Background/Purpose: PsA is a chronic, inflammatory disease with multiple manifestations, with arthritis and skin involvement. Other areas of inflammation include enthesitis, dactylitis and nail involvement. Unresolved enthesitis leads to chronic pain and reduced quality of life¹. IL-17 inhibitors have demonstrated benefits across multiple disease features. Izokibep is a unique IL-17A inhibitor with high potency (0.3 pM), small size (18.6 kD) and half-life extending albumin binding.

The purpose is to assess the efficacy of izokibep 40 mg Q2W and 80 mg Q2W versus placebo on measures of enthesitis (most common being Leeds Enthesitis Index (LEI), as well as SPARCC), dactylitis and nails, and explore how these disease features impact quality of life (PsAID questionnaire) over 16 weeks. Drug safety was evaluated.

¹McInnes, IB., J Rheumatol 2019;46:1458–61; doi:10.3899/jrheum.180792

Methods: A randomized, double-blind, placebo-controlled, study was conducted with placebo (Pbo), izokibep 40 mg Q2W or 80 mg Q2W delivered subcutaneously to Week 16 (ClinicalTrials.gov, NCT04713072). Patients met CASPAR criteria and required ≥3 swollen and ≥3 tender joints (66/68 joint count), an inadequate response to NSAIDs, csDMARDs or TNF inhibitors to enroll. The presence of enthesitis, dactylitis or nail involvement was not required. Enthesitis was assessed by the LEI and SPARCC, dactylitis by the Leeds-B scale, and target nail involvement by NAPSI. Safety and tolerability were evaluated by history, exam, adverse events and lab findings.

Results: 135 patients were randomized across 28 European sites in 7 countries from June 2020 to July 2021. Mean age was 48.5, mean BMI 29.0 kg/m², mean swollen joint count of 9.9 and mean tender joint count of 16.7 and mean PsA duration of 7.1 years. 80% were on csDMARD and 13% had failed TNF inhibitors. Enthesitis was present at baseline on the LEI in 32% (n=43) and in 77% (n=104) on the SPARCC with dactylitis present in 32% (n=43). NAPSI – target nail was collected on all patients. The ACR50 primary was met by 13% on placebo, 48% on izokibep 40 mg Q2W and 52% on izokibep 80 mg Q2W, p=0.0003. The LEI showed 88% with complete resolution at 16 weeks on izokibep 80 mg Q2W. SPARCC enthesitis also showed dose related improvement as did the Leeds Dactylitis Index (Table 1). Figure 1 shows those with enthesitis at baseline had a higher proportion of clinically meaningful improvements on the PsAID vs. all patients (53% vs. 41% respectively for izokibep 80 mg Q2W).

Safety evaluation showed no serious or severe adverse events up to week 16. AE rate overall was 52.3% for Pbo, 65.9% for 40 mg Q2W and 55.3% for 80 mg Q2W. The most common AEs (≥ 5% in any group) were injection site reaction or erythema, headache, hypertension, diarrhea, URTI. Two patients had AESI: one mild, transient vulvovaginal Candida infection; one injection site reaction leading to discontinuation.

Conclusion: Izokibep showed high levels of efficacy across enthesitis, dactylitis and nail scores that were clinically meaningful and statistically significant. Patients with enthesitis at baseline had the largest improvements in PsAID. The izokibep safety profile was generally consistent with other IL-17A inhibitors; in this trial, events were mostly similar to placebo.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/izokibep-demonstrates-clinically-relevant-efficacy-benefits-on-enthesitis-dactylitis-and-nail-outcomes-in-active-psa-patients-a-16-week-randomized-placebo-controlled-trial/