On October 20, 2025 GRAIL, Inc. (Nasdaq: GRAL), a healthcare company whose mission is to detect cancer early when it can be cured, and the University of Oxford, reported that positive long-term results from an extended registry follow-up of the SYMPLIFY study will be presented on Oct. 21 at the Early Detection of Cancer Conference (EDCC) in Portland, Oregon.

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SYMPLIFY, a prospective observational study, is the first large-scale evaluation of a multi-cancer early detection (MCED) test in individuals who presented with symptoms to primary care and were referred for diagnostic follow-up for suspicion of cancer. In SYMPLIFY, the Galleri test was used to assess blood samples from more than 6,000 participants with symptoms of cancer who followed standard diagnostic pathways. However, as a non-interventional study, the results of the tests were unknown to physicians and did not inform the approach to diagnosis. No MCED results were returned to participants or their clinicians during the study.

"The conversion of false positive results to cancer diagnosis in this updated analysis of the SYMPLIFY study highlights the importance of proactive follow-up on positive MCED results, as one third of the apparent false positive results were actually cancers the standard-of-care diagnostic process couldn’t immediately identify," said Brian D. Nicholson, MRCGP, DPhil, Associate Professor at the Nuffield Department of Primary Care Health Sciences, University of Oxford, United Kingdom and co-lead investigator of the study. "Additionally, the results underscore the value of Galleri’s Cancer Signal Origin prediction, which aligned with the eventual diagnosis in almost all of the cases initially considered to be false positives. We are pleased to present these data at EDCC and have submitted this analysis for full publication."

Previous SYMPLIFY results showed potential of MCED testing in people with symptoms suggestive of cancer

Most people diagnosed with cancer visit primary care with symptoms before diagnosis1. Many of these people report common, non-specific symptoms such as bloating, unexplained weight loss or abdominal pain, which can be attributed to various conditions as well as cancer2.

The primary analysis of the SYMPLIFY study, previously published in The Lancet Oncology, supported the feasibility of using the Galleri test to assist clinicians with decisions regarding referral from primary care. In that analysis, which followed participants until diagnostic resolution or up to nine months, Galleri’s positive predictive value (PPV) was 75.5%. When a cancer signal was detected, the test accurately predicted the Cancer Signal Origin (CSO) in 84.8% of cases.

Updated results demonstrate importance of continued follow-up after a cancer signal is detected

Patients reported to have a false positive Galleri result were followed for 24 months in national cancer registries for England and Wales. The analysis showed that 35.4% (28 of 79 participants) were later diagnosed with cancer within 24 months of enrollment. This reduction in false positives from 79 to 51 resulted in an increase of PPV to 84.2%. In aggregate, 27 of these 28 participants had a correct CSO prediction which could have led to a faster or more efficient diagnosis. In more than half of these cases, the cancer type diagnosed was not congruent with the original diagnostic clinic to which the patient was referred by the general practitioner based on the clinical presentation:

16 of the 28 (57.1%) were diagnosed with cancer within nine months of enrollment.
Eight of the 16 (50%) were diagnosed with cancers that were correctly predicted by the Galleri test’s CSO finding, but were incongruent with the diagnostic pathway chosen by the general practitioner based on the participants’ presenting symptoms.
12 of the 28 (42.9%) were diagnosed 10-24 months after enrollment.
Seven of the 12 (58.3%) were diagnosed outside the original referral pathway; in those cases, the CSO also was correct, matching the site that was ultimately diagnosed.
"The SYMPLIFY study, focused on patients presenting with symptoms, adds to the breadth of our clinical experience in asymptomatic populations. This robust data demonstrates the potential benefit of the Galleri test as a diagnostic tool for individuals presenting with symptoms of cancer, particularly where those symptoms are non-specific. The fact that, in all but one of the additional patients diagnosed with cancer, a Galleri CSO prediction correctly identified the cancer type, including in many cases where the symptoms were non-specific, further reinforces the value of the Galleri test’s CSO capability," said Sir Harpal Kumar, President, International Business & BioPharma at GRAIL. "Furthermore, the 24-month follow-up data being presented at EDCC underscore the importance of continued follow-up to help identify cancers that may initially be missed in diagnostic evaluation. These latest results add to the body of evidence that Galleri could support clinical decision-making in primary care for referral to urgent diagnostic investigations of cancer and drive more efficient use of diagnostic capacity."

About the SYMPLIFY Study
SYMPLIFY is a prospective multicentre observational study and represents the first large-scale evaluation of an MCED test in symptomatic patients who were referred from the primary care setting due to clinical suspicion of cancer. The study enrolled 6,238 patients, aged 18 years and older, in England and Wales who were referred for urgent imaging, endoscopy or other diagnostic modalities to investigate symptoms suspicious for possible cancer. Of the total enrolled patients, there were 5,461 evaluable patients who achieved diagnostic resolution. GRAIL’s MCED test was performed in batches, blinded to clinical outcome, and results were compared with the diagnosis obtained by standard of care pathways to assess the test’s performance.

The University of Oxford sponsored the SYMPLIFY study and was responsible for data collection, analysis and interpretation. The study was funded by GRAIL with support from National Health Service (NHS) England, NHS Wales, the National Institute for Health and Care Research (NIHR) and NIHR Oxford Biomedical Research Centre.

(Press release, Grail, OCT 20, 2025, View Source [SID1234656831])