Data Demonstrating DecisionDx®-Melanoma’s Ability to Risk-Stratify Patients According to Melanoma-Specific Survival to be Shared during the 2022 ASCO Annual Meeting

FRIENDSWOOD, Texas--(BUSINESS WIRE)-- Castle Biosciences, Inc. (Nasdaq: CSTL), a company improving health through innovative tests that guide patient care, today announced that an abstract demonstrating the ability of the Company’s DecisionDx®-Melanoma test to risk-stratify patients with cutaneous melanoma according to their survival likelihood will be available online during the upcoming 2022 American Society of Clinical Oncology (ASCO) Annual Meeting, being held virtually and in Chicago, June 3-7, 2022.

Details are as follows:

• Abstract Title: “Validation of the 31-gene expression profile test to stratify melanoma-specific survival in an unselected, prospectively tested cohort of patients with stage IIB-III cutaneous melanoma”
• Abstract number: e21538

About DecisionDx®-Melanoma

DecisionDx-Melanoma is a gene expression profile test that uses an individual patient’s tumor biology to predict individual risk of cutaneous melanoma (CM) metastasis or recurrence, as well as the risk of sentinel lymph node positivity, independent of traditional staging factors, and has been studied in more than 6,300 patient samples. Using tissue from the primary melanoma, the test measures the expression of 31 genes. Additionally, Castle has an ongoing collaboration with the National Cancer Institute (NCI) to link DecisionDx-Melanoma testing data with data from the Surveillance, Epidemiology and End Results (SEER) Program’s registries on CM cases. This collaboration has resulted in Castle’s analysis of 5,226 samples (clinically tested through December 31, 2018) in a study to evaluate melanoma-specific survival and overall survival; in this study, patients tested with DecisionDx-Melanoma had better survival rates than untested patients, and the data suggested that DecisionDx-Melanoma can accurately risk-stratify for disease progression to aid in risk-aligned treatment plans for improved patient outcomes and survival. The test has been validated in four archival risk of recurrence studies of 901 patients and six prospective risk of recurrence studies including more than 1,600 patients. Additionally, impact on patient management plans for one of every two patients tested has been shown in five multi-center/single-center studies including more than 800 patients. The consistent performance and accuracy demonstrated in these studies provides confidence in disease management plans that incorporate DecisionDx-Melanoma test results. To predict risk of recurrence and likelihood of sentinel lymph node positivity, the Company utilizes its proprietary algorithms, i31-ROR and i31-SLNB, to produce an Integrated Test Result. Through March 31, 2022, DecisionDx-Melanoma has been ordered 97,288 times for patients with cutaneous melanoma.

More information about the test and disease can be found at www.CastleTestInfo.com.

About Castle Biosciences

Castle Biosciences (Nasdaq: CSTL) is a leading diagnostics company improving health through innovative tests that guide patient care. The Company aims to transform disease management by keeping people first: patients, clinicians, employees and investors.

Castle’s current portfolio consists of tests for skin cancers, uveal melanoma, Barrett’s esophagus and mental health conditions. Additionally, the Company has active research and development programs for tests in other diseases with high clinical need, including its test in development to predict systemic therapy response in patients with moderate-to-severe psoriasis, atopic dermatitis and related conditions. To learn more, please visit www.CastleBiosciences.com and connect with us on LinkedIn, Facebook, Twitter and Instagram.

DecisionDx-Melanoma, DecisionDx-CMSeq, DecisionDx-SCC, myPath Melanoma, DecisionDx DiffDx-Melanoma, DecisionDx-UM, DecisionDx-PRAME, DecisionDx-UMSeq, TissueCypher and IDgenetix 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 the ability of our DecisionDx®-Melanoma test to risk-stratify patients with cutaneous melanoma according to their survival likelihood. The words “potential,” “may,” “can,” “anticipates,” “believes” 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: subsequent study or trial results and findings may contradict earlier study or trial results and findings or may not support the results obtained in this study, including with respect to the discussion of DecisionDx®-Melanoma in this press release; actual application of our DecisionDx®-Melanoma test may not provide the aforementioned benefits to patients; and the risks set forth under the heading “Risk Factors” in our Quarterly Report on Form 10-Q for the three months ended March 31, 2022, 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.

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Investor Contact:

Camilla Zuckero

czuckero@castlebiosciences.com

Media Contact:

Allison Marshall

amarshall@castlebiosciences.com

Source: Castle Biosciences, Inc.