Castle Biosciences Launches AdvanceAD-Tx™ to Help Guide Systemic Treatment Decision Making in Patients with Moderate-to-Severe Atopic Dermatitis

Rhea-AI Summary

Castle Biosciences (Nasdaq: CSTL) launched AdvanceAD-Tx on November 3, 2025, a 487-gene expression profile test to guide systemic treatment choice for patients aged 12+ with moderate-to-severe atopic dermatitis.

Validation data showed 30.4% of samples had a JAK inhibitor responder profile; those treated with JAKi reached EASI-90 by three months at 45.5% vs 8.3% (p=0.021), had higher vIGA-AD clear rates (36.4% vs 0%, p=0.006), more “no itch” reports (45.5% vs 8.3%, p=0.021), and remained flare-free more often (54.5% vs 16.7%, p=0.041).

Castle estimates a U.S. TAM of $33 billion, is pursuing reimbursement pathways, and is beginning a measured limited-access commercial launch in November 2025 with phased expansion through 2026.

Positive

• 30.4% of tested samples showed a JAKi responder profile
• EASI-90 by three months: 45.5% vs 8.3% (JAKi vs Th2, p=0.021)
• vIGA-AD clear (0) by three months: 36.4% vs 0% (p=0.006)
• 54.5% remained flare-free on JAKi vs 16.7% (p=0.041)
• Company estimates U.S. TAM of $33 billion

Negative

• Commercial launch is limited access beginning November 2025, delaying broad revenue impact
• Company is pursuing reimbursement pathways, indicating reimbursement is not yet finalized
• Only 30.4% of samples had a JAKi responder profile, limiting immediate test applicability

News Market Reaction

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On the day this news was published, CSTL gained 1.92%, reflecting a mild positive market reaction. Argus tracked a peak move of +19.3% during that session. Our momentum scanner triggered 24 alerts that day, indicating elevated trading interest and price volatility. This price movement added approximately $18M to the company's valuation, bringing the market cap to $929M at that time. Trading volume was very high at 4.2x the daily average, suggesting strong buying interest.

Data tracked by StockTitan Argus on the day of publication.

Validation study data show AdvanceAD-Tx can identify patients with AD who have a ‘JAKi responder profile’ and a superior response to JAKi therapies compared to Th2-targeted therapies

FRIENDSWOOD, Texas, Nov. 03, 2025 (GLOBE NEWSWIRE) -- Castle Biosciences, Inc. (Nasdaq: CSTL), a company improving health through innovative tests that guide patient care, today announced the launch of AdvanceAD-Tx™, a gene expression profile (GEP) test designed to guide systemic treatment decision making in patients ages 12 and older with moderate-to-severe atopic dermatitis (AD).

This innovative 487-GEP test is designed to identify patients with a Janus kinase inhibitor (JAKi) responder profile who are more likely to achieve an Eczema Area and Severity Index improvement of 90% (EASI-90), more quickly and with reduction of flares and itch by three months when treated with a JAK inhibitor than those treated with a T helper type 2 (Th2)-targeted therapy.

“Selecting the right systemic therapy for patients with atopic dermatitis can be a challenge, and too often patients end up cycling through multiple treatments before finding one that works,” said Jonathan I. Silverberg, M.D., Ph.D., MPH, IDENTITY study author and associate professor of dermatology at the George Washington University School of Medicine and Health Sciences in Washington, D.C. “AdvanceAD-Tx is designed to uncover the biology driving each patient’s disease so we can better match the right treatment to the right patient from the start, helping them achieve relief faster and avoid unnecessary delays in care.”

“With AdvanceAD-Tx, we are extending the power of precision medicine into an additional dermatologic indication,” said Derek Maetzold, chief executive officer of Castle Biosciences. “Castle’s expansion into atopic dermatitis reflects the Company’s strategy to leverage our proven technology into new clinical areas with large unmet needs. The U.S. total addressable market opportunity represents an estimated $33 billion, and AdvanceAD-Tx is expected to serve as a growth catalyst alongside our established dermatologic and gastrointestinal tests.”

AdvanceAD-Tx
Intended use population: Based on a one-year prevalence, it is estimated that there are approximately 13.2 million patients ages 12 and older in the United States with moderate-to-severe AD.¹
IDENTITY study data: In the validation cohort, affected lesions from patients aged 12 or older with AD were tested using the AdvanceAD-Tx test. All patients were either starting or switching to a systemic Th2-targeted therapy or a JAKi. The test revealed that 30.4% of samples tested had a JAKi responder profile. The patients with a JAKi responder profile who were treated with a JAKi achieved a higher rate of EASI-90 (a 90% or greater reduction in disease severity on the Eczema Area and Severity Index) by three months compared to those treated with a Th2-targeted therapy (45.5% vs 8.3%, p=0.021). Additionally, they were more likely to achieve a validated investigator global assessment score of clear (vIGA-AD 0, 36.4% vs 0%, p=0.006), were significantly more likely to report “no itch” by three months (45.5% vs. 8.3%, p=0.021) and remain flare-free during treatment (54.5% vs. 16.7%, p=0.041). These patients also reached EASI90 3.8 times faster (p=0.049).
Clinical integration: The test utilizes Castle’s existing laboratory workflows, enabling streamlined adoption for dermatologists already familiar with DecisionDx® testing.
Reimbursement strategy: Castle is pursuing multiple reimbursement pathways.
Launch details: AdvanceAD-Tx is being made commercially available through a measured, limited access launch beginning November 2025, with phased, expanded availability anticipated throughout 2026.

“AdvanceAD-Tx underscores Castle’s commitment to the dermatology community and developing clinically meaningful innovations that improve patient outcomes,” said Matthew Goldberg, M.D., senior vice president, medical, at Castle Biosciences. “We’re applying the same disciplined, data-driven approach that made our DecisionDx franchise successful to an area where patients and clinicians need better tools.”

