Castle Biosciences Stock Price, News & Analysis
Company Description
Castle Biosciences, Inc. (Nasdaq: CSTL) is a diagnostics company in the biotechnology and molecular testing space that focuses on improving health through tests that guide patient care. According to the company’s public disclosures, its primary focus is on dermatologic and gastroenterological disease, where it develops personalized, clinically actionable molecular tests intended to support disease management and patient outcomes.
Castle Biosciences states that it aims to put people first by empowering patients and clinicians and informing care decisions through rigorous science and advanced molecular tests that support more confident treatment planning. The company’s stock is listed on The Nasdaq Global Market under the ticker symbol CSTL, and it is incorporated in Delaware. Its activities place it within the broader category of research and development in biotechnology and professional, scientific, and technical services.
Core areas of focus
The company’s current portfolio, as described in its news releases, consists of tests for skin cancers, Barrett’s esophagus and uveal melanoma. Castle Biosciences also reports active research and development programs for tests in these and other diseases with high clinical need, including a test to help guide treatment decisions for patients with moderate-to-severe atopic dermatitis.
Castle highlights two core testing "franchises" that act as key revenue drivers:
- Dermatologic testing, centered on skin cancers and atopic dermatitis
- Gastrointestinal testing, focused on Barrett’s esophagus and related cancer risk
Dermatology and skin cancer tests
In dermatology, Castle Biosciences emphasizes a portfolio of proprietary gene expression profile (GEP) and related tests. These include:
- DecisionDx-Melanoma, described as a GEP test designed to analyze tumor biology and deliver a personalized risk assessment for patients with stage I–III cutaneous melanoma. Company materials state that the test provides two distinct outputs: a personalized risk of sentinel lymph node positivity and a personalized risk of recurrence and/or metastasis, combining molecular insights with select clinicopathologic features to support risk-aligned management decisions, such as sentinel lymph node biopsy consideration, follow-up intensity, imaging and referrals.
- DecisionDx-SCC, referenced as a test for patients with high-risk cutaneous squamous cell carcinoma. Castle reports that DecisionDx-SCC has been validated to predict individual risk of metastasis, benefit from adjuvant radiation therapy and risk of local recurrence, with results intended to support tailored post-surgical management and treatment pathway recommendations.
- MyPath Melanoma, described as a diagnostic GEP test for patients with difficult-to-diagnose melanocytic lesions, supporting the diagnosis of melanoma.
- DecisionDx-UM, a GEP test that uses a patient’s tumor biology to predict personalized risk of metastasis from uveal melanoma, a rare eye cancer. The company notes that the test stratifies patients into low-, intermediate- or high-risk groups to help guide personalized care decisions, including surveillance intensity, medical oncology referral and clinical trial consideration.
- DecisionDx-PRAME and DecisionDx-UMSeq, which Castle identifies as part of its offering for patients with uveal melanoma, providing molecular insights from a single biopsy sample alongside DecisionDx-UM.
Castle reports that DecisionDx-Melanoma is supported by a substantial body of peer-reviewed evidence and has been clinically validated in a large number of patient samples. Company communications also reference its use in conjunction with established staging systems, such as the American Joint Committee on Cancer (AJCC) staging, to enhance risk stratification and prognostic precision.
Gastroenterology and Barrett’s esophagus
In gastroenterology, Castle Biosciences highlights TissueCypher Barrett’s Esophagus as a precision medicine test designed and extensively validated to predict a patient’s personalized risk of progression from Barrett’s esophagus to high-grade dysplasia or esophageal adenocarcinoma. The company notes that TissueCypher is indicated for patients with non-dysplastic Barrett’s esophagus, indefinite for dysplasia or low-grade dysplasia, and that its five-year risk assessment is intended to help physicians tailor care to each patient’s risk of developing high-grade dysplasia or esophageal adenocarcinoma.
