Recent AGA 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 Castle Biosciences’ TissueCypher® Test

Castle’s TissueCypher test has been shown to improve the risk stratification of patients with Barrett’s esophagus (BE)^1,2

Castle Biosciences, Inc. (Nasdaq: CSTL), a company improving health through innovative tests that guide patient care, today announced that the latest American Gastroenterological Association (AGA) clinical practice guideline recognized that not all patients with non-dysplastic BE (NDBE) are at low risk of developing esophageal cancer. The guideline acknowledges the role that tissue-based biomarkers, including the tissue systems pathology test (TissueCypher, also known as TSP-9), can play in identifying high-risk NDBE patients who may benefit from endoscopic eradication therapy (EET) to prevent disease progression.³

BE with high-risk features can often be effectively treated with EET, such as ablation, which involves either burning or freezing the abnormal esophageal lining. However, the ability to reliably identify patients at increased risk of progression is crucial to avoid missing patients who develop esophageal cancer as well as limiting the over treatment of patients who have a lower risk of progression. Studies have shown that TissueCypher is an independent predictor of progression in patients with BE. Further, a pooled analysis of clinical data from the Mayo Clinic showed that patients with NDBE, traditionally deemed to be at a lower risk of advancing to esophageal cancer, who receive TissueCypher high-risk scores, are 18-times more likely to progress than patients with low-risk scores.¹

In the recently published AGA guideline, the expert panel of authors acknowledge the role that tissue-based biomarkers (particularly aberrant p53 or TissueCypher, alone or in combination with clinical and endoscopic characteristics) can play in stratifying the large pool of patients with NDBE to help identity those at high risk of progression for consideration of treatment with EET at an early, precancerous stage.

“We are pleased that the AGA has recognized that there is a high-risk subset of NDBE patients who may benefit from early intervention with EET and importantly, have acknowledged that tissue-based biomarker testing can help identify these patients,” said Emmanuel Gorospe, M.D., board-certified gastroenterologist and GI medical director at Castle Biosciences. “This clinical need was the driving factor behind the development of the TissueCypher test, which provides a deeper look into a patient’s esophageal tissue to identify molecular signs of progression that may lead to cancer down the road.”

In 2022, the AGA’s “Clinical Practice Update on New Technology and Innovation for Surveillance and Screening in Barrett’s Esophagus” included a best practice advice statement that said TissueCypher may be utilized for the risk-stratification of patients with NDBE.⁴

About TissueCypher Barrett’s Esophagus Test

The TissueCypher Barrett’s Esophagus test is Castle’s precision medicine test designed to predict future development of high-grade dysplasia (HGD) and/or esophageal cancer in patients with Barrett’s esophagus (BE). The TissueCypher Barrett’s Esophagus test is indicated for use in patients with endoscopic biopsy confirmed BE that is graded non-dysplastic (NDBE), indefinite for dysplasia (IND) or low-grade dysplasia (LGD); its clinical performance has been supported by 13 peer-reviewed publications of BE progressor patients with leading clinical centers around the world. The test received Advanced Diagnostic Laboratory Test (ADLT) status from the Centers for Medicare & Medicaid Services (CMS) in March 2022. Learn more at www.CastleBiosciences.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, 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-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: TissueCypher’s continued ability to (i) be an independent predictor of progression in patients with BE and (ii) help stratify the large pool of patients with NDBE to help identity those at high-risk of progression for consideration of treatment with EET at an early, precancerous stage The words “can,” “would” 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 shown in this study, including with respect to the discussion of TissueCypher in this press release; actual application of our TissueCypher test 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, our Quarterly Report on Form 10-Q for the quarter ended March 31, 2024 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.

1. Iyer PG, Codipilly DC, Chandar AK, et al. Prediction of progression in Barrett's esophagus using a tissue systems pathology test: a pooled analysis of international multicenter studies. Clin Gastroenterol Hepatol. 2022;20(12):2772-2779.e8. doi:10.1016/j.cgh.2022.02.033
2. Davison JM, Goldblum JR, Duits LC, et al. A tissue systems pathology test outperforms the standard-of-care variables in predicting progression in patients with Barrett's esophagus. Clin Transl Gastroenterol. 2023;14(11):e00631. Published 2023 Nov 1. doi:10.14309/ctg.0000000000000631
3. Rubenstein JH, Sawas T, Wani S, et al. AGA clinical practice guideline on endoscopic eradication therapy of Barrett’s esophagus and related neoplasia. Gastroenterology. 2024;166(6):1020-1055. doi: 10.1053/j.gastro.2024.03.019
4. Muthusamy VR, Wani S, Gyawali CP, Komanduri S; CGIT Barrett’s Esophagus Consensus Conference Participants. AGA clinical practice update on new technology and innovation for surveillance and screening in Barrett's esophagus: Expert Review. Clin Gastroenterol Hepatol. 2022;20(12):2696-2706.e1. doi: 10.1016/j.cgh.2022.06.003

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