Why carry out this study?

Guselkumab, a fully human monoclonal antibody that inhibits the interleukin-23 p19 subunit, demonstrated efficacy in improving the overall signs and symptoms of psoriatic arthritis (PsA) in adults with active disease in the phase 3, randomized, placebo-controlled DISCOVER-1 (1 year; tumor necrosis factor-inhibitor-naïve and -experienced) and DISCOVER-2 (2 years; biologic-naïve) studies.

In post hoc analyses of pooled patients with active PsA and imaging-confirmed sacroiliitis (identified by the investigator) from DISCOVER-1 and DISCOVER-2, guselkumab-treated patients had greater improvements in symptoms of axial disease as assessed by least squares (LS) mean changes in Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) and Ankylosing Spondylitis Disease Activity Score (ASDAS) at week 24 compared with placebo.

We further investigated the effect of guselkumab treatment on maintenance and extent of improvements in axial symptoms through 2 years in the DISCOVER-2 cohort of patients with imaging-confirmed sacroiliitis.

What was learned from this study?

Guselkumab-treated patients had greater LS mean improvements in total BASDAI, spinal pain (BASDAI Question #2), and ASDAS scores, as well as greater response rates for achieving ≥ 50% improvement in BASDAI and ASDAS responses (clinically important improvement, major improvement, and inactive disease) at week 24 vs. placebo; mean improvements and response rates for achieving stringent response criteria (determined using nonresponder imputation) were sustained through 1 and 2 years.

Exploratory analyses in HLA-B*27+ and HLA-B*27– patients showed separation from placebo for LS mean changes in BASDAI, spinal pain, modified BASDAI (excludes Question #3 [peripheral joint pain]), and ASDAS at week 24; changes in BASDAI scores tended to be numerically larger in HLA-B*27– patients, while results were similar between the subgroups when using the ASDAS.

Although limited by the small sample sizes, the treatment effect of guselkumab was consistent in both males and females, with increasing response rates for achievement of BASDAI 50 and ASDAS major improvement over time through 2 years.