See accompanying slide deck for more information regarding AdvanceAD-Tx.

About Castle Biosciences
Castle Biosciences (Nasdaq: CSTL) is a leading diagnostics company improving health through innovative tests that guide patient care. With a primary focus in dermatologic and gastroenterological disease, we develop personalized, clinically actionable solutions that help improve disease management and patient outcomes.

We put people first—empowering patients and clinicians and informing care decisions through rigorous science and advanced molecular tests that support more confident treatment planning. To learn more, visit www.CastleBiosciences.com and connect with us on LinkedIn, Instagram, Facebook and X. 

DecisionDx-Melanoma, DecisionDx-CMSeq, i31-SLNB, i31-ROR, DecisionDx-SCC, MyPath Melanoma, AdvanceAD-Tx, TissueCypher, DecisionDx-UM, DecisionDx-PRAME and DecisionDx-UMSeq are trademarks of Castle Biosciences, Inc.

About AdvanceAD-Tx
AdvanceAD-Tx is a non-invasive gene expression profile (GEP) test designed to guide systemic treatment decisions for patients aged 12 years and older with moderate-to-severe atopic dermatitis (AD). Using RNA expression data from lesional skin samples, the test evaluates 487 genes across 12 skin and inflammatory pathways to reveal the underlying immune biology driving an individual patient’s disease. Results classify patients into one of two molecular profiles: Janus Kinases (JAK) Inhibitor Responder Profile or T helper 2 (Th2) Molecular Profile.

The test has shown that patients with a JAK Inhibitor Responder Profile who are treated with JAK inhibitor therapy experience significantly greater clinical benefit—including improved and faster skin clearance (EASI-90), reduced itch, fewer flares and better quality of life by three months—compared to those treated with Th2-targeted therapy. AdvanceAD-Tx provides clinicians with objective, molecular-based insights to help personalize systemic treatment decisions and improve care for patients.

Forward Looking Statements
This press release contains forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended, which are subject to the “safe harbor” created by those sections. These forward-looking statements include, but are not limited to, statements concerning: the ability of AdvanceAD-Tx to (i) bring substantial added value to clinicians and their patients, (ii) provide clinicians with an individualized response profile indicating a patient’s likelihood of experiencing substantial improvement, and (iii) uncover the biology driving each patient’s disease; the accuracy of the 487-GEP tests; our plans to leverage our technology to expand into atopic dermatitis; our estimates about the total addressable market opportunity for AdvanceAD-Tx; and Castle’s ability to achieve near- and long-term success with AdvanceAD-Tx . The words “may”, “can”, and similar expressions are intended to identify forward intentions or expectations disclosed in our forward-looking statements, and you should not place undue reliance on our forward-looking statements. Actual results or events could differ materially from the plans, intentions and expectations disclosed in the forward-looking statements that we make. These forward looking statements involve risks and uncertainties that could cause actual results to differ materially from those in the forward-looking statements, including, without limitation: subsequent study or trial results and findings may contradict earlier study or trial results and findings or may not support the results obtained in these studies, including with respect to the discussion of our tests in this press release; actual application of our tests may not provide the aforementioned benefits to certain patients; and the risks set forth under the heading “Risk Factors” in our Annual Report on Form 10-K for the year ended December 31, 2024, and our Quarterly Report on Form 10-Q for the quarter ended September 30, 2025, each as filed or to be filed with the SEC, and in our other filings with the SEC. The forward-looking statements are applicable only as of the date on which they are made, and we do not assume any obligation to update any forward-looking statements, except as may be required by law

Media Contact:
Allison Marshall – Corporate Communications
amarshall@castlebiosciences.com

Investor Contact:
Camilla Zuckero – Investor Relations
czuckero@castlebiosciences.com

_______________
¹ Atopic Dermatitis in America Study: A Cross-Sectional Study Examining the Prevalence and Disease Burden of Atopic Dermatitis in the US Adult Population. DOI:https://doi.org/10.1016/j.jid.2018.08.028
Patient burden and quality of life in atopic dermatitis in US adults: A population-based cross-sectional study. DOI:https://doi.org/10.1016/j.jid.2018.08.028

FAQ

What is AdvanceAD-Tx from Castle Biosciences (CSTL) and when was it launched?

AdvanceAD-Tx is a 487-gene expression profile test to guide systemic therapy in moderate-to-severe atopic dermatitis; it launched on November 3, 2025.

How does AdvanceAD-Tx predict response to JAK inhibitors versus Th2 therapies for CSTL patients?

In validation data, patients with a JAKi responder profile treated with JAKi achieved EASI-90 at 45.5% vs 8.3% for Th2-targeted therapy by three months (p=0.021).

What percentage of tested patients had a JAKi responder profile with AdvanceAD-Tx?

The validation cohort showed 30.4% of samples tested had a JAKi responder profile.

Does AdvanceAD-Tx have reimbursement and commercial availability for CSTL investors?

Castle is pursuing multiple reimbursement pathways and began a measured, limited-access commercial launch in November 2025 with phased expansion planned in 2026.

What clinical benefits were reported for JAKi-treated patients with a JAKi responder profile?

They achieved faster EASI-90 (reached 3.8x faster, p=0.049), more 'no itch' reports (45.5% vs 8.3%, p=0.021), and higher flare-free rates (54.5% vs 16.7%, p=0.041).

What market opportunity did Castle Biosciences (CSTL) cite for AdvanceAD-Tx in the U.S.?

Castle cited an estimated U.S. total addressable market of approximately $33 billion for atopic dermatitis systemic treatment decision support.