APEX Part B: Zumilokibart Achieves Primary Endpoint in Atopic Dermatitis

All 3 dose regimens of zumilokibart, an investigational half-life-extended monoclonal antibody targeting interleukin 13 (IL-13), have met the primary endpoint of Eczema Area and Severity Index 75 (EASI-75) response versus placebo at Week 16 in adults with moderate to severe atopic dermatitis, according to topline results from the phase 2 APEX Part B trial announced by AbbVie.¹

The full findings were scheduled for a late-breaking presentation at the 2026 European Academy of Dermatology and Venereology (EADV) Congress in Vienna, Austria, on September 30, 2026, at 4:15 pm CEST in Hall A. Based on these data, AbbVie selected the mid-dose regimen to carry forward into phase 3 development.¹

Zumilokibart, also known as APG777, is a humanized IgG1 antibody designed to block formation of the IL-13Rα1-IL-4Rα heterodimer. Clinical data have shown a half-life of about 77 days in humans, a property AbbVie is currently assessing as a basis for less frequent dosing.¹

What Did the APEX Part B Trial Evaluate?

APEX Part B (NCT07003425) is an ongoing randomized, double-blind, placebo-controlled phase 2 dose-regimen-finding study in adults with moderate to severe atopic dermatitis.¹˒² For this analysis, there were 346 individuals taking part in the analysis randomized 1:1:1:1 to low-, mid-, or high-dose zumilokibart or placebo across a 16-week induction period.¹

The primary endpoint was the proportion of participants achieving at least a 75% reduction from baseline in EASI score at the 16-week mark. EASI scores range from 0, suggesting the presence of clear skin, to 72, reflecting severe disease. Pruritus, or itch, was measured via the patient-reported Itch Numeric Rating Scale (I-NRS), scored from 0 - 10.¹

The mid-dose regimen matched the induction regimen previously studied in APEX Part A.¹

How Effective Was Zumilokibart for Skin Clearance and Itch?

Each zumilokibart regimen produced a statistically significant EASI-75 response compared with placebo at Week 16. AbbVie has not yet released response rates for individual arms.¹

The mid- and high-dose regimens also outperformed placebo across key secondary end points, including near-complete or complete skin clearance measured by EASI-90 and EASI-100 and itch improvement of at least 4 points on the I-NRS (I-NRS4).¹

Early separation from placebo was observed with the mid-dose regimen, which achieved greater percent reductions in EASI by week 1 and in I-NRS by Week 2.¹

Melinda Gooderham, MD, FRCPC, of the SKiN Centre for Dermatology and Queen's University in Ontario, Canada, pointed to dosing frequency as a meaningful consideration when choosing long-term therapy for a chronic condition such as atopic dermatitis. She said the Week 16 skin and itch improvements justify further study of zumilokibart as a long-term treatment.¹

What Adverse Events Were Reported with Zumilokibart?

Through the 16-week mark, the most common treatment-emergent adverse events, occurring in at least 5% of subjects in any group, included nasopharyngitis, headache, noninfective conjunctivitis, upper respiratory tract infection, urinary tract infection, and atopic dermatitis. The release did not break down event rates by treatment arm.¹

Kori Wallace, MD, vice president and global head of immunology clinical development at AbbVie, noted a continued need for atopic dermatitis drugs combining meaningful disease control with greater convenience. She characterized the move to phase 3, along with assessments of extended dosing intervals, as a key move toward a differentiated treatment option.¹

Zumilokibart is not approved by any regulatory authority, and its safety and efficacy have not been established.¹ AbbVie noted the phase 3 program will further assess the efficacy, safety, and dosing profile of the mid-dose regimen, including extended dosing intervals.

Editor's Note: This summary has been edited for grammar and clarity using artificial intelligence tools.

References

1. 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. News release. AbbVie. September 30, 2026. Accessed September 30, 2026. https://www.prnewswire.com/news-releases/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-2026-302893602.html.

2. A long-term safety and efficacy study evaluating APG777 in atopic dermatitis. ClinicalTrials.gov identifier: NCT07003425. Updated 2026. Accessed September 30, 2026. https://clinicaltrials.gov/study/NCT07003425.