Guardant Health Presents Data Demonstrating Utility of Comprehensive Genetic Profiling with Guardant360® Liquid Biopsy Test to Guide Treatment for Advanced Breast Cancer Patients at 2021 San Antonio Breast Cancer Symposium

GuardantINFORM^™ platform offers real-world evidence to identify unmet need for patients with advanced breast cancer

sGuardant Health, Inc. (Nasdaq: GH), a leading precision oncology company, today announced it will present new data demonstrating the benefits of using the Guardant360^® liquid biopsy test to help guide targeted therapy options for patients with advanced breast cancer at the 2021 San Antonio Breast Cancer Symposium (SABCS) on December 7-11. These studies were based on data from the GuardantINFORM^™ real-world clinical genomic platform, which features extensive de-identified genomic data and aggregated commercial payer claims from advanced cancer patients who received the Guardant360 liquid biopsy assay.

Data from one study (Abstract P5-13-29) confirmed that patients with BRCA1/2 reversion mutations, thought to cause acquired therapeutic resistance, experienced worse survival outcomes when treated with a PARP inhibitor as compared to patients without reversion mutations. The study also validates recent advancements in homologous recombination deficiency (HRD) assessment in the Guardant360 lab developed test (LDT), detecting additional inactivating alterations in BRCA1/2, including copy number loss and large genomic rearrangements. These data further demonstrate the Guardant360 test’s ability to reliably identify patients with advanced breast cancer who are most likely to benefit from PARP inhibitor treatment.

Another study (Abstract P1-18-07) using the GuardantINFORM platform demonstrated that, for advanced breast cancer patients with PIK3CA mutations identified using the Guardant360 liquid biopsy and subsequently treated with alpelisib, there was no significant difference in treatment outcomes regardless of whether they had clonal or subclonal PIK3CA mutations. This suggests patients with these mutations may benefit from alpelisib targeted therapy irrespective of mutation clonality.

“These studies further support the tremendous value that our Guardant360 liquid biopsy test and GuardantINFORM real-world clinical genomic platform bring to physicians, and most importantly the patients they treat,” said Helmy Eltoukhy, Guardant Health Co-CEO. “Guardant360 identifies mutations driving the cancer, which enables the physician to match a patient with the right precision therapy without the need for a tissue biopsy, which can be difficult and time-consuming, potentially delaying treatment for patients with advanced breast cancer.”

Full List of Guardant Health Presentations:

• Analytical and clinical validation of a ctDNA assay for detecting copy number loss and structural rearrangement variants contributing to homologous recombination and repair (HRR) deficiency (Abstract Number: P5-13-29)
• Impact of PIK3CA mutation (PIK3CA-mt) clonality on alpelisib (ALP) activity based on real-world evidence (RWE) following liquid biopsy testing (Abstract Number: P1-18-07)
• SOLTI-1903 HOPE: Real-world clinical practice study to assess the impact of using genomic data on the next treatment decision making-choice in patients with locally advanced or metastatic breast cancer in Spain (Abstract Number: OT2-06-01)
• Early changes in circulating tumor DNA and its effect on clinical outcomes in patients with advanced breast cancer receiving the CDK4/6 inhibitor palbociclib: Genotyping results from POLARIS (Abstract Number: P1-18-05)

The full abstracts can be found at the official SABCS website here.

About the Guardant360^® Liquid Biopsy Test

The Guardant360 liquid biopsy test is part of the market leading Guardant360 portfolio that offers oncologists end-to-end testing solutions from treatment selection to treatment response monitoring. Since it was first introduced, the Guardant360 liquid biopsy test has become widely accepted for blood-based comprehensive genomic profiling (CGP) with more than 250 peer-reviewed publications including over 60 clinical outcomes studies. It has been trusted by more than 9,000 oncologists with more than 200,000 tests performed to date.

About GuardantINFORM^™

The GuardantINFORM clinical-genomic platform is intended to help accelerate research and development of the next generation of cancer therapeutics by offering biopharma partners an in-silico platform that combines de-identified longitudinal clinical information and genomic data collected from the Guardant360 liquid biopsy test. With data from more than 160,000 patients diagnosed with locally advanced and metastatic cancers, this robust dataset offers real-world insights into anti-cancer therapy use in the clinic, tumor evolution, and treatment resistance throughout each patient’s treatment journey for many advanced solid tumor cancers, including non-small cell lung, breast, colon, and prostate.

About Guardant Health

Guardant Health is a leading precision oncology company focused on helping conquer cancer globally through use of its proprietary tests, vast data sets and advanced analytics. The Guardant Health oncology platform leverages capabilities to drive commercial adoption, improve patient clinical outcomes and lower healthcare costs across all stages of the cancer care continuum. Guardant Health has commercially launched Guardant360^®, Guardant360 CDx, Guardant360 TissueNext^™, Guardant360 Response^™, and GuardantOMNI^® tests for advanced stage cancer patients, and Guardant Reveal^™ for early-stage cancer patients. These tests fuel development of its LUNAR screening program, which aims to address the needs of asymptomatic individuals eligible for cancer screening.

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, 2020 and in its other reports filed with 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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