Castle Biosciences Study Highlights Need for Molecular Guidance in Atopic Dermatitis Treatment

FRIENDSWOOD, Texas, Sept. 24, 2026 /CourierPR/ -- Castle Biosciences, Inc., a company dedicated to improving patient care through innovative tests, has published new findings that highlight the clinical need for molecular guidance in the treatment of atopic dermatitis (AD). The study, which was published in the journal *Dermatology and Therapy*, underscores the challenges patients face in achieving their treatment goals and the strong interest in molecular testing to guide systemic therapy selection.

According to the study, more than half of the patients who used targeted systemic therapies modified their treatment due to a lack of efficacy. Among those surveyed, 94% of patients open to a new systemic therapy expressed a desire for molecular testing to help identify a more effective treatment. This indicates a significant gap in current treatment approaches and a clear patient demand for more personalized care.

The findings support the clinical need for molecular guidance in AD care, as highlighted by the company's AdvanceAD-Tx test. This non-invasive gene expression profile (GEP) test is designed to guide systemic treatment decisions for patients aged 12 years and older with moderate-to-severe atopic dermatitis. By evaluating RNA expression data from lesional skin scraping samples, the test can classify patients into one of two molecular profiles: a Janus kinase (JAK) Inhibitor Responder Profile or a T helper type 2 (Th2) Molecular Profile.

The study, which included 43 patients and caregivers, revealed that itch control, effective skin clearance, and safety or absence of side effects were the most important factors when considering AD treatment. Among participants who had used systemic therapy, inadequate skin clearance and persistent itching were the most frequently reported reasons for switching systemic therapies or adding topical treatment.

Castle Biosciences has previously demonstrated the ability of the AdvanceAD-Tx test to identify differences in systemic therapy class response in patients with moderate-to-severe AD. A prospective, multicenter clinical validation study in the *Journal of the American Academy of Dermatology* showed that patients identified by the test as having a JAK Inhibitor Responder Profile who were treated with a JAK inhibitor were 5.5 times more likely to achieve at least 90% improvement in Eczema Area and Severity Index (EASI-90) by three months. These patients also achieved that response 3.8 times faster than those with the same molecular profile who were treated with a Th2-targeted therapy.

The results of this study support the clinical need for molecular guidance in AD care and reinforce the value of the AdvanceAD-Tx test in personalizing systemic therapy decisions based on an individual patient's underlying disease biology. Castle Biosciences continues to develop innovative tests that guide patient care, aiming to improve health outcomes for patients with various dermatological and gastroenterological diseases.