Dr. Axe Wire · Study decoded · health

Guselkumab Slows Joint Damage Through 48 Weeks in Psoriatic Arthritis

A phase 3 trial found the biologic drug guselkumab kept joint damage low and symptoms controlled in adults with active psoriatic arthritis through 48 weeks.

By Dr. Axe Editorial Team · October 29, 2026 · 1 source · Understand

Photo: Pexels

At a glance

What they found: Joint damage score rose only 0.6-0.8 points through 48 weeks.
Who was studied: 1,020 biologic-naïve adults with active, erosive psoriatic arthritis.

A biologic drug for psoriatic arthritis kept joint damage progression low and controlled disease activity through 48 weeks of treatment, according to the APEX Study on guselkumab, published October 20, 2026 in Arthritis & Rheumatology.

1,020adults studied

71-74%ACR20 response

93%completed treatment

0.60-0.78damage score rise

A phase 3 trial of 1,020 biologic-naïve adults with active, erosive psoriatic arthritis found that guselkumab kept disease under control through 48 weeks. Participants were randomized to guselkumab every four weeks (273 people), guselkumab at weeks 0 and 4 then every eight weeks (371 people), or placebo switched to guselkumab at week 24 (376 people). By week 48, 93% (950 of 1,020) had completed study treatment. Among those on guselkumab from the start, ACR20 response rates (at least 20% improvement in joint symptoms) ranged from 71% to 74%, ACR50 from 51% to 56%, and ACR70 from 31% to 35%. Joint damage, scored on a standard imaging scale, rose only 0.60 to 0.78 points. Between 74% and 80% achieved 90% skin-symptom clearance, and 36% to 41% reached minimal disease activity.

In the group that started on placebo, the damage score rose 0.96 points in the first 24 weeks and 0.41 points in the 24 weeks after switching to guselkumab, and their response rates rose through week 48. Adverse event rates were similar for guselkumab and placebo through week 24 and stayed stable through week 48.

In general, guselkumab blocks a signaling protein that drives inflammation in joints and skin; this study did not test how much that explains the results. For someone with psoriatic arthritis, less joint damage building up over a year matters more than symptom relief alone.

Joint Damage Progression Slowed After Switching to Guselkumab

Arthritis & Rheumatology, 2026, Ritchlin et al.

Every participant was on guselkumab by week 48, so there is no placebo-controlled comparison at that final timepoint, only the within-group change after the switch. Response rates used imputation for missing data rather than only observed results.

Dr. Axe’s Take

A drug that slows joint erosion matters if you're watching your hands or feet change shape year over year. But blocking one signaling protein doesn't address why the immune system started attacking the joints, which I'd expect ties back to gut health, chronic stress and inflammatory eating. The cost is a long-term immune-suppressing drug, and infection risk is the side effect to watch. If you're on guselkumab, don't change it on your own; any change happens with your prescriber. Alongside it, I'd build meals around wild-caught fish, colorful vegetables and bone broth.

— Dr. Axe

Take the Cellular Health Quiz →

Study summary

Who: 1,020 biologic-naïve adults with active, erosive psoriatic arthritis
Design: Phase 3b randomized, double-blind, placebo-controlled trial, 48 weeks
Dose: Guselkumab every 4 weeks, or at weeks 0 and 4 then every 8 weeks, vs placebo switched to guselkumab at week 24
Primary result: ACR20 response 71-74%; joint damage score rose only 0.60-0.78 points through 48 weeks
Secondary: 74-80% reached 90% skin clearance (PASI90); 36-41% reached minimal disease activity; among placebo-randomized participants who switched to guselkumab, joint damage score change was 0.96 weeks 0-24 and 0.41 weeks 24-48
Funding / conflicts: Funding and conflicts not reported in the abstract.
Date: Oct 20, 2026