Zumilokibart Phase 2 Results Show EASI-75 Benefit in Atopic Dermatitis

AbbVie has reported positive primary results from the Phase 2 APEX Part B dose-regimen-finding study of zumilokibart (APG777) in adults with moderate to severe atopic dermatitis (AD). The findings are being presented as a late-breaking abstract at the 2026 European Academy of Dermatology and Venereology (EADV) Congress in Vienna, held September 30 to October 3.

Zumilokibart is an investigational, half-life-extended monoclonal antibody targeting interleukin-13 (IL-13). It has not been approved by any regulatory authority, and its safety and efficacy have not been established.

A chronic skin disease with ongoing treatment needs

Atopic dermatitis is a chronic inflammatory skin disease characterized by skin lesions and itch. Although treatment options have expanded, long-term disease control and treatment convenience remain important considerations for patients requiring systemic therapy.

AbbVie is investigating whether the extended half-life of zumilokibart can support longer dosing intervals while maintaining control of both skin manifestations and itch.

How zumilokibart works

Zumilokibart is a high-affinity, humanized IgG1 monoclonal antibody that targets IL-13. The antibody prevents formation of the IL-13Rα1–IL-4Rα heterodimer, thereby blocking IL-13 signaling.

The molecule has been engineered for an extended half-life, with clinical data demonstrating a half-life of approximately 77 days in humans. This pharmacokinetic characteristic is being evaluated as part of the development strategy for less frequent dosing.

 Design of the APEX Part B study

APEX Part B (NCT07003425) is an ongoing randomized, double-blind, placebo-controlled Phase 2 dose-regimen-finding study evaluating zumilokibart in adults with moderate to severe AD.

For the 16-week induction analysis, 346 participants were randomized in a 1:1:1:1 ratio to low-, mid-, or high-dose zumilokibart regimens or placebo. The mid-dose regimen was identical to the induction regimen evaluated in the earlier APEX Part A study.

The primary endpoint was the proportion of participants achieving EASI-75 at Week 16, defined as at least a 75% improvement from baseline in the Eczema Area and Severity Index.

All three dose regimens met the primary endpoint

All three zumilokibart regimens demonstrated statistically significant improvements in EASI-75 response compared with placebo at Week 16. The reported EASI-75 response rates were:

• High-dose: 61.6%
• Mid-dose: 65.9%
• Low-dose: 50.5%
• Placebo: 23.4%

The results established statistically significant activity across all three dose regimens and supported selection of the mid-dose regimen for Phase 3 development.

The mid-dose regimen produced the numerically highest EASI-75 response among the three active treatment groups in this analysis, although the study was designed primarily to identify an appropriate dose regimen for further development rather than to establish superiority between the active doses.

Improvements in skin clearance and itch

The study also evaluated deeper skin clearance and patient-reported itch outcomes.

At Week 16, the mid- and high-dose regimens demonstrated significantly greater improvements than placebo across key secondary endpoints, including EASI-90, EASI-100 and I-NRS4. EASI-90 and EASI-100 represent at least 90% and 100% improvements from baseline in EASI, respectively.

For the mid-dose regimen, the detailed results showed:

• EASI-90: 47.4% versus 9.3% with placebo
• EASI-100: 16.5% versus 3.4% with placebo
• I-NRS4: 50.5% versus 13.9% with placebo
• vIGA 0/1: 46.0% versus 10.9% with placebo
• Very low disease activity: 20.6% versus 4.5% with placebo

I-NRS4 refers to a ≥4-point reduction from baseline on the Itch Numeric Rating Scale among participants meeting the relevant baseline itch criterion.

The mid-dose regimen also showed greater percentage reductions than placebo in overall skin severity based on EASI as early as Week 1, while improvement in itch based on I-NRS was evident by Week 2.

These findings indicate that the investigational antibody produced improvements across both physician-assessed measures of skin disease and patient-reported itch during the 16-week induction period.

Safety profile

The most common treatment-emergent adverse events reported through Week 16, occurring in at least 5% of participants in any treatment group, included nasopharyngitis, headache, noninfective conjunctivitis, upper respiratory tract infection, atopic dermatitis and urinary tract infection.

The available Phase 2 findings supported continued clinical development of the selected mid-dose regimen. However, as an investigational therapy, the overall safety and efficacy profile of zumilokibart remains under evaluation in ongoing clinical studies.

Mid-dose regimen selected for Phase 3

Based on the Phase 2 APEX Part B findings, AbbVie selected the mid-dose regimen for Phase 3 development. The next stage will further evaluate the efficacy, safety and dosing profile of zumilokibart, including its potential to support extended dosing intervals.

The APEX program is therefore assessing not only whether IL-13 inhibition can improve the clinical manifestations of moderate to severe AD, but also whether the prolonged pharmacokinetic profile of zumilokibart can translate into a less frequent treatment schedule.

EASI is a validated measure of AD severity ranging from 0, representing clear skin, to 72, representing the most severe disease. The I-NRS measures itch intensity on a scale from 0, no itch, to 10, worst imaginable itch.

Zumilokibart remains investigational, and its safety and efficacy have not yet been established. The APEX Part B study is registered under NCT07003425 on ClinicalTrials.gov.

Reference

AbbVie Highlights Positive Results from the Phase 2 APEX Part B Study of Zumilokibart in Moderate to Severe Atopic Dermatitis, as a Late Breaker at EADV 2026. AbbVie.  September 30, 2026.

A Long-term Safety and Efficacy Study Evaluating APG777 in Atopic Dermatitis, ClinicalTrials.gov ID NCT07003425