As the multi-cancer early detection (MCED) field evolves, we and others have asserted that it is essential – in order for individuals to have confidence in a test – that it must have demonstrated performance in a prospective trial in the intended use population (Ofman 2025). In addition, payor and large health system adoption of a test across their populations requires evidence that the use of the test improves outcomes across a population, and the benefits outweigh potential harms. To understand whether Galleri provides a meaningful benefit at population scale, we needed a randomized controlled trial (RCT) to evaluate whether screening with Galleri improves outcomes in real-world practice.

That is why we launched the NHS-Galleri trial in England in 2021 (NCT05611632; ISRCTN91431511). The NHS-Galleri trial – the only population-scale RCT of an MCED – is evaluating annual screening with Galleri alongside standard NHS cancer care (Neal 2022). Reflecting the huge public appetite for a test like this, we enrolled more than 140,000 people in just over 10 months during 2021–2022 (Swanton 2025) – a remarkable achievement, particularly in the shadow of the COVID-19 pandemic. 

As we look ahead to the main trial results in 2026, here’s what to expect – and why the trial was designed the way it was.

A Large, Pragmatic RCT Embedded In The NHS
We designed the trial within the NHS to leverage high quality, nationally collected, consistently curated and centralized cancer datasets, enabling prospective follow-up of every participant’s cancer and health status. This infrastructure supports robust evaluation of outcomes, diagnostic pathways, treatments, complications and healthcare resource use (Neal 2022). 

Leveraging the NHS DigiTrials invitation system enabled us to enroll more than 140,000 individuals aged 50 to 77, who had no signs or symptoms raising clinical suspicion of cancer and who had not been diagnosed or treated for cancer in the prior three years. Critically, we designed the invitation system and trial operations to mitigate the “healthy volunteer” effect seen in almost all large cancer screening trials conducted to date and successfully recruited a demographically representative cohort, including from the most socio-economically deprived communities, where the cancer burden is highest (Swanton 2025).

Participants were randomized after their first blood draw to either:

Crucially, Galleri’s “Cancer Signal Origin” (CSO) feature – which indicates the tissue or organ most likely to be the source of a detected cancer signal – enabled diagnostic investigation through existing NHS pathways. This helped focus diagnostic workups more efficiently and consistently across sites, while ensuring parity between intervention and control arms through standard-of-care pathways (Lowenhoff 2025; Neal 2022).

Late-stage Reduction as the Primary Objective
The primary objective of the NHS-Galleri trial is to demonstrate a statistically significant reduction in the incidence of late-stage cancers in the intervention arm compared with the control arm. This will be assessed after the follow-up of the three annual screens and should be available in mid 2026 (Neal 2022). 

To maximize clinical relevance and statistical rigor, the analysis will be conducted sequentially across three prespecified cancer groupings. First, we will look for a statistically significant reduction in stage III and IV cancer in a pre-specified group of 12 cancer types that together represent approximately two-thirds of cancer deaths in the UK and US, most of which do not have any screening available today (Note 1). If a statistically significant reduction is found, the primary objective is met. A subsequent analysis will look for a difference in all routinely staged cancer types other than prostate cancer (given that prostate cancer is known to be subject to overdiagnosis, which impacts the perceived benefit of late-stage reduction). If the second evaluation also shows a significant reduction, then all stageable cancers, including prostate, will be analyzed. This stepwise approach concentrates first on cancers where there is the greatest unmet need and where earlier detection could have the greatest impact on outcomes. 

The primary objective of the NHS-Galleri trial is grounded in a growing body of evidence showing that, across multiple cancers, reductions in late-stage disease are strongly associated with reductions in cancer mortality (Dai 2024; Sasieni 2025a). In other words, if a screening program reliably shifts diagnoses from late to earlier stages, we should expect to see mortality benefits emerge over time. Measuring late-stage incidence after three annual screens, rather than waiting solely for mortality data, allows earlier, evidence-based decisions on next steps, enabling us to start improving outcomes much earlier than would otherwise be the case.

Importantly, although the trial is not designed or statistically powered to detect a reduction in cancer-specific mortality, this will be assessed in several complementary ways. First, in the near-term, we will model predicted cancer-specific mortality based on observed differences in stage distribution between the trial arms, benchmarking against outcomes for similar NHS cancer patients. Second, we will conduct a novel “nested mortality” analysis that focuses on where screening would confer benefit – among test-positive individuals – by retrospectively testing stored samples from control participants who are later diagnosed with cancer (Hackshaw 2021; Sasieni 2025b). Finally, observed cancer-specific mortality will be reported at three and six years after the final screen; most screening studies have taken a decade or two to read out their mortality findings. 

What Else Will the Trial Tell Us?
The NHS-Galleri trial will also consider other very important objectives, including: reduction in stage IV cancer; performance of the Galleri test, including PPV and false positive rate; increase in overall cancer detection rate (see our recent performance primer for more detail on these measures); safety; and healthcare resource utilization (see Neal 2022 for more detail on key secondary and exploratory objectives).

