• The first readout from Guardant’s research collaboration with the Parker Institute for Cancer Immunotherapy (PICI) shows Guardant Reveal detected responses to immunotherapy across multiple tumor types and identified non-responders up to 5 months earlier than standard methods
• Study shows Guardant Reveal’s promise for confirming effective therapies earlier and optimizing treatment faster in patients with advanced cancer

Guardant Health, Inc. (Nasdaq: GH), a leading precision oncology company, today announced the first clinical readout from their collaboration in the RADIOHEAD study with the Parker Institute for Cancer Immunotherapy (PICI), a network of the largest concentration of immuno-oncology (IO) expertise in the world. The data, published today in Cancer Research Communications, a journal of the American Association for Cancer Research, found that Guardant Reveal successfully detected responses to immunotherapy across multiple solid tumor types in advanced stage cancer patients and identified non-responders more than three months—and in some cases nearly five months—before disease progression was visible by standard methods.

Approximately 30% of patients with advanced-stage cancer receive immunotherapy treatment, with varying degree and duration of response. This study analyzed a large cohort of more than 500 patients with various advanced solid tumors, including lung, skin, head and neck, breast, GI, GU, and gynecologic cancers, receiving immunotherapy in a real-world setting to assess if blood-based monitoring could predict response accurately and faster than standard of care methods. The strong association found between long-term patient outcomes and changes in tumor fraction as measured with the tissue-free, methylation-based Guardant Reveal supports the use of blood-based monitoring to help predict treatment response and improve decision-making in cancer care.

“Precise serial monitoring at the molecular level provides real value to oncologists and to patients using immunotherapy,” said Craig Eagle, M.D., Chief Medical Officer at Guardant Health. “This study shows that Guardant Reveal has the potential to revolutionize how oncologists assess patient response, identifying earlier insights that can empower them to make informed decisions faster and improve patient outcome and quality of care.”

“Our RADIOHEAD study of Guardant Reveal in advanced stage cancers provides patients with a new caliber of precision monitoring in order to create better patient outcomes,” said Tarak Mody, PhD, Chief Business Officer at PICI. “These findings exemplify PICI’s commitment to forging mission-driven partnerships to bring cutting-edge technology into clinical practice, accelerate discoveries, and advance the development of curative immune therapies for patients.”

Key study findings include:

• Improved patient outcomes associated with any reduction in tumor fraction
• 75% lower risk of progression in patients with ≥80% decrease in tumor fraction
• Disease progression identified up to 5 months prior to standard of care methods

The full manuscript in Cancer Research Communications is available here.

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.

About RADIOHEAD

The RADIOHEAD (Resistance Drivers for Immuno-Oncology Patients Interrogated by Harmonized Molecular Datasets) program is a pan-tumor, prospective cohort study of 1,070 immunotherapy-naïve patients receiving standard-of-care immune checkpoint inhibitor regimens. Conducted across 49 U.S. community oncology clinics, the study includes over 3,700 longitudinal blood samples collected at pretreatment, early on-treatment, and immune-related adverse event timepoints, with a focus on major immuno-oncology indications such as non-small cell lung cancer (~1,400 samples) and malignant melanoma (~500 samples). Multi-omic profiling (including circulating tumor DNA analysis, whole-exome sequencing, transcriptomics, high-dimensional immune profiling, and serum proteomics) is paired with detailed clinical and demographic data to enable deep translational insights. This comprehensive dataset provides a unique opportunity to uncover mechanisms of response, resistance, and toxicity, and to apply machine learning approaches to explore immune and disease pathways.

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.

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