Izokibep Demonstrates Durable Efficacy in Phase 3 Study in Hidradenitis Suppurativa as Presented at AAD 2026

Regulatory

March 27, 2026

Stockholm, Sweden, March 27, 2026. Affibody AB (“Affibody”) today announced positive 32-week data from a global Phase 3 study of the next generation IL-17A inhibitor izokibep in hidradenitis suppurativa (HS), that will be presented at the 2026 American Academy of Dermatology (AAD) Annual Meeting, taking place March 27-31 in Denver.

As previously announced, the Phase 3 study of izokibep in HS met the primary endpoint of HiSCR75 at week 12, as well as several key secondary endpoints including HiSCR90 and HiSCR100.

At week 16, the study was unblinded and patients originally randomized to receive izokibep continued treatment with izokibep 160 mg once weekly (QW), while patients initially receiving placebo were crossed over to receive izokibep 160 mg QW through week 32.

By week 32, patients continuously receiving izokibep demonstrated sustained efficacy, and patients initially receiving placebo achieved notable rates of response following crossover to izokibep. HiSCR75/90/100 response rates at week 32 were 40%/26%/22% in the izokibep arm and 32%/19%/15% in the crossover arm. No new safety signals were observed with extended exposure to izokibep or upon crossover.

“These data demonstrate izokibep’s ability to provide durable clinical benefit for patients with highly burdensome hidradenitis suppurativa,” said principal investigator Kim Papp, M.D., Ph.D., Probity Medical Research, Inc. and Division of Dermatology, Temerty Faculty of Medicine, University of Toronto, Canada. “The sustained efficacy and favorable safety profile observed with longer‑term exposure strongly support izokibep’s potential as a promising new treatment option for this difficult‑to‑treat disease.”

“The 32-week Phase 3 data further strengthen our confidence in izokibep as a differentiated drug candidate in hidradenitis suppurativa,” said David Bejker, Chief Executive Officer of Affibody. “The competitive profile seen with continued potent and selective inhibition of IL-17A in HS adds to the previously reported positive long-term results in psoriatic arthritis and psoriasis and underscores the value izokibep could offer patients.”

Details about the e-Poster:
Title: 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 Number: 71352

Additional information about AAD 2026 is available at: 2026 AAD Annual Meeting

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 3 Hidradenitis Suppurativa clinical study

The Phase 3 clinical study (NCT05905783) was a global, multicenter, randomized double-blind, placebo-controlled trial evaluating the safety and efficacy of izokibep dosed subcutaneously 160 mg every week (QW) versus placebo. The study included 258 randomized patients with moderate-to-severe HS. The primary endpoint was the proportion of patients achieving HiSCR75 at week 12. Further endpoints included HiSCR90 and HiSCR100 as well as later timepoints. At week 16, the study was unblinded, and patients receiving placebo were switched to izokibep 160 mg QW.

For more information about the Phase 3 HS clinical study, please visit www.clinicaltrials.gov.

About Hidradenitis Suppurativa

HS is a chronic inflammatory skin disease which typically manifests in areas with high concentrations of sweat glands causing inflammatory nodules, abscesses, draining fistulas, malodor, scarring, and severe pain. HS is a highly burdensome condition that profoundly impairs patients’ quality of life.

HiSCR measures response to treatment in HS with HiSCR75 indicating at least a 75% reduction in total abscess and inflammatory nodule count (AN count), with no increase in abscess count, and no increase in draining fistula count relative to baseline. Higher order measures such as HiSCR90, and HiSCR100 indicate 90%, and 100% reduction respectively.

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.

Izokibep Demonstrates Durable Efficacy in Phase 3 Study in Hidradenitis Suppurativa as Presented at AAD 2026