Guselkumab in erosive psoriatic arthritis: joint damage stayed low through a year

Design

Phase 3b randomised, double-blind, placebo-controlled trial (placebo crossover at week 24)

Population

1,020 biologic-naive adults with active, erosive psoriatic arthritis

Primary outcome

ACR response and radiographic progression through week 48

Effect

ACR20 71–74%; vdH-S change 0.60–0.78; placebo-switch progression 0.96 → 0.41

APEX is a phase 3b, double-blind trial of guselkumab, an IL-23p19 inhibitor, in 1,020 biologic-naive adults with active psoriatic arthritis, raised CRP and at least two erosive joints. Patients received guselkumab every four weeks, every eight weeks after induction, or placebo until week 24 and then guselkumab. Week 48 results appear in Arthritis & Rheumatology.

With both dosing schedules, ACR20, ACR50 and ACR70 responses were 71–74%, 51–56% and 31–35% at week 48. Mean radiographic progression was low (change in modified Sharp score 0.60 to 0.78). About three in five patients had a clinically meaningful functional improvement, 74–80% reached PASI 90 for skin, and 36–41% reached minimal disease activity. In patients switched from placebo, radiographic progression slowed from 0.96 in the first 24 weeks to 0.41 in the next 24. Adverse event rates remained stable.

By enrolling only patients with erosive disease, the trial puts structural damage at the centre. It supports IL-23 inhibition as a structure-modifying option, not only a skin-focused one. The weeks 24 to 48 data are uncontrolled, as all patients were then on guselkumab.

• Guselkumab maintained ACR20 responses in about three-quarters of patients at 48 weeks in erosive psoriatic arthritis.
• Radiographic progression remained low with both four-weekly and eight-weekly dosing.
• Progression slowed after placebo patients switched to guselkumab.
• Skin clearance was high, with PASI 90 in 74–80%, useful where skin disease is prominent.
• Record baseline radiographs of hands and feet to track erosive progression on any advanced therapy.

Why it matters

IL-23 inhibitors have been seen as skin-first drugs; this trial supports a role in preventing joint damage too.

Don't overread it

After week 24 all patients received guselkumab, so the 48-week comparison is not placebo-controlled.

The statistics, in plain English

A modified Sharp score change below 1 point over a year is small; the slowing from 0.96 to 0.41 after switching suggests a treatment effect, though without a concurrent control.

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