GRAIL Presents PATHFINDER 2 Results of More Than 35,000 Participants Showing the Galleri® Test Substantially Increased Cancer Detection With Robust Performance and Favorable Safety at 2026 ASCO Annual Meeting

Rhea-AI Summary

GRAIL (Nasdaq: GRAL) reported full PATHFINDER 2 results in 35,878 adults 50+ using the Galleri multi-cancer early detection blood test alongside standard screenings.

Adding Galleri increased screen-detected cancers up to 6.5-fold, with high specificity, 60.3% positive predictive value, strong episode sensitivity, and low invasive procedure rates.

Positive

• Galleri increased screen-detected cancers up to 6.5-fold when added to USPSTF A/B screenings
• Galleri detected nearly 3x more cancers when added to A/B/C screenings including prostate
• 60.3% positive predictive value based on 173 cancers in 287 positive tests
• 99.6% specificity, corresponding to a false-positive rate under 0.4%
• 53% of new Galleri-detected cancers were stage I-II; 70.9% were stage I-III
• Cancer signal origin correctly identified in 91.3% of cases with a median 48-day diagnostic resolution

Negative

• Episode sensitivity for all cancers was 39.3%, below the 69.8% for 12 highest-mortality cancers
• Median time to diagnostic resolution of 48 days after a positive test
• Study-related adverse events and one serious adverse event occurred during diagnostic work-ups
• Participant anxiety increased temporarily after a positive test and cancer diagnosis

Market Context

This announcement highlights robust PATHFINDER 2 results for Galleri, including a 6.5-fold boost in ...

Analysis

This announcement highlights robust PATHFINDER 2 results for Galleri, including a 6.5-fold boost in screen-detected cancers, 60.3% positive predictive value, and 99.6% specificity with low rates of invasive follow-up. Earlier filings already emphasized large-scale studies like PATHFINDER 2 and the NHS-Galleri trial. Investors may focus on how these data support regulatory review, clinician adoption, and integration plans as outlined in recent earnings and proxy disclosures.

Key Figures

PATHFINDER 2 cohort size: 35,878 participants Increase in cancer detection: 6.5 fold Early-stage detection share: 53.0% +5 more

8 metrics

PATHFINDER 2 cohort size 35,878 participants Prospective interventional study in adults 50 and older

Increase in cancer detection 6.5 fold Added Galleri to recommended screenings for select cancers

Early-stage detection share 53.0% New cancers detected by Galleri at stage I or II

Detected stages I–III 70.9% New cancers detected by Galleri at stages I–III

Positive predictive value (PPV) 60.3% Cancer diagnosis after a positive Galleri test

Episode sensitivity (12 cancers) 69.8% Cancers responsible for two-thirds of U.S. cancer deaths

Specificity 99.6% Galleri test specificity; false positive rate <0.4%

Correct CSO identification 91.3% Accuracy in predicting Cancer Signal Origin (CSO)

Historical Context

5 past events · Latest: May 27 (Neutral)

Pattern 5 events

Date	Event	Sentiment	24h Move	Catalyst
May 27	Inducement equity grants	Neutral	+3.5%	RSU inducement awards to new hires under Nasdaq Listing Rule 5635(c)(4).
May 26	Conference presentation	Neutral	+3.6%	Announcement of presentation at Goldman Sachs 47th Annual Global Healthcare Conference.
May 21	Conference appearance	Neutral	-1.0%	Jefferies Global Healthcare Conference presentation scheduling and webcast availability.
May 05	Earnings and pipeline	Positive	+15.3%	Q1 2026 revenue growth, Galleri volume increase, PMA review, and ASCO data plans.
Apr 30	Investor conference	Neutral	-0.8%	Planned presentation at BofA Securities 2026 Health Care Conference.

24h Move is the share-price change in the day after each event; other market factors may also have contributed.

Pattern Detected

Recent news—especially the Q1 2026 earnings and clinical/data updates—has generally coincided with positive price reactions, while routine conference appearances and corporate items have had smaller, mixed impacts.

Recent Company History

Over the past two months, GRAIL has focused on investor outreach and clinical validation for Galleri. Q1 2026 results on May 5 highlighted $40.8M revenue and strong Galleri growth, which coincided with a 15.35% gain. Subsequent conference presentations (Jefferies, BofA, Goldman Sachs) and inducement grants saw modest single‑digit moves. Today’s PATHFINDER 2 data at ASCO extends the previously flagged plan to showcase major Galleri studies at ASCO 2026.

Key Terms

multi-cancer early detection, mced, positive predictive value, specificity, +3 more

7 terms

multi-cancer early detection medical

"The Galleri Multi-Cancer Early Detection (MCED) Test Increased Cancer Detection..."

A multi-cancer early detection test is a medical screening tool—often a simple blood test—that looks for biological signals, such as abnormal DNA or protein patterns, that could indicate many different cancers before symptoms appear. For investors it matters because successful tests can reshape demand for diagnostics, influence healthcare spending and insurance coverage, and create new revenue streams or risks for companies across diagnostics, treatment and screening services; think of it as a smoke alarm that can warn of problems throughout an entire house rather than just one room.

mced medical

"PATHFINDER 2 provides important additional data on the performance and safety of MCED testing"

A multi-cancer early detection (MCED) test is a blood-based screening tool designed to detect signs of many different cancers from a single sample, often before symptoms appear. For investors, MCEDs matter because they represent a potential shift from disease-by-disease screening to a one-stop early-warning test, which could unlock large markets, change clinical practice, and carry regulatory, reimbursement and adoption risks similar to other breakthrough medical technologies; think of it as a smoke alarm that tries to spot many types of fires early.

positive predictive value medical

"The likelihood of receiving a cancer diagnosis following a positive test result (positive predictive value or PPV)..."

Positive predictive value is a measure of how likely it is that a positive result actually indicates a true positive. For investors, it helps assess how reliable a signal or indicator is in predicting real opportunities or risks, similar to how knowing that a weather forecast predicts rain accurately helps you decide whether to carry an umbrella. A higher positive predictive value means greater confidence that a positive signal truly reflects a meaningful event.

specificity medical

"Specificity was 99.6%, translating to a false positive rate of less than 0.4%."

Specificity measures how well a diagnostic test or screening correctly identifies people who do not have a condition — the percentage of healthy cases the test labels as negative. Think of it as a smoke alarm that stays quiet when there’s no fire; high specificity means fewer false alarms. For investors, specificity affects regulatory approval, clinical adoption, follow-up costs, and the perceived reliability and market potential of medical products.

false positive rate medical

"Specificity was 99.6%, translating to a false positive rate of less than 0.4%."

The false positive rate is the share of cases a test or system flags as positive when in fact nothing is present — like a smoke detector that sounds for burnt toast instead of a real fire. For investors it measures how often a product, clinical test, or algorithm gives misleading alerts, which can drive extra costs, regulatory concerns, lower trust, and affect revenue or adoption forecasts.

cancer signal origin medical

"the test correctly identified the Cancer Signal Origin (CSO) 91.3% of the time..."

Cancer signal origin is the anatomical site or tissue type where molecular signs of cancer — such as pieces of DNA, proteins or other markers found in a blood or tissue test — are coming from. Knowing the origin is like hearing a smoke alarm and finding which room is on fire: it helps doctors choose the right diagnostic follow‑ups and treatments, and it matters to investors because accurate origin detection can make diagnostic tests more valuable, marketable and likely to gain regulatory approval.

invasive procedure medical

"only 0.6% of all safety-analyzable participants had an invasive procedure..."

An invasive procedure is a medical intervention that enters the body by cutting or puncturing the skin or by inserting instruments into internal spaces, organs, or vessels—for example, surgery or catheter-based treatments. Investors care because such procedures carry higher regulatory scrutiny, development costs, and potential liability, and their success or adoption can directly affect a health company's revenue, reimbursement prospects, and market valuation; think of it as a more complex product launch with greater rules and risks.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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The Galleri Multi-Cancer Early Detection (MCED) Test Increased Cancer Detection 6.5 Fold When Added to Recommended Screenings for Breast, Colorectal, Cervical and Lung Cancer

71% of the New Cancers Detected by the Galleri Test Were in Stages I-III

MENLO PARK, Calif., May 31, 2026 /PRNewswire/ -- GRAIL, Inc. (Nasdaq: GRAL), a healthcare company whose mission is to detect cancer early when it can be cured, today announced that positive performance and safety results from the analysis of the full 35,878 cohort of its registrational PATHFINDER 2 study are being presented during an oral session at the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting^[1].

The PATHFINDER 2 study evaluated the safety and performance of the Galleri^® multi-cancer early detection (MCED) test when used alongside standard-of-care cancer screenings in the U.S. and Canada. The prospective PATHFINDER 2 study is the largest interventional study of an MCED in North America to date and includes 35,878 participants in a broad, intended-use population of adults aged 50 and older with no clinical suspicion of cancer.

"Cancer outcomes depend not only on better treatments, but on finding cancer before it advances and spreads. Earlier detection can open the door to more treatment options at any stage and increase the chance for cure," said Josh Ofman, MD, MSHS, President and CEO-Elect at GRAIL. "These PATHFINDER 2 results add to the growing body of clinical evidence in a large, representative intended-use population showing that the Galleri test can meaningfully increase cancer detection beyond recommended screening with strong performance and a highly favorable safety profile. Along with the NHS-Galleri trial results, these findings reinforce the clinical benefit of Galleri and its potential to transform early cancer detection at population scale."

Galleri Increases the Number of Cancers Detected and Can Detect Them Early

While effective screening improves early cancer detection, in the U.S., only 14% of all cancers are detected by guideline-recommended screening tests^[2]. In PATHFINDER 2, 60% of diagnosed cancers were screen-detected (264/440). Adding Galleri to recommended screenings for breast, cervical, colorectal, and lung cancers (USPSTF A and B recommendations) led to a 6.5 fold increase in the number of cancers found by screening. Galleri detected nearly three times as many cancers when added to standard-of-care screening for breast, cervical, colorectal, lung, and prostate cancers (USPSTF A, B, and C recommendations).

More than half (53.0%) of the new cancers detected by Galleri were stage I or II, and 71.3% of these have no USPSTF A and B recommended screening. More than two-thirds (70.9%) of the new cancers detected by Galleri were detected at stages I-III, when treatment with curative intent is more often possible.

"PATHFINDER 2 provides important additional data on the performance and safety of MCED testing," said Karthik Giridhar, M.D., assistant professor of oncology at Mayo Clinic and a principal investigator on the PATHFINDER 2 study. "MCED tests are not a replacement for existing screening, but they have the potential to complement current approaches by helping detect cancer signals across multiple cancer types, including some for which routine screening is not currently available."

Robust Performance Metrics Consistent with Previous Studies

The Galleri test detected a cancer signal in 287 participants, and of those, cancer was diagnosed in 173 participants. The likelihood of receiving a cancer diagnosis following a positive test result (positive predictive value or PPV) was 60.3%, consistent with previously reported initial results of PATHFINDER 2 and higher than the first PATHFINDER study. 

Since PATHFINDER 2 is a prospective clinical trial where the cancer status of participants is unknown at the outset, episode sensitivity – the ability to detect cancer that could be confirmed within 12 months after the blood draw – is evaluated in the study. Galleri demonstrated strong performance, with 69.8% episode sensitivity for the 12 cancers responsible for two-thirds of cancer deaths in the U.S. For all cancers, episode sensitivity was 39.3%.

Specificity was 99.6%, translating to a false positive rate of less than 0.4%.

"The up to 6.5 fold improvement in screen-detected cancers with Galleri in PATHFINDER 2 study, coupled with the greater than 20% reduction in Stage 4 cancers observed in the NHS-Galleri trial, is really exciting data that help support Galleri's performance in a diverse and representative population," said Nima Nabavizadeh, MD, Associate Professor of Radiation Medicine at Oregon Health & Science University. "As an oncologist, I have seen too many patients diagnosed only after their cancer has spread, when treatment decisions become more difficult. By helping find more cancers earlier, when more treatment options may be available, there is great potential for multi-cancer early detection to transform cancer screening."

Galleri Pinpoints Cancer Signal Origin Allowing Efficient Diagnostic Workups

A key benefit of the Galleri test is its ability to predict where in the body the cancer signal is coming from. The PATHFINDER 2 study demonstrated that the test correctly identified the Cancer Signal Origin (CSO) 91.3% of the time, leading to efficient diagnostic workups. Diagnostic resolution took a median of 48 days, and only 0.6% of all safety-analyzable participants had an invasive procedure (213/35,335) following a positive MCED test result. A total of 90.5% of invasive procedures were nonsurgical.

Screening with the Galleri test had a favorable safety profile, with a low false-positive rate and a low rate of invasive procedures. There were five study-related adverse events reported during diagnostic evaluation, only in those with cancer diagnosis. Anxiety temporarily increased for participants with a positive MCED test and subsequent cancer diagnosis, and returned to baseline by 12 months, as has been observed for other screening tests. One serious adverse event related to the diagnostic work-up was identified after the data lock. Follow-up is ongoing; this and any other findings after data lock will be reported in full in the next interim analysis.

About PATHFINDER 2 (NCT05155605)
PATHFINDER 2 is a prospective, multi-center, interventional study evaluating the safety and performance of Galleri in approximately 35,000 individuals aged 50 years and older who are eligible for guideline-recommended cancer screening in the United States. The primary objectives of the study are 1) to evaluate the safety and performance of the Galleri MCED test based on the number and type of diagnostic evaluations performed in participants who receive a cancer signal detected test result, and 2) to evaluate the performance of the Galleri MCED test across various measures, including PPV, negative predictive value (NPV), episode sensitivity, specificity, and CSO prediction accuracy. Participants who receive a cancer signal detected result undergo additional diagnostic testing based on the predicted CSO to determine if a cancer is present. Secondary objectives include utilization of guideline-recommended cancer screening procedures after use of the MCED test, and participant reported outcomes over several time points, including an assessment of participants' anxiety and satisfaction with the MCED test. 

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, Calif. 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 (MCED) test screens for more than 50 cancer types, including many deadly cancers that currently lack screening options, such as pancreatic, ovarian and liver/bile duct cancers^[3]. The Galleri test is the only MCED test clinically proven through a randomized controlled trial to increase earlier cancer detection (Stage I-III) and reduce Stage IV diagnoses - enabling more patients to have curative treatment^[4]. When added to standard-of-care screening, the Galleri test reduced Stage IV diagnosis by more than 20% after the first year of screening across all stageable cancers^4,*. The Galleri test increased cancer detection by screening four times versus standard of care screening alone⁴. The Galleri test has the lowest false positive rate among MCED tests** and the ability to predict the Cancer Signal of Origin with greater than 90% accuracy, helping guide efficient diagnostic evaluation^1,4,[5]. The Galleri test is backed by a robust evidence program, with more than 380,000 participants across multiple studies, including the NHS-Galleri trial, the first and only randomized controlled trial for an MCED test. The Galleri test has delivered consistent performance across these studies. 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.

*A statistically significant reduction was not observed in combined stage III–IV diagnoses across three screening rounds for the 12 deadly cancers.

**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, extrapolation of trends in the results, comparability of the results to a real world setting, benefits of population screening with Galleri, the applicability of the PATHFINDER 2 results to the commercial or FDA versions of the Galleri test, and plans to submit the results for publication, 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.

^[1] Giridhar K, et al. Safety and Performance Results From PATHFINDER 2 (PF2), a Registrational Study of a Multi-Cancer Early Detection (MCED) Test in an Intended-Use Population [presentation]. American Society of Clinical Oncology (ASCO) Annual Meeting; 2026 May 29-June 2

^[2] NORC at the University of Chicago. Percent of cancers detected by screening in the U.S. https://cancerdetection.norc.org/ (2022).

^[3] 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

^[4] Swanton C. 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 [presentation]. American Society of Clinical Oncology (ASCO) Annual Meeting; 2026 May 29-June 2.

^[5] GRAIL, Inc. False positive rate. [Data on file: GR-2025-0256]

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SOURCE GRAIL, Inc.

FAQ

What is GRAIL (GRAL) PATHFINDER 2 and how many participants were enrolled?

PATHFINDER 2 is a prospective study evaluating the Galleri multi-cancer early detection test in routine screening, enrolling 35,878 adults 50 and older. According to GRAIL, it is the largest interventional MCED study in North America, assessing safety and performance in an intended-use population.

How much did the Galleri test improve cancer detection in PATHFINDER 2 for GRAL?

Galleri increased screen-detected cancers up to 6.5-fold when added to recommended breast, cervical, colorectal and lung screenings. According to GRAIL, the test also found nearly three times as many cancers when combined with standard screening, including prostate, compared with guideline-based screening alone.

What early-stage cancer detection results did GRAIL (GRAL) report from PATHFINDER 2?

Galleri detected many cancers at earlier stages, with 53% of new Galleri-detected cancers in stage I or II. According to GRAIL, 70.9% of new Galleri-detected cancers were stages I-III, when treatment with curative intent may be more feasible for patients.

What were the Galleri test sensitivity and specificity metrics in GRAIL (GRAL) PATHFINDER 2?

Galleri showed 69.8% episode sensitivity for 12 cancers causing about two-thirds of U.S. cancer deaths, and 39.3% for all cancers. According to GRAIL, specificity reached 99.6%, resulting in a reported false-positive rate under 0.4% in the study population.

What positive predictive value (PPV) did the Galleri test show for GRAL in PATHFINDER 2?

The Galleri test had a positive predictive value of 60.3%, with cancer diagnosed in 173 of 287 participants with a positive test. According to GRAIL, this PPV was consistent with earlier PATHFINDER 2 data and higher than in the first PATHFINDER study.

How accurately did Galleri identify cancer signal origin in GRAIL (GRAL) PATHFINDER 2?

Galleri correctly identified the cancer signal origin in 91.3% of relevant cases, aiding targeted diagnostic workups. According to GRAIL, diagnostic resolution took a median of 48 days, and only 0.6% of safety-analyzable participants underwent an invasive procedure following a positive MCED result.

What safety and adverse event data did GRAIL (GRAL) report for Galleri in PATHFINDER 2?

Screening with Galleri showed a favorable safety profile, with low false-positive and invasive procedure rates. According to GRAIL, there were five study-related adverse events during diagnostic evaluation, one serious adverse event identified after data lock, and temporary anxiety increases that returned to baseline by 12 months.