GRAIL to Present New Data From NHS-Galleri and PATHFINDER 2 at 2026 ASCO Annual Meeting

Detailed NHS-Galleri Trial Results Will be Presented as a Late-Breaking Abstract in an Oral Presentation

Final PATHFINDER 2 Study Results Will be Presented as a Late-Breaking Abstract in an Oral Presentation

More than 174,000 Participants Enrolled Across Both Studies, Demonstrating the Scientific Rigor of Galleri^®Clinical Development Program

MENLO PARK, Calif., April 21, 2026 - GRAIL, Inc. (Nasdaq: GRAL), a healthcare company whose mission is to detect cancer early when it can be cured, will present additional data from both the NHS-Galleri trial and the PATHFINDER 2 study further evaluating the Galleri^® multi-cancer early detection (MCED) test at the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago, May 29-June 2, 2026.

The NHS-Galleri trial presentation will expand on topline results announced in February 2026. The NHS-Galleri trial, the first and only randomized controlled study of an MCED test, was designed to demonstrate population-level impact through the reduction of late-stage cancer diagnosis and increased cancer detection rate within England's National Health Service (NHS). The trial evaluated annual screening with the Galleri test in addition to standard of care screening over three years in more than 142,000 demographically representative participants aged 50 to 77, compared to standard of care screening alone.

Building on initial results presented at the European Society for Medical Oncology (ESMO) Congress in October 2025, the complete PATHFINDER 2 dataset of more than 32,000 evaluable participants will be presented. Conducted under an FDA-approved investigational device exemption, PATHFINDER 2 is the largest MCED interventional study in North America in an intended-use population with no clinical suspicion of cancer.

"The goal of cancer screening is to detect cancer before it becomes advanced or spreads, when treatment options may be broader, care and cost may be less intensive, and the opportunity for cure is often greater. Yet the status quo still leaves too many cancers unscreened. In the U.S., more than 70 percent of cancer deaths are from cancers without recommended screening tests," said Josh Ofman, MD, MSHS, President of GRAIL. "These results from NHS-Galleri and PATHFINDER 2, two large, rigorous studies, underscore Galleri's strong performance, ability to shift detection of cancers earlier before metastatic disease, and strong safety profile. We look forward to sharing these findings, which strengthen the body of evidence supporting the clinical utility, performance, and safety of Galleri in intended-use populations and reflect GRAIL's extensive experience building a robust evidence base for multi-cancer early detection."

ASCO Presentations
Title: NHS-Galleri: Primary results from a randomised controlled trial to assess the clinical utility of a multi-cancer early detection (MCED) test in population screening

Abstract Number: LBA100
Session Title: Clinical Science Symposium - ctDNA in Clinical Practice: From Detection to Clinical Decision-Making
Presentation type: Oral Presentation
Date/Time: Saturday, May 30, 2026 - 8:00 am-9:30 am CDT

Title: Safety and performance results from PATHFINDER 2 (PF2), a registrational study of a multi-cancer early detection (MCED) test in an intended-use population

Abstract Number: LBA10509
Session Title: Rapid Oral Abstract Session - Prevention, Risk Reduction, and Genetics
Presentation type: Oral Presentation
Date/Time: May 31, 2026 - 9:45 am-11:15 am CDT

Title: Implementation of a multi-cancer early detection (MCED) test in a private practice: adoption, performance, and repeat-testing patterns

Abstract Number: 10532
Presentation Type: Poster #493
Date/Time: June 1, 2026 - 1:30-4:30 pm CDT

About GRAIL
GRAIL is a healthcare company whose mission is to detect cancer early, when it can be cured. GRAIL is focused on alleviating the global burden of cancer by using the power of next-generation sequencing, population-scale clinical studies, and state-of-the-art machine learning, software, and automation to detect and identify multiple deadly cancer types in earlier stages. GRAIL's targeted methylation-based platform can support the continuum of care for screening and precision oncology, including multi-cancer early detection in symptomatic patients, risk stratification, minimal residual disease detection, biomarker subtyping, treatment and recurrence monitoring. GRAIL is headquartered in Menlo Park, CA with locations in Washington, D.C., North Carolina, and the United Kingdom.

For more information, visit grail.com.

About Galleri^®
The Galleri multi-cancer early detection test is a proactive tool to screen for cancer. With a simple blood draw, Galleri can detect more than 50 types of cancer before symptoms appear- when they can be easier to treat and are potentially curable². Galleri is the only available MCED test with demonstrated performance in patients screened for cancer²*. The Galleri test increases the number of cancers detected seven-fold when added to recommended screening for breast, cervical, colorectal and lung cancers, and has the lowest false positive rate of any MCED test on the market^1,2,3,4,**The Galleri test doubles the number of cancers detected when added to standard of care cancer screening, and has the lowest false positive rate of any MCED test^1,2,3,4,**. When a cancer signal is found, Galleri provides a cancer signal of origin with high accuracy to help guide an efficient diagnostic work-up^4,5,6. The Galleri test requires a prescription from a licensed healthcare provider and should be used in addition to recommended cancer screenings such as mammography, colonoscopy, prostate-specific antigen (PSA) test, or cervical cancer screening. The Galleri test is recommended for adults with an elevated risk for cancer, such as those aged 50 or older.

