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Castle Biosciences (Nasdaq: CSTL) posts Q2 growth, raises 2026 view

Filing Impact
(High)
Filing Sentiment
(Neutral)
Form Type
8-K

Rhea-AI Filing Summary

Castle Biosciences reported strong top-line growth in Q2 2026. Revenue was $103.5 million, up from $86.2 million in Q2 2025, as total test reports for core diagnostics DecisionDx-Melanoma and TissueCypher rose 32%. GAAP gross margin was 74.9% and Adjusted Gross Margin was 76.3%. The company posted a small net loss of $2.1 million, or $0.07 per share, versus net income of $4.5 million a year earlier, while Adjusted EBITDA improved to $12.4 million from $10.4 million.

For the first six months of 2026, revenue reached $187.2 million, compared with $174.2 million in 2025. Cash, cash equivalents and marketable investment securities totaled $266.8 million as of June 30, 2026. Net cash used in operations was $6.9 million in the first half, versus $14.8 million provided a year earlier. Reflecting demand trends, Castle raised its 2026 total revenue guidance to $365–375 million from $345–355 million and now expects positive Adjusted EBITDA in the third quarter, fourth quarter and full year 2026.

Operationally, test volumes for TissueCypher and AdvanceAD-Tx grew, DecisionDx-SCC volumes softened, and new clinical and regulatory milestones were achieved, including New York State approval and an industry award for AdvanceAD-Tx and additional supportive studies for DecisionDx-Melanoma and TissueCypher.

Positive

  • Q2 2026 revenue rose to $103.5 million from $86.2 million, with core test volumes up 32%, indicating solid demand for Castle Biosciences’ key diagnostics.
  • 2026 revenue guidance was raised to $365–375 million from $345–355 million, and management now expects positive Adjusted EBITDA for Q3, Q4 and the full year 2026.

Negative

  • Q2 2026 swung to a net loss of $2.1 million from net income of $4.5 million a year earlier, reflecting higher operating expenses.
  • Operating cash flow for the first half of 2026 was a $6.9 million outflow, compared with $14.8 million provided in the prior-year period, and Adjusted EBITDA fell to $7.3 million from $23.4 million.

Filing Explained

As of June 30, the reported $266.8 million liquidity figure included $204,689 thousand of securities and $62,116 thousand of cash.

This July 30 Form 8-K reports the company’s second-quarter results under Items 2.02 and 7.01; its press release and slides are exhibits, but the filing says this information is not treated as filed for Section 18 purposes or incorporated by reference unless expressly referenced.

Form 8-K reports specified material events, with item numbers identifying the event category; here, Item 2.02 covers results and Item 7.01 covers Regulation FD disclosure.

As of June 30, 2026, cash and equivalents were $62,116 thousand and marketable investment securities were $204,689 thousand; the reported $266.8 million liquidity figure therefore included both holdings rather than cash alone.

Item 2.02 Results of Operations and Financial Condition Financial
Disclosure of earnings results, typically an earnings press release or preliminary financials.
Item 7.01 Regulation FD Disclosure Disclosure
Material non-public information disclosed under Regulation Fair Disclosure, often investor presentations or guidance.
Item 9.01 Financial Statements and Exhibits Exhibits
Financial statements, pro forma financial information, and exhibit attachments filed with this report.
Q2 2026 Revenue $103.5 million Net revenues for the quarter ended June 30, 2026, versus $86.2 million in Q2 2025
Q2 2026 Net (Loss) Income $(2.1) million Net loss for the quarter, versus net income of $4.5 million in Q2 2025
Q2 2026 Adjusted EBITDA $12.4 million Non-GAAP Adjusted EBITDA for the quarter, up from $10.4 million in Q2 2025
Cash and Investments $266.8 million Cash, cash equivalents and marketable investment securities as of June 30, 2026
2026 Revenue Guidance Range $365–375 million Updated total revenue guidance for full-year 2026, raised from $345–355 million
Core Test Volume Growth 32% Increase in Q2 2026 total test reports for DecisionDx-Melanoma and TissueCypher versus Q2 2025
First-Half 2026 Net Cash from Operations $(6.9) million Net cash used in operating activities for the six months ended June 30, 2026, versus $14.8 million provided in 2025
Q2 2026 Adjusted Gross Margin 76.3% Non-GAAP Adjusted Gross Margin percentage for Q2 2026, based on Adjusted Revenues
Adjusted EBITDA financial
"Adjusted EBITDA was $12.4 million, compared to $10.4 million for the same period in 2025."
Adjusted EBITDA is a way companies measure how much money they make from their core operations, like running a business, by removing certain costs or income that aren’t part of regular business activities. It helps investors see how well a company is doing without distractions from unusual expenses or gains, making it easier to compare companies or track performance over time.
Adjusted Gross Margin financial
"Gross margin was 75%, and Adjusted Gross Margin was 76%, compared to 77% and 80%."
Adjusted gross margin is a measure of how much profit a company makes from its sales after accounting for certain expenses or one-time costs, but before deducting other operating expenses. It helps investors see the company's core profitability more clearly by removing factors that might distort the usual profit picture, similar to a runner measuring their speed without considering obstacles or weather. This metric provides a clearer view of the company's ongoing financial health.
Barrett’s esophagus medical
"TissueCypher Barrett’s Esophagus test reports delivered in the quarter were 14,988."
A condition in which the normal lining of the lower esophagus is replaced by tissue more like the intestine, often from long-term acid reflux. It matters to investors because it increases the chance of developing esophageal cancer, driving demand for screening tests, medical procedures and drug development; like a warning light on a car, it signals greater need for medical care and possible regulatory activity that can affect healthcare company revenues.
gene expression profile medical
"AdvanceAD-Tx is Castle's clinically validated gene expression profile test designed to guide treatment."
A gene expression profile is a snapshot of which genes in a cell or tissue are switched on and how strongly they are producing their products, like a theater marquee showing which plays are running and how popular each is. For investors, these profiles matter because they can indicate whether a drug or diagnostic is likely to work, reveal which patient groups will benefit, and reduce development time and risk—factors that influence a biotech company’s value and commercial prospects.
sentinel lymph node biopsy medical
"DecisionDx-Melanoma's integrated sentinel lymph node biopsy test result (i31-SLNB) outperforms the MIA nomogram."
A sentinel lymph node biopsy is a surgical procedure that removes and tests the first lymph node(s) that drain fluid from a tumor to see if cancer has spread. Think of it as checking the first security checkpoint after a breach; a negative result often means less extensive surgery and lower treatment costs, while a positive result can change therapy, prognosis, regulatory decisions and market demand for related diagnostics and treatments, making it important to investors.
Revenue Q2 2026 $103.5 million up from $86.2 million in Q2 2025
Net (loss) income Q2 2026 $(2.1) million compared with net income of $4.5 million in Q2 2025
Adjusted EBITDA Q2 2026 $12.4 million up from $10.4 million in Q2 2025
First-half 2026 revenue $187.2 million up from $174.2 million for the six months ended June 30, 2025
Cash and investments $266.8 million cash, cash equivalents and marketable investment securities as of June 30, 2026
Guidance

Castle Biosciences now guides 2026 total revenue to $365–375 million, increased from $345–355 million, and expects positive Adjusted EBITDA for the third quarter, fourth quarter and full year 2026.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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FAQ

What were Castle Biosciences (CSTL) Q2 2026 revenues?
Castle Biosciences reported Q2 2026 revenue of $103.5 million, up from $86.2 million in Q2 2025. Growth was supported by a 32% increase in total test reports for core drivers DecisionDx-Melanoma and TissueCypher, partially offset by lower DecisionDx-SCC volumes.

Did Castle Biosciences (CSTL) earn a profit in Q2 2026?
Castle Biosciences posted a Q2 2026 net loss of $2.1 million, or $0.07 per share. This compares with net income of $4.5 million in Q2 2025. Despite the loss, Adjusted EBITDA was $12.4 million, up from $10.4 million a year earlier.

How did Castle Biosciences (CSTL) update its 2026 revenue guidance?
Castle Biosciences raised its 2026 total revenue guidance to $365–375 million, up from a prior range of $345–355 million. Management also now expects to deliver positive Adjusted EBITDA in the third quarter, fourth quarter and for the full year 2026.

What is Castle Biosciences’ (CSTL) cash position as of June 30, 2026?
As of June 30, 2026, Castle Biosciences held $266.8 million in cash, cash equivalents and marketable investment securities. This liquidity supports ongoing R&D, commercialization efforts and capital investments, even as first-half operating activities used $6.9 million of cash.

