• This marks the second FDA-approved indication for Guardant360 CDx as a companion diagnostic in breast cancer treatment
• ESR1 mutations are present in 40% of HR+, HER2- advanced breast cancers

Guardant Health, Inc. (Nasdaq: GH), a leading precision oncology company, today announced that the U.S. Food and Drug Administration (FDA) has approved its Guardant360^® CDx as a companion diagnostic to identify advanced breast cancer patients with ESR1 mutations who may benefit from Eli Lilly and Company’s Inluriyo (imlunestrant). Guardant360 CDx was approved in conjunction with Inluriyo for the treatment of adults with estrogen receptor-positive (ER+), human epidermal growth factor receptor 2-negative (HER2–), ESR1-mutated advanced or metastatic breast cancer whose disease progressed after at least one line of endocrine therapy (ET).

“This FDA approval provides another treatment for breast cancer patients with ESR1 mutations for their specific type of cancer along with expanded access to comprehensive genomic profiling with a simple blood draw,” said Helmy Eltoukhy, Guardant Health chairman and co-CEO. “Precision testing plays a critical role in helping physicians identify the correct treatment, providing patients and their doctors with the comprehensive genomic profiling needed to see if they are eligible to receive the right treatment and improving outcomes.”

Breast cancer remains the second leading cause of cancer death among women in the United States.¹ Guardant360 CDx was used to identify patients who had ESR1 mutations in the Phase 3 EMBER-3 trial, in which Inluriyo was found to reduce the risk of progression or death by 38% versus ET.² Patients with ESR1 E380, V422del, S463, L469, L536, Y537, and D538 mutations detected by Guardant360 CDx are eligible for treatment with Inluriyo.

The Inluriyo approval as a companion diagnostic marks the sixth CDx claim approved by the FDA for Guardant360 CDx, and the second FDA-approved indication in breast cancer treatment, following a similar approval for ORSERDU™ (elacestrant) granted by the FDA in 2023.

For more information about Inluriyo, please visit https://inluriyo.lilly.com/.

About Guardant360 CDx

The first FDA-approved blood test for complete genomic testing, Guardant360 CDx is approved as a companion diagnostic for multiple therapies in non-small cell lung cancer. It is also the only FDA-approved companion diagnostic for targeted therapy in advanced breast cancer patients with ESR1 mutations. The test is broadly covered by Medicare and commercial insurers, representing over 300 million lives. For more information, visit the Guardant360 CDx website.

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.

Guardant Health 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. 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.

¹ https://www.cancer.org/cancer/types/breast-cancer/about/how-common-is-breast-cancer.html

²tps://investor.lilly.com/news-releases/news-release-details/us-fda-approves-inluriyo-imlunestrant-adults-er-her2-esr1

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