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Castle’s presentations at AAD include the latest findings from the Company’s ongoing collaboration with the National Cancer Institute’s Surveillance, Epidemiology, and End Results (SEER) Program Registries, providing new data from a study of more than 5,000 patients confirming that testing with DecisionDx®-Melanoma is associated with improved survival in patients with cutaneous melanoma (CM) FRIENDSWOOD, Texas--(BUSINESS WIRE)-- Castle Biosciences Inc. (Nasdaq: CSTL), a company improving health through innovative tests that guide patient care, today announced that it will share data across its dermatologic portfolio of gene expression profile (GEP) tests via oral and electronic poster presentations at the 2024 AAD Annual Meeting, taking place March 8-12 in San Diego. “Our presentations at the 2024 AAD Annual Meeting add to the growing body of evidence supporting the use of our tests in guiding improved, personalized care for patients with skin cancers,” said Robert Cook, Ph.D., senior vice president of research and development at Castle Biosciences. “In collaboration with leading dermatologists dedicated to advancing patient care, we are excited to share our latest findings which highlight how our tests are empowering both clinicians and patients with meaningful, clinically actionable information that can refine risk and inform important treatment decisions.” Castle will present the following abstracts at AAD. Abstract content will be available throughout the meeting in the online viewing portal and at the on-site viewing stations, and will also be published online in the Fall 2024 Journal of the American Academy of Dermatology (JAAD) supplement. DecisionDx®-Melanoma Oral Poster Presentation Title: 31-GEP testing is associated with improved melanoma-specific survival relative to untested patients: an analysis of patients <65 years old Presenter and Lead Author: Michael Tassavor, M.D., Skin Cancer Center, Cincinnati Abstract Number: 51667 Date: March 9, 2024 Time: 4:50-4:55 p.m. Pacific Time Location: San Diego Convention Center (Upper Level, Sails Pavilion, Poster Center 1) Summary: For patients with CM, the median age at diagnosis is 66 years old, suggesting that almost half of newly diagnosed patients are younger than 65. In this large study of unselected, clinically tested patients with CM who were under 65 (n=5,183), the DecisionDx-Melanoma (31-GEP) test identified patients at higher risk of melanoma-specific death who may benefit from more aggressive management, including imaging surveillance. In the study, use of the DecisionDx-Melanoma test was associated with improved melanoma-specific survival relative to untested patients. This is clinically significant, as identifying high-risk patients allows for earlier detection of recurrence, while the tumor burden is lower, which has been shown to lead to better response to therapy. DecisionDx®-SCC Oral Poster Presentation Title: Consistent utilization of the 40-gene expression profile (40-GEP) test in high-risk cutaneous squamous cell carcinoma (cSCC) by clinicians according to intended use indications Presenter and Lead Author: Jane Yoo, M.D., Icahn School of Medicine at Mount Sinai, New York Abstract Number: 54153 Date: March 9, 2024 Time: 10:30-10:35 a.m. Pacific Time Location: San Diego Convention Center (Upper Level, Sails Pavilion, Poster Center 2) Summary: This study provides summary metrics regarding DecisionDx-SCC (40-GEP) test results and patient risk factors for tumor samples clinically tested in the first three years of the test’s availability between September 2020 and August 2023 (n=16,930). The study data demonstrate that clinicians are utilizing the DecisionDx-SCC test appropriately for patients with high-risk cutaneous squamous cell carcinoma (SCC). These patients are at a higher risk of poor outcomes compared to the general SCC patient population, yet over 70% of patients received a Decision-SCC Class 1 test result, indicating they are at a lower biological risk for metastasis. Each DecisionDx-SCC Class result was present in the various subgroupings of risk factors in the study (patients with 1-2, 3-4 and more than 5 risk factors), demonstrating that the test provides independent risk assessment from clinicopathological presentation. These data support incorporating the test’s results into clinical practice to improve the accuracy of risk predictions to guide more personalized treatment plans for patients. MyPath® Melanoma ePoster Title: Enabling access to prognostic gene expression profile (GEP) testing for invasive melanoma by leveraging RNA-based testing in the diagnostic workflow Abstract Number: 52819 Summary: Reaching a definitive diagnosis of melanoma can be challenging. Ancillary testing can provide clarity and a definitive