What non-GAAP metrics does Castle Biosciences (CSTL) highlight?
Castle Biosciences emphasizes Adjusted Revenues, Adjusted Gross Margin and Adjusted EBITDA. For Q2 2026, Adjusted Gross Margin was 76.3% and Adjusted EBITDA was $12.4 million. These measures exclude items like prior-period revenue adjustments, acquisition-related amortization and stock-based compensation.

What recent product and regulatory milestones has Castle Biosciences (CSTL) achieved?
Castle Biosciences’ AdvanceAD-Tx test received assay approval from the New York State Department of Health and won a “Genomics Innovation Award.” New multicenter data also supported DecisionDx-Melanoma in sentinel lymph node biopsy decision-making and TissueCypher in Barrett’s esophagus risk stratification.
0001447362FALSE00014473622026-07-302026-07-30

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

FORM 8-K
CURRENT REPORT
Pursuant to Section 13 or 15(d)
of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): July 30, 2026

Castle Biosciences, Inc.
(Exact name of registrant as specified in its charter)
     
Delaware 001-38984 77-0701774
(state or other jurisdiction
of incorporation)		 (Commission
File Number)		 (I.R.S. Employer
Identification No.)
1500 W. Parkwood Ave, Suite 400
Friendswood, Texas
77546
(Address of principal executive offices)(Zip Code)

Registrant’s telephone number, including area code: (866) 788-9007

(Former name or former address, if changed since last report.)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions: 

☐    Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)
☐    Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12) 
☐    Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b)) 
☐    Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c)) 
 
Securities registered pursuant to Section 12(b) of the Act:
Title of each classTrading Symbol(s) Name of each exchange on which registered
Common Stock, $0.001 par value per shareCSTL The Nasdaq Global Market

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b–2 of the Securities Exchange Act of 1934 (§ 240.12b–2 of this chapter).
Emerging growth company ☐ 
If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐ 


Item 2.02    Results of Operations and Financial Condition.

On July 30, 2026, Castle Biosciences, Inc. (the “Company”) issued a press release announcing its financial results for the second quarter ended June 30, 2026. A copy of the press release is attached hereto as Exhibit 99.1 and incorporated herein by reference.

The information contained or incorporated in this Current Report on Form 8-K, including Exhibit 99.1, shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section, nor shall it be deemed to be incorporated by reference into any filing under the Exchange Act or the Securities Act of 1933, as amended (the “Securities Act”), except as expressly set forth by specific reference in such filing to this Current Report on Form 8-K.

Item 7.01    Regulation FD Disclosure.

On July 30, 2026, the Company made available the slide presentation attached hereto as Exhibit 99.2. Information from this slide presentation may also be used by the management of the Company in future meetings regarding the Company.

The information contained or incorporated in this Item 7.01 of this Current Report on Form 8-K, including Exhibit 99.2, shall not be deemed “filed” for purposes of Section 18 of the Exchange Act or otherwise subject to the liabilities of that section, nor shall it be deemed to be incorporated by reference into any filing under the Exchange Act or the Securities Act except as expressly set forth by specific reference in such filing to this Current Report on Form 8-K.

Item 9.01    Financial Statements and Exhibits.
(d) Exhibits.
Exhibit
NumberDescription
99.1
Press release issued July 30, 2026.
99.2
Slide presentation.
104Inline XBRL for the cover page of this Current Report on Form 8-K.



SIGNATURES
Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has caused this report to be signed on its behalf by the undersigned hereunto duly authorized.
CASTLE BIOSCIENCES, INC.
By:/s/ Frank Stokes
Frank Stokes
Chief Financial Officer
Date: July 30, 2026
 




cstllogo01a.jpg
Exhibit 99.1


Castle Biosciences Reports Second Quarter 2026 Results
Delivered Q2 2026 revenue of $103.5 million
Q2 2026 total test reports for our core revenue drivers (DecisionDx®-Melanoma, TissueCypher®) increased 32% over Q2 2025
Raising full-year 2026 revenue guidance to $365-375 million from $345-355 million

Conference call and webcast today at 4:30 p.m. ET

FRIENDSWOOD, Texas – July 30, 2026 – Castle Biosciences, Inc. (Nasdaq: CSTL), a company improving health through innovative tests that guide patient care, today announced its financial results for the second quarter ended June 30, 2026.

“The Castle Biosciences team delivered another outstanding quarter,” said Derek Maetzold, president and chief executive officer of Castle Biosciences. “We believe our strong growth through the first half of 2026 demonstrates the clinical value our tests bring to patient care and the dedication of our talented team to deliver results so that our clinician customers and patients can act with confidence.

“Given this momentum, we are raising our 2026 total revenue guidance to $365-375 million, up from our previous range of $345-355 million. We also now expect to achieve positive Adjusted EBITDA for the third quarter, the fourth quarter and the full year 2026.

“We are also encouraged by an independent study supporting the clinical impact of AdvanceAD-Tx™ in guiding systemic treatment selection. At the Revolutionizing Atopic Dermatitis meeting in June, data from a multi-center study showed only 54.3% of patients receiving baseline systemic therapy were initially on pathway-concordant treatment; however, following testing with our AdvanceAD-Tx test, 97.8% of patients were initiated on molecularly concordant systemic therapy.

I want to thank the entire Castle team for their focus, commitment and disciplined execution, which continue to advance our mission of improving health through innovative tests that guide patient care.”

Second Quarter Ended Jun. 30, 2026, Financial and Operational Highlights
•Revenues were $103.5 million, compared to $86.2 million in the second quarter of 2025. Affecting second 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.

Core revenue drivers:
•Second quarter 2026 total test reports for our core revenue drivers (DecisionDx-Melanoma, TissueCypher) increased 32% over the second quarter of 2025:
◦DecisionDx-Melanoma test reports delivered in the quarter were 10,280, compared to 9,981 in the second quarter of 2025.
◦TissueCypher Barrett’s Esophagus test reports delivered in the quarter were 14,988, compared to 9,170 in the second quarter of 2025.



Additional tests:
◦DecisionDx-SCC test reports delivered in the quarter were 4,011, compared to 4,762 in the second quarter of 2025.
◦MyPath® Melanoma test reports delivered in the quarter were 1,061, compared to 1,166 in the second quarter of 2025.
◦DecisionDx®-UM test reports delivered in the quarter were 482, compared to 468 in the second quarter of 2025.

•Gross margin was 75%, and Adjusted Gross Margin was 76%, compared to 77% and 80%, respectively, for the same periods in 2025.
•Net loss, which includes non-cash stock-based compensation expense of $11.6 million, was $2.1 million, compared to net income of $4.5 million for the same period in 2025.
•Net loss per share and Adjusted Net Loss per Share, Basic and Diluted, was $0.07, compared to net income per share and Adjusted Net Income per Share, Basic and Diluted, of $0.16 and $0.15, respectively, for the same period in 2025.
•Adjusted EBITDA was $12.4 million, compared to $10.4 million for the same period in 2025.
•Net cash provided by operations was $15.2 million, compared to net cash provided by operations of $20.8 million for the same period in 2025.

Six Months Ended Jun. 30, 2026, Financial and Operational Highlights
•Revenues were $187.2 million, compared to $174.2 million for the six months ended June 30, 2025. Affecting comparison to 2025 includes 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.

Core revenue drivers:
•First half 2026 total test reports for our core revenue drivers (DecisionDx-Melanoma, TissueCypher) increased 34% over the six months ended June 30, 2025.
◦DecisionDx-Melanoma test reports delivered in the six months ended June 30, 2026, were 20,301, compared to 18,602 for the same period in 2025.
◦TissueCypher Barrett’s Esophagus test reports delivered in the six months ended June 30, 2026, were 26,733, compared to 16,602 for the same period in 2025.
Additional tests:
◦DecisionDx-SCC test reports delivered in the six months ended June 30, 2026, were 7,713, compared to 9,137 for the same period in 2025.
◦MyPath Melanoma test reports delivered in the six months ended June 30, 2026, were 2,034, compared to 2,092 for the same period in 2025.
◦DecisionDx-UM test reports delivered in the six months ended June 30, 2026, were 974, compared to 938 for the same period in 2025.

•Gross margin for the six months ended June 30, 2026, was 74%, and Adjusted Gross Margin was 77%, compared to 63% and 81%, respectively, for the same period in 2025.
•Net loss, which includes non-cash stock-based compensation expense of $21.4 million, was $16.6 million, compared to net loss of $21.3 million for the same period in 2025.
•Net loss per share and Adjusted Net Loss per Share, Basic and Diluted, was $0.55, compared to net loss per share and Adjusted Net Loss per Share, Basic and Diluted, of $0.74 and $0.04, respectively, for the same period in 2025.
•Adjusted EBITDA was $7.3 million, compared to $23.4 million for the same period in 2025.


