AbbVie's Zumilokibart Hits Phase 2 Endpoint For Atopic Dermatitis

With all three dose regimens meeting the primary endpoint in the Phase 2 APEX Part B study, AbbVie's zumilokibart is moving toward Phase 3 development, a transition that will require CMC teams and fill-finish operations to begin planning for the scale-up of a half-life extended monoclonal antibody targeting IL-13.

APEX Part B was a randomized, double-blind, placebo-controlled dose-finding study enrolling 346 adults with moderate-to-severe atopic dermatitis, randomized 1:1:1:1 across low-, mid-, and high-dose zumilokibart regimens and placebo over a 16-week induction period. The primary endpoint, proportion of participants achieving EASI-75 at Week 16, was met across all three active arms, with statistically significant improvements versus placebo. The mid-dose regimen, which matched the induction dose evaluated in APEX Part A, was selected for Phase 3 advancement.

Secondary endpoint data reinforce the dose selection rationale. The mid- and high-dose regimens demonstrated significantly greater improvement than placebo in near-complete or complete skin clearance (EASI-90/100) and itch reduction based on the Itch Numeric Rating Scale (I-NRS). Notably, the mid-dose arm showed measurable reductions in skin severity at Week 1 and itch at Week 2, a rapid onset profile that will likely feature in the Phase 3 protocol design and labeling strategy. The most common treatment-emergent adverse events through Week 16 included nasopharyngitis, headache, noninfective conjunctivitis, upper respiratory tract infection, atopic dermatitis, and urinary tract infection.

For manufacturing and regulatory teams, the half-life extension built into zumilokibart's molecular design carries direct process implications. Extended-half-life mAbs typically involve modified Fc engineering, which can affect upstream expression yields, downstream purification selectivity, and formulation stability profiles. Fill-finish operations will need to account for dosing interval flexibility, a key differentiator AbbVie is pursuing in Phase 3, which may influence container closure selection and extractables and leachables assessments under 21 CFR Part 211 and ICH Q1 stability requirements.

Results were presented as a late-breaker at the 2026 EADV Congress in Vienna (September 30 – October 3); the Phase 3 program's design, including extended dosing interval evaluation, will set the next set of process validation and regulatory submission timelines to watch.

Source: AbbVie News Center via AbbVie press release, September 30, 2026.