Friendswood, Texas – September 24, 2026 -- More than half of atopic dermatitis (AD) patients who used targeted systemic therapies modified treatment because the drugs failed to work, according to a new study published in Dermatology and Therapy by Castle Biosciences, Inc. (Nasdaq: CSTL).
Study finds 55% of systemic therapy users switched due to lack of efficacy
The research surveyed 43 AD patients and caregivers who completed a 32-question assessment at the 2024 National Eczema Association Eczema Expo. Among respondents who had used targeted systemic therapies, 55% reported modifying treatment because of insufficient results. Inadequate skin clearance and persistent itching were cited as the most frequent reasons for switching drugs or adding topical treatments.
83% of respondents want molecular testing, rising to 94% among those open to new therapy
Overall, 83% of study participants expressed interest in molecular testing to guide treatment selection. That figure climbed to 94% among patients open to starting a new systemic therapy. Respondents ranked itch control (70%), effective skin clearance (58%) and safety or absence of side effects (50%) as the top priorities when evaluating AD treatment options.
Diego Ruiz Dasilva, M.D., a board-certified dermatologist at Forefront Dermatology in Virginia Beach, Virginia, and the study's author, said patients want better disease control and more information to guide treatment decisions. He said Castle's AdvanceAD-Tx test allows objective molecular data to be brought into treatment conversations to help personalize systemic therapy choices.
AdvanceAD-Tx test links molecular profile to 5.5-fold greater treatment response
The findings build on a separate prospective, multicenter validation study published in the Journal of the American Academy of Dermatology, which assessed AdvanceAD-Tx's ability to predict systemic therapy class response in moderate-to-severe AD patients. Patients with a Janus kinase (JAK) Inhibitor Responder Profile who received JAK inhibitor therapy were 5.5 times more likely to achieve at least 90% improvement in Eczema Area and Severity Index (EASI-90) scores by three months, reaching that response 3.8 times faster than similarly profiled patients treated with a T helper type 2 (Th2)-targeted therapy. Patients with a Th2 Molecular Profile showed comparable outcomes regardless of which therapy class they received.
Non-invasive test evaluates 487 genes across 12 biological pathways
AdvanceAD-Tx is a gene expression profile test for patients aged 12 and older with moderate-to-severe AD. Using RNA data extracted from lesional skin scraping samples rather than biopsies, the test analyzes 487 genes across 12 inflammatory and cutaneous biology pathways to classify patients into either a JAK Inhibitor Responder Profile or a Th2 Molecular Profile.