Taken together, these data will provide a comprehensive view of the benefits and risks of introducing annual MCED screening alongside existing NHS programs.

In particular, a reduction in stage IV cancer diagnoses will be a critically important outcome. With a substantial and growing arsenal of effective treatments for many stage III cancers (Cohen 2025, Gondal 2023, Forde 2025, Uppaluri 2025), it is increasingly the case that a shift from stage IV to stage III will provide the biggest contribution to improving outcomes across many cancer types.

Furthermore, trial results will tell us whether adoption could shift diagnoses away from emergency presentations – currently around 20% of cases – which have the worst outcomes (NDRS), and increase the proportion of all cancer cases found through screening, currently around 6% in the UK and 14% in the US (NDRS, NORC).

Conclusion: What To Expect In 2026 And Beyond
In 2026, the NHS-Galleri trial will report on whether annual screening with Galleri reduces the incidence of late-stage cancer relative to standard care. These results will be of global significance. In the UK, the results will inform recommendations from the National Screening Committee and potential next steps, such as an expanded in-service evaluation within the NHS. Longer term read-outs will add important context over time.  

The opportunity is profound. Positive results, including a reduction in late-stage cancers, would mark a long-overdue shift in how we find cancer – one that could be scaled equitably through public health systems worldwide to potentially benefit millions.

Note 1: The 12 pre-specified cancer types are: anus, bladder, colon/rectum, esophagus, head and neck, liver/bile duct, lung, lymphoma, myeloma/plasma cell neoplasm, ovary, pancreas, stomach.

References

Clarke CA, et al. 2020. Cancer Epidemiol Biomarkers Prev. 29(5):895-902. doi: 10.1158/1055-9965.EPI-19-1366.

Cohen R et al. 2025. ESMO Open. 10(3):104481. doi: 10.1016/j.esmoop.2025.104481.

Dai JY, et al. 2024. J Med Screen. 31(4):211-222. doi: 10.1177/09691413241256744.

Forde PM, et al. 2025. 393(8):741-752. doi: 10.1056/NEJMoa2502931.

Gondal TA, et al. 2023. Curr Oncol. 30(3):3232-3250. doi: 10.3390/curroncol30030246.

Hackshaw A, Berg CD. 2021. Lancet Oncol. 22(10):1360-1362. doi: 10.1016/S1470-2045(21)00204-7.

Lowenhoff I, et al. 2025. Front Oncol. 15:1511816. doi: 10.3389/fonc.2025.1511816.

National Disease Registration Service. Routes to Diagnosis 2006-2020. Available at: https://nhsd-ndrs.shinyapps.io/routes_to_diagnosis/.

Neal RD, et al. 2022. Cancers (Basel). 14(19):4818. doi: 10.3390/cancers14194818.

NORC at the University of Chicago. (2022). Percent of Cancers Detected by Screening in the U.S. Available at: https://cancerdetection.norc.org/

Ofman J et a. 2025. Available at: https://grail.com/stories/not-all-mced-tests-are-created-equal-the-realities-of-mced-test-development-and-validation/

Sasieni P, et al. 2025a. Ann Oncol. 36(6): 706-708. doi: 10.1016/j.annonc.2025.03.001. 

Sasieni P, Brentnall AR. 2025b. JNCI. 117(3):450–455. doi: 10.1093/jnci/djae251.

Swanton C, et al. 2025. Clin Trials. 22(2):227-238. doi: 10.1177/17407745241302477.

Uppaluri R, et al. 2025. New Engl J Med. 393(1):37-50. doi: 10.1056/NEJMoa2415434.

Cancer screening has transformed outcomes for several cancers, but the vast majority of cancer deaths still occur in patients who have cancers without recommended screening tests. Multi-cancer early detection (MCED) tests can help address that gap. Rather than screening for one cancer at a time, the Galleri® MCED test looks for a shared cancer signal in blood and, when a signal is found, predicts the Cancer Signal Origin (CSO) with high accuracy to help guide follow-up. 

To develop and launch Galleri, GRAIL has built what we believe is the largest clinical program in genomic medicine to-date, enrolling more than 380,000 participants across nine clinical trials. Many of these studies have published results (Liu 2020, Klein 2021, Jamshidi 2022, Nicholson 2023, Schrag 2023), including clinical validation across our CCGA3 case-control study and the PATHFINDER interventional trial in an intended-use screening population (Klein 2021, Schrag 2023, Ofman 2025). 

