Zumilokibart Shows Promise with Twice-Yearly Dosing for Atopic Dermatitis

Apogee reports 52-week results for zumilokibart (APG777) in moderate-to-severe atopic dermatitis

Apogee Therapeutics this month released 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), showing sustained and — in many patients — deepening clinical responses with maintenance dosing every three or six months (Source: Apogee Therapeutics press release, APEX part A 52-week data).

What zumilokibart is and how it works

Zumilokibart (APG777) is an extended half-life, subcutaneous monoclonal antibody designed to selectively block the cytokine interleukin-13 (IL-13), a key driver of inflammation, skin barrier dysfunction, and itch in many people with AD (Source: Apogee Therapeutics press release, APEX part A 52-week data).

The company reported that the drug achieved greater than 99% IL-13 inhibition in the APEX program, an effect intended to provide long-lasting suppression of the inflammatory pathway with less frequent injections compared with some current therapies (Source: Apogee Therapeutics press release, APEX part A 52-week data).

Early human pharmacology and safety data from a first-in-human study also described the half-life extension strategy used with APG777 and supported development of less-frequent dosing schedules (Source: Lim XQ, Winter E, Nograles K, et al., first-in-human APG777 study).

Trial design: APEX part A at a glance

APEX part A enrolled adults with moderate-to-severe AD and tested a 360 mg dose of zumilokibart over a 52-week period, including an induction phase followed by maintenance doses given either every 3 months or every 6 months (Source: Apogee Therapeutics press release, APEX part A 52-week data).

The company analyzed outcomes in two groups: patients who responded by week 16 (the week 16 responder population) and the full group of patients who received zumilokibart regardless of their early response (the full treated population) (Source: Apogee Therapeutics press release, APEX part A 52-week data).

Key 52-week findings

Among patients who met response criteria at week 16, maintenance dosing produced strong durability: 75% of those on three-month maintenance and 85% of those on six-month maintenance maintained an EASI-75 response at week 52 (Source: Apogee Therapeutics press release, APEX part A 52-week data).

Within that same week-16 responder group, vIGA 0/1 (Validated Investigator Global Assessment scores indicating clear or almost clear skin) was preserved in 86% of patients on three-month dosing and 78% on six-month dosing at week 52 (Source: Apogee Therapeutics press release, APEX part A 52-week data).

Importantly, when investigators looked at the full treated population — which included people who had not reached response thresholds at week 16 — they observed continued improvement across measures of skin lesions and itch through 52 weeks, a pattern described by the study team as further deepening of response over time (Source: Apogee Therapeutics press release, APEX part A 52-week data).

Safety and tolerability

The safety profile reported in part A was consistent with what clinicians see with other IL-13–targeting biologics, with the most commonly reported treatment-emergent adverse events being noninfective conjunctivitis, upper respiratory tract infection, and nasopharyngitis (Source: Apogee Therapeutics press release, APEX part A 52-week data).

No new or unexpected safety signals were described in the 52-week dataset, according to the company’s summary; investigators emphasized that continued monitoring in larger controlled studies will be essential to fully define the risk–benefit profile (Source: Apogee Therapeutics press release, APEX part A 52-week data).

How this fits into the current treatment landscape

The therapeutic options for moderate-to-severe AD have expanded substantially over recent years and now include biologics that target interleukin signaling and oral JAK inhibitors. Familiar examples include dupilumab (Dupixent), tralokinumab (Adbry), and lebrikizumab (Ebglyss), along with oral agents such as upadacitinib (Rinvoq) and abrocitinib (Cibinqo) (Source: FDA approvals and company prescribing information).

Despite these advances, treatment adherence remains a practical challenge for many patients. For example, dupilumab is typically administered every two weeks for many patients, which can amount to up to 26 injections per year and may be burdensome for people with needle aversion or limited access to clinic services (Source: Dupixent prescribing information, Sanofi/Regeneron).

Against that backdrop, therapies that maintain or deepen clinical benefit with far less frequent injections could make a meaningful difference for patients facing adherence, logistic, or quality-of-life barriers to frequent dosing (Source: Apogee Therapeutics press release, APEX part A 52-week data).