diagnosis for problematic lesions. The MyPath Melanoma (23-GEP) diagnostic test returns accurate results quickly, with approximately 80% of cases tested receiving an actionable result in a median of four business days. Between March 1 and July 31, 2023, approximately 60% of ambiguous lesions tested with MyPath received a benign test result, potentially reducing overdiagnosis and overtreatment for diagnostically challenging lesions. Lesions that receive a malignant test result (approximately 20% of lesions tested with MyPath in the five-month study timeframe) can be tested with the DecisionDx-Melanoma risk stratification test, using the same extracted tumor material when available, to inform risk-aligned decisions about sentinel lymph node biopsy, surveillance imaging and patient follow-up schedules. Approximately 80% of clinically tested lesions with a malignant MyPath result have sufficient biopsy tumor content for DecisionDx-Melanoma testing. About DecisionDx-Melanoma DecisionDx-Melanoma is a gene expression pro stratification test. It is designed to inform two clinical questions in the management of cutaneous melanoma: a patient’s individual risk of sentinel lymph node (SLN) positivity and a patient's personal risk of melanoma recurrence and/or metastasis. By integrating tumor biology with clinical and pathologic factors using a validated proprietary algorithm, DecisionDx-Melanoma is designed to provide a comprehensive and clinically actionable result to guide risk-aligned patient care. DecisionDx-Melanoma has been shown to be associated with improved patient survival and has been studied in more than 10,000 patient samples. DecisionDx-Melanoma’s clinical value is supported by 50 peer-reviewed and published studies, providing confidence in disease management plans that incorporate the test’s results. Through Dec. 31, 2023, DecisionDx-Melanoma has been ordered more than 150,000 times for patients diagnosed with cutaneous melanoma. About DecisionDx-SCC DecisionDx-SCC is a 40-gene expression pro that uses an individual patient’s tumor biology to predict individual risk of cutaneous squamous cell carcinoma metastasis for patients with one or more risk factors. The test result, in which patients are stratified into a Class 1 (low), Class 2A (higher) or Class 2B (highest) risk category, predicts individual metastatic risk to inform risk-appropriate management. Peer-reviewed publications have demonstrated that DecisionDx-SCC is an independent predictor of metastatic risk and that integrating DecisionDx-SCC with current prognostic methods can add positive predictive value to clinician decisions regarding staging and management. About MyPath Melanoma MyPath Melanoma is Castle’s gene expression pro designed to provide an accurate, objective result to aid dermatopathologists and dermatologists in characterizing difficult-to-diagnose melanocytic lesions. Of the approximately two million suspicious pigmented lesions biopsied annually in the U.S., Castle estimates that approximately 300,000 of those cannot be confidently classified as either benign or malignant through traditional histopathology methods. For these cases, the treatment plan can also be uncertain. Obtaining accurate, objective ancillary testing can mean the difference between a path of overtreatment or the risk of undertreatment. Interpreted in the context of other clinical, laboratory and histopathologic information, MyPath Melanoma is designed to reduce uncertainty and provide confidence for dermatopathologists and help dermatologists deliver more informed patient management plans. 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, Barrett’s esophagus, mental health conditions and uveal melanoma. Additionally, the Company has active research and development programs for tests in other diseases with high clinical need, including its test in development to help guide systemic therapy selection for patients with moderate-to-severe atopic dermatitis, psoriasis and related conditions. To learn more, please visit and connect with us on LinkedIn, Facebook, X and Instagram. DecisionDx-Melanoma, DecisionDx-CMSeq, DecisionDx-SCC, MyPath Melanoma, DiffDx-Melanoma, TissueCypher, IDgenetix, 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: the ability of our tests to (i) guide improved, personalized care for patients with skin cancers and (ii) provide meaningful, clinically actionable information that can refine risk and inform important treatment decisions. The words “believe,” “can” 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 these studies, including with respect to the discussion of our tests in this press release; actual application of our tests may not provide the aforementioned benefits to patients; and the risks set forth under the heading “Risk Factors” in our Annual Report on Form 10-K for the year ended December 31, 2023, 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.