As we approach completing submission of our Premarket Approval (PMA) package to the FDA in the first half of 2026, attention is turning to readouts from our two registrational trials: PATHFINDER 2, the largest U.S.-based interventional MCED study, and NHS-Galleri, the first and only population-scale randomized controlled trial of an MCED. With initial results from PATHFINDER 2 expected at the European Society for Medical Oncology (ESMO) Congress in October 2025 (GRAIL 2025 [1]), the readout will be an important milestone for understanding how MCED can be implemented in everyday clinical practice, as well as the path to population scale adoption.

What PATHFINDER 2 is Designed to Do

PATHFINDER 2 is a prospective, single-arm, return-of-results trial designed to evaluate Galleri’s performance, safety, and implementation in an intended-use population. A clinical utility measure — the cancer detection rate in the population when added to SOC screening tests — will also be assessed. The trial enrolled 35,878 adults aged 50 and older across healthcare systems in the U.S. and Canada who were eligible for routine, guideline-recommended screening and had no signs or symptoms raising clinical suspicion of cancer. 

The cohort was intentionally diverse by race, ethnicity, age (including those over 80), and prior cancer history, to reflect day-to-day clinical practice and help minimize the “healthy volunteer bias” often seen in screening trials. Participants provided a single blood draw at enrollment and were followed for 12 months to determine cancer status (i.e., presence or absence of cancer). 

The primary objectives are two-fold: to evaluate the safety of Galleri in terms of the blood draw and diagnostic testing triggered by the test result, and to evaluate performance of the Galleri test in individuals eligible for cancer screening.

Diagnostic Testing and Safety

Because PATHFINDER 2 returns results to participants and their providers, it captures diagnostic pathways in real time. For those with a “Cancer Signal Detected” result, we track what follow-up tests were ordered, how invasive they were, and how quickly a diagnostic resolution (whether cancer was present or not) was reached. Building on the first PATHFINDER trial, where most evaluations began with imaging and invasive procedures were generally reserved for cases with clear clinical pathways, PATHFINDER 2 also focuses on safety, with the goal of minimizing unnecessary testing, avoiding harm where possible, and helping people with a positive result reach diagnostic resolution efficiently. 

For participants with a “No Cancer Signal Detected” result, our communications to participants reinforce a critical message: continue all routine screenings for cancers like breast, cervical, colorectal, lung (for those at high risk), and prostate. MCED is designed to complement, not replace, guideline-recommended screening.

Key Performance and Clinical Utility Measures and Why They Matter

PATHFINDER 2 will also report a standard set of performance measures, covered in more detail in a separate post. Two measures are worth calling out here, both of which are critical measures of a multi-cancer test’s performance: 

Both are crucial for evaluating MCED test performance. On an individual-level, a higher PPV – partially driven by maintaining a very low false positive rate of 0.5% as well as the aggregate prevalence of cancers – means fewer unnecessary procedures and higher confidence in a positive test result. On a population-level, a higher CDR means many more screen-detected cancers are found before symptoms arise in the patient population. 

We believe that measures such as PPV and CDR are the most informative for understanding an MCED test’s performance, and that these must be measured in an intended use population trial like PATHFINDER 2 (Ofman 2025).

What PATHFINDER 2 Is Not Designed to Do

Equally important is what this trial is not designed to address. PATHFINDER 2 does not measure whether adding MCED to usual care reduces late-stage cancer incidence, a clinical utility endpoint. Those types of endpoints require large randomized controlled trials with multi-year testing and follow-up (Kumar 2024, Neal 2022). The NHS-Galleri trial in England was designed specifically for that purpose and results are expected in mid-2026. 

Building on Prior Evidence

Although no single study can answer every question, the PATHFINDER 2 trial represents a pivotal step. It builds on our robust clinical validation studies: the case-control CCGA study (Klein 2021) and the interventional intended use PATHFINDER trial (Schrag 2023). The first PATHFINDER trial showed that adding MCED to recommended screening more than doubled the number of cancers detected, that most CSO-directed follow-up evaluations led directly to diagnostic resolution, and that invasive procedures were largely concentrated in those who truly had cancer. That trial also reported a high PPV of 43.1%, underscoring the urgency of that directed workup (Schrag 2023). PATHFINDER 2 builds on these results in a much larger, more diverse U.S. cohort.  And, more recently, the PATHFINDER 2 and NHS-Galleri trials reported encouraging top-line results, including PPVs that are substantially higher than observed in prior clinical studies (GRAIL 2025 [2], GRAIL 2025 [3]).

Looking Ahead

In the bigger picture, PATHFINDER 2 is expected to clarify how MCED can be implemented in routine practice, as well as the additional cancers detected when added to SOC screening (cancer detection rate). NHS-Galleri is intended to inform what population-scale use could mean for reducing late-stage diagnoses and improving longer-term outcomes. 

Together, these trials are providing an expanded evidence base for responsible, large-scale adoption of MCED. For patients, providers, and health systems, the PATHFINDER 2 readout represents a meaningful step towards population-scale MCED implementation, and ultimately a paradigm shift in cancer screening. 

