Apogee Therapeutics' zumilokibart (APG777), an investigational anti-IL-13 monoclonal antibody, met its primary and all key secondary endpoints with high statistical significance in part B of the phase 2 APEX trial, the company announced this week. The results support advancement of the mid-dose into phase 3 trials planned for the second half of 2026, pending regulatory interactions.1
APEX part B enrolled 346 adults with moderate to severe atopic dermatitis (AD), randomized 1:1:1:1 to high-, mid-, or low-dose zumilokibart or placebo. The primary endpoint was EASI-75 at week 16.
Key Takeaways
- Zumilokibart (APG777), an investigational anti-IL-13 monoclonal antibody, met its primary endpoint of EASI-75 in 65.9% of mid-dose patients at week 16, versus 23.4% on placebo (p<0.001)
- All key secondary endpoints were met at week 16, including IGA 0/1 (46.0% vs 10.9%), EASI-90 (47.4% vs 9.3%), and I-NRS ≥4 reduction (50.5% vs 13.9%)
- Very low disease activity (EASI-90 + I-NRS 0/1) was achieved in 20.6% of mid-dose patients versus 4.5% on placebo
- Zumilokibart's induction regimen required 4 injection days versus 9 with the current standard of care
- Part A maintenance data showed efficacy was maintained—and in some cases improved—with every-3- or 6-month dosing through 52 weeks
- The mid-dose was selected for phase 3 advancement based on comparable efficacy to the high dose and a lower conjunctivitis rate (10.6% vs 20.7%)
- Apogee plans to initiate phase 3 trials in moderate to severe AD in the second half of 2026, with phase 2 studies in EoE and asthma to follow
Mid-dose zumilokibart achieved EASI-75 in 65.9% of patients versus 23.4% on placebo—a placebo-adjusted response rate of 41.9% (p<0.001). The high dose achieved 61.6% and the low dose 50.5%, both statistically significant versus placebo. Comparable efficacy between mid- and high-dose, combined with a more favorable tolerability profile at mid-dose, drove the dose selection.
"Zumilokibart delivered in its APEX part B dose-ranging study,” said Christopher Bunick, MD, PhD, associate professor of dermatology at Yale School of Medicine and Dermatology Times editor in chief, in an exclusive statement. “This extended half-life IL-13 targeted biologic led to substantial improvement at week 16 in its AD patients, with high levels of EASI-75, EASI-90, EASI-100, and IGA 0/1 response, potentially placing it as best-in-AD among biologics and on par numerically with JAK inhibitor responses. Particularly reassuring was the fact that the part B efficacy data at week 16 was highly consistent with the part A data. With respect to safety, zumilokibart had a low noninfectious conjunctivitis rate (5.9%) and a very low discontinuation rate, all favorable for patient adherence."
MORE ON AD
Mid-dose zumilokibart achieved IGA 0/1 in 46.0% of patients versus 10.9% on placebo, EASI-90 in 47.4% versus 9.3%, and a clinically meaningful itch reduction (I-NRS ≥4) in 50.5% versus 13.9% at week 16. Complete skin clearance (EASI-100) was reached in 16.5% of patients versus 3.4% on placebo. Very low disease activity—defined as EASI-90 plus I-NRS 0/1—was achieved in 20.6% of mid-dose patients versus 4.5% on placebo (p<0.01 for both); the company characterized this composite outcome as not previously reported with any biologic.
Zumilokibart's induction regimen required 4 injection days compared with 9 for the current standard of care.2 Part A data from APEX previously showed efficacy maintained—and in some cases continued to improve—with every-three- or six-month dosing through 52 weeks.
Zumilokibart was generally well tolerated, with a safety profile consistent with other agents in the class. The most common treatment-emergent adverse events were nasopharyngitis, headache, and noninfective conjunctivitis. Conjunctivitis rates showed a dose-dependent pattern: 10.6% at the planned phase 3 mid-dose, 15.1% at the low dose, and 20.7% at the high dose.
"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," said Ruth Ann Vleugels, MD, MPH, MBA, director of the atopic dermatitis program at Mass General Brigham and professor of dermatology at Harvard Medical School. "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."
Jonathan I. Silverberg, MD, PhD, MPH, professor of dermatology at The George Washington University School of Medicine and Health Sciences, noted the replicability of the itch and skin data relative to prior studies, describing the findings as supportive of sustained disease control with reduced dosing frequency.
Apogee plans to initiate the ADventure 1, ADventure 2, and ADventure TCS phase 3 trials—evaluating monotherapy and combination with background topical corticosteroids—in the second half of 2026. The company also disclosed plans to begin a phase 2a study in eosinophilic esophagitis in the second half of 2026 and a phase 2b study in moderate to severe asthma in the first half of 2027.
References
- 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. News release. Apogee Therapeutics. Published May 27, 2026. Accessed May 27, 2026. https://investors.apogeetherapeutics.com/news-releases/news-release-details/apogee-therapeutics-announces-positive-16-week-part-b-induction
- Davis DMR, Drucker AM, Alikhan A, et al. Guidelines of care for the management of atopic dermatitis in adults with phototherapy and systemic therapies. J Am Acad Dermatol. 2024;90(2):e43-e56. doi:10.1016/j.jaad.2023.08.102
