Apogee Therapeutics (Nasdaq: APGE), a clinical-stage biotech based in San Francisco and Boston, reported 52-week maintenance data from the Phase II APEX Part A trial of zumilokibart (APG777) in moderate-to-severe atopic dermatitis, with results showing that patients maintained and deepened clinical responses on dosing schedules of every three or six months. If confirmed in placebo-controlled and Phase III studies, the zumilokibart atopic dermatitis data could position the anti-IL-13 antibody as a less frequently dosed alternative to current biologics that require injections as often as every two weeks.
The APEX trial (NCT05942655) is a Phase II study evaluating zumilokibart at 360mg administered subcutaneously at three- and six-month intervals in adults with moderate-to-severe atopic dermatitis. Part A assessed maintenance of response over 52 weeks among patients who had completed a 16-week induction period.
Zumilokibart Phase 2 Results: Maintenance and Deepening of Responses
Among patients who achieved response at Week 16, 75% and 85% maintained EASI-75 — a 75% or greater reduction in the Eczema Area and Severity Index — with every three-month and every six-month dosing, respectively. Maintenance of clear or almost clear skin, measured by validated Investigator's Global Assessment (vIGA) scores of 0 or 1, was observed in 86% of patients on three-month dosing and 78% on six-month dosing. The company also reported that deepening of response occurred across all lesional and itch endpoints in the full population of patients initially randomized to zumilokibart, not solely among Week 16 responders. The EASI-75 zumilokibart results, together with the vIGA data, form the core of the efficacy case the company is building ahead of Phase III.
Zumilokibart was well tolerated across both dosing regimens over the full 52-week study period. The most common treatment-emergent adverse events were noninfective conjunctivitis, upper respiratory tract infection, and nasopharyngitis — a profile the company described as generally consistent with other agents in the IL-13 inhibitor class.
Mechanism and Drug Context: How APG777 Targets IL-13
Zumilokibart is a subcutaneous monoclonal antibody engineered with an extended half-life that targets interleukin-13, a cytokine considered a primary driver of the inflammation, barrier dysfunction, and pruritus characteristic of atopic dermatitis. According to the company, zumilokibart achieves greater than 99% inhibition of IL-13, which Apogee Therapeutics argues underpins the rapid onset and sustained depth of response observed in the APEX trial atopic dermatitis data. The extended half-life engineering is what enables the three- and six-month dosing intervals that distinguish the Apogee Therapeutics APG777 program from existing biologics in the class.
Positioning Among Current Moderate-to-Severe Atopic Dermatitis Treatments
The moderate-to-severe atopic dermatitis treatment landscape has expanded in recent years with the approval of dupilumab (Dupixent), an anti-IL-4 receptor alpha antibody administered every two weeks; tralokinumab (Adbry), an anti-IL-13 antibody dosed every two weeks during induction and every two to four weeks thereafter; and oral JAK inhibitors including upadacitinib (Rinvoq) and abrocitinib (Cibinqo). Dupilumab remains the most widely prescribed biologic in the indication.