References

GRAIL, Inc [3] (2025, September 25). GRAIL to Present New Galleri® Data From More Than 32,000 Participants Across the PATHFINDER 2, SYMPLIFY and REFLECTION Studies at ESMO Congress 2025 and EDCC [press release]. https://grail.com/press-releases/grail-to-present-new-galleri-data-from-more-than-32000-participants-across-the-pathfinder-2-symplify-and-reflection-studies-at-esmo-congress-2025-and-edcc/

GRAIL, Inc. [2] (2025, May 13). GRAIL Reports First Quarter 2025 Financial Results [press release]. https://grail.com/press-releases/grail-reports-first-quarter-2025-financial-results/

GRAIL, Inc. [3] (2025, June 18). GRAIL Announces Positive Top-Line Results From The Galleri® PATHFINDER 2 Registrational Study [Press release]. https://grail.com/press-releases/grail-announces-positive-top-line-results-from-the-galleri%e2%93%a1-pathfinder-2-registrational-study/

Jamshidi A, Liu MC, Klein EA, et al. Evaluation of cell-free DNA approaches for multi-cancer early detection. Cancer Cell. 2022;40(12):1537-1549.e12.  

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):1167-1177. doi: 10.1016/j.annonc.2021.05.806.

Liu MC, Oxnard GR, Klein EA, et al. Sensitive and specific multi-cancer detection and localization using methylation signatures in cell-free DNA. Ann Oncol. 2020;31(6):745-759. 

Neal RD, Johnson P, Clarke CA, et al. Cell-Free DNA–Based Multi-Cancer Early Detection Test in an Asymptomatic Screening Population (NHS-Galleri): Design of a Pragmatic, Prospective Randomised Controlled Trial. Cancers (Basel). 2022;14(19):4818.

Nicholson BD, Oke J, Virdee PS, et al. Multi-cancer early detection test in symptomatic patients referred for cancer investigation in England and Wales (SYMPLIFY): a large-scale, observational cohort study. JAMA Onc. 2023;24(7):733-743.

Ofman J, Hall MP, Clarke-Dur C. Not all MCED tests are created equal: the realities of test development and validation. July 31, 2025. Available at grail.com. Accessed September 10, 2025.

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. 

For further details about Galleri test performance, visit grail.com and galleri.com.

View the white paper here.

By Joshua Ofman MD, MSHS, GRAIL President; Megan P. Hall Ph.D., GRAIL Medical Affairs; Christina Clarke Dur Ph.D. GRAIL Cancer Epidemiology

Multi-cancer early detection (MCED) tests hold enormous promise, but will only achieve their public health and clinical impact if the tests are validated rigorously in the appropriate “intended use” population: adults at elevated risk with no clinical suspicion of cancer.

While there are several MCED tests in the discovery and development phase, we believe that no cancer screening test should be introduced into clinical practice until its performance has been prospectively validated in the intended use population. The Food and Drug Administration (FDA) has announced a similar approach for how safety and effectiveness is established for diagnostic tests (Note 1). GRAIL’s GalleriⓇ MCED test was not launched until the PATHFINDER study, which was conducted under an FDA-approved investigational device exemption application, confirmed Galleri’s performance in the intended use population: adults aged 50 and above with no clinical suspicion of cancer (Schrag 2023). Clinical validation from an interventional study in the intended use population must not be confused with analytical or basic validation from confirmatory sample sets in discovery and development studies. 

Why is clinical validation in the intended use population so important for cancer screening? 
For certain MCED tests in development, promising performance in retrospective case-control studies has not consistently been confirmed by trials in the intended use population evaluating performance in clinical practice. Retrospective case-control studies may have significant study design flaws. For example, studies may be small, have cases and controls that are highly selected and not representative of cancer prevalence in the general population, or are not appropriately “matched” – e.g., the samples are from different times, different clinics or health systems, and/or patients of different ages. These limitations can lead to non-reproducible results, which may include detecting study artifacts rather than cancer, not clearly distinguishing (or even combining) training and validation sample sets, batch effects (differences in sample handling and machine conditions), or other technical artifacts. This has been observed previously with ovarian cancer tests (e.g., Petricoin 2002, Baggerly 2005) and other early MCED technologies (e.g., Cohen 2018, Lennon 2020). For example, the original CancerSEEK assay is a case-control study that reported a specificity of greater than 99% (Cohen 2018). However, when studied in a clinical trial in the intended use population, the specificity of the first blood test was 95.3% (at least a 4.7 times higher false-positive rate), with a positive predictive value (PPV) of 5.9% (Lennon 2020). 

Unfortunately for the MCED field, some test developers are claiming results from small, retrospective case-controlled studies as “validation” with no reported plans for prospective studies in the intended use population (Abraham 2025, Seeking Alpha). The results of such studies may appear promising at first glance, but they should not be considered validation for real-world screening readiness. There is simply no way to establish a test’s safety or benefits until clinical validation performance has been established in the intended use population. 