Voices from investigators

Christopher Bunick, MD, PhD, associate professor of dermatology at Yale School of Medicine, commented that the 52-week results suggest an extended half-life IL-13 biologic may deliver sustained efficacy with more convenient dosing intervals of three or six months, if phase 3 data ultimately confirm these findings (Source: Apogee Therapeutics press release, APEX part A 52-week data).

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 be a clinically meaningful change in practice for many patients who struggle with frequent injections (Source: Apogee Therapeutics press release, APEX part A 52-week data).

Emma Guttman‑Yassky, MD, PhD, of the Icahn School of Medicine at Mount Sinai, highlighted that the continued deepening of responses beyond week 16 was particularly encouraging for patients who did not achieve full benefit early in treatment, suggesting some people may require longer exposure to reach optimal control (Source: Apogee Therapeutics press release, APEX part A 52-week data).

Clinical implications and what clinicians should consider

For clinicians weighing biologics for AD, the APEX part A data raise an important question: could dosing frequency become a differentiating factor in therapeutic choice for certain patients? (Source: Apogee Therapeutics press release, APEX part A 52-week data).

Less frequent maintenance dosing — potentially as few as two to four injections per year if phase 3 confirms these signals — may be particularly attractive for patients with adherence challenges, needle fatigue, work or caregiving responsibilities, or limited access to infusion clinics (Source: Apogee Therapeutics press release, APEX part A 52-week data).

That said, clinicians should be cautious about drawing final conclusions until larger, placebo-controlled studies validate both the efficacy durability and the long-term safety profile of zumilokibart compared with existing standards of care (Source: Apogee Therapeutics press release, APEX part A 52-week data).

What’s next for APG777 and the APEX program

Apogee has said that APEX part B, a randomized, placebo-controlled dose-optimization study enrolling 347 patients across four arms, is underway and is expected to report 16-week induction data in the second quarter of 2026 (Source: Apogee Therapeutics press release, APEX part A 52-week data).

The company anticipates beginning phase 3 trials in the second half of 2026, with a potential regulatory submission timeline that targets a possible commercial launch in 2029 if pivotal results and regulatory review are favorable (Source: Apogee Therapeutics press release, APEX part A 52-week data).

Until those larger studies are completed, the 52-week part A results are an encouraging signal but not definitive evidence that less-frequent IL-13 blockade will outperform or simply replace current approaches for all patients with moderate-to-severe AD (Source: Apogee Therapeutics press release, APEX part A 52-week data).

Bottom line

The 52-week findings from APEX part A position zumilokibart (APG777) as a promising extended half-life anti–IL-13 biologic that may offer durable and deepening responses with maintenance dosing every three or six months for adults with moderate-to-severe atopic dermatitis (Source: Apogee Therapeutics press release, APEX part A 52-week data).

These results are hypothesis-generating for the field: they suggest convenience and adherence advantages could come without compromising efficacy — but phase 3 data and broader safety surveillance will be essential before clinicians change practice (Source: Apogee Therapeutics press release, APEX part A 52-week data).

Sources

1. Apogee Therapeutics press release. “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.” Published March 23, 2026. (Source: Apogee Therapeutics press release, APEX part A 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.” Clinical and Translational Science. doi:10.1111/cts.70456 (Source: Lim et al., first-in-human APG777 study)
3. Dupixent (dupilumab) prescribing information. Sanofi and Regeneron Pharmaceuticals; U.S. FDA labeling and company prescribing information. (Source: Dupixent prescribing information)
4. Adbry (tralokinumab) approval information. Leo Pharma; U.S. FDA approval and company product information. (Source: Leo Pharma, Adbry)
5. Ebglyss (lebrikizumab) approval information. Eli Lilly; U.S. FDA approval and company product information. (Source: Eli Lilly, Ebglyss)
6. Rinvoq (upadacitinib) approval information. AbbVie; U.S. FDA approval and company product information. (Source: AbbVie, Rinvoq)
7. Cibinqo (abrocitinib) approval information. Pfizer; U.S. FDA approval and company product information. (Source: Pfizer, Cibinqo)