FRIENDSWOOD, Texas--( BUSINESS WIRE )--Castle Biosciences, Inc. (Nasdaq: CSTL), a company improving health through innovative tests that guide patient care, will present new data across its dermatologic portfolio of commercially available and pipeline gene expression profile (GEP) tests at the 2024 Winter Clinical Dermatology Conference - Hawaii, being held Jan. 12-17 in Honolulu, Hawaii. “We are committed to challenging current disease management paradigms and building the evidence supporting our portfolio of clinically actionable molecular tests and their use to improve decision-making for patients with skin cancers and inflammatory skin diseases,” said Robert Cook, Ph.D., senior vice president of research and development at Castle Biosciences. “As such, we are proud to share our latest data at Winter Clinical – Hawaii in collaboration with leading physicians who we believe share our vision of transforming the management of these potentially serious diseases.” Highlights from Castle’s posters at Winter Clinical – Hawaii are included below. Posters will be displayed for viewing in the Coral Ballroom 2 through Jan. 16 at 1 p.m. Hawaii Standard Time. DecisionDx-Melanoma Real-world evidence confirms risk stratification of the 31-GEP and i31-GEP in prospectively tested patients with stage I-III cutaneous melanoma Summary: To further advance personalized patient care, Castle’s DecisionDx-Melanoma test result, based on a patient’s tumor biology, was integrated with clinical and pathological factors using a validated proprietary algorithm (i31-GEP for risk of recurrence, or ROR). The i31-GEP ROR provides a more personalized, precise risk of tumor recurrence to guide clinical management of CM. This study aimed to validate the DecisionDx-Melanoma test and i31-GEP ROR algorithm in a real-world cohort of patients with stage I-III CM (n=1,831) who received the DecisionDx-Melanoma test as part of their routine clinical care. The study confirmed the independent and significant risk-stratification provided by DecisionDx-Melanoma and its integrated i31-GEP ROR algorithm, identifying patients at high risk of melanoma recurrence to guide important, risk-appropriate interventions, such as imaging surveillance and immunotherapy, that can potentially improve patient outcomes. View poster here . DecisionDx-SCC The 40-gene expression profile (40-GEP) test identifies cutaneous squamous cell carcinoma (cSCC) patients at high risk of metastasis within lower-staged tumors to better guide treatment decisions Summary: This study evaluated the ability of DecisionDx-SCC to independently improve the identification of lower-staged tumors at increased risk of metastasis. Improved risk assessment in these lower-staged subsets is important as up to one-third of all metastatic events have been reported for patients originally staged with T1 tumors. Within a cohort of SCC patients considered lower risk by current staging alone, DecisionDx-SCC identified those at a substantially higher risk of metastasis. These results represent a clinically significant improvement in risk assessment for SCC patients with observed rates of metastasis over 10% and 20%, respectively, which are clinically actionable for nodal staging or post-operative adjuvant radiation. Combining traditional risk classification systems with a patient’s individual biologic risk, as provided by the DecisionDx-SCC test, can improve the accuracy of risk assessment to inform important patient treatment decisions. View poster here . MyPath Melanoma Diagnostic discordance among histopathological reviewers for difficult-to-diagnose melanocytic lesions Summary: Diagnostic discordance in cutaneous melanocytic lesions is well documented and prevalent among difficult-to-diagnose cases, for which histopathology may be insufficient for a definitive diagnosis. MyPath Melanoma testing is available for ambiguous melanocytic neoplasms to add clarity to these diagnoses. This study showed that in a large cohort of patients with suspicious lesions (n=3,317), approximately 24% were difficult to diagnose, supporting the need for an objective diagnostic tool like MyPath Melanoma to aid in providing an accurate diagnosis to help ensure appropriate patient management. View poster here . Inflammatory Skin Disease Pipeline Program Gene expression differences identified in skin samples of mycosis fungoides, atopic dermatitis and psoriasis Summary: The goal of Castle’s innovative pipeline initiative is to develop a genomic test aimed at guiding systemic therapy selection for patients with moderate-to-severe atopic dermatitis (AD), PSO and related conditions. The test in development would help personalize therapy selection for patients based on their