GRAIL shares surged 35% after U.S. Food and Drug Administration staff reviewers raised no major concerns regarding key analytical and safety aspects of Galleri, the company’s blood-based multi-cancer screening test. The development comes ahead of a September 23, 2026 meeting of the FDA’s Molecular and Clinical Genetics Panel, which will review GRAIL’s application for premarket approval of Galleri.
GRAIL submitted its Premarket Approval application on January 29, 2026. The proposed indication is for Galleri to be used in adults 50 years of age or older for screening and early detection of multiple types of cancer. The test analyzes cancer-specific methylation patterns in cell-free DNA from a blood sample and produces either a “Cancer Signal Detected” or “No Cancer Signal Detected” result. When a cancer signal is found, Galleri also predicts the likely anatomical origin of that signal.
The FDA briefing document indicates that agency reviewers have no outstanding questions for the advisory panel regarding Galleri’s analytical performance. The FDA also said it does not have outstanding panel questions concerning the primary safety analyses or the methodology used to bridge results from the earlier investigational version of the test to Galleri.
However, the upcoming advisory committee meeting will address several important questions about the test’s effectiveness and proposed labeling. Among the central issues is whether the clinical evidence supports describing Galleri specifically as an “early detection” test, rather than more generally as a test for detecting multiple cancers.
The FDA is also asking advisers to evaluate Galleri’s performance across individual cancer types, including cancers that already have established screening methods and cancers for which there are currently no guideline-recommended screening programs. The panel will consider the potential benefits and risks of the test and whether certain cancer types may require additional warnings, limitations, or other risk-mitigation measures.
Galleri is a next-generation sequencing-based blood test that identifies methylation patterns in cