Affibody has announced positive Phase III results in hidradenitis suppurativa (HS), a chronic skin condition marked by painful nodules, abscesses, and draining fistulas.
The Swedish company will present 16-week data from a 258-patient global study at the European Academy of Dermatology & Venereology (EADV) Congress in Paris taking place from 17 to 20 September.
The randomized Phase III trial (NCT05905783) tested weekly subcutaneous doses of izokibep against placebo. The study met its primary endpoint at week 12, with a significant proportion of patients achieving HiSCR75, at least a 75% reduction in inflammatory nodules and abscesses without worsening elsewhere.
Key secondary measures, including HiSCR90 and HiSCR100, also showed improvement. By week 16, responses deepened, pointing to sustained and possibly increasing benefit over time. The safety profile remained favorable, with no unexpected signals.
A Drug With A Checkered Past
Izokibep, a small engineered protein targeting the inflammatory cytokine IL-17A, has traveled a winding path through development. Originally advanced in partnership with Acelyrin, the drug was once pitched as a potential pipeline-in-a-product across multiple autoimmune diseases.
That ambition faltered in 2024, when Acelyrin terminated its program in noninfectious uveitis after a Phase IIb/III trial (NCT05384249) failed to meet efficacy endpoints.
The uveitis study was designed to test whether tight binding to IL-17A could translate into vision-preserving benefit. Instead, the data showed no statistically meaningful separation from placebo. Soon after, the company decided not to pursue further investment in the indication.
Acelyrin’s difficulties went beyond trial outcomes. By mid-2024, Affibody, izokibep’s original developer, reacquired full rights to the molecule. The move signaled both a course correction and renewed conviction that the drug still had promise in dermatology and rheumatology, where IL-17A inhibition is well validated.
Izokibep’s Development Program
Beyond HS, the drug has shown encouraging results in psoriatic arthritis (PsA). A Phase IIb/III study (NCT05623345) reported meaningful improvements in joint symptoms and skin clearance, with efficacy comparable to established IL-17 inhibitors. Preliminary data in ankylosing spondylitis also showed promise, though development there has been slower.
Affibody argues that izokibep’s high-potency selectivity for IL-17A could confer an advantage over broader IL-17 blockade strategies. By sparing other subunits, the drug may achieve strong efficacy while avoiding some of the safety trade-offs of next-generation dual inhibitors.
Affibody’s latest Phase III results could mark a turning point for izokibep, shifting the narrative from past disappointments to renewed opportunity. The company is expected to use the data to inform regulatory strategies and potential partnerships, particularly in HS and PsA, where the scientific rationale is strongest.
