APEX: Positive 16-Week Data Released on Zumilokibart for Atopic Dermatitis

Apogee Therapeutics has announced positive topline findings from Part B of the phase 2 APEX trial evaluating zumilokibart (APG777), an investigational anti–interleukin-13 monoclonal antibody, in adults with moderate-to-severe atopic dermatitis.1

According to the company’s release, the randomized, placebo-controlled study met both its primary and secondary efficacy endpoints at 16 weeks, with those on the mid-dose regimen showing the strongest overall balance of efficacy and tolerability. The release points to the company’s intention to advance the mid-dose formulation into phase 3 development, pending regulatory authority discussions.

“Patients with atopic dermatitis and their physicians want therapies that provide durable and deeper disease control with less frequent dosing,” Ruth Ann Vleugels, MD, MPH, MBA, Heidi and Scott C. Schuster Distinguished Chair in Dermatology and Director of the Atopic Dermatitis Program at Mass General Brigham and Professor of Dermatology, said in a statement.1 “The APEX Part B results align extremely well with these patient-centric goals, particularly the achievement of very low disease activity, or vLDA, with simultaneous robust improvement in lesion and itch benefit in more than one fifth of mid-dose patients, which are results not seen with any biologic to date.”

These data follow the 52-week maintenance findings released from Part A of the phase 2 APEX study on zumilokibart (APG777) in adults with atopic dermatitis.2 The APEX Part B trial involved 346 adult participants with moderate-to-severe atopic dermatitis who were randomized equally to receive high-, mid-, or low-dose zumilokibart or placebo, with investigators looking at the proportion of those attaining at least a 75% reduction in Eczema Area and Severity Index (EASI-75) scores at the 16-week mark as the primary endpoint.

At Week 16, EASI-75 responses were observed in 65.9% of patients receiving the mid-dose treatment, compared with 61.6% in the high-dose arm and 50.5% in the low-dose group. By comparison, 23.4% of placebo-treated participants achieved EASI-75. Both the mid- and high-dose groups demonstrated statistically significant improvements versus placebo (P < .001).

The company highlighted the placebo-adjusted EASI-75 response rate for the mid-dose cohort at 41.9%. Several secondary efficacy endpoints also favored zumilokibart therapy. Among those on the mid-dose regimen, 46.0% achieved a Validated Investigator’s Global Assessment (IGA) score of 0 or 1, indicating clear or almost clear skin, compared with 10.9% in the placebo group (P < .001).

Additionally, 47.4% of participants in the mid-dose arm achieved EASI-90 responses versus 9.3% of placebo recipients (P < .001). A clinically meaningful itch improvement, defined as at least a 4-point Itch Numeric Rating Scale (I-NRS) reduction, was reported in 50.5% of subjects on the mid-dose therapy compared with 13.9% of those in the placebo arm (P < .001).

Investigators also reported complete skin clearance (EASI-100) in 16.5% of patients receiving mid-dose zumilokibart, compared with 3.4% of placebo-treated patients (P < .01). Very low disease activity (vLDA), defined as EASI-90 combined with an I-NRS score of 0 or 1, occurred in 20.6% of participants in the mid-dose cohort versus 4.5% of those assigned placebo (P < .01).

Safety findings were described as generally consistent with previously reported outcomes for therapies targeting the IL-13 pathway. The most frequently reported treatment-emergent adverse events included nasopharyngitis, headache, and noninfectious conjunctivitis.

Rates of conjunctivitis appeared to vary according to dose level. The pooled conjunctivitis incidence for the mid-dose regimen selected for phase 3 development was 10.6%, compared with 15.1% in the low-dose group and 20.7% among patients receiving the high dose.

The investigational biologic enters an increasingly competitive atopic dermatitis treatment landscape that includes agents such as risankizumab (Skyrizi) and bimekizumab (Bimzelx). However, the company has positioned zumilokibart as a potential “best-in-class” IL-13 inhibitor based on its durability profile and dosing strategy.

“The Part B induction data demonstrated that zumilokibart delivered robust efficacy within the first 16 weeks with significantly fewer injections versus the current standard-of-care,” Vleugels said in her statement.1 “Together with Part A data demonstrating that zumilokibart can be dosed every 3 to 6 months in maintenance with continuous and even enhanced efficacy, we are seeing a strong clinical profile that offers what dermatologists are looking for in clinical practice for our patients.”

Outside of atopic dermatitis, the company stated that it is continuing to advance development plans for additional inflammatory indications, including asthma and eosinophilic esophagitis. Apogee noted that planned trial designs for those programs have already been disclosed. Following eventual regulatory feedback, the company plans to initiate phase 3 analyses of zumilokibart in atopic dermatitis within the second half of 2026.

References

1. Apogee Therapeutics Announces Positive 16-Week Part B Induction Dose Optimization Results from Phase 2 APEX Trial of Zumilokibart in Moderate-to-Severe Atopic Dermatitis. Apogee Therapeutics. May 27, 2026. https://investors.apogeetherapeutics.com/news-releases/news-release-details/apogee-therapeutics-announces-positive-16-week-part-b-induction.

2. Smith T. APEX: Zumilokibart Shows Durable Response at 52 Weeks in Atopic Dermatitis. HCPLive. March 23, 2026. Accessed May 27, 2026. https://www.hcplive.com/view/apex-zumilokibart-shows-durable-response-52-weeks-atopic-dermatitis.