Izokibep Shows Sustained Phase 3 HiSCR Response in Biologic-Naïve and Experienced HS Patients

A phase 3, randomized, double-blind, placebo-controlled, multicenter study presented in a poster at the 2026 American Academy of Dermatology (AAD) Annual Meeting evaluated the efficacy and safety of izokibep, a novel IL-17A inhibitor, in patients with moderate-to-severe hidradenitis suppurativa (HS).¹

Background and Study Design

Izokibep, developed by Affibody, a partner of Acelyrin Inc., is a small protein therapeutic designed to selectively and potently neutralize IL-17A, a cytokine implicated in the pathogenesis of HS through its role in neutrophilic inflammation and immune dysregulation. Although biologic therapies have improved HS outcomes, unmet needs remain, particularly for patients who fail or have an inadequate response to existing agents.

The study enrolled adult patients with moderate to severe HS who were randomized to receive izokibep or placebo. Key inclusion criteria included a diagnosis of HS for at least 1 year and the presence of inflammatory lesions meeting established thresholds. Patients were categorized by prior biologic exposure, allowing for assessment of efficacy in both biologic-naïve and biologic-experienced populations. Treatment was administered over a 32-week period, with efficacy assessed using standard HS outcome measures.

Efficacy Results

The primary endpoint was achievement of Hidradenitis Suppurativa Clinical Response (HiSCR), defined as at least a 50% reduction in total abscess and inflammatory nodule (AN) count with no increase in abscesses or draining fistulas. After 32 weeks, a significantly greater proportion of patients treated with izokibep achieved HiSCR compared with placebo, demonstrating robust clinical efficacy. Response rates were consistent across multiple sensitivity analyses and were observed as early as initial assessment time points, with continued improvement through the end of the trial. Importantly, efficacy was maintained across subgroups, including patients with prior biologic exposure, a population often associated with more treatment-resistant disease.

Secondary endpoints further supported the clinical benefit of izokibep. Patients receiving active treatment demonstrated greater reductions in inflammatory lesion counts, including abscesses and nodules, compared with placebo. Improvements were also observed in measures of disease severity and patient-reported outcomes, including pain reduction, a key driver of disease burden in HS.

Safety and Tolerability

The safety profile of izokibep was consistent with expectations for IL-17 pathway inhibition and aligned with prior clinical research.² Adverse events were generally mild to moderate in severity, with no new or unexpected safety signals identified. Rates of serious adverse events and treatment discontinuations due to adverse events were low and comparable between treatment groups. As with other IL-17 inhibitors, monitoring for infections remains important, although no significant increase in serious infections was reported in this analysis.

The durability of response through week 32 is particularly noteworthy, as HS is a chronic condition requiring sustained disease control. The continued improvement over time suggests that izokibep may provide both rapid and durable therapeutic benefit.

These results contribute to a growing body of evidence supporting the role of IL-17A in HS pathophysiology and reinforce the therapeutic potential of targeting this pathway. Compared with existing treatment options, izokibep’s novel molecular design may offer advantages in potency and tissue penetration, although further comparative studies are needed to fully elucidate its place in the treatment landscape. Ongoing and future studies will also clarify long-term efficacy and safety, but this data represents a promising advance in addressing the substantial unmet needs in HS management.

References

1. Papp K, Bechara F, Porter M, et al. Efficacy of izokibep, a novel interleukin-17A inhibitor, in moderate to severe hidradenitis suppurativa: Week 32 results from a randomized, double-blind, placebo-controlled, multicenter, phase 3 study. Poster presented at the 2026 American Academy of Dermatology Annual Meeting. Denver, Colorado. March 27-31, 2026.

2. Acelyrin, Inc. announces positive top-line results from its global phase 2b/3 clinical trial of izokibep in psoriatic arthritis. News release. BioSpace. Published March 11, 2024. Accessed March 30, 2026. https://www.biospace.com/article/releases/acelyrin-inc-announces-positive-top-line-results-from-its-global-phase-2b-3-clinical-trial-of-izokibep-in-psoriatic-arthritis/