Affibody Medical Investor Relations

Affibody’s Partner ACELYRIN Announces Positive Top-line Results for Izokibep in Psoriatic Arthritis and Long-Term Clinical Benefits in Hidradenitis Suppurativa


March 11, 2024

  • Phase 2b/3 psoriatic arthritis clinical trial met the primary endpoint of ACR50 at 16 weeks versus placebo with high statistical significance. Robust responses were achieved for ACR70, PASI100, ACR50/PASI100, and Minimal Disease Activity.
  • Long-term 32-week data from Phase 2b hidradenitis suppurativa study demonstrated sustained responses and deepening clinical benefit. Deep and consistent responses were observed for placebo patients switching to active treatment.
  • Favorable safety profile of izokibep was confirmed in both trials, consistent with the IL-17A class and previous izokibep experience.

Solna, Sweden, March 11, 2024. Affibody’s partner ACELYRIN, INC. today announced that the global Phase 2b/3 clinical trial of izokibep in psoriatic arthritis (PsA) met its primary endpoint with high statistical significance. Positive long-term data from a Phase 2b clinical trial in hidradenitis suppurativa (HS) were also announced.

In the Phase 2b/3 PsA trial the primary endpoint of ACR50 at week 16 was met with high statistical significance. Robust clinical responses were also achieved for ACR70, PASI100, as well as composite endpoints ACR50/PASI100 and Minimal Disease Activity.

Izokibep was well-tolerated with a favorable safety profile consistent with previous experience and the IL-17A class. The PsA trial had a low study discontinuation rate of less than 3%. Mild-to-moderate injection site reactions (ISRs) were observed with discontinuations due to ISR less than 2%.

“It is encouraging to see the positive effect of izokibep in these hard to treat patients. Deep responses have been reported with izokibep across indications. High orders of response such as ACR70 in PsA and HiSCR100 in HS demonstrate the unique ability of izokibep to help patients otherwise inadequately treated,” said Affibody Chief Medical Officer, Nikolai Brun.

In PsA, ACELYRIN expects the reported Phase 2b/3 trial to be the first of two registrational trials.

In addition, ACELYRIN today announced long-term data from a Phase 2b HS trial. The data demonstrated that continued treatment with izokibep led to further clinical improvements over time with maintained favorable safety profile. These results are from an open label extension and include all subjects through week 32.

Patients who switched from placebo to izokibep at week 16 achieved a similar speed and magnitude of response, as those who began treatment with izokibep at baseline, for HiSCR, draining tunnels, skin pain, and Dermatology Life Quality Index. High orders of HiSCR were achieved with the majority of patients achieving HiSCR75 and about a third achieving HiSCR100 by week 16 and through 32 weeks.

“We are pleased to see the exciting results – especially the robust placebo cross-over responses – from this long-term follow up in HS, despite the initial primary endpoint of this study not meeting statistical significance. The HS data together with the positive data in PsA bolsters our excitement for izokibep and confirms izokibep as a leading candidate among the next generation IL-17 treatments,” said David Bejker, CEO of Affibody. “Izokibep continues with strong momentum and we look forward to additional readouts during the year from ongoing late-stage trials.”

Topline data from an ongoing Phase 3 HS trial (NCT05905783) are expected by the end of 2024. ACELYRIN plans an additional Phase 3 trial in HS of approximately 400 patients to address FDA guidance on size of safety database.

Further data from the PsA and HS trials will be presented at future scientific meetings. Additional information about the results can be found at

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) and 80 mg every four weeks (Q4W) versus placebo. 351 adult patients with active PsA were enrolled across 71 sites in the United States and Europe and randomized across the four arms. Dose sequencing in the 160 mg Q2W and 80 mg Q4W arms was impacted by a third-party programming error. The range of pharmacokinetic data from both the 160 mg QW and Q2W arms in PsA demonstrated comparable exposures to the same dose levels from the Phase 2b HS study.

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

About the Phase 2b Hidradenitis Suppurativa clinical trial
The Phase 2b clinical trial (NCT05355805) 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. At week 16, patients who received placebo were randomized to either the weekly or every two-week active treatment arm and all patients were assessed through week 32. The objective of the study was to determine the effect of izokibep versus placebo on various measures of clinical impact and determine the appropriate dose(s) for further clinical development in hidradenitis suppurativa.

For more information about the Phase 2b HS clinical trial, please visit