•Net cash used in operations was $6.9 million, compared to $14.8 million net cash provided by operations for the same period in 2025.
Cash, Cash Equivalents and Marketable Investment Securities
As of Jun. 30, 2026, the Company’s cash, cash equivalents and marketable investment securities totaled $266.8 million.
2026 Outlook
Castle Biosciences is raising its guidance for anticipated total revenue in 2026. The Company now anticipates generating between $365-375 million in total revenue in 2026, compared to the previously provided guidance of between $345-355 million. Further, the Company expects to achieve positive Adjusted EBITDA for the third quarter, the fourth quarter and the full year 2026.

Second Quarter and Recent Accomplishments and Highlights

Dermatology - Skin Cancer
•The Company announced the publication of a prospective, multicenter study in Dermatology and Therapy demonstrating that DecisionDx-Melanoma's integrated sentinel lymph node biopsy test result (i31-SLNB) outperforms the Melanoma Institute Australia (MIA) nomogram in identifying patients at low and high risk of SLN positivity, supporting more informed SLNB decision-making for patients with cutaneous melanoma (CM). This is the second multicenter study showing that the i31-SLNB result outperforms the MIA nomogram in assessing SLN positivity risk. See the Company's news release from June 25, 2026, for more information.

Dermatology - Atopic Dermatitis
•The Company announced that its AdvanceAD-Tx test has received assay approval from the New York State Department of Health (NYSDOH). With this approval, Castle has New York State approval for all tests within its dermatology and ophthalmology portfolios, its TissueCypher test within gastroenterology and its clinical laboratories in Phoenix and Pittsburgh. See the Company's news release from July 14, 2026, for more information.
•The Company announced that its AdvanceAD-Tx test was selected as the winner of the "Genomics Innovation Award" in the 10th annual MedTech Breakthrough Awards program, which recognizes companies driving meaningful progress and improving patient care across the global health and medical technology industry. AdvanceAD-Tx is Castle's clinically validated gene expression profile (GEP) test designed to guide systemic treatment decision making in patients 12 and older with moderate-to-severe atopic dermatitis (AD). This marks the fifth MedTech Breakthrough Award that Castle has earned for its innovative testing solutions. See the Company's news release from May 12, 2026, for more information.

Pipeline Initiatives
•In June 2026, the first patient was enrolled in DETECT-AD, a multicenter prospective clinical study being conducted through Castle's collaboration with SciBase, a global medical technology company, specializing in early detection and prevention in dermatology. The study will investigate the ability of Electrical Impedance Spectroscopy (EIS) to predict the onset of flares in patients with AD, with the goal of enabling proactive interventions and improving patient quality of life.

Corporate
•The Company announced that Frank Stokes, its chief financial officer, has been named a 2026 CFO Awards honoree by the Houston Business Journal. Stokes is among 22 chief financial officers from across the Greater Houston area recognized for their financial leadership and contributions to their organizations' success. See the Company's news release from June 23, 2026, for more information.



Conference Call and Webcast Details
Castle Biosciences will hold a conference call on Thursday, July 30, 2026, at 4:30 p.m. Eastern time to discuss its second quarter 2026 results and provide a corporate update.

A live webcast of the conference call can be accessed here: https://event.choruscall.com/mediaframe/webcast.html?webcastid=gbu0MZxe or via the webcast link on the Investor Relations page of the Company’s website, https://ir.castlebiosciences.com/. 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 August 20, 2026.
There will be a brief Question & Answer session following management commentary.
Use of Non-GAAP Financial Measures (UNAUDITED)
In this release, we use the metrics of Adjusted Revenues, Adjusted Gross Margin, Adjusted EBITDA and Adjusted Net (Loss) Income per Share, Basic and Diluted, which are non-GAAP financial measures and are not calculated in accordance with generally accepted accounting principles in the United States (GAAP). Adjusted Revenues and Adjusted Gross Margin reflect adjustments to GAAP net revenues to exclude net positive and/or net negative revenue adjustments recorded in the current period associated with changes in estimated variable consideration related to test reports delivered in previous periods. Adjusted Gross Margin further excludes acquisition-related intangible asset amortization. Adjusted EBITDA excludes from net loss: interest income, interest expense, income tax benefit or expense, depreciation and amortization expense, stock-based compensation expense and net losses (gains) on equity securities. Adjusted Net (Loss) Income per Share, Basic and Diluted, excludes a one-time adjustment of an acceleration of amortization expense for our IDgenetix test from net loss.

We use Adjusted Revenues, Adjusted Gross Margin, Adjusted EBITDA and Adjusted Net (Loss) Income per Share, Basic and Diluted, internally because we believe these metrics provide useful supplemental information in assessing our revenue and operating performance reported in accordance with GAAP, respectively. We believe that Adjusted Revenues, when used in conjunction with our test report volume information, facilitates investors’ analysis of our current-period revenue performance and average selling price performance by excluding the effects of revenue adjustments related to test reports delivered in prior periods, since these adjustments may not be indicative of the current or future performance of our business. We believe that providing Adjusted Revenues may also help facilitate comparisons to our historical periods. Adjusted Gross Margin is calculated using Adjusted Revenues and therefore excludes the impact of revenue adjustments related to test reports delivered in prior periods, which we believe is useful to investors as described above. We further exclude acquisition-related intangible asset amortization in the calculation of Adjusted Gross Margin. We believe that excluding acquisition-related intangible asset amortization may facilitate gross margin comparisons to historical periods and may be useful in assessing current-period performance without regard to the historical accounting valuations of intangible assets, which are applicable only to tests we acquired rather than internally developed. Adjusted Net (Loss) Income per Share, Basic and Diluted, is calculated by excluding a one-time adjustment of an acceleration of amortization expense for our IDgenetix test from net loss. We believe that providing Adjusted Net (Loss) Income per Share, Basic and Diluted, may also help facilitate comparisons to our historical periods. We believe Adjusted EBITDA may enhance an evaluation of our operating performance because it excludes the impact of prior decisions made about capital investment, financing, investing and certain expenses we believe are not indicative of our ongoing performance. However, these non-GAAP financial measures may be different from non-GAAP financial measures used by other companies, even when the same or similarly titled terms are used to identify such measures, limiting their usefulness for comparative purposes.

These non-GAAP financial measures are not meant to be considered in isolation or used as substitutes for net revenues, gross margin, net loss or net loss per share reported in accordance with GAAP; should be considered in conjunction with our financial information presented in accordance with GAAP; have no standardized meaning prescribed by GAAP; are unaudited; and


are not prepared under any comprehensive set of accounting rules or principles. In addition, from time to time in the future, there may be other items that we may exclude for purposes of these non-GAAP financial measures, and we may in the future cease to exclude items that we have historically excluded for purposes of these non-GAAP financial measures. Likewise, we may determine to modify the nature of adjustments to arrive at these non-GAAP financial measures. Because of the non-standardized definitions of non-GAAP financial measures, the non-GAAP financial measure as used by us in this press release and the accompanying reconciliation tables have limits in their usefulness to investors and may be calculated differently from, and therefore may not be directly comparable to, similarly titled measures used by other companies. Accordingly, investors should not place undue reliance on non-GAAP financial measures. Reconciliations of these non-GAAP financial measures to the most directly comparable GAAP financial measures are presented in the tables at the end of this release.
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, Facebook, X and Instagram.

