On May 31, 2026 GRAIL, Inc. (Nasdaq: GRAL), a healthcare company whose mission is to detect cancer early when it can be cured, reported 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) (Free ASCO Whitepaper) Annual Meeting.
Schedule your 30 min Free 1stOncology Demo!
Discover why more than 1,500 members use 1stOncology™ to excel in:
Early/Late Stage Pipeline Development - Target Scouting - Clinical Biomarkers - Indication Selection & Expansion - BD&L Contacts - Conference Reports - Combinatorial Drug Settings - Companion Diagnostics - Drug Repositioning - First-in-class Analysis - Competitive Analysis - Deals & Licensing
Schedule Your 30 min Free Demo!
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.
(Press release, Grail, MAY 31, 2026, View Source [SID1234666272])