For more information, visit galleri.com.

* The Galleri test performance metrics were derived from the outcomes of an interventional clinical study of patients presenting for screening without clinical suspicion of cancer, a study population that reflects the intended use population.
** Test performance metrics do not represent results of a head-to-head comparative study. Separate studies have different designs, objectives, and participant populations, which limits the ability to draw conclusions about comparative performance.

Important Galleri Safety Information
The Galleri test is recommended for use in adults with an elevated risk for cancer, such as those age 50 or older. The test does not detect all cancers and should be used in addition to routine cancer screening tests recommended by a healthcare provider. The Galleri test is intended to detect cancer signals and predict where in the body the cancer signal is located. Use of the test is not recommended in individuals who are pregnant, 21 years old or younger, or undergoing active cancer treatment. Results should be interpreted by a healthcare provider in the context of medical history, clinical signs, and symptoms. A test result of No Cancer Signal Detected does not rule out cancer. A test result of Cancer Signal Detected requires confirmatory diagnostic evaluation by medically established procedures (e.g., imaging) to confirm cancer. If cancer is not confirmed with further testing, it could mean that cancer is not present or testing was insufficient to detect cancer, including due to the cancer being located in a different part of the body. False positive (a cancer signal detected when cancer is not present) and false negative (a cancer signal not detected when cancer is present) test results do occur. Rx only.

Laboratory/Test Information
The GRAIL clinical laboratory is certified under the Clinical Laboratory Improvement Amendments of 1988 (CLIA) and accredited by the College of American Pathologists. The Galleri test was developed - and its performance characteristics were determined - by GRAIL. The Galleri test has not been cleared or approved by the Food and Drug Administration. The GRAIL clinical laboratory is regulated under CLIA to perform high-complexity testing. The Galleri test is intended for clinical purposes.

GRAIL Forward Looking Statements
This press release contains forward-looking statements. In some cases, you can identify these statements by forward-looking words such as "aim," "anticipate," "believe," "continue," "could," "estimate," "expect," "intend," "may," "might," "plan," "potential," "predict," "should," "would," or "will," the negative of these terms, and other comparable terminology. These forward-looking statements, which are subject to risks, uncertainties, and assumptions about us, may include statements related to the potential benefits, uses and impacts of the Galleri test, our expectations regarding the results and outcomes of the NHS-Galleri trial and the PATHFINDER 2 study, the potential clinical utility, performance and safety profile of the Galleri test, the impact of clinical evidence on adoption into practice, cancer screening, public health and patient outcomes, among others.

These statements are only predictions based on our current expectations and projections about future events and trends. There are important factors that could cause our actual results, level of activity, performance, or achievements to differ materially and adversely from those expressed or implied by the forward-looking statements, including those factors and numerous associated risks discussed under the section entitled "Risk Factors" in our Annual Report on Form 10-K for the period ended December 31, 2025. Moreover, we operate in a dynamic and rapidly changing environment. New risks emerge from time to time. It is not possible for our management to predict all risks, nor can we assess the impact of all factors on our business or the extent to which any factor, or combination of factors, may cause actual results, level of activity, performance, or achievements to differ materially and adversely from those contained in any forward-looking statements we may make.

Forward-looking statements relate to the future and, accordingly, are subject to inherent uncertainties, risks, and changes in circumstances that are difficult to predict and many of which are outside of our control. Although we believe the expectations and projections expressed or implied by the forward-looking statements are reasonable, we cannot guarantee future results, level of activity, performance, or achievements. Our actual results, financial condition and success in our business strategies and operations may differ materially from those indicated in the forward-looking statements. Except to the extent required by law, we undertake no obligation to update any of these forward-looking statements after the date of this press release to conform our prior statements to actual results or revised expectations or to reflect new information or the occurrence of unanticipated events.

<sup>References
1. Nabavizadeh N, et al. Safety and Performance of a Multi-Cancer Early Detection (MCED) Test in an Intended-Use Population: Initial Results from the Registrational PATHFINDER 2 Study. Proffered Presentation Presented at: European Society for Medical Oncology (ESMO) Annual Meeting; October 17-21, 2025; Berlin, Germany.
2. Klein EA, Richards D, Cohn A, et al. Clinical validation of a targeted methylation-based multi-cancer early detection test using an independent validation set. Ann Oncol. 2021 Sep;32(9):1167-77. doi: 10.1016/j.annonc.2021.05.806
3. GRAIL, Inc. False positive rate. [Data on file: GR-2025-0256]
4. Schrag D, Beer TM, McDonnell CH, et al. Blood-based tests for multi-cancer early detection (PATHFINDER): a prospective cohort study. Lancet. 2023;402:1251-1260. doi: 10.1016/S0140-6736(23)01700-2
5. GRAIL, Inc. Enhanced Cancer Signal Origin prediction. [Data on file: VV-TMF-59592]
6. Hackshaw A, et al. Cancer Cell. 2022;40(2):109-13.</sup>