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

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 our expectations regarding: Castle’s 2026 total revenue guidance of $365-375 million; expectations for achieving positive Adjusted EBITDA in future periods; continued top-line performance and growth of test volumes; the ability of DecisionDx-Melanoma, DecisionDx-SCC, TissueCypher and AdvanceAD-Tx to bring substantial added value to clinicians and their patients; the ability of DecisionDx-Melanoma to support more informed SLNB decision-making for patients with CM; the ability of TissueCypher to (i) predict a patient's five-year risk of progression from BE and (ii) help clinicians tailor management decisions based on an individual patient's risk profile; the ability of AdvanceAD-Tx to guide systemic treatment decision making in patients with AD; Castle’s expectations with respect to DETECT-AD, including the timing and results of the study; and Castle’s ability to achieve near- and long-term success and the continued growth of our portfolio. The words “anticipate,” “believe,” “can,” “could,” “expect,” “goal,” “guidance,” “may,” “plan,” “potentially,” “providing,” “upcoming,” “will” and similar expressions are intended to identify forward-looking statements, although not all forward-looking statements contain these identifying words. We may not actually achieve the plans, 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 our actual results to differ materially from those in the forward-looking statements, including, without limitation: our assumptions or expectations regarding reimbursement for our products and subsequent coverage decisions; our estimated total addressable markets for our products and product candidates and the related expenses, capital requirements and potential needs for additional financing; the anticipated cost, timing and success of our product candidates; our plans to research, develop and commercialize new tests; our ability to successfully integrate new businesses, assets, products or


technologies acquired through acquisitions; the effects of macroeconomic events and conditions, including inflation and monetary supply shifts, labor shortages, liquidity concerns at, and failures of, banks and other financial institutions or other disruptions in the banking system or financing markets, recession risks, supply chain disruptions, tariffs, outbreaks of contagious diseases and geopolitical events (such as the ongoing conflicts in the Middle East and Ukraine-Russia conflict), among others, on our business and our efforts to address any impact on our business; the possibility that subsequent study or trial results and findings may contradict earlier study or trial results and findings or may not support the results discussed in this press release, including with respect to the tests discussed in this press release; our planned installation of additional equipment and supporting technology infrastructures and implementation of certain process efficiencies may not enable us to increase the future scalability of our TissueCypher Test; the possibility that actual application of our tests may not provide the aforementioned benefits to patients; the possibility that our newer gastroenterology franchise may not contribute to the achievement of our long-term financial targets as anticipated; and the risks set forth under the heading “Risk Factors” in our Annual Report on Form 10-K for the year ended December 31, 2025 and our Quarterly Reports on Form 10-Q for the quarters ended March 31, 2026 and June 30, 2026, each 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.

Investor Relations Contact:
Camilla Zuckero
czuckero@castlebiosciences.com
281-906-3868

Media Contact:
Allison Marshall
amarshall@castlebiosciences.com

###



CASTLE BIOSCIENCES, INC.
CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS
(UNAUDITED)
(in thousands, except per share data)

Three Months Ended
June 30,		Six Months Ended
June 30,
2026202520262025
NET REVENUES$103,546 $86,188 $187,225 $174,176 
OPERATING EXPENSES
Cost of sales (exclusive of amortization of acquired intangible assets)23,700 17,626 44,233 34,009 
Research and development14,543 12,787 28,971 25,375 
Selling, general and administrative66,122 58,065 131,021 116,685 
Amortization of acquired intangible assets2,251 1,961 4,477 30,286 
Total operating expenses, net106,616 90,439 208,702 206,355 
Operating loss(3,070)(4,251)(21,477)(32,179)
Interest income2,356 2,944 4,901 6,043 
Net (losses) gains on equity securities(630)1,185 1,392 (240)
Interest expense(193)(21)(327)(38)
Other loss(153)— (592)— 
Loss before income taxes(1,690)(143)(16,103)(26,414)
Income tax expense (benefit)370 (4,666)479 (5,089)
Net (loss) income$(2,060)$4,523 $(16,582)$(21,325)
(Loss) earnings per share:
Basic$(0.07)$0.16 $(0.55)$(0.74)
Diluted$(0.07)$0.15 $(0.55)$(0.74)
Weighted-average shares outstanding:
Basic30,399 28,914 30,148 28,763 
Diluted30,399 29,545 30,148 28,763 

Stock-Based Compensation Expense
Stock-based compensation expense is included in the unaudited condensed consolidated statements of operations as follows (in thousands):
Three Months Ended
June 30,		Six Months Ended
June 30,
2026202520262025
Cost of sales (exclusive of amortization of acquired intangible assets)$1,420 $1,422 $2,677 $2,878 
Research and development1,678 1,962 3,121 3,857 
Selling, general and administrative8,491 7,824 15,567 15,652 
Total stock-based compensation expense$11,589 $11,208 $21,365 $22,387 


CASTLE BIOSCIENCES, INC.
CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS
(UNAUDITED)
(in thousands)

Three Months Ended
June 30,		Six Months Ended
June 30,
2026202520262025
Net (loss) income$(2,060)$4,523 $(16,582)$(21,325)
Other comprehensive loss:
Net unrealized loss on marketable investment securities(193)(92)(523)(191)
Comprehensive (loss) income$(2,253)$4,431 $(17,105)$(21,516)


CASTLE BIOSCIENCES, INC.
CONDENSED CONSOLIDATED BALANCE SHEETS
(in thousands)

June 30, 2026December 31, 2025
ASSETS(unaudited)
Current Assets
Cash and cash equivalents$62,116 $116,729 
Marketable investment securities204,689 182,776 
Accounts receivable, net48,341 43,382 
Inventory10,580 10,254 
Prepaid expenses and other current assets15,374 7,956 
Total current assets341,100 361,097 
Long-term accounts receivable, net1,661 1,878 
Property and equipment, net104,682 97,443 
Operating lease assets14,196 14,795 
Goodwill and other intangible assets, net95,096 99,574 
Other assets – long-term4,442 3,769 
Total assets$561,177 $578,556 
LIABILITIES AND STOCKHOLDERS’ EQUITY
Current Liabilities
Accounts payable$9,668 $18,711 
Accrued compensation26,893 38,287 
Contingent consideration1,500 1,000 
Operating lease liabilities1,417 1,325 
Current portion of long-term debt2,917 417 
Other accrued and current liabilities14,114 8,937 
Total current liabilities56,509 68,677 
Long-term debt7,158 9,640 
Noncurrent portion of contingent consideration— 1,500 
Noncurrent operating lease liabilities24,894 25,217 
Noncurrent finance lease liabilities264 314 
Deferred tax liability2,322 2,335 
Total liabilities91,147 107,683 
Stockholders’ Equity
Preferred stock— — 
Common stock31 30 
Additional paid-in capital711,121 694,860 
Accumulated deficit(240,866)(224,284)
Accumulated other comprehensive (loss) income(256)267 
Total stockholders’ equity470,030 470,873 
Total liabilities and stockholders’ equity$561,177 $578,556 





CASTLE BIOSCIENCES, INC.
CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS
(UNAUDITED)
(in thousands)
Six Months Ended
June 30,
20262025
OPERATING ACTIVITIES
Net loss$(16,582)$(21,325)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization7,999 33,178 
Stock-based compensation expense21,365 22,387 
Net (gains) losses on equity securities(1,392)240 
Deferred income taxes(13)(5,437)
Accretion of discounts on marketable investment securities(846)(2,606)
Other767 219 
Change in operating assets and liabilities:
Accounts receivable(4,742)(1,307)
Prepaid expenses and other current assets(7,544)(4,696)
Inventory(326)(231)
Operating lease assets599 664 
Other assets(788)(13)
Accounts payable886 1,689 
Operating lease liabilities(231)(869)
Accrued compensation(11,394)(7,582)
Other accrued and current liabilities5,314 474 
Net cash (used in) provided by operating activities(6,928)14,785 
INVESTING ACTIVITIES
Purchases of marketable investment securities(109,622)(92,832)
Proceeds from maturities of marketable investment securities80,100 80,300 
Proceeds from maturities of debt securities classified as held-to-maturity5,600 — 
Purchases of debt securities classified as held-to-maturity— (5,569)
Asset acquisition, net of cash and cash equivalents acquired— (18,726)
Proceeds from sale of equity securities3,248 — 
Purchases of property and equipment(21,105)(14,003)
Proceeds from sale of property and equipment13 21 
Net cash used in investing activities(41,766)(50,809)
FINANCING ACTIVITIES
Proceeds from exercise of common stock options417 37 
Payment of employees’ taxes on vested restricted stock units and performance-based restricted stock units(7,391)(3,104)
Proceeds from contributions to the employee stock purchase plan2,103 1,482 
Payment of contingent consideration(1,000)— 
Repayment of principal portion of finance lease liabilities(48)(57)
Proceeds from lease incentives received— 190 
Net cash used in financing activities(5,919)(1,452)
NET CHANGE IN CASH AND CASH EQUIVALENTS(54,613)(37,476)
Beginning of period116,729 119,709 
End of period$62,116 $82,233 