According to a systematic review and meta-analysis cited by Castle, TissueCypher has been shown across multiple published studies to provide clinically validated risk stratification and to outperform traditional pathology or clinical factors alone in identifying patients at increased risk of developing esophageal cancer. The company reports that TissueCypher has been studied in biopsies from thousands of patients and that it uses an AI-driven spatialomics approach to identify molecular signatures that can precede the development of dysplasia.
Atopic dermatitis and AdvanceAD-Tx
Castle Biosciences has also expanded into atopic dermatitis with AdvanceAD-Tx, a gene expression profile test designed to guide systemic treatment decision making in patients ages 12 and older with moderate-to-severe atopic dermatitis. Company materials describe AdvanceAD-Tx as a non-invasive test that uses RNA expression data from lesional skin samples to evaluate hundreds of genes across multiple skin and inflammatory pathways, classifying patients into a Janus kinase inhibitor responder profile or a T helper 2 molecular profile.
The company reports validation data indicating that patients with a Janus kinase inhibitor responder profile who are treated with a Janus kinase inhibitor can experience greater clinical benefit than those treated with T helper 2–targeted therapy, including improved and faster skin clearance, reduced itch, fewer flares and better quality of life over a defined period. Castle positions AdvanceAD-Tx as an extension of its precision medicine approach into an additional dermatologic indication.
Business model and markets served
Based on its public descriptions, Castle Biosciences operates as a molecular diagnostics and precision medicine company that develops and provides proprietary tests used by clinicians in dermatology, oncology and gastroenterology. The company’s tests are ordered by clinicians to support diagnosis, risk stratification and treatment planning for conditions such as cutaneous melanoma, cutaneous squamous cell carcinoma, Barrett’s esophagus, uveal melanoma and atopic dermatitis.
Castle’s communications indicate that its products are used in skin cancer and gastroenterology markets, and that its core revenue drivers include DecisionDx-Melanoma and TissueCypher. The company also references additional tests, such as DecisionDx-SCC, MyPath Melanoma and DecisionDx-UM, as part of its broader portfolio.
Regulatory filings and corporate governance
Castle Biosciences files reports with the U.S. Securities and Exchange Commission (SEC) as a public company. Its common stock, with a par value of $0.001 per share, trades under the symbol CSTL on The Nasdaq Global Market. In its SEC filings, the company identifies Delaware as its state of incorporation and provides detailed information on financial results, corporate governance and bylaw amendments.
For example, an 8-K filing dated August 5, 2025, describes amendments and restatements to the company’s bylaws, covering topics such as stockholder meeting procedures, director nominations, quorum and voting thresholds, proxy solicitation rules, and indemnification of directors and officers. Other 8-K filings report the release of quarterly financial results and the availability of investor presentations.
Scale and financial disclosures
Castle Biosciences regularly reports its revenues, test volumes and other financial metrics in earnings releases and related SEC filings. These disclosures indicate that the company generates revenue from its portfolio of molecular tests and that it tracks test report volume across its core revenue drivers and additional tests. The company also reports on cash, cash equivalents and marketable investment securities as part of its financial position.
While specific financial figures change over time and are detailed in periodic reports, Castle’s public communications emphasize growth in test volume for its core revenue drivers and ongoing investment in research and development to expand its test portfolio.
Research, evidence base and clinical integration
Castle Biosciences highlights a strong emphasis on clinical evidence and collaboration with academic and clinical institutions. Company materials reference multiple prospective studies, meta-analyses and systematic reviews supporting the performance of its tests, including DecisionDx-Melanoma, DecisionDx-UM and TissueCypher.
For DecisionDx-Melanoma, the company cites more than 50 peer-reviewed publications, including prospective studies and meta-analyses, and notes that the test has been clinically validated in more than 10,000 patient samples and ordered more than 220,000 times since launch. For DecisionDx-UM, Castle references more than 25 peer-reviewed publications involving more than 5,000 patients and notes that the test is included in the American Joint Committee on Cancer Staging Manual and the National Comprehensive Cancer Network Guidelines for uveal melanoma.
