Castle Biosciences' AdvanceAD-Tx Test Identifies Patients More Likely to Benefit from JAK Inhibitor Therapy

Study shows test can stratify atopic dermatitis patients by molecular profile to guide personalized treatment

Published on Feb. 27, 2026

Got story updates? Submit your updates here. ›

Castle Biosciences announced the publication of a prospective clinical validation study in the Journal of the American Academy of Dermatology demonstrating that its AdvanceAD-Tx test can identify patients with moderate-to-severe atopic dermatitis who are significantly more likely to achieve greater and faster clinical responses when treated with a Janus kinase inhibitor (JAKi) compared to T helper type 2 (Th2)-targeted therapies.

Why it matters

The study shows that AdvanceAD-Tx can provide objective molecular insight to help clinicians better align systemic therapy choices with an individual patient's disease biology earlier in the treatment journey, potentially improving outcomes that matter to patients with atopic dermatitis.

The details

The independent validation cohort found that approximately 30% of patients were identified as having a JAK Inhibitor Responder Profile. Among these patients, those treated with a JAKi were 5.5 times more likely to achieve at least 90% improvement in Eczema Area and Severity Index (EASI-90) by three months compared to those treated with Th2–targeted therapies. Patients with a JAK Inhibitor Responder Profile who received a JAKi also achieved a response nearly four times faster, were more likely to achieve near-complete or complete skin clearance, report no itch, remain flare-free, and report improved quality of life.

  • The new publication follows Castle's recent limited access commercial launch of AdvanceAD-Tx in late 2025.
  • The full paper is available online.

The players

Castle Biosciences, Inc.

A company improving health through innovative tests that guide patient care, with a primary focus in dermatologic and gastroenterological disease.

Mark G. Lebwohl, M.D.

Senior study author, dean for clinical therapeutics and professor and chairman emeritus of the Kimberly and Eric J. Waldman Department of Dermatology at the Icahn School of Medicine at Mount Sinai in New York.

Rebecca Critchley-Thorne, Ph.D.

Vice president, research and development, at Castle Biosciences.

Got photos? Submit your photos here. ›

What they’re saying

“Atopic dermatitis can look similar on the surface, but the biology driving the disease can differ meaningfully from patient to patient. This study shows that AdvanceAD-Tx can provide objective molecular insight to help clinicians better align systemic therapy choices with an individual patient's disease biology earlier in the treatment journey and improve outcomes that matter to patients.”

— Mark G. Lebwohl, M.D., Senior study author, dean for clinical therapeutics and professor and chairman emeritus of the Kimberly and Eric J. Waldman Department of Dermatology at the Icahn School of Medicine at Mount Sinai in New York (Journal of the American Academy of Dermatology)

“Together, these results highlight how aligning systemic therapy selection with an individual patient's molecular profile may help streamline care by reducing unnecessary treatment changes and accelerating meaningful clinical improvement. By better understanding the biology driving each patient's disease, AdvancedAD-Tx can help clinicians move beyond non–molecularly guided prescribing and enable more confident, evidence-based decisions earlier in the treatment journey.”

— Rebecca Critchley-Thorne, Ph.D., Vice president, research and development, at Castle Biosciences (Journal of the American Academy of Dermatology)

The takeaway

This study demonstrates the potential for AdvanceAD-Tx to personalize treatment for patients with moderate-to-severe atopic dermatitis by identifying those most likely to benefit from JAK inhibitor therapy, which could lead to faster and deeper treatment responses and improved quality of life for these patients.