CASTLE BIOSCIENCES, INC.
Reconciliation of Non-GAAP Financial Measures (UNAUDITED)
The table below presents the reconciliation of Adjusted Revenues, Adjusted Gross Margin and Adjusted Net (Loss) Income Per Share, Basic and Diluted, which are non-GAAP financial measures. See "Use of Non-GAAP Financial Measures (UNAUDITED)" above for further information regarding the Company's use of non-GAAP financial measures.
Three Months Ended
June 30,		Six Months Ended
June 30,
(in thousands, except per share data)2026202520262025
Adjusted Revenues
Net revenues (GAAP)$103,546$86,188$187,225$174,176
Revenue associated with test reports delivered in prior periods(3,685)(6)1,2731,996
Adjusted Revenues (Non-GAAP)$99,861$86,182$188,498$176,172
Adjusted Gross Margin
Gross margin (GAAP)1
$77,595$66,601$138,515$109,881
Amortization of acquired intangible assets2,2511,9614,47730,286
Revenue associated with test reports delivered in prior periods(3,685)(6)1,2731,996
Adjusted Gross Margin (Non-GAAP)$76,161$68,556$144,265$142,163
Gross Margin percentage (GAAP)2
74.9 %77.3 %74.0 %63.1 %
Adjusted Gross Margin percentage (Non-GAAP)3
76.3 %79.5 %76.5 %80.7 %
Adjusted Net (Loss) Income Per Share, Basic and Diluted
Net (loss) income (GAAP)$(2,060)$4,523$(16,582)$(21,325)
Amortization of acquired intangible assets4
———20,099
Adjusted Net (Loss) Income (Non-GAAP)$(2,060)$4,523$(16,582)$(1,226)
Weighted-average shares outstanding:
Basic30,39928,91430,14828,763
Diluted30,39929,54530,14828,763
Net loss per share (GAAP)5
Basic$(0.07)$0.16$(0.55)$(0.74)
Diluted$(0.07)$0.15$(0.55)$(0.74)
Adjusted Net (Loss) Income Per Share (Non-GAAP)6
Basic$(0.07)$0.16$(0.55)$(0.04)
Diluted$(0.07)$0.15$(0.55)$(0.04)
1.Calculated as net revenues (GAAP) less the sum of cost of sales (exclusive of amortization of acquired intangible assets) and amortization of acquired intangible assets.
2.Calculated as gross margin (GAAP) divided by net revenues (GAAP).
3.Calculated as Adjusted Gross Margin (Non-GAAP) divided by Adjusted Revenues (Non-GAAP).
4.Represents a one-time adjustment of an acceleration of amortization expense for our IDgenetix test during the three months ended March 31, 2025.
5.Calculated as net (loss) income (GAAP) divided by weighted-average shares outstanding, basic and diluted.
6.Calculated as Adjusted Net (loss) income (Non-GAAP) divided by weighted-average shares outstanding, basic and diluted.



The table below presents the reconciliation of Adjusted EBITDA, which is a non-GAAP financial measure. See "Use of Non-GAAP Financial Measures (UNAUDITED)" above for further information regarding the Company's use of non-GAAP financial measures.
Three Months Ended
June 30,		Six Months Ended
June 30,
(in thousands)2026202520262025
Adjusted EBITDA
Net (loss) income$(2,060)$4,523 $(16,582)$(21,325)
Interest income(2,356)(2,944)(4,901)(6,043)
Interest expense193 21 327 38 
Income tax expense (benefit)370 (4,666)479 (5,089)
Depreciation and amortization4,070 3,414 7,999 33,178 
Stock-based compensation expense11,589 11,208 21,365 22,387 
Net losses (gains) on equity securities630 (1,185)(1,392)240 
Adjusted EBITDA (Non-GAAP)$12,436 $10,371 $7,295 $23,386 


©2026 Castle Biosciences 1 Empowering people, informing care decisions July 2026

 

©2026 Castle Biosciences 2 Disclaimers Forward Looking Statements This presentation 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: our anticipated 2026 revenue; our positioning for continued growth and value creation; our estimated U.S. total addressable market for our commercially available tests; our ongoing studies generating data and their impact on driving adoption of our tests; study observations and interpretations of study data, including conclusions about the benefits and impact of our tests on treatment decisions and patient outcomes; our ability to advance penetration of our tests with clinicians and payers; our ability to carry out our commercial strategies; our future approach to capital allocation; pipeline opportunities to expand screening and diagnostic support for patients; our test volume growth strategy and expectations; our ability to maintain strong adjusted gross margin and a strong balance sheet; our anticipated path to near term adjusted EBITDA positivity; and the timing and achievement of program milestones. The words “anticipates,” “can,” “could,” “estimates,” “expects,” “may,” “potential,” “target,” “guidance” and similar expressions are intended to identify forward-looking statements, although not all forward-looking statements contain these identifying words. We may not actually achieve the plans, 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 our actual results to differ materially from those in the forward-looking statements, including, without limitation: our estimates and assumptions underlying our estimated U.S. total addressable market for our commercially available tests; our assumptions or expectations regarding continued reimbursement for our products and subsequent coverage decisions; Novitas’ local coverage determination signifying non-coverage by Medicare of our DecisionDx-SCC test; our estimated total addressable markets for our product candidates; the expenses, capital requirements and potential needs for additional financing, the anticipated cost, timing and success of our product candidates; our plans to research, develop and commercialize new tests; our ability to successfully integrate new businesses, assets, products or technologies acquired through acquisitions or developed through collaborations; the effects of macroeconomic events and conditions, including inflation and monetary supply shifts, tariffs and disruptions to trade, labor shortages, liquidity concerns at, and failures of, banks and other financial institutions or other disruptions in the banking system or financing markets and recession risks, supply chain disruptions, outbreaks of contagious diseases and geopolitical events (such as the ongoing conflicts in the Middle East and Ukraine-Russia conflict), among others, on our business and our efforts to address its impact on our business; the possibility that subsequent study or trial results and findings may contradict earlier study or trial results and findings or may not support the results discussed in this presentation, including with respect to the diagnostic and prognostic tests discussed in this presentation; our planned installation of additional equipment and supporting technology infrastructures and implementation of certain process efficiencies may not enable us to increase the future scalability of our TissueCypher Test; the possibility that actual application of our tests may not provide the anticipated benefits to patients; the possibility that our newer gastroenterology and mental health franchises may not contribute to the achievement of our long-term financial targets as anticipated; and the risks set forth under the heading “Risk Factors” in our Annual Report on Form 10-K for the year ended December 31, 2025, and our subsequent Quarterly Reports on Form 10-Q, each 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.

 

©2026 Castle Biosciences 3 Disclaimers Financial Information; Non-GAAP Financial Measures In this presentation, we use the metrics of Adjusted Revenues, Adjusted Gross Margin and Adjusted EBITDA, which are non-GAAP financial measures and are not calculated in accordance with generally accepted accounting principles in the United States (GAAP). Adjusted Revenues and Adjusted Gross Margin reflect adjustments to GAAP net revenues to exclude net positive and/or net negative revenue adjustments recorded in the current period associated with changes in estimated variable consideration related to test reports delivered in previous periods. Adjusted Gross Margin further excludes acquisition-related intangible asset amortization. Adjusted EBITDA excludes from net loss: interest income, interest expense, income tax benefit or expense, depreciation and amortization expense, stock-based compensation expense and net (gains) losses on equity securities. We use Adjusted Revenues, Adjusted Gross Margin and Adjusted EBITDA internally because we believe these metrics provide useful supplemental information in assessing our revenue and operating performance reported in accordance with GAAP. We believe that Adjusted Revenues, when used in conjunction with our test report volume information, facilitates investors’ analysis of our current-period revenue performance and average selling price performance by excluding the effects of revenue adjustments related to test reports delivered in prior periods, since these adjustments may not be indicative of the current or future performance of our business. We believe that providing Adjusted Revenues may also help facilitate comparisons to our historical periods. Adjusted Gross Margin is calculated using Adjusted Revenues and therefore excludes the impact of revenue adjustments related to test reports delivered in prior periods, which we believe is useful to investors as described above. We further exclude acquisition-related intangible asset amortization in the calculation of Adjusted Gross Margin. We believe that excluding acquisition-related intangible asset amortization may facilitate gross margin comparisons to historical periods and may be useful in assessing current-period performance without regard to the historical accounting valuations of intangible assets, which are applicable only to tests we acquired rather than internally developed. We believe Adjusted EBITDA may enhance an evaluation of our operating performance because it excludes the impact of prior decisions made about capital investment, financing, investing and certain expenses we believe are not indicative of our ongoing performance. However, these non-GAAP financial measures may be different from non-GAAP financial measures used by other companies, even when the same or similarly titled terms are used to identify such measures, limiting their usefulness for comparative purposes. These non-GAAP financial measures are not meant to be considered in isolation or used as substitutes for net revenues, gross margin, or net (loss) income reported in accordance with GAAP; should be considered in conjunction with our financial information presented in accordance with GAAP; have no standardized meaning prescribed by GAAP; are unaudited; and are not prepared under any comprehensive set of accounting rules or principles. In addition, from time to time in the future, there may be other items that we may exclude for purposes of these non- GAAP financial measures, and we may in the future cease to exclude items that we have historically excluded for purposes of these non-GAAP financial measures. Likewise, we may determine to modify the nature of adjustments to arrive at these non-GAAP financial measures. Because of the non-standardized definitions of non-GAAP financial measures, the non-GAAP financial measure as used by us in this press release and the accompanying reconciliation tables have limits in their usefulness to investors and may be calculated differently from, and therefore may not be directly comparable to, similarly titled measures used by other companies. Accordingly, investors should not place undue reliance on non-GAAP financial measures. Reconciliations of these non-GAAP financial measures to the most directly comparable GAAP financial measures are presented in the tables at the end of this presentation. Industry and Market Data This presentation includes certain information and statistics obtained from third-party sources. The Company has not independently verified the accuracy or completeness of any such third- party information.