If tests without sufficient validation are prematurely offered and result in patient harm, the entire field of MCED could be set back, which has the potential to dramatically impact public health. Harms to individual patients may result from missing deadly cancers, the risks of excessive diagnostic follow-ups resulting from tests with high false-positive rates, and the risk of over-diagnosing indolent cancers. The only way to understand, quantify, and minimize these patient risks is by ensuring that any test introduced into clinical practice has been adequately and rigorously validated with strong performance characteristics in the intended use population. 

The first clinically introduced MCED test – Galleri – is supported by strong, published results from large and well-designed case-controlled studies, interventional trials, and real-world studies in the intended use population (Klein 2021, Schrag 2023, Atwood 2024). Specifically, the Galleri test’s robust specificity and cancer signal origin (CSO) accuracy in two of the largest and most diverse trials ever conducted in cancer screening, including the first and only MCED randomized controlled trial, has confirmed what was observed in earlier studies (Klein 2021, Schrag 2023, Giridhar 2024, Neal 2022, GRAIL 2025 [1], GRAIL 2025 [2]). Importantly, the PPV substantially increased in these larger and more representative trials (GRAIL 2025 [1], GRAIL 2025 [2]) and cancer detection rates were substantially higher when added to standard of care (SOC) screening in PATHFINDER 2 compared to PATHFINDER (GRAIL 2025 [2]). The results of this breakthrough technology and the education of the clinical community have helped catalyze the entire MCED field. However, the MCED field is at risk if other MCED tests are launched without the same approach to validation and without rigorously demonstrating a favorable benefit-risk profile. 

Cancer is soon to become the leading killer worldwide, and the current status quo of cancer screening is unacceptable. We only look for three cancers in women (breast, colon, and cervical), two in men (colon and prostate), and leverage an additional screen (lung) for heavy smokers (Nicholson 2024, Davidson 2021, Krist  2021, Curry SJ 2018, Grossman DC 2018). While these screening tests are saving lives, we recently estimated with the American Cancer Society that nearly 80% of cancer deaths result from all of the other cancers we are not screening for today (Ofman 2025) – there is no mechanism to detect those cancers before symptoms appear, when cancers are more treatable and outcomes are better. The SOC screening paradigm only identifies 14% of cancers in the population (Ofman 2025) in the U.S. Adding the Galleri test to SOC screening could dramatically increase the cancer detection rate in the population (Hackshaw 2021) without increasing the risk of over-diagnosis (Chen 2020, Swanton 2025). In the PATHFINDER trial in the intended use population, adding Galleri to SOC more than doubled the number of cancers detected, with half being in stages 1 or 2 (Schrag 2023).

It is quite apparent that not all MCED tests are created equal. For this reason, any comparison of test performance must be evidence-driven and based on the study design, as we describe below (Note 2). For example, it would be clinically inappropriate to compare the results from a case-control study against those from an interventional study. 

To realize the tremendous promise of MCED tests, and continue to develop this important field, all test developers must be held to high standards. Our families, our loved ones, and patients are depending on us. 

Note 1: FDA Guidance Documents Supporting Methodologies and Expectations for Clinical Validation 

Design Considerations for Pivotal Clinical Investigations for Medical Devices

“Sites from which subjects or samples are chosen for studies that support the intended use of the device should be representative of the types of sites where the device is intended to be used. Subjects or samples should also represent the proposed target population. Estimates of overall performance from non-representative sites or subjects may suffer from selection bias.” 

Statistical Guidance on Reporting Results from Studies Evaluating Diagnostic Tests

“We note at the outset that evaluation of a new diagnostic test should compare a new product’s outcome (test results) to an appropriate and relevant diagnostic benchmark using subjects/patients from the intended use population; that is, those subjects/patients for whom the test is intended to be used.” 

In Vitro Diagnostic (IVD) Device Studies – FAQs

“Studies should be performed in a representative sample of the intended use population (i.e., representation of both diseased and non-diseased cases, and controlling for subject demographics and morbidity factors that may affect the level of device performance).”

Note 2: A Checklist for Careful Evaluation of Blood-Based MCED Studies

There are important considerations when evaluating the results of an MCED study or comparing results between studies. 

