On May 6, 2026 Castle Biosciences, Inc. (Nasdaq: CSTL), a company improving health through innovative tests that guide patient care, reported its financial results for the first quarter ended March 31, 2026.

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"The Castle Biosciences team delivered outstanding results to start 2026, delivering $83.7 million in revenue," said Derek Maetzold, president and chief executive officer of Castle Biosciences. "I thank our team for their dedication and focus, which translates directly to our performance. Our momentum this quarter reflects our robust execution and the strength of our core revenue drivers, with both DecisionDx-Melanoma and TissueCypher achieving double digit year-over-year test volume growth, 16% and 58%, respectively. As a result of our first quarter performance and continued confidence in the business, we are raising our 2026 total revenue guidance to $345-355 million, compared to the previously provided guidance of $340-350 million.

"In addition, during the quarter we expanded the body of evidence supporting our market-leading DecisionDx-Melanoma test. Specifically, we announced new data from a prospective, multicenter, U.S. based study demonstrating that patients with a less than 5% predicted risk of sentinel lymph node positivity had an actual positivity rate of just 2.6%, reinforcing DecisionDx-Melanoma’s ability to guide sentinel lymph node biopsy decision-making in line with guideline thresholds. Our substantial body of evidence is a key driver of adoption and an important differentiator for DecisionDx-Melanoma and our innovative test portfolio more broadly, reinforcing our position of strength as we continue to execute across the business."

First Quarter Ended Mar. 31, 2026, Financial and Operational Highlights
•Revenues were $83.7 million, compared to $88.0 million in the first quarter of 2025. Affecting first quarter 2026 revenue was the change in DecisionDx-SCC Medicare coverage effective April 24, 2025, the re-focus of our commercial efforts, as well as the discontinuation of IDgenetix in May 2025.
◦Revenues for our non-dermatologic tests were $42.6 million, compared to $25.0 million during the same period in 2025.

Core revenue drivers:
•First quarter 2026 total test reports for our core revenue drivers (DecisionDx-Melanoma, TissueCypher) increased 36% over the first quarter of 2025:
◦DecisionDx-Melanoma test reports delivered in the quarter were 10,021, compared to 8,621 in the first quarter of 2025.
◦TissueCypher Barrett’s Esophagus test reports delivered in the quarter were 11,745, compared to 7,432 in the first quarter of 2025.

Additional tests:
◦DecisionDx-SCC test reports delivered in the quarter were 3,702, compared to 4,375 in the first quarter of 2025.
◦MyPath Melanoma test reports delivered in the quarter were 973, compared to 926 in the first quarter of 2025.
◦DecisionDx-UM test reports delivered in the quarter were 492, compared to 470 in the first quarter of 2025.

•Gross margin was 73%, and Adjusted Gross Margin was 76%, compared to 49% and 81%, respectively, for the same periods in 2025. Affecting first quarter 2025 gross margin was the one-time adjustment of an acceleration of amortization expense of approximately $20.1 million.
•Net cash used in operations was $22.1 million, compared to net cash used in operations of $6.0 million for the same period in 2025. First quarter 2026 cash use reflects payout of employee annual cash bonuses as well as certain health care benefit payments, totaling $28.8 million, that are not expected to recur during the remainder of 2026.
•Net loss, which includes non-cash stock-based compensation expense of $9.8 million, was $14.5 million, compared to net loss of $25.8 million for the same period in 2025.
•Net loss per share, Basic and Diluted, was $0.49, compared to net loss per share, Basic and Diluted of $0.90 and Adjusted Net Loss per Share, Basic and Diluted, of $0.20, for the same period in 2025.
•Adjusted EBITDA was $(5.1) million, compared to $13.0 million for the same period in 2025.

Cash, Cash Equivalents and Marketable Investment Securities
As of Mar. 31, 2026, the Company’s cash, cash equivalents and marketable investment securities totaled $261.7 million.
2026 Outlook
Castle Biosciences is raising its guidance for anticipated total revenue in 2026. The Company now anticipates generating between $345-355 million in total revenue in 2026, compared to the previously provided guidance of between $340-350 million.
First Quarter and Recent Accomplishments and Highlights

Dermatology – Skin Cancer
•The Company presented new data at the 2026 American Academy of Dermatology Annual Meeting demonstrating that its DecisionDx-Melanoma test refines mortality risk within American Joint Committee on Cancer (AJCC) stages for patients with cutaneous melanoma (CM). The data showed that DecisionDx-Melanoma identifies clinically meaningful differences in mortality risk among patients within the same stage, which may help clinicians more confidently escalate care for higher-risk patients while avoiding unnecessary interventions in those at lower risk of poor outcomes. See the Company’s news release from March 27, 2026, for more information.
•The Company also announced new data from a prospective, multicenter study evaluating DecisionDx-Melanoma’s integrated sentinel lymph node biopsy (i31-SLNB) test result. The study data confirmed that the i31-SLNB accurately predicts SLN positivity and identifies low-risk patients who may safely consider forgoing SLNB while maintaining favorable long-term outcomes. These results expanded upon earlier publications from the same prospective, multicenter clinical study and further strengthened the growing body of evidence supporting the role of DecisionDx-Melanoma in guiding SLNB decision-making. The paper, available in Future Oncology, confirmed that DecisionDx-Melanoma’s i31-SLNB identifies patients below the 5% National Comprehensive Cancer Network (NCCN) threshold for forgoing sentinel lymph node biopsy and outperforms traditional staging

criteria and other predictive gene expression profile (GEP) tests. See the Company’s news release from March 9, 2026, for more information.
•The Company presented new data at the European Congress of Dermato-Oncology (EADO) Congress and the American College of Mohs Surgery (ACMS) Annual Meeting demonstrating that its DecisionDx-Melanoma test provides independent, personalized prognostic information beyond AJCC staging, identifying biologically high-risk patients—including those with thin and early-stage disease—and supporting more precise, risk-aligned clinical management. See the Company’s news release from April 21, 2026, for more information.
•The Company is supporting a series of initiatives across the country during May in recognition of Skin Cancer Awareness Month, including advocacy walks, community skin cancer screenings and patient education programs in collaboration with leading patient advocacy organizations. These efforts are aimed at expanding access to early detection, education and community-based resources to help prevent skin cancer and improve patient outcomes. See the Company’s news release from May 5, 2026, for more information.
Gastroenterology
•The Company announced that new data from Mayo Clinic researchers, presented at Digestive Disease Week, demonstrate that its TissueCypher test improves risk stratification and informs real-world management decisions for patients with Barrett’s esophagus, including influencing surveillance intervals in more than half of patients and enabling more personalized, risk-aligned care. See the Company’s news release from May 4, 2026, for more information.

Dermatology – Atopic Dermatitis
•The Company announced the publication of a prospective, multicenter clinical validation study in the Journal of the American Academy of Dermatology (JAAD) 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 compared to T helper type 2-targeted therapies. See the Company’s news release from February 19, 2026, for more information.

Conference Call and Webcast Details
Castle Biosciences will hold a conference call on Wednesday, May 6, 2026, at 4:30 p.m. Eastern time to discuss its first quarter 2026 results and provide a corporate update.
A live webcast of the conference call can be accessed here: View Source or via the webcast link on the Investor Relations page of the Company’s website, View Source Please access the webcast at least 10 minutes before the conference call start time. An archive of the webcast will be available on the Company’s website until May 27, 2026.
There will be a brief Question & Answer session following management commentary.

(Press release, Castle Biosciences, MAY 6, 2026, View Source [SID1234665186])