 

©2026 Castle Biosciences 4 Registered Trademarks DecisionDx-Melanoma, DecisionDx-CMSeq, i31-SLNB, i31-ROR, DecisionDx-SCC, MyPath Melanoma, AdvanceAD-Tx, TissueCypher, Esopredict, DecisionDx-UM, DecisionDx-PRAME and DecisionDx-UMSeq are trademarks of Castle Biosciences, Inc.

 

©2026 Castle Biosciences 5 Improving health through innovative tests that guide patient care OUR MISSION Transforming disease management by keeping people first: patients, clinicians, employees, and investors OUR VISION

 

©2026 Castle Biosciences 6 Second Quarter 2026 Results Highlights Frank Stokes, Castle Biosciences chief financial officer, was named a 2026 CFO Awards honoree by the Houston Business Journal. 5 AdvanceAD-Tx test received assay approval from the New York State Department of Health (NYSDOH). Approval expands access to Castle's precision medicine test designed to guide systemic treatment decision making in patients with moderate-to-severe atopic dermatitis (AD). 6 As of June 30, 2026, cash, cash equivalents and marketable investment securities totaled $266.8 million. 2 3 4 1 Total test reports for our core revenue drivers (DecisionDx-Melanoma, TissueCypher) increased 32% in 2Q26 year over year. Raised 2026 total revenue guidance to $365-375 million, up from $345- 355 million previously reported. AdvanceAD-Tx test was selected as the winner of the "Genomics Innovation Award" in the 10th annual MedTech Breakthrough Awards program, which recognizes companies driving meaningful progress and improving patient care across the global health and medical technology industry.

 

©2026 Castle Biosciences 7 Proven strategy designed to drive value creation for our stakeholders FOCUS on best/first-in-class tests with high, unmet clinical need and significant market opportunity BUILD robust clinical evidence PENETRATE target markets to further test adoption by clinicians and payers

 

©2026 Castle Biosciences 8 Answering clinical questions to guide care along the patient journey 1. Collaboration and license agreement with SciBase Holding AB (“SciBase”) announced in June 2025 RESCUE/ PREVENTION DIFFERENTIAL DIAGNOSTIC SUPPORT RISK STRATIFICATION THERAPY SELECTION GUIDANCE MRD=minimal residual disease SCREENING SUPPORT Dermatology Ophthalmology Pipeline test to diagnose GI disease (non-endoscopic cell collection device) Pipeline test to diagnose GI disease (non-endoscopic cell collection device) SciBase Collaboration Atopic Dermatitis (AD) Flares Pipeline1 Gastroenterology

 

©2026 Castle Biosciences 9 Clinical portfolio and pipeline tests Franchise Test Indication/Utility ~U.S. TAM1/Use Population Discovery Development Commercial Dermatology Cutaneous melanoma/ risk of sentinel lymph node positivity, recurrence & metastasis ~$540M/ 130k patients w/ invasive CM Cutaneous squamous cell carcinoma/ risk of metastasis & local recurrence; likelihood of benefit from ART ~$820M/ 200k patients with high-risk SCC Ambiguous melanocytic lesions/ malignant potential ~$600M/ 300k patients w/ ambiguous lesions Atopic dermatitis/ therapy guidance ~$33B/ ~10 million patients ages 12+ in U.S. one- year prevalence SciBase collaboration pipeline test Atopic dermatitis/ prediction of flares Gastroenterology Barrett’s esophagus/ risk of progression to high-grade dysplasia or esophageal adenocarcinoma ~$1B Pipeline test (non-endoscopic collection device) GI disease/ diagnostic test Ophthalmology Uveal melanoma/ risk of metastasis ~$10M 1. U.S. TAM= Total addressable market based on estimated patient population assuming average reimbursement rate among all payors.

 

©2026 Castle Biosciences 10 DecisionDx-Melanoma DERMATOLOGY Provides comprehensive, personalized, genomic tumor information to guide management for patients with cutaneous melanoma demonstrated change in management for 1 of 2 patients tested3 ~252,500 patients with a clinical DecisionDx- Melanoma order from ~17,550 clinicians4 50% Clinical Validity, Utility and Demonstrated Patient Outcomes Demonstrated clinical validity, utility and impact, backed by 58 peer-reviewed publications1, including two publications (Bailey et al. 2023 and Dhillon et al. 2023) demonstrating an association with testing and improved patient outcomes SLNB Guidance and Patient Outcomes2 New data from Castle’s ongoing prospective multicenter study evaluating DecisionDx-Melanoma’s i31- SLNB test result show the test accurately predicts SLN positivity, outperforms staging criteria and other GEP tests, and identifies patients below the 5% NCCN threshold who may safely forgo SLNB with favorable long-term outcomes 1. As of December 31, 2025, 2. Beard T, Guenther JM, Leong SP, et al. The integrated 31-gene expression profile test identifies low-risk patients with cutaneous melanoma who can forego the SLNB procedure: results from a prospective, multicenter trial. Future Oncol. Published online [March 13, 2026]. doi: https://doi.org/10.1080/14796694.2026.2640227.; 3. Dillon et al. 2022; 4. Data as of June 30, 2026; 5. U.S. TAM = Total addressable market based on estimated patient population assuming average reimbursement rate among all payors. SLN(B)=sentinel lymph node (biopsy) ~$540M Estimated U.S. TAM5

 

©2026 Castle Biosciences 11 Individual risk of SLNB positivity Individual risk of recurrence ? 31-GEP Class Score Ulceration Breslow thickness Age Mitotic rate Ulceration Age Breslow thickness Mitotic rate SLN status Tumor location Collaborative study with the National Cancer Institute’s SEER Program Registries is the largest real- world study of GEP testing in melanoma (n=4,687): • SEER cohort of unselected, prospectively tested patients shows improved survival for patients tested with DecisionDx-Melanoma compared to untested patients​ with 29% lower 3-year melanoma-specific and 17% lower 3-year overall mortality, and • DecisionDx-Melanoma provided significant, independent risk stratification of patients with cutaneous melanoma SLN- patients with a high-risk DecisionDx-Melanoma result had routine imaging surveillance added to their treatment plan. These patients: • Had their recurrence detected ~10 months earlier, with 62% lower tumor burden • Were more likely to start immunotherapy when offered (76.3% vs 67.9%) • Saw improved overall survival outcomes at 45 months (86.8% vs 75%) Whitman et al. JCO Precis. Oncol. 2021; Jarell et al. J. Am. Acad. Dermatol. 2022 Bailey et al. JCO Precis. Oncol. 2023; Dhillon et al. Arch Dermatol Res. 2023 “Patients who received routine imaging after high- risk GEP test scores had an earlier recurrence diagnosis with lower tumor burden, leading to better clinical outcomes.” Clinical use of DecisionDx-Melanoma is associated with improved patient survival DecisionDx-Melanoma provides precise, personalized risk prediction for two critical clinical questions

 

12©2026 Castle Biosciences DECIDE Study was successful! Patients predicted to have <5% SLN positivity had a 2.6% actual rate DECIDE Study was successful! Patients predicted to have <5% SLN positivity had a 2.6% actual rate Beard et al. Future Oncology 2026, Beard et al. SSO Annual Conference 2026. Phoenix, AZ. SLN positivity rates by i31-SLNB result <5% 5-10% >10% Fold Difference <5% vs. >10% T1-T4 2.6% 7.0% 21.4% 8x higher% SLN+ T1b-T2a 1.4% 7.4% 18.5% 13x higher % SLN+ Patients with >10% predicted risk had 8-13x higher SLN positivity Patients with <5% predicted risk had very low SLN positivity

 