  1. What was the study design? Well-designed case-control studies, in which cancer patients are tested after diagnosis, can provide estimates of “test sensitivity.” Interventional studies in the intended use population provide estimates of “episode sensitivity,” because patients are followed for a defined time period to understand what cancers may have been missed by the test, and whether apparent false positive test results actually precede a cancer diagnosis. Performance that is applicable to actual clinical use should be assessed in the intended use population and comparisons should not be made across different study designs. 
  2. In an interventional study, what is the length of the episode? Interventional studies define an episode duration (e.g., 12 months to define the cancer status) to estimate episode sensitivity. Studies with different episode durations may have different sensitivity estimates and are difficult to compare and cannot be compared to estimates of test sensitivity from case-controlled studies.  
  3. Were the sensitivity estimates reported at the same specificity? Any estimates of test sensitivity must be compared in relation to the reported levels of specificity. For example, a 98.5% specificity has a 3x higher false positive rate than a specificity of 99.5%. With a lower specificity, a test would be expected to have a higher sensitivity estimate, all other factors held constant.  
  4. What is the overall cancer incidence and case mix in the study population? Overall cancer incidence rate over the episode may be influenced by the percentage of cancer survivors or other high-risk groups. Cancer case mix is one of the most important study characteristics for interpreting performance. If a population is rife with indolent forms of breast and prostate cancer or late-stage cancers versus more deadly cancers across all stages, the performance characteristics will be very different. Studies that exclude certain cancer types should not be directly compared to studies with a different case mix of cancers, as this will impact the results. 
  5. In the interventional studies, what was the intensity and timing of guideline-based screening or imaging? This will have an impact on the results. 
  6. What is the extent of the healthy volunteer effect? In screening trials, it is usual to have participants who are healthier than the general population, with lower overall cancer incidence rates and higher adherence to guideline-based screening. This can impact the cancer case mix. It is generally appropriate to standardize the cancer case mix to that of a standard population (e.g., SEER) to generate estimates of performance that can be more easily compared across different study populations.
  7. Finally, are the results reported from the MCED blood test itself, or from a combination of tests? (e.g., blood test + PET-CT) 

References:

Abraham, J., Domenyuk, V., Perdigones, N. et al. Validation of an AI-enabled exome/transcriptome liquid biopsy platform for early detection, MRD, disease monitoring, and therapy selection for solid tumors. Sci Rep 2025;15:21173 doi:10.1038/s41598-025-08986-0.

Atwood C, Moy S, Kindy MS, et al. REFLECTION: Initial Findings From a Real-World Evidence Study of Multi-Cancer Early Detection (MCED) and Toxic Exposures Among Veterans in the Veterans Affairs Healthcare System (VA). Poster and Presentation at the Early Detection of Cancer Conference (EDCC); October 22-24, 2024; San Francisco, CA.

Baggerly KA, Coombes KR, Morris JS. Bias, Randomization, and Ovarian Proteomic Data: A Reply to “Producers and Consumers. Cancer Informatics 2005;1. doi:10.1177/117693510500100101.

Chen X, Dong Z, Hubbell E, et al. Prognostic Significance of Blood-Based Multi-cancer Detection in Plasma Cell-Free DNA. Clin Cancer Res 2020;27(15): 4221–4229. doi:10.1126/science.abb9.

Cohen JD, Li L, Wang Y, et al. Detection and localization of surgically resectable cancers with a multi-analyte blood test. Science 2018;359(6378):926–930. 

Curry SJ, Krist AH, Owens DK, et al. Screening for Cervical Cancer: US Preventive Services Task Force Recommendation Statement. JAMA 2018;320;(7):674-686. doi:10.1001/jama.2018.10897.

Davidson KW, Marry MJ, Mangione CM, et al. Screening for Colorectal Cancer: US Preventive Services Task Force Recommendation Statement. JAMA 2021;325;(19):1965-1977. doi:10.1001/jama.2021.6238. 

Giridhar KV, Demeure MJ, Kim RH, et al. PATHFINDER 2: A Prospective Study to Evaluate Safety and Performance of a Multi-Cancer Early Detection Test in a Population Setting. Cancer Res 2024;84(6_Supplement):4784. doi.org/10.1158/1538-7445.AM2024-4784.

GRAIL, Inc. [1] (2025, May 13). GRAIL Reports First Quarter 2025 Financial Results [press release]. https://grail.com/press-releases/grail-reports-first-quarter-2025-financial-results/

GRAIL, Inc. [2] (2025, June 18). GRAIL Announces Positive Top-Line Results From The Galleri® PATHFINDER 2 Registrational Study [Press release]. https://grail.com/press-releases/grail-announces-positive-top-line-results-from-the-galleri%e2%93%a1-pathfinder-2-registrational-study/

Grossman DC, Curry SJ, Owens DK, et al. Screening for Prostate Cancer: US Preventive Services Task Force Recommendation Statement. JAMA 2018;319;(18):1901-1913. doi:10.1001/jama.2018.3710.

Hackshaw A, Cohen SS, Reichert H, Kansal AR, Chung KC, Ofman JJ. Estimating the population health impact of a multi-cancer early detection genomic blood test to complement existing screening in the US and UK. Br J Cancer 2021;125(10):1432-1442. doi: 10.1038/s41416-021-01498-4.

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):1167-1177. doi: 10.1016/j.annonc.2021.05.806.

