Could Twice Yearly Dosing Be Enough? Zumilokibart Data Raise the Bar for AD

Today, Apogee Therapeutics announced 52-week maintenance data from part A of its phase 2 APEX trial evaluating zumilokibart (APG777) in adults with moderate to severe atopic dermatitis (AD), reporting sustained and deepening clinical responses with both 3- and 6-month dosing intervals.¹ The results, also to be presented March 28 at the American Academy of Dermatology Annual Meeting in Denver, add to a growing body of evidence for a drug class targeting IL-13, while raising questions about how extended dosing intervals might influence real-world treatment adherence.²

“The newly released data on AD patients treated with 52-weeks of zumilokibart demonstrates that this extended half-life IL-13 targeted biologic can deliver efficacy and maintenance of that response over time with more convenient, less frequent dosing, at 3 or 6 months intervals,” said Christopher Bunick, MD, PhD, associate professor of dermatology at Yale School of Medicine and editor in chief of Dermatology Times. “Such dosing schedules will be transformative for the atopic dermatitis patient experience if the efficacy and safety profiles are reassuring after completion of the phase 2 program and the forthcoming phase 3 trials. Overall, an exciting display of innovation in atopic dermatitis therapy translating into clinical benefit for patients.”

The Current Landscape

The therapeutic landscape for AD has advanced considerably over the past decade with the approval of dupilumab (Dupixent; Sanofi and Regeneron Pharmaceuticals) (IL-4Rα), tralokinumab (Adbry; Leo Pharma) (IL-13), and lebrikizumab (Ebglyss; Eli Lilly) (IL-13), alongside JAK inhibitors including upadacitinib (Rinvoq; AbbVie) and abrocitinib (Cibinqo; Pfizer). Despite these options, adherence remains a clinical challenge — dupilumab, for example, requires biweekly injections, totaling up to 26 administrations annually.

Zumilokibart is an extended half-life subcutaneous monoclonal antibody that selectively targets IL-13, designed to achieve sustained cytokine suppression with less frequent dosing. The drug reportedly achieved greater than 99% IL-13 inhibition in the APEX trial.

Trial Design and 52-Week Data Summary

APEX part A evaluated 360 mg zumilokibart in patients with moderate to severe AD over 52 weeks, examining 2 maintenance dosing intervals — every 3 months and every 6 months — following an induction phase. Analyses were conducted in 2 populations: patients who responded at week 16 and the full zumilokibart-treated population regardless of early response status.

Among week 16 responders, 75% of patients receiving 3-month dosing and 85% receiving 6-month dosing maintained an EASI-75 response at week 52. Validated Investigator Global Assessment (vIGA) scores of 0 or 1 were maintained by 86% of patients on 3-month dosing and 78% on 6-month dosing within that same responder population.

Notably, the full treated population — including patients who had not met response thresholds at week 16 — continued to show deepening of response across all lesional and itch endpoints through 52 weeks, a pattern that investigators described as distinct from the efficacy plateau observed with some existing therapies.

The safety profile was reported as consistent with other agents in the class. The most commonly reported treatment-emergent adverse events were noninfective conjunctivitis, upper respiratory tract infection, and nasopharyngitis — a profile familiar to clinicians managing patients on IL-13–targeting biologics.

Investigator Perspectives

Ruth Ann Vleugels, MD, MPH, MBA, director of the atopic dermatitis program at Brigham and Women's Hospital, noted that quarterly or even biannual dosing would represent a clinically meaningful shift. "The durability and efficacy demonstrated in APEX phase 2 part A through 1 year makes the profile for zumilokibart even more compelling as a future go-to treatment for this disease," she said.

Emma Guttman-Yassky, MD, PhD, of the Icahn School of Medicine at Mount Sinai, highlighted the significance of continued response deepening beyond the 16-week mark. "These 52-week findings for the full population are particularly encouraging for patients who did not fully respond during the first 16 weeks of treatment, suggesting that responses to zumilokibart may continue to deepen over time."

Clinical Implications

For clinicians, the 52-week data introduce a potentially relevant question about dosing frequency as a factor in biologic selection. If confirmed in phase 3, the possibility of 2 to 4 dosing days per year could hold particular appeal in patients with adherence challenges, needle fatigue, or logistical barriers to frequent clinic visits.

Definitive conclusions remain premature. APEX part B — a placebo-controlled dose optimization study enrolling 347 patients across 4 arms — is expected to report 16-week induction data in the second quarter of 2026. Phase 3 trials are anticipated to begin in the second half of 2026, with a potential regulatory submission timeline targeting a 2029 commercial launch, pending clinical and regulatory outcomes.

References

1. Apogee Therapeutics announces positive phase 2 part A 52-week data of zumilokibart (APG777), demonstrating maintenance and deepening of responses with every 3- and 6-month dosing in moderate-to-severe atopic dermatitis. News release. Apogee Therapeutics. Published March 23, 2026. Accessed March 23, 2026. https://investors.apogeetherapeutics.com/news-releases/news-release-details/apogee-therapeutics-announces-positive-phase-2-part-52-week-data
2. Lim XQ, Winter E, Nograles K, et al. A first-in-human, single- and multiple-dose study of APG777, a half-life-extended anti-IL-13 monoclonal antibody, in healthy volunteers. Clin Transl Sci. 2025;18(12):e70456. doi:10.1111/cts.70456