New Izokibep Data in Psoriatic Arthritis to be Presented at ACR Convergence 2026

Regulatory

November 2, 2026

Stockholm, Sweden, November 2, 2026. Affibody Medical AB (“Affibody”) today announced new analyses from its global Phase 2b/3 study of the next generation IL-17A inhibitor izokibep in psoriatic arthritis (PsA). The results demonstrate consistent efficacy across clinically relevant patient subgroups, composite endpoints of disease activity, and patient-reported outcomes (PROs). The data will be presented as two posters at the American College of Rheumatology (ACR) Convergence 2026, taking place November 6–11 in Orlando.

As previously announced, the pivotal Phase 2b/3 study of izokibep in PsA met the primary endpoint of ACR50 at 16 weeks with high statistical significance, as well as several secondary endpoints including PASI90, minimal disease activity (MDA) and quality-of-life measures. At week 16, patients originally randomized to izokibep kept receiving izokibep per their original dose and schedule, while patients receiving placebo were switched to izokibep 160 mg once weekly (QW) up to week 52.

The new analyses demonstrate that patients treated with izokibep QW or every two weeks (Q2W) consistently achieved higher rates of ACR50 at week 16 compared to placebo-treated patients across clinically relevant patient subgroups, including prior tumor necrosis factor inhibitor (TNFi) use, baseline enthesitis status, baseline body surface area involvement, and baseline bodyweight. Similar results were also observed for MDA and across hard-to-reach endpoints such as ACR70 and ACR50/PASI100.

For patients originally randomized to izokibep, week 16 response rates were maintained or further increased through week 52 across evaluated subgroups, while patients crossing over from placebo to izokibep at week 16 improved responses.

In a separate analysis, patients treated with izokibep QW or Q2W demonstrated significantly greater improvements from baseline compared to placebo in composite measures of disease activity including Disease Activity in PsA (DAPSA) and clinical DAPSA (cDAPSA), as well as significantly higher rates of very low disease activity (VLDA) at week 16.

In addition, patients receiving izokibep reported significant improvements from baseline versus placebo in PROs such as fatigue (FACIT-F), functional disability (HAQ-DI), and spinal pain. Izokibep treatment also resulted in significant improvements versus placebo across all nine domains of the Psoriatic Arthritis Impact of Disease (PsAID-9), including pain, fatigue, skin problems, work and/or leisure activities, functional capacity, discomfort, sleep disturbance, coping and anxiety.

At week 52, patients continuously receiving izokibep showed further increased responses, and patients who switched from placebo to izokibep at week 16 demonstrated marked improvements.

Professor Frank Behrens and Professor Philip Mease, investigators in the study, will present the new results in two poster presentations at ACR 2026 on Sunday, November 8 and on Monday, November 9, respectively.

“Psoriatic arthritis is a heterogeneous disease. Understanding how patients with different clinical characteristics respond to treatment and whether improvements can be expected across multiple domains is paramount in disease control,” said Professor Philip Mease, M.D., Rheumatology Research, Providence Swedish Medical Center and University of Washington School of Medicine, Seattle, WA, USA. “These results are encouraging, showing consistent responses with izokibep across clinically relevant patient subgroups, together with improvements in stringent measures of disease activity and in patient-reported outcomes that reflect the impact of the disease on patients’ daily lives.”

The presentation details are as follows:
Title: Efficacy of Izokibep, a Novel IL-17A Inhibitor, in Patients With Active Psoriatic Arthritis: A Subgroup Analysis From a Randomized, Double-Blind, Placebo-Controlled, Multicenter, Phase 2b/3 Study.
Date/Time: Sunday, November 8, 2026 at 10:30AM-12:30PM EST.
Presenter: Professor Frank Behrens, M.D., Goethe-University Frankfurt, Fraunhofer-Institute for Translational Medicine and Pharmacology, Frankfurt, Germany.
Format: Poster
Abstract number: 0360

Title: Efficacy of Izokibep, a Novel IL-17A Inhibitor, in Patients With Active Psoriatic Arthritis: Composite Measures of Disease Activity and Patient-Reported Outcomes From a Randomized, Double-Blind, Placebo-Controlled, Multicenter, Phase 2b/3 Study.
Date/Time: Monday, November 9, 2026 at 10:30AM-12:30PM EST.
Presenter: Professor Philip Mease, M.D., Rheumatology Research, Providence Swedish Medical Center and University of Washington School of Medicine, Seattle, WA, USA.
Format: Poster
Abstract number: 1313

Additional information about ACR 2026 is available at: Annual Meeting | American College of Rheumatology

About izokibep

Izokibep is an Affibody^® molecule designed to selectively inhibit IL-17A with high potency. It is only about one-tenth the size of a monoclonal antibody and has been engineered to reach difficult-to-treat tissues by incorporating an albumin binding domain that also results in improved pharmacokinetic (PK) properties. Clinical trial data support the hypothesis that these unique characteristics of izokibep may provide clinically meaningful and differentiated benefits for patients, including improvements in stringent measures of disease activity. Izokibep has been administered to more than a thousand patients, some of whom have been dosed for more than three years.

Late-stage trials of izokibep in hidradenitis suppurativa (HS) and psoriatic arthritis (PsA) have demonstrated levels of clinical response comparable with next generation approaches to IL-17 inhibition. These data also demonstrate that targeting IL-17A alone with greater potency can achieve the same or better clinical responses than agents targeting IL-17 subunits more broadly, without their associated safety liabilities.

About the Phase 2b/3 Psoriatic Arthritis clinical trial

The Phase 2b/3 clinical trial (NCT05623345) is a global, multi center, randomized double-blind, placebo-controlled trial evaluating the safety and efficacy of izokibep dosed subcutaneously 160 mg every week (QW) or every two weeks (Q2W) versus placebo. 343 adult patients with active PsA were enrolled across 96 sites in the United States, Canada and Europe. At week 16, patients originally randomized to izokibep kept receiving izokibep per their original dose and schedule, while patients receiving placebo were switched to izokibep 160 mg once weekly (QW) up to week 52.

For more information about the Phase 2b/3 PsA clinical trial, please visit www.clinicaltrials.gov.

About Psoriatic Arthritis

Psoriatic arthritis (PsA) is a chronic immune-mediated inflammatory disease characterized by multiple manifestations including joint inflammation, skin lesions (psoriasis), and enthesitis (painful inflammation of the tissues that connect ligament and tendons to bone), all contributing to reduced quality of life and the risk of permanent disability. The pathology is dominated by pro-inflammatory T-helper (Th-17) cells that lead to over expression of IL-17, IL-23, and TNF cytokines. It is estimated that approximately 30% of people currently living with psoriasis will develop PsA over time. There remains a large unmet need for more effective therapies to treat PsA across all disease manifestations.

About Affibody® molecules

Affibody^® molecules are a novel drug class of small therapeutic proteins with characteristics surpassing monoclonal antibodies (mAbs) and antibody fragments. The company has created a large library consisting of more than ten billion Affibody^® molecules, all with unique binding sites, from which binders to given targets are selected. Affibody^® molecules are only 6 kDa in size.

They have demonstrated clinical benefit both as tumor-targeting moieties and as efficacious disease modifying agents in autoimmune indications by utilizing the inherent differentiated properties of the platform.

About Affibody

Affibody is a clinical stage radiopharmaceutical company developing next generation Radioligand Therapies (RLTs) designed to deliver highly selective tumor targeting across a wide range of cancers. Leveraging decades of innovation in Affibody^® molecule discovery and engineering, together with deep understanding of the RLT field, the company is advancing a novel pipeline focused on oncology indications with high unmet medical need. Affibody’s lead RLT candidate, ABY-271, is currently being evaluated in a first-in-human clinical study in HER2-positive metastatic breast cancer.

The Affibody^® platform has also demonstrated clinical value in immunology and inflammation, with multiple programs being advanced through strategic partnerships.

Affibody’s main shareholder, Patricia Industries, is a part of Investor AB.

Further information can be found at: www.affibody.com.

New Izokibep Data in Psoriatic Arthritis to be Presented at ACR Convergence 2026