Sonelokimab in Active Psoriatic Arthritis: Phase 2 Trial Report

In the randomized, placebo-controlled ARGO phase 2 trial, adults with active psoriatic arthritis were evaluated in a study that also included adalimumab as a reference arm. Investigators tested sonelokimab, an IL-17A/IL-17F-inhibiting nanobody, using induction and noninduction regimens and reported that the induction schedules met the primary week 12 efficacy target versus placebo. Those induction regimens also met prespecified joint and skin secondary targets at the same time point. The publication reports efficacy and safety outcomes through week 24.

The study randomized 207 adults with active psoriatic arthritis to three sonelokimab regimens, placebo, or adalimumab 40 mg every 2 weeks. Induction dosing used sonelokimab 60 mg or 120 mg at weeks 0, 2, 4, and 6, then every 4 weeks from week 8. A third regimen used 60 mg every 4 weeks without induction. Adalimumab served as a within-study reference arm that was not powered for formal comparisons. This dosing framework distinguished early and later response patterns across groups.

With sonelokimab induction dosing, the primary ACR50 endpoint was achieved by 46.3% on 60 mg and 46.5% on 120 mg, versus 20.0% on placebo. Key secondary ACR20 responses were 78.0% and 72.1% with induction dosing, versus 37.5% with placebo. Among participants with baseline psoriasis involving at least 3% body surface area, PASI 90 responses reached 76.9% and 59.3% with induction dosing, versus 15.4% with placebo. The noninduction regimen showed numerically higher ACR50 than placebo (36.6% vs 20.0%) but did not meet the primary week 12 endpoint. Overall, earlier joint and skin responses were concentrated in the induction schedules.

Investigators described continued response accrual through week 24, including higher ACR thresholds, PASI 100, minimal disease activity, and composite joint-skin outcomes such as ACR70 plus PASI 100. Minimal disease activity reached 61.0% in the 60-mg induction arm, and up to 48.1% of patients treated with sonelokimab achieved ACR70 plus PASI 100 at week 24.

Safety findings were described as generally comparable across study groups during both the placebo-controlled period and the full 24-week analysis. Any-grade treatment-emergent adverse events occurred in 29.3% to 39.5% of sonelokimab-treated patients during part A, compared with 38.5% on placebo and 35.7% on adalimumab. Common events included nasopharyngitis, upper respiratory tract infection, injection-site erythema, and headache, and four cases of mild to moderate oral candidiasis were reported. Investigators also reported no inflammatory bowel disease, major adverse cardiovascular events, depression, suicidal ideation and behavior, or AST or ALT elevations above 3 times the upper limit of normal with sonelokimab. Overall, the investigators characterized the tolerability profile as broadly similar across arms.

Key Takeaways

• Induction sonelokimab regimens were reported to meet the week 12 joint and skin efficacy targets versus placebo in this phase 2 trial.
• Higher-threshold and multidomain responses were described as continuing through week 24, with subgroup findings presented as broadly consistent observations.
• The study described a safety profile that was generally comparable across groups, with common mild events and mild to moderate oral candidiasis reported.