A Double-Blind, Randomized, Vehicle-Controlled Phase 2 Study to Assess the Efficacy and Safety of GX-03 in Adult Subjects With Moderate to Severe Atopic Dermatitis (Eczema)

This is a Phase 2, adaptive, randomized, double-blind, vehicle-controlled study evaluating the efficacy, safety, and tolerability of GX-03 topical ointment (a non-systemic formulation containing polyhexanide) compared with matching vehicle control in adult participants with atopic dermatitis (AD).

Stage 1 (Completed):

Stage 1 enrolled 50 participants (53 subjects randomized, 50 completed) using broad severity eligibility criteria (baseline EASI >7 or vIGA-AD 3 or 4) to evaluate treatment behavior and biomarker concordance across a wide spectrum of AD phenotypes. Following completion of the 8-week evaluation period in 50 participants, an unblinded interim review was conducted by an Independent Data Monitoring Committee (IDMC).

Stage 2 (Active / Recruiting):

Guided by Stage 1 findings, Stage 2 prospectively evaluates GX-03 in an expanded cohort of approximately 135 participants (target: 120 completing the study). Stage 2 enrollment is stratified across three baseline EASI severity bands (1.1-7.0, 7.1-15.9, and 16.0 or above) and enriched for participants with severe baseline PP-NRS of 7 or above).

In both stages, eligible participants are randomized in a 1:1 ratio to receive topically applied GX-03 or matching vehicle control self-administered to affected skin areas at least twice daily for 8 consecutive weeks.

Efficacy assessments are conducted at Week 4, and Week 8 using a superiority testing framework. To control the overall Type I error rate across multiple primary and key secondary endpoints in Stage 2, a Hochberg multiplicity adjustment procedure will be applied. Evaluated endpoints include:

• Week 4 vIGA-AD Success (vIGA-AD Success defined as a score of 0 or 1 with at least 2 grade improvement).
• Week 4 EASI-75 (EASI-75 defined as at least a 75% reduction in Eczema Area Severity Index)
• Week 8 EASI-90 (EASI-90 defined as at least a 90% reduction in Eczema Area Severity Index)
• Week 8 EASI-100 (EASI-100 defined as 100% reduction in Eczema Area Severity Index)

Safety Monitoring:

Safety assessments include treatment-emergent adverse events (TEAEs), serious adverse events (SAEs), local site tolerability monitoring, and concomitant medication reviews across the treatment and follow-up periods.

Participants must meet all of the following criteria:

• Adults aged 18 to 80 years, inclusive
• Male or female subjects in good general health as determined by medical history
• Subjects meeting all of the following baseline criteria:

• Baseline EASI Score of ≥ 1.1
• Baseline vIGA-AD Score of 3 or 4
• Baseline PP-NRS Score of ≥ 7
• Ability to read, understand, and provide written informed consent in English
• Ability to read, understand, and provide written informed consent in English
• Willingness and ability to comply with study procedures, including study visits and daily topical application
• Agreement to use only the assigned study product on designated areas of interest for the duration of the study

Exclusion criteria

Individuals meeting any of the following criteria will be excluded:

• Pregnant, breastfeeding, or planning pregnancy during the study
• Presence of any skin condition or dermatologic disease that could interfere with study treatment or assessments
• Use of systemic or topical immunosuppressive therapies, including corticosteroids, within 3 weeks prior to enrollment
• Use of anti-inflammatory medications (e.g., topical steroids, ibuprofen, celecoxib); steroid nasal or ophthalmic drops are permitted
• Use of topical medications at the test sites within 72 hours prior to enrollment
• Damaged or altered skin at or near test sites (e.g., sunburn, tattoos, scars, uneven pigmentation) that could confound evaluations
• Any medical condition that, in the investigator's judgment, places the subject at undue risk or compromises study integrity