Guardant Health to Present 14 Abstracts Demonstrating the Power of Multiomic Liquid Biopsy Tests in Predicting Outcomes and Tailoring Treatment for Early and Metastatic Breast Cancer at the 2025 San Antonio Breast Cancer Symposium

• Presentations highlight advancements in cancer recurrence detection with Guardant Reveal and real-time treatment response monitoring with Guardant360 Liquid

Guardant Health, Inc. (NASDAQ:GH), a leading precision oncology company, will present a total of 14 abstracts with its research collaborators from multiple studies demonstrating the value of its tissue-free liquid biopsy tests at the 2025 San Antonio Breast Cancer Symposium (SABCS), taking place Dec. 9–12, 2025.

Oral presentations will highlight results generated with Guardant Reveal, the company's tissue-free test for detecting minimal residual disease (MRD) and Guardant360 Liquid, the company's comprehensive multiomic profiling test, both leveraging Guardant's proprietary epigenomic technology powered by the Guardant Infinity Smart Platform. Collectively, these studies demonstrate how blood-based testing can uncover risk, guide treatment selection, and influence long-term patient management across the breast cancer continuum, from early-stage disease through metastatic settings.

Guardant's MRD presentations reinforce the value of tissue-free circulating tumor DNA (ctDNA) testing for both neoadjuvant treatment response assessment and post-treatment surveillance in early-stage breast cancer. In a retrospective analysis of HER2-positive patients, ctDNA measured with Guardant Reveal demonstrated strong prognostic significance in the neoadjuvant setting, showing a correlation with pathological complete response and three-year invasive disease-free survival. In an independent study of triple-negative breast cancer patients, Guardant Reveal accurately predicted relapse risk and detected ctDNA more frequently and earlier than orthogonal methods.

Together, these findings demonstrate the validity of Guardant Reveal as a reliable approach for ctDNA detection and monitoring in both neoadjuvant and surveillance settings.

"Breast cancer care increasingly depends on understanding tumor biology at every stage of disease, and Guardant's data continues to reaffirm the growing value of multiomic liquid biopsy as a powerful, non-invasive tool to equip providers with the data necessary to tailor therapy and treatment," said Dr. Craig Eagle, Chief Medical Officer at Guardant Health. "We look forward to sharing our findings demonstrating the power of blood in helping provide clinicians with deeper clarity and more confident decision-making for their patients."

Other data highlights to be presented include:

• Data showcasing the clinical utility of Guardant Reveal in predicting outcomes in patients with early-stage HER2-positive breast cancer. In this analysis, early ctDNA clearance throughout treatment was linked to better outcomes, underscoring ctDNA as a sensitive marker of treatment response and highlighting the value of tissue-free testing for real-time response monitoring.
• Data supporting the clinical value potential of non-invasive, methylation-based, continuous breast cancer subtype monitoring by Guardant360 Liquid to uncover tumor evolution and heterogeneity that may guide more precise treatment decisions. In this analysis, Guardant360 Liquid showed agreement to tissue-based monitoring and replicated previously reported accuracy.
• Data showcasing Guardant360 Liquid methylation-based breast cancer subtyping feature as a noninvasive liquid tool to dynamically reassess ER, HER2 and triple negative status in patients who are resistant to ER therapy but don't carry an ESR1 mutation. In this study, Guardant360 Liquid predicted real-world outcomes in previously AI-treated patients receiving subsequent lines of therapy.

Guardant-Led Research at SABCS 2025

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

For information and updates from the conference, visit booth #942 and follow Guardant Health on LinkedIn, X (Twitter) and Facebook.

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 any current and periodic 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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