Guardant Health and Collaborators to Present Over 19 Studies Demonstrating Role of Liquid Biopsy in Advancing Precision Oncology at 2025 ASCO Annual Meeting

• Plenary session to highlight use of Guardant360 CDx test in detecting emerging ESR1 mutations during first line endocrine therapy in advanced breast cancer in Phase 3 SERENA-6 trial
• Oral session to feature largest study evaluating tissue-free epigenomic-based molecular residual disease (MRD) detection in colon cancer using Guardant Reveal

Guardant Health, Inc. (NASDAQ:GH), a leading precision oncology company, today announced the company and its research collaborators will present data from more than 19 studies, including a landmark plenary session on the Phase 3 SERENA-6 trial, demonstrating the critical role of Guardant liquid biopsy tests in cancer screening, therapy selection and recurrence monitoring at the 2025 American Society for Clinical Oncology (ASCO) Annual Meeting in Chicago.

Featured presentations demonstrate the use of Guardant's portfolio of blood tests, real-world data and AI to identify genomic and epigenomic biomarkers that can inform treatment decisions across a variety of solid tumor types. Studies also highlight new capabilities of the Guardant360 Liquid test to identify molecular tumor type in carcinomas of unknown primary and confirm the absence of actionable biomarkers, both enabled by the Guardant Infinity™ smart liquid biopsy platform, Presentation highlights include:

• Abstract LBA4 plenary session demonstrating the use of the Guardant360® CDx test in detecting emergent ESR1 mutations during first-line endocrine-based therapy and ahead of disease progression in patients with HR+/HER2- advanced breast cancer in the Phase 3 SERENA-6 trial
• Abstract 3504 oral session evaluating tissue-free epigenomic-based molecular residual disease (MRD) detection using Guardant Reveal™ in stage III colon cancer patients after surgery and prior to adjuvant therapy. This study showed a robust prognostic utility of Reveal to identify patients with poorer disease-free and overall survival in a large clinical trial cohort of over 2,000 patients with a median follow-up of 6.1 years.
• Abstract 3584 providing analytic and clinical validation of an algorithm to predict the absence of actionable mutations in ctDNA-negative colorectal and non-small cell lung cancer samples, utilizing genomic and epigenomic profiling with the Guardant360 Liquid test.
• Abstract 3073 demonstrating application of an epigenomic-based classifier to identify tumor type on liquid biopsy in cancer of unknown primary origin. Study provides validation data for the new molecular tumor type feature of Guardant360 Liquid utilizing DNA methylation signatures across thousands of cancer-specific differentially methylated regions for 14 cancer types.

"The data we and our research colleagues are presenting at ASCO demonstrate the clear and growing contribution of liquid biopsy in transforming cancer care and helping to improve patient outcomes," said Helmy Eltoukhy, Guardant Health chairman and co-CEO. "The SERENA-6 study in particular highlights how we are pushing the boundaries of what can be done with liquid biopsy in characterizing disease and potential drug efficacy, providing insights that could potentially change clinical practice."

The full abstracts for Guardant Health and a list of all abstracts being presented at ASCO 2025 can be found on the ASCO website.

For information and updates from the conference, follow Guardant Health on LinkedIn, X (Twitter) and Facebook or visit ASCO booth #25077.

Guardant Health and collaborator presentations at ASCO

About Guardant Health

Guardant Health is a leading precision oncology company focused on guarding wellness and giving every person more time free from cancer. Founded in 2012, Guardant is transforming patient care and accelerating new cancer therapies by providing critical insights into what drives disease through its advanced blood and tissue tests, real-world data and AI analytics. Guardant tests help improve outcomes across all stages of care, including screening to find cancer early, monitoring for recurrence in early-stage cancer, and treatment selection for patients with advanced cancer. For more information, visit guardanthealth.com and follow the company on LinkedIn, X (Twitter) and Facebook.

Forward-Looking Statements

This press release contains forward-looking statements within the meaning of federal securities laws, including statements regarding the potential utilities, values, benefits and advantages of Guardant Health's liquid biopsy tests or assays, which involve risks and uncertainties that could cause the actual results to differ materially from the anticipated results and expectations expressed in these forward-looking statements. These statements are based on current expectations, forecasts and assumptions, and actual outcomes and results could differ materially from these statements due to a number of factors. These and additional risks and uncertainties that could affect Guardant Health's financial and operating results and cause actual results to differ materially from those indicated by the forward-looking statements made in this press release include those discussed under the captions "Risk Factors" and "Management's Discussion and Analysis of Financial Condition and Results of Operation" and elsewhere in its Annual Report on Form 10-K for the year ended December 31, 2024, and in its other reports filed with or furnished to the Securities and Exchange Commission thereafter. The forward-looking statements in this press release are based on information available to Guardant Health as of the date hereof, and Guardant Health disclaims any obligation to update any forward-looking statements provided to reflect any change in its expectations or any change in events, conditions, or circumstances on which any such statement is based, except as required by law. These forward-looking statements should not be relied upon as representing Guardant Health's views as of any date subsequent to the date of this press release.

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