molecular profile and help determine which therapy may best help to manage their symptoms. At the recent 2023 Fall Clinical Dermatology Conference®, Castle presented data showing the ability of its pipeline test in development to identify distinct gene expression profiles of super-responders to an AD therapy and also distinguish between AD, PSO and mycosis fungoides (MF) skin lesions. Castle’s poster at Winter Clinical – Hawaii builds on this data by showing the ability of the pipeline test in development to determine the gene expression profile of super-responders to a PSO therapy. View poster here . About DecisionDx®-Melanoma DecisionDx-Melanoma is a gene expression profile risk stratification test. It is designed to inform two clinical questions in the management of cutaneous melanoma: a patient’s individual risk of sentinel lymph node (SLN) positivity and a patient's personal risk of melanoma recurrence and/or metastasis. By integrating tumor biology with clinical and pathologic factors using a validated proprietary algorithm, DecisionDx-Melanoma is designed to provide a comprehensive and clinically actionable result to guide risk-aligned patient care. DecisionDx-Melanoma has been shown to be associated with improved patient survival and has been studied in more than 10,000 patient samples. DecisionDx-Melanoma’s clinical value is supported by more than 40 peer-reviewed and published studies, providing confidence in disease management plans that incorporate the test’s results. Through Sept. 30, 2023, DecisionDx-Melanoma has been ordered more than 146,000 times for patients diagnosed with cutaneous melanoma. About DecisionDx®-SCC DecisionDx-SCC is a 40-gene expression profile test that uses an individual patient’s tumor biology to predict individual risk of cutaneous squamous cell carcinoma metastasis for patients with one or more risk factors. The test result, in which patients are stratified into a Class 1 (low), Class 2A (higher) or Class 2B (highest) risk category, predicts individual metastatic risk to inform risk-appropriate management. Peer-reviewed publications have demonstrated that DecisionDx-SCC is an independent predictor of metastatic risk and that integrating DecisionDx-SCC with current prognostic methods can add positive predictive value to clinician decisions regarding staging and management. About MyPath® Melanoma MyPath Melanoma is Castle’s gene expression profile test designed to provide an accurate, objective result to aid dermatopathologists and dermatologists in characterizing difficult-to-diagnose melanocytic lesions. Of the approximately two million suspicious pigmented lesions biopsied annually in the U.S., Castle estimates that approximately 300,000 of those cannot be confidently classified as either benign or malignant through traditional histopathology methods. For these cases, the treatment plan can also be uncertain. Obtaining accurate, objective ancillary testing can mean the difference between a path of overtreatment or the risk of undertreatment. Interpreted in the context of other clinical, laboratory and histopathologic information, MyPath Melanoma is designed to reduce uncertainty and provide confidence for dermatopathologists and help dermatologists deliver more informed patient management plans. About Castle’s Inflammatory Skin Disease Pipeline Program Inflammatory skin disease accounts for a significant number of patient visits to both primary care and dermatology clinics across the United States every year. Psoriasis (PSO) and atopic dermatitis (AD) are among the most common inflammatory skin conditions, and patient quality of life is severely impacted by these chronic diseases. Fortunately, systemic medications developed over the past 15 years have demonstrated a significant improvement in patients’ lives. In the United States alone, there are about 18 million patients diagnosed with PSO and AD, and approximately 450,000 patients annually are eligible for these systemic therapies. While there are now many effective treatment options available for those with moderate-to-severe inflammatory skin diseases, current clinical practice relies on a trial-and-error approach for therapy selection. To answer this unmet clinical need, in 2021, Castle initiated a prospective, multi-center clinical study (IDENTITY) to develop and validate a gene expression profile (GEP) test to help guide systemic therapy selection for patients with moderate-to-severe AD, PSO and other related diseases. In 2022, the Company initiated a second, prospective study (SIGNAL-MF) to investigate the possibility of the pipeline test including an ancillary component to help identify lesions that may be mycosis fungoides (MF), a rare and serious type of skin cancer, often referred to as cutaneous T-cell lymphoma, that is easily mistaken for AD and PSO. MF requires a rigorous histologic and molecular workup to diagnose, and patients with MF being treated for presumed AD or PSO can further delay this critical diagnosis. 