13©2026 Castle Biosciences Prospective data confirm that DecisionDx-Melanoma i31-SLNB result improves SLNB decision-making and supports favorable patient outcomes Prospective data confirm that DecisionDx- Melanoma i31-SLNB result improves SLNB decision- making and supports favorable patient outcomes Beard et al. Future Oncology 2026 1 Accurate risk stratification Patients with a <5% i31-SLNB result have high recurrence-free survival (97.8%) at 3 years 3 Favorable patient outcomes Low-risk test results are associated with very low SLNB positive outcomes. The i31-SLNB gives physicians greater confidence in identifying which patients can avoid SLNB. 2 Confidence in clinical decision-making

 

©2026 Castle Biosciences 14 TissueCypher GASTROENTEROLOGY A leading risk-stratification test designed to predict risk of progression to esophageal cancer in patients with Barrett’s esophagus Clinical Validity and Utility Demonstrated validity, utility and impact, backed by 17 peer-reviewed publications1 demonstrating the ability and performance of the test in risk-stratifying patients with Barrett’s esophagus to guide risk-appropriate treatment decisions Recognition from AGA 2024 Clinical Practice Guideline acknowledges that individuals who may be at increased risk of progression to esophageal cancer might be identified using tissue- based biomarkers, particularly TissueCypher 2022 Recognized in the Clinical Practice Update on New Technology and Innovation for Surveillance and Screening in Barrett’s Esophagus as a tool that may be used by physicians to risk stratify non-dysplastic patients ~415,000 patients receiving upper GI endoscopies per year who meet intended use criteria for TissueCypher 1 in 40 patients progress to esophageal cancer within 5 years (among BE patients)2 ~$1B 1. As of December 31, 2025, 2. Shaheen et al. Gastroenterology 2000; 3. U.S. TAM = Total addressable market based on estimated patient population assuming average reimbursement rate among all payors; 4. Data as of June 30, 2026. Estimated U.S. TAM3 Ordering clinicians4 ~5,490

 

©2026 Castle Biosciences 15 TissueCypher provides individualized 5-year risk of progression to HGD or EAC Low RiskHigh Risk • High Risk score enables increased surveillance or early intervention to prevent cancer1 • Low Risk score minimizes over-treatment and supports extension of surveillance intervals to guideline recommendations1 Indicated for NDBE, IND, and LGD 1. Rubenstein JH, et al. Gastroenterology. 2024.

 

©2026 Castle Biosciences 16 TissueCypher provides independent prediction of progression n=699 patients1-6, 150 incident progressors, 40 prevalent cases, 509 non-progressors No significant risk stratification 62% progressors detected 7.8x ↑ risk 2.7x ↑ risk 1. Critchley-Thorne RJ, et al. Cancer Epidemiol Biomarkers Prev. 2016; 2. Critchley-Thorne RJ, et al. Cancer Epidemiol Biomarkers Prev. 2017; 3. Davison JM, et al. Am J Gastroenterol. 2020; 4. Frei NF, et al. Clin Transl Gastroenterol. 2020; 5. Frei NF, et al. Am J Gastroenterol. 2021; 6. Davison JM, et al. Clin & Transl Gastroenterol. 2023. Real world histologic grading TissueCypher risk class

 

©2026 Castle Biosciences 17 AdvanceAD-Tx DERMATOLOGY A non-invasive molecular test that is designed to detect the underlying immune biology of atopic dermatitis (AD) that is driving an individual patient’s AD and thus helps to guide systemic treatment decision making in patients with moderate- to-severe AD Validated in Real-World Patients • The AdvanceAD-Tx test has been clinically validated in patients 12 years and older with moderate-to-severe AD. The clinical validation study included both systemic treatment naïve patients and those who were on a systemic treatment but considering a switch in therapy. • The test can be ordered at any point in the patient’s treatment journey and provides valuable molecular insight to help guide therapy-class selection. Ordering the test early may help reduce uncertainty, minimize trial-and-error, and support more timely disease control. ~10m patient population of moderate-to- severe AD patients 12+ years of age, based on one-year prevalance1 ~$33 billion 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; https://www.census.gov/data/tables/time- series/demo/popest/2020s-national-detail.html 2. https://pmc.ncbi.nlm.nih.gov/articles/PMC11904833/pdf/ActaDV-105-41504.pdf; 3. U.S. TAM = Total addressable market based on estimated patient population assuming average reimbursement rate among all payors. of patients who started on an advanced biologic or JAKi switched to another advanced systemic therapy2 ~27% Estimated U.S. TAM3

 

18©2026 Castle Biosciences AdvanceAD-Tx results are intended to aid, not replace, clinical judgment. All treatment decisions should be made by the clinician in the context of the patient’s overall clinical picture. AdvanceAD-Tx guides systemic treatment choice for patients with moderate-to-severe atopic dermatitis AdvanceAD-Tx guides systemic treatment choice for patients with moderate-to-severe atopic dermatitis Moderate-to- severe AD patient ≥12 years JAK Inhibitor Responder Profile Gene expression profile is associated with a significantly higher clinical benefit from JAK inhibitor treatment Th2 Molecular Profile Gene expression profile is associated with similar clinical benefit regardless of treatment with a Th2-targeted or JAK inhibitor therapy • Quantifies expression of 487 genes from 12 immune, inflammatory, and cutaneous pathways associated with AD • Applies a validated neural network algorithm • Guides systemic treatment decision making

 

19©2026 Castle Biosciences AdvanceAD-Tx identifies patients who have a superior response to JAK inhibitor therapies AdvanceAD-Tx identifies patients who have a superior response to JAK inhibitor therapies Silverberg JI, Eichenfield LF, Armstrong AW, et al. The 487-gene expression profile test guides systemic therapy selection to improve outcomes for patients with atopic dermatitis: results from a prospective trial. J Am Acad Dermatol. 2026. doi:10.1016/j.jaad.2026.02.034. Presented at Fall Clinical Dermatology Conference 2025. Data on file. 5.5x Improvement in skin clearance (EASI-90) More patients achieved ≥90% improvement in skin clearance 1 in 2 Reported “no itch” compared to 0 More patients reported “no itch” in the last week 3.8x Faster time to EASI-90 Patients reached clearance more quickly 5.5x Improvement in quality of life (DLQI 0) More patients reported no impact on daily life CONTINUE 1 in 3 Experienced clear skin compared to 0 More patients achieved completely clear skin (vIGA- AD 0) Clinician Reported Outcomes Patient Reported Outcomes Patients with JAK Inhibitor Responder Profile who are treated with a JAK inhibitor therapy, compared to those treated with a Th2-targeted therapy achieve the following by 3 months: 3.3x Improvement in flare-free rate More patients remained flare-free

 

20©2026 Castle Biosciences The AdvanceAD-Tx test meaningfully impacts clinical decision-making in guiding systemic treatment selection Ames et al. Revolutionizing Atopic Dermatitis (RAD) Conference 2026. The result distribution supports the heterogeneity of atopic dermatitis Th2 JAKi53.3%46.6% Percentage of patients who received each result The test was ordered across treatment lines To inform subsequent therapy decisions To guide initial systemic therapy selection 77.8% 22.2% • An independent, multi-center case series evaluated the clinical utility of the test in guiding initial or subsequent systemic therapy selection among 45 sequentially tested, unselected patients with moderate-to-severe atopic dermatitis. • Primary outcomes included baseline alignment between molecular profile and therapy, treatment modifications following testing, and rates of initiation of molecularly aligned therapy.

 

21©2026 Castle Biosciences 97.8% of treatment decisions were aligned with AdvanceAD-Tx test result Ames et al. Revolutionizing Atopic Dermatitis (RAD) Conference 2026. Of patients were receiving treatment concordant with their molecular profile prior to testing POST TESTING DECISIONS THERAPEUTIC CLASS SWITCHING TREATMENT DISTRIBUTION After testing, therapeutic class switching occurred in 71.4% of patients 51% of patients switched from Th2-targeted biologics to JAK inhibitors 20% of patients switched from a JAK inhibitor to a Th2- targeted biologic Overall, post-testing treatment distribution shifted to 21 Patients receiving JAK inhibitors 14 Patients receiving Th2- targeted biologics 54.3% Of patients tested with AdvanceAD-Tx initiated molecularly aligned therapy based on the test results. 97.8%

 

©2026 Castle Biosciences 22 Financials

 

©2026 Castle Biosciences 23 Second Quarter 2026 Financial Highlights Total Revenue Cash Position4 Operating Cash Flow Total Report Volume Adjusted Gross Margin1,2 Adjusted EBITDA3 $103.5M $266.8M$15.2M30,822 76.3% $12.4M 1. Adjusted Gross Margin is a non-GAAP measure. See Non-GAAP reconciliations at the end of this presentation for a reconciliation of Adjusted Gross Margin to its most closely comparable GAAP measure. 2. Calculated as Adjusted Gross Margin (Non-GAAP) divided by Adjusted Revenues (Non-GAAP). 3. Adjusted EBITDA is a non-GAAP measure. See non-GAAP reconciliations at the end of this presentation for a reconciliation of Adjusted EBITDA to its most closely comparable GAAP measure. 4. As of June 30, 2026; includes Cash, Cash Equivalents & Marketable Investment Securities. Track record of consistent execution and strong business fundamentals 2Q26

 

©2026 Castle Biosciences 24 Second Quarter 2026 Test Volume Results 2Q26 2Q25 Core Revenue Drivers: • DecisionDx-Melanoma 10,280 9,981 • TissueCypher 14,988 9,170 Additional Tests: • DecisionDx-SCC1 4,011 4,762 • MyPath Melanoma 1,061 1,166 • DecisionDx-UM 482 468 1. Affecting second quarter ended June 30, 2026, test report volume was the change in Medicare coverage effective April 24, 2025, and re-focus of our commercial efforts. Total test reports for our core revenue drivers increased 32% in 2Q26 compared to 2Q25

 

©2026 Castle Biosciences 25 A disciplined approach to capital allocation Commercial optimization Focused R&D efforts to build evidentiary support and develop tests Strategic opportunities, including within our current therapeutic areas

 

©2026 Castle Biosciences 26 Well positioned for continued value creation Drive robust test volume growth Maintain strong Adjusted Gross Margin Maintain strong balance sheet Follow disciplined capital allocation Path to near term Adjusted EBITDA positivity

 

©2026 Castle Biosciences 27 Appendix

 

©2026 Castle Biosciences 28 DecisionDx-SCC DERMATOLOGY Designed to provide risk assessment and treatment guidance for patients with high-risk SCC Clinical Validity and Utility Demonstrated validity, utility and impact, backed by 24 peer-reviewed publications1, including data showing that DecisionDx-SCC can significantly impact patient management plans in a risk-appropriate manner within established guidelines Real-World Use Framework Several published studies in 2024 supported the use of DecisionDx-SCC to predict likelihood of benefit from adjuvant radiation therapy (ART); two of these studies represent the largest2 and second largest3 studies completed to date to evaluate the effectiveness of ART in SCC Estimated U.S. TAM5 ~200,000 ~68% ~$820M patients diagnosed annually with SCC and classified as high risk in the U.S. of clinicians ordering DecisionDx-SCC also ordered DecisionDx- Melanoma4 1. As of December 31, 2025, 2. Arron et al. International Journal of Radiation Oncology, Biology & Physics 2024; 3. Ruiz et al. Future Oncology 2024; 4. six-months ended June 30, 2026; 5. U.S. TAM = Total addressable market based on estimated patient population assuming average reimbursement rate among all payors; 6. Data as of June 30, 2026. patients with a clinical DecisionDx- SCC order from ~7,850 clinicians6 ~67,300

 

©2026 Castle Biosciences 29 40-GEP + PNI, poor differentiation, immunosuppression, tumor diameter and tumor location Test ordered Biopsy from a patient with high-risk cutaneous SCC i40-GEP Result (MFS on validation cohort) Clinical Utility Based on metastatic risk 0-5% Metastatic Risk • Safe to defer imaging • Safe to defer ART Class 1A Low Risk MFS 97.3% | LRFS 96.8% ART Benefit Low Likelihood Class 1B Moderate Risk MFS 94.6% | LRFS 90.0% ART Benefit Low Likelihood Class 2A High Risk MFS 77.9% | LRFS 83.1% ART Benefit Low Likelihood Class 2B Highest Risk MFS 66.2% | LRFS 82.1% ART Benefit High Likelihood 5-10% Metastatic Risk • Consider increased surveillance • Consider imaging • Safe to defer ART >20% Metastatic Risk • Recommend increased surveillance • Recommend imaging • Recommend multidisciplinary consult • Unlikely benefit from ART >20% Metastatic Risk • Recommend increased surveillance • Recommend imaging • Recommend multidisciplinary consult • Likely benefit from ART The overall validation cohort MFS is 88.8% Clinicians consider the following management for patients with 10-20% metastatic risk: • Recommend increased surveillance • Recommend Imaging • Consider multidisciplinary consult • Consider ART DecisionDx-SCC informs patient management decisions Ratner et al, AAD Innovation Academy 2026.

 

©2026 Castle Biosciences 30 MyPath Melanoma DERMATOLOGY Aids in the diagnosis and management for patients with ambiguous melanocytic lesions Clinical Validity and Utility Demonstrated validity, utility and impact, backed by 20 peer-reviewed publications1 demonstrating the performance and utility of the test in providing objective information to aid in diagnosis in ambiguous melanocytic lesions Guideline Support • National Comprehensive Cancer Network guidelines for cutaneous melanoma in the principles for molecular testing • American Society of Dermatopathology in the Appropriate Use Criteria for ancillary diagnostic testing • American Academy of Dermatology guidelines of care for the management of primary cutaneous melanoma Estimated U.S. TAM3 ~300,000 patients each year present with a diagnostically ambiguous lesion 50,000+ lesions tested clinically2 ~$600M 1. As of December 31, 2025, 2. As of June 30, 2026; 3. U.S. TAM = Total addressable market based on estimated patient population assuming average reimbursement rate among all payors.

 

©2026 Castle Biosciences 31 DecisionDx-UM OPHTHALMOLOGY The standard of care for evaluating metastatic risk in uveal melanoma Standard of Care • Utilized in approximately 80% of newly diagnosed patients • Included in NCCN Guidelines and considered standard of care peer-reviewed publications ~8 in 10 ~2,000 39 patients diagnosed in the U.S. annually patients diagnosed with UM in the U.S. receive the test as part of their diagnostic workup Clinical Validity and Utility Demonstrated validity, utility and impact, backed by 39 peer-reviewed publications, which included more than 5,500 patients, representing the largest body of evidence for a molecular prognostic test in this field All data as of June 30, 2026, except peer-reviewed publications, which is as of December 31, 2025

 

©2026 Castle Biosciences 32 Reconciliation of Non-GAAP Financial Measures (Unaudited) The table below presents the reconciliation of Adjusted Revenues and Adjusted Gross Margin, which are non-GAAP financial measures. See “Financial information; Non-GAAP Financial Measures" above for further information regarding the Company's use of non-GAAP financial measures. (In thousands) Three months ended Jun. 30, 2026 Mar. 31, 2026 Dec. 31, 2025 Sep. 30, 2025 Jun. 30, 2025 Adjusted Revenues Net revenues (GAAP) $103,546 $83,679 $87,010 $83,043 $86,188 Revenue associated with test reports delivered in prior periods (3,685) 551 (5,134) (2,498) (6) Adjusted Revenues (Non-GAAP) $99,861 $84,230 $81,876 $80,545 $86,182 Adjusted Gross Margin Gross margin (GAAP)1 $77,595 $60,920 $66,419 $62,063 $66,601 Amortization of acquired intangible assets 2,251 2,226 2,276 2,276 1,961 Revenue associated with test reports delivered in prior periods (3,685) 551 (5,134) (2,498) (6) Adjusted Gross Margin (Non-GAAP) $76,161 $63,697 $63,561 $61,841 $68,556 Gross Margin percentage (GAAP)2 74.9% 72.8% 76.3% 74.7% 77.3% Adjusted Gross Margin percentage (Non-GAAP)3 76.3% 75.6% 77.6% 76.8% 79.5%

 

©2026 Castle Biosciences 33 Reconciliation of Non-GAAP Financial Measures (Unaudited) The table below presents the reconciliation of Adjusted EBITDA, which is a non-GAAP financial measure. See “Financial information; Non-GAAP Financial Measures" above for further information regarding the Company's use of non-GAAP financial measures. (In thousands) Three months ended Jun. 30, 2026 Mar. 31, 2026 Dec. 31, 2025 Sep. 30, 2025 Jun. 30, 2025 Adjusted EBITDA Net (loss) income $(2,060) $(14,522) $(2,332) $(501) $4,523 Interest income (2,356) (2,545) (2,896) (2,833) (2,944) Interest expense 193 134 24 24 21 Income tax expense (benefit) 370 109 (382) 115 (4,666) Depreciation and amortization 4,070 3,929 3,777 3,816 3,414 Stock-based compensation expense 11,589 9,776 11,406 12,100 11,208 Net losses (gains) on equity securities 630 (2,022) 1,855 (3,561) (1,185) Adjusted EBITDA (Non-GAAP) $12,436 $(5,141) $11,452 $9,160 $10,371

 

©2026 Castle Biosciences 34 Thank You

 

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