TissueCypher is described as being backed by numerous peer-reviewed publications and studied in biopsies from thousands of patients, with evidence that it can identify high-risk patients whose progression rates exceed guideline-based thresholds for intensified care. Castle also notes that its tests are designed to integrate into existing clinical workflows, such as routine endoscopic practice for TissueCypher and dermatology practice for DecisionDx tests and AdvanceAD-Tx.
Company positioning and strategy
Across its public statements, Castle Biosciences characterizes itself as a diagnostics company focused on improving health through tests that guide patient care, with a primary focus in dermatologic and gastroenterological disease. The company describes a strategy of leveraging its molecular testing technology into new clinical areas with high unmet need, as illustrated by the development and launch of AdvanceAD-Tx for atopic dermatitis.
Castle also emphasizes workforce culture and recognition in external rankings and awards, as well as participation in investor conferences and publication of new clinical data at medical meetings. These activities are presented as part of its effort to expand adoption of its tests and to support clinicians with evidence-based tools for personalized disease management.
FAQs about Castle Biosciences (CSTL)
- What does Castle Biosciences, Inc. do?
Castle Biosciences, Inc. is a diagnostics company that develops and provides molecular tests designed to guide patient care. Its portfolio focuses on dermatologic and gastroenterological diseases, including skin cancers, Barrett’s esophagus and uveal melanoma, with tests intended to support diagnosis, risk stratification and treatment planning. - On which exchange does CSTL trade?
According to the company’s SEC filings, Castle Biosciences’ common stock trades on The Nasdaq Global Market under the ticker symbol CSTL. - Which diseases are a primary focus for Castle Biosciences?
Company materials state that Castle Biosciences has a primary focus in dermatologic and gastroenterological disease. Its current portfolio includes tests for skin cancers, Barrett’s esophagus and uveal melanoma, and it has research and development programs for additional tests in these and other diseases with high clinical need. - What are Castle Biosciences’ core revenue drivers?
In its financial communications, Castle identifies DecisionDx-Melanoma and TissueCypher Barrett’s Esophagus as core revenue drivers, noting growth in total test reports for these tests over time. - What is DecisionDx-Melanoma?
DecisionDx-Melanoma is described by the company as a gene expression profile test that analyzes tumor biology to deliver a personalized risk assessment for patients with stage I–III cutaneous melanoma. It provides estimates of sentinel lymph node positivity and risk of recurrence or metastasis, intended to guide risk-aligned management decisions. - What is TissueCypher Barrett’s Esophagus?
TissueCypher Barrett’s Esophagus is a precision medicine test designed to predict a patient’s personalized risk of progression from Barrett’s esophagus to high-grade dysplasia or esophageal adenocarcinoma. Castle reports that it has been extensively validated and can help physicians tailor surveillance and treatment based on individual risk. - How does Castle Biosciences address uveal melanoma?
For uveal melanoma, Castle offers DecisionDx-UM, DecisionDx-PRAME and DecisionDx-UMSeq from a single biopsy sample. These tests provide molecular insights intended to support personalized risk assessment for metastasis and to inform treatment planning. - What is AdvanceAD-Tx?
AdvanceAD-Tx is a gene expression profile test developed by Castle Biosciences to guide systemic treatment decisions for patients aged 12 years and older with moderate-to-severe atopic dermatitis. The test classifies patients into molecular profiles associated with response to specific systemic therapies, with the goal of helping clinicians select treatments based on underlying disease biology. - How does Castle Biosciences describe its approach to patient care?
Castle states that it puts people first by empowering patients and clinicians and informing care decisions through rigorous science and advanced molecular tests. Its tests are designed to provide personalized, clinically actionable information that can support more confident treatment planning and risk-aligned management. - Where can investors find official information about Castle Biosciences?
Investors can review Castle Biosciences’ filings with the U.S. Securities and Exchange Commission, including Forms 10-K, 10-Q and 8-K, for official information on financial results, governance and risk factors. The company also issues press releases and investor presentations that are referenced in its SEC filings.