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, Barrett’s esophagus, mental health conditions and uveal melanoma. Additionally, the Company has active research and development programs for tests in other diseases with high clinical need, including its test in development to help guide systemic therapy selection for patients with moderate-to-severe atopic dermatitis, psoriasis and related conditions. To learn more, please visit www.CastleBiosciences.com and connect with us on LinkedIn , Facebook , X and Instagram . DecisionDx-Melanoma, DecisionDx-CM Seq , DecisionDx-SCC, MyPath Melanoma, DiffDx-Melanoma, TissueCypher, IDgenetix, DecisionDx-UM, DecisionDx-PRAME and DecisionDx-UM Seq 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 ability to continue building the evidence supporting our portfolio of clinically actionable molecular tests and their use to improve decision-making for patients with skin cancers; the ability of DecisionDx-Melanoma and its integrated i31-GEP ROR algorithm, to identify patients at high risk of melanoma recurrence in order to guide important, risk-appropriate interventions, such as imaging surveillance and immunotherapy and improve patient outcomes; the ability of combining traditional risk classification systems with a patient’s individual biologic risk, as provided by the DecisionDx-SCC test, to improve the accuracy of risk assessment to inform important patient treatment decisions; the ability of MyPath Melanoma to aid in providing an accurate diagnosis to help ensure appropriate patient management; and the ability of its innovative pipeline initiative to identify distinct gene expression profiles of super-responders to an AD therapy and also distinguish between AD, PSO and MF skin lesions. The words “can,” “may” 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, including with respect to the discussion of DecisionDx-Melanoma, DecisionDx-SCC, MyPath Melanoma and Castle’s inflammatory skin disease pipeline test in this press release; actual application of our tests may not provide the aforementioned benefits to patients; and the risks set forth under the heading “Risk Factors” in our Annual Report on Form 10-K for the year ended December 31, 2022, our Quarterly Report on Form 10-Q for the three months ended September 30, 2023, 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.

Video abstracts reinforce the clinical validity and utility of the Company’s skin cancer test portfolio, including DecisionDx®-Melanoma, DecisionDx®-SCC and MyPath® Melanoma FRIENDSWOOD, Texas--(BUSINESS WIRE)-- Castle Biosciences, Inc. (Nasdaq: CSTL), a company improving health through innovative tests that guide patient care, today announced that data spanning its dermatologic portfolio of gene expression profile (GEP) tests was recently presented at the 2023 American Society for Dermatologic Surgery (ASDS) Annual Meeting in Chicago. “The robust data presented at ASDS underscores the value of GEP testing across multiple skin cancer indications” said Robert Cook, Ph.D., senior vice president of research and development at Castle Biosciences. “The studies presented reinforce our commitment to research and development and showcase the utility of our tests in guiding more informed and risk-aligned patient care.” Highlights from Castle’s seven video abstracts presented at ASDS are included below. DecisionDx®-Melanoma Clinically significant risk-stratification prediction in stage I cutaneous melanoma with the integrated 31-gene expression profile (i31-GEP) Presenting Author: Michael Tassavor, M.D., Skin Cancer Center, Cincinnati Summary: No specific risk threshold provides clinicians guidance regarding when to alter treatment plans or increase management intensity for patients with stage I cutaneous melanoma (CM). The study data demonstrated the ability of the DecisionDx-Melanoma test to identify patients with stage I CM at high risk of tumor recurrence (recurrence free survival of 89.8%, p=0.002). View video abstract here. Validation of the i31-GEP for sentinel lymph node biopsy metastasis in patients with T1b-T2a cutaneous melanoma: Results of an independent performance study First Author: Peter A. Prieto, M.D., MPH, University of Rochester Medical Center, Rochester, New York Summary: National Comprehensive Cancer Network (NCCN) guidelines recommend that the sentinel lymph node biopsy (SLNB) procedure can be considered for patients with an expected risk of SLN positivity above 5%. In this independent cohort of patients with T1b-T2a tumors (n=177), the DecisionDx-Melanoma test identified patients with less than 5% risk of SLN positivity who may consider foregoing the procedure and could have reduced the number of SLNBs by 45% in T1b tumors, 14% in T2a tumors and 28% overall. View video abstract here. DecisionDx®-SCC Association of a 40-gene expression pro risk of metastatic disease progression of cutaneous squamous cell carcinoma (cSCC) and benefit of adjuvant radiation therapy (ART) Presenting Author: Sarah Arron, M.D., Ph.D., Peninsula Dermatology, Burlingame, California Summary: ART is recommended based on high-risk clinicopathologic features of SCC, but these criteria are wide-ranging, encompassing a broad range of patients. Thus, many patients receive treatment with only a subset appearing to benefit. This study determined that the DecisionDx-SCC test can identify patients who would most likely benefit from ART to reduce metastatic disease progression. Specifically, patients with a Class 2B (highest metastatic risk) test result who were treated with ART had 50% higher metastasis-free survival rates than Class 2B patients who did not receive ART. Additionally, a DecisionDx-SCC Class 2B result was the only risk factor that successfully identified patients who would benefit from ART. View video abstract here. Using the 40-gene expression profile (40-GEP) test in Medicare-eligible cutaneous squamous cell carcinoma (cSCC) patients reduces healthcare costs when guiding adjuvant radiation therapy (ART) decisions Presenting Author: Aaron S. Farberg, M.D., Baylor Scott & White Health System, Dallas Summary: The study aimed to determine if using the DecisionDx-SCC test to guide ART decisions could reduce healthcare costs in the management of cSCC. The study found that using the DecisionDx-SCC test to guide ART decisions for Medicare-eligible cSCC patients could result in cost savings to the healthcare system ranging from $145 million to approximately $1 billion annually. View video abstract here. Incorporating the 40-gene expression profile (40-GEP) test in clinicopathologic staging improves metastatic risk assessment for cutaneous squamous cell carcinoma (cSCC) patients with one or more high-risk factors Presenting Author: Sarah Arron, M.D., Ph.D. Summary: Three clinicopathologic-based risk assessment systems (Brigham and Women’s Hospital (BWH) staging, American Joint Committee on Cancer 8th Edition (AJCC8) staging and NCCN) are used to guide treatment pathway decisions in patients with high-risk cSCC; however, each has accuracy limitations. The large, combined cohort (including 420 patients from the initial validation cohort and 534 patients from a novel, independent cohort) confirmed that the DecisionDx-SCC test provides significant risk stratification within high-risk cSCC patients. Multivariate and likelihood analyses demonstrate the improvement of metastatic risk prediction by the addition of DecisionDx-SCC in models that include NCCN, BWH or AJCC8 systems. View video abstract here. The 40-gene expression profile (40-GEP) test demonstrates impactful clinical utility in the management of cutaneous squamous cell carcinoma (cSCC) patients Presenting Author: Brent R. Moody, M.D., Skin Cancer Surgery Center, Nashville, Tennessee Summary: This multicenter, retrospective study was designed to explore physician management patterns for patient follow-up, surveillance and treatments when including DecisionDx-SCC test results as part of clinical care of patients with high-risk cSCC. The study found that in a real-world patient cohort, the risk stratification provided by the DecisionDx-SCC test was the most influential factor in risk-aligned management changes. Additionally, the test’s results were more significant in the physicians’ decision to escalate or de-escalate care than any other traditional risk factor considered in the study. View video abstract here. MyPath® Melanoma Gene expression profiling in the diagnostic work-up of melanocytic lesions Presenting Author: Hadas Skupsky, M.D., F.A.A.D., Laser Skin Care Center, Long Beach, California; University of California Irvine, Irvine, California Summary: MyPath Melanoma testing is available for ambiguous melanocytic neoplasms to add clarity to diagnoses. Case studies were presented utilizing a variety of immunohistochemical stains and testing with MyPath Melanoma to aid in the determination of a final diagnosis and inform surgical planning for otherwise diagnostically ambiguous cases. View video abstract here. About DecisionDx®-Melanoma DecisionDx-Melanoma is a gene expression pro stratification test. It is designed to inform two clinical questions in the management of cutaneous melanoma: a patient’s individual risk of sentinel lymph node (SLN) positivity and a patient's personal risk of melanoma recurrence and/or metastasis. By integrating tumor biology with clinical and pathologic factors using a validated proprietary algorithm, DecisionDx-Melanoma is designed to provide a comprehensive and clinically actionable result to guide risk-aligned patient care. DecisionDx-Melanoma has been shown to be associated with improved patient survival and has been studied in more than 10,000 patient samples. DecisionDx-Melanoma’s clinical value is supported by more than 40 peer-reviewed and published studies, providing confidence in disease management plans that incorporate the test’s results. Through Sept. 30, 2023, DecisionDx-Melanoma has been ordered more than 146,000 times for patients diagnosed with cutaneous melanoma. About DecisionDx®-SCC DecisionDx-SCC is a 40-gene expression pro that uses an individual patient’s tumor biology to predict individual risk of cutaneous squamous cell carcinoma metastasis for patients with one or more risk factors. The test result, in which patients are stratified into a Class 1 (low), Class 2A (moderate) or Class 2B (high) risk category, predicts individual metastatic risk to inform risk-appropriate management. Peer-reviewed publications have demonstrated that DecisionDx-SCC is an independent predictor of metastatic risk and that integrating DecisionDx-SCC with current prognostic methods can add positive predictive value to clinician decisions regarding staging and management. About MyPath® Melanoma MyPath Melanoma is Castle’s gene expression pro designed to provide an accurate, objective result to aid dermatopathologists and dermatologists in characterizing difficult-to-diagnose melanocytic lesions. Of the approximately two million suspicious pigmented lesions biopsied annually in the U.S., Castle estimates that approximately 300,000 of those cannot be confidently classified as either benign or malignant through traditional histopathology methods. For these cases, the treatment plan can also be uncertain. Obtaining accurate, objective ancillary testing can mean the difference between a path of overtreatment or the risk of undertreatment. Interpreted in the context of other clinical, laboratory and histopathologic information, MyPath Melanoma is designed to reduce uncertainty and provide confidence for dermatopathologists and help dermatologists deliver more informed patient management plans. More information about Castle’s tests can be found at . 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 help guide systemic therapy selection for patients with moderate-to-severe atopic dermatitis, psoriasis and related conditions. To learn more, please visit and connect with us on LinkedIn, Facebook, X and Instagram. DecisionDx-Melanoma, DecisionDx-CMSeq, DecisionDx-SCC, MyPath 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 continued value of GEP testing across multiple skin cancer indications; our ability to improve the care of patients with skin cancers and inflammatory skin conditions through innovative tests that can guide more informed disease management decisions; the potential of the DecisionDx-Melanoma test to identify patients with stage I CM at high risk of tumor recurrence; the continued ability of the DecisionDx-Melanoma test was validated to identify patients with less than 5% risk of SLN positivity; the ability of the DecisionDx-SCC test to (i) identify patients who would most likely benefit from ART to reduce metastatic disease progression, (ii) result in cost savings to the healthcare system ranging from $145 million to approximately $1 billion annually, (iii) provide significant risk stratification within high-risk cSCC patients, (iv) influence physicians’ decisions to escalate or de-escalate care; the ability of MyPath Melanoma to (i) aid in the determination of a final diagnosis and inform surgical planning for otherwise diagnostically ambiguous cases and (ii) reduce uncertainty and provide confidence for dermatopathologists and help dermatologists deliver more informed patient management plans; and the ability of DecisionDx-Melanoma to provide a comprehensive and clinically actionable result to guide risk-aligned patient care. The words “can,” “may” 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, including with respect to the discussion of DecisionDx-Melanoma, DecisionDx-SCC, MyPath Melanoma and Castle’s inflammatory skin disease pipeline test in this press release; actual application of our tests may not provide the aforementioned benefits to patients; and the risks set forth under the heading “Risk Factors” in our Annual Report on Form 10-K for the year ended December 31, 2022, our Quarterly Report on Form 10-Q for the three months ended September 30, 2023, 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. View source version on businesswire.com: Contacts Investor Contact: Camilla Zuckero czuckero@castlebiosciences.com Media Contact: Allison Marshall amarshall@castlebiosciences.com Source: Castle Biosciences Inc. View this news release online at: