Durable Inhibition of Structural Damage Progression and Improvements in Joint Disease Activity with Guselkumab in Active and Erosive Psoriatic Arthritis: Week 48 Results from Apex

Objectives APEX ( NCT04882098 ) evaluates guselkumab (GUS), a fully human mAb able to bind CD64 and selectively inhibit the IL-23p19-subunit, in participants (pts) with active and erosive PsA. At Week(W)24, GUS demonstrated significantly higher ACR20 rates (primary endpoint) and radiographic progression inhibition vs placebo (PBO; major secondary endpoint). Here we report W48 findings. Methods APEX enrolled adults with active PsA (≥3 tender, ≥3 swollen joints; CRP ≥0.3 mg/dL) and ≥2 erosive joints on radiographs of hands/feet, despite previous non-biologic therapy. The modified full analysis set comprised 1020 randomized pts (273 GUS 100mg Q4W; 371 GUS 100mg at W0/W4 then Q8W; 376 PBO-to-GUS Q4W at W24). Key endpoints through W48 included ACR20/ACR50 rates and least squares mean (LSM) change in PsA-modified van der Heijde-Sharp (vdH-S) score per reading session 2 (W0/24/48 radiographs). Exposure-adjusted incidence rates of adverse events (AEs) per 100 pt-years (100PY) [95% CI] are reported through W48. Results GUS Q4W/Q8W ACR20 rates increased from W24 (67%/68% vs 47% PBO; both p<0.001) to W48 (71%/74%). GUS ACR50 rates increased from W24 (41%/42% vs 20% PBO; both nominal-p<0.001) to W48 (51%/56%). At W48, 71% and 48% of PBO-to-GUS Q4W pts achieved ACR20 and ACR50, respectively. Reading session 2 results indicated continued suppression of radiographic progression with GUS Q4W/Q8W from W0-24 (LSM changes in PsA-modified vdH-S score: 0.36/0.46) throughout W24-48 (0.24/0.32). Radiographic progression in the PBO group from W0-24 (0.96) was curtailed by GUS W24-48 (0.41). Through W24, AE incidence rates with GUS Q4W/Q8W (168[146-191]/163[145-183]) and PBO (174[155-195]) were similar. Incidence rates did not increase with continued GUS (W0-48: 147 [132-163]/148 [136-162]), or after PBO-to-GUS transition (W24-48: 156 [138-176]). Conclusion In biologic-naïve adults with active and erosive PsA, inhibition of radiographic progression and joint disease activity improvements with GUS were durable through W48 without increased AE incidence, further substantiating GUS benefit for preserving joint health.