Krist AH, Davidson KW, Mangione CM, et al. Screening for Lung Cancer: US Preventive Services Task Force Recommendation Statement. JAMA 2021;325;(10):962-970. doi:10.1001/jama.2021.1117.

Lennon AM, Buchanan AH, Kinde I, et al. Feasibility of blood testing combined with PET-CT to screen for cancer and guide intervention. Science. 2020 Jul 3;369(6499):eabb9601. doi: 10.1126/science.abb9601. Epub 2020 Apr 28.

Neal RD, Johnson P, Clarke CA, et al. Cell-Free DNA-Based Multi-Cancer Early Detection Test in an Asymptomatic Screening Population (NHS-Galleri): Design of a Pragmatic, Prospective Randomised Controlled Trial. Cancers 2022;14(19):4818. doi: 10.3390/cancers14194818.

Nicholson WK, Silverstein M, Wong JB, et al. Screening for Breast Cancer: US Preventive Services Task Force Recommendation Statement. JAMA 2024;331;(22):1918-1930. doi:10.1001/jama.2024.5534.

Ofman JJ, Dahut W, Jemal A, Chang ET, Clarke CA, Hubbell E, Kansal AR, Kurian AW, Colditz GA, Patel AV. Estimated proportion of cancer deaths not addressed by current cancer screening efforts in the United States. Cancer Biomark 2025 Jan;42(1):18758592241308754. doi: 10.1177/18758592241308754. Epub 2025 Mar 20. PMID: 40109213.

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This Statement has been prepared in accordance with paragraph 22(2) of Schedule 19 of the UK Finance Act 2016 for the financial year ending December 31, 2024.

How GRAIL manages UK tax risk

GRAIL seeks to be as compliant as possible with local tax legislation, worldwide tax regulations, and corporate social responsibility.  We seek to report and pay the fair amount of tax due, in the appropriate jurisdiction, at the correct time. This is part of GRAIL’s desire to build trust in the tax system amid a period of large-scale international tax reform. GRAIL will not engage in artificial activity purely for tax purposes.  

GRAIL’s attitude towards tax planning

GRAIL’s goal is to fully and accurately comply with our tax obligations with the highest integrity.

Where material uncertainty exists in any area of its business, GRAIL seeks advice to ensure that it is fully compliant with applicable laws.

GRAIL will uphold the applicable tax laws in each country of operation through non-abusive methods of practice and therefore aim to be compliant both with the law as written and the law’s intended effects, where known.

The level of risk that GRAIL is prepared to accept for UK taxation

Rather than fixing set thresholds for acceptable UK tax risk, GRAIL assesses risk on a case-by-case basis based on the relevant facts and circumstances, within the context of the business activities and with the assistance of external advisers where appropriate.

GRAIL’s approach towards its dealings with HMRC

GRAIL seeks to remain transparent and to establish a constructive relationship with HM Revenue & Customs (“HMRC”).  Additionally, we will proactively engage with HMRC, in order to build trust and to reduce uncertainty and risk. GRAIL is cooperative and is committed to working collaboratively with all taxing authorities.

We believe screening individuals for many types of cancer with a multi-cancer early detection (MCED) test represents a significant opportunity to reduce the burden of cancer. Today, with a unanimous vote to advance the “Nancy Gardner Sewell Medicare Multi-Detection Early Detection Screening Coverage Act,” the House Committee on Ways and Means took an important step on the path to ensuring Medicare beneficiaries and their doctors can access these innovative screening tests once they are FDA-approved. While this is a necessary legislative step, in order to become law the bill would have to be passed by the House and the Senate, and then signed into law by the President.

GRAIL stands with the policymakers and cancer community leaders who are working to ensure, through legislation, that Medicare beneficiaries — who have the highest risk for cancer due to age — do not face unnecessary barriers to access.

We believe screening individuals for many types of cancer with a multi-cancer early detection (MCED) test represents a significant opportunity to reduce the burden of cancer.  However, without Congressional action, Medicare beneficiaries and their doctors may face significant delays in accessing these innovative screening tests once they are FDA-approved.  Led by the American Cancer Society’s Cancer Action Network and the Prevent Cancer Foundation, a group of 52 national advocacy organizations today shared their enthusiastic support for meaningful, timely access to MCED technologies and their endorsement of advancing this legislation with its associated policy updates.  GRAIL stands with the policymakers and cancer community leaders who are working to ensure, through legislation, that Medicare beneficiaries — who have the highest risk for cancer due to age — do not face unnecessary barriers to access. 

View the presentation deck here.

To read the blog post from NHS England, click here.

The NHS-Galleri trial, which started enrolling participants in 2021, was designed to inform implementation of the Galleri test as a national screening programme if recommended by the UK National Screening Committee on the basis of the final study results, which are expected in 2026. The trial was designed with three consecutive years of screening in order to achieve the primary endpoint, which is the absolute reduction in the number of late stage (Stage III and IV) cancer diagnoses. 

