guselkumab-label-as-the-only-il-23-inhibitor-to-demonstrate-significant-inhibition-of-joint-structural-damage-in-active-psoriatic-arthritis

3. Mease PJ, Ritchlin CT, Coates LC, et al. Inhibition of structural damage progression with the selective interleukin-23 inhibitor guselkumab in participants with active PsA: results through week 24 of the phase 3b, randomized, double-blind, placebo-controlled APEX study. Ann Rheum Dis. 2025:S0003-4967(25)04305-5. doi:10.1016/j.ard.2025.08.006