Positive 52-week Phase 2b/3 Data of Izokibep in Psoriatic Arthritis to be Presented at EULAR 2026

Regulatory

May 21, 2026

Stockholm, Sweden, May 21, 2026. Affibody AB (“Affibody”) today announced that positive 52-week data from a global Phase 2b/3 study of izokibep in psoriatic arthritis (PsA) will be presented as an oral presentation at the European Congress of Rheumatology (EULAR) 2026, taking place June 3-6 in London.

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. Week 52 results demonstrated continued improvement over time for patients randomized to either of the izokibep groups (160 mg every two weeks (Q2W) or 160 mg every week (QW)), and rapid improvement in patients following crossover from placebo to izokibep treatment. Izokibep was well-tolerated with a favorable safety profile consistent with previous studies.

Professor Philip Mease, investigator in the study, will present the week 52 study results in an oral presentation at EULAR 2026 on Wednesday, June 3.

“The encouraging 52-week data demonstrate that izokibep provides durable efficacy across key clinical endpoints in psoriatic arthritis, with a favorable safety profile,” said Professor Philip Mease, M.D., Rheumatology Research, Providence Swedish Medical Center and University of Washington School of Medicine, Seattle, WA, USA. “These results underscore izokibep’s potential to offer patients meaningful long-term disease control.”

The presentation details are as follows:
Title: Efficacy and Safety of Izokibep, a Novel IL-17A Inhibitor, in Patients With Active Psoriatic Arthritis: Week 52 Results From a Randomised, Double-Blind, Placebo-Controlled, Multicentre, Phase 2b/3 Study.
Date/Time: Wednesday, June 3, 2026 at 18:20 – 18:30 CET.
Presenter: Professor Philip Mease, M.D., Rheumatology Research, Providence Swedish Medical Center and University of Washington School of Medicine, Seattle, WA, USA.
Abstract number: OP073

Additional information about EULAR 2026 is available at: EULAR 2026 | EULAR Congress

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 resolution of key manifestations of disease. 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.

Positive 52-week Phase 2b/3 Data of Izokibep in Psoriatic Arthritis to be Presented at EULAR 2026