As described in March, NHS England planned to look at a snapshot of selected first year results (the prevalent screening round with one year of follow-up) from the NHS-Galleri trial to assess whether there is enough compelling early evidence to initiate a pilot of Galleri within the NHS setting. This first year analysis was conducted solely to determine whether there was an early sign of compelling patient benefit, sufficient for the NHS to accelerate an implementation before the final study readout. Three robust, ambitious and pre-specified criteria were assessed: the positive predictive value (PPV) of the Galleri test, the number of late-stage cancers detected and the total number of cancers detected in the intervention arm compared with the control arm. Notably, this was not an interim analysis of the trial primary endpoint, as that analysis requires data from all three rounds of screening.

Based on a snapshot of first-year results from the ongoing NHS-Galleri trial, NHS England has decided to await final results from the three-year trial before determining whether to initiate a pilot of the Galleri test in the NHS.

Advised by a multidisciplinary expert panel, NHS England determined that, while the early analysis showed that the assessed clinical performance of Galleri was very promising — consistent with or better than Galleri’s clinical performance observed in previous published studies — there is not yet enough early compelling evidence to accelerate implementation through a pilot programme at this stage.

As described by the NHS, “Committing to accelerate implementation of the test in the NHS at scale would have been an exceptional step, requiring exceptional data after just one year, and while what we have seen is very promising, the data so far do not support moving at such a fast pace.” Instead, NHS England will make a decision on the basis of the final trial results, expected in 2026. 

This early look at certain selected metrics provides only a limited view. As demonstrated in previous cancer screening trials, results from the first screening round do not always reflect the final results, especially for reduction in late stage diagnosis. In the US National Lung Screening Trial (NLST) for example, participants underwent three annual screenings. Ultimately, the trial demonstrated a significant relative reduction in mortality for those who received low-dose CT screening. However, no reduction in stage IV cancers was observed after the first year of screening. This is because a prevalent screening round often includes many asymptomatic cancers in later stages that have not been ‘swept out’ by that first year of screening. In NLST, the stage IV incidence was reduced after that first year of screening – and was maintained throughout the follow-up period. 

The NHS-Galleri trial – like numerous other cancer screening trials – was designed with multiple years of screening, and thus it remains important to complete the trial and evaluate the primary objective and endpoints at the end of the study. 

Diagnosing more cancers before they present symptomatically is central to GRAIL’s mission and is also a core part of NHS England’s Long Term Plan to transform cancer outcomes. NHS England has reiterated its belief that multi-cancer early detection is an important innovation that could become a core component of its ambition to reduce late-stage cancer diagnosis in the future.

The NHS-Galleri trial completes appointments with the final blood samples being taken in July 2024 and the ongoing involvement of participants (and any subsequent diagnostic follow up in the NHS) remains critical to fully understanding the test’s potential benefit at population scale. We await the final results and I would like to reiterate my sincere appreciation to the more than 140,000 participants who generously volunteered to take part in the trial to contribute to, and advance, this valuable field of science and medicine. 

GRAIL remains focused on our mission to detect cancer early, when it can be cured.

Revenue for the first quarter of 2023, comprised of Galleri test sales and biopharmaceutical partnerships revenue, was $26.7 million. 

We continue to see uptake for Galleri in health systems, clinics and the employer and life insurance channels across the U.S. We surpassed 10,000 Galleri prescribers in early 2024, and we have completed more than 180,000 commercial Galleri tests cumulatively as of the end of March. With forward leaning payors and employers across a multitude of sectors, commercial engagements remains strong. 

Our registrational clinical studies are progressing. The NHS-Galleri study is anticipated to complete its third and final round of planned blood draws in July, and we have enrolled more than 30,000 participants in our PATHFINDER 2 study. Study results for NHS-Galleri are anticipated in 2026. Interim results from PATHFINDER 2 are expected in 2025 when we have a full year follow-up on the first 25,000 patients. Together, these studies are anticipated to include approximately 175,000 participants and support our PMA submission to the FDA. 

Additionally, the Galleri-Medicare study (REACH) will enroll 50,000 Medicare beneficiaries for three annual tests, evaluating the performance and clinical impact of Galleri compared to a matched synthetic control. This study is an important addition to our body of clinical and real-world evidence for multi-cancer early detection.

We continue to pursue potential applications for our technology in precision oncology settings and recently announced a novel risk-classification assay to be included in a lung cancer study in collaboration with AstraZeneca. Data evaluating our methylation technology’s capability in molecular subtyping were recently presented at the American Association for Cancer Research (AACR) Annual Meeting 2024. 

Recent Business Highlights

In the precision oncology setting, we shared data illustrating the potential adaptability of our methylation platform in identifying cancer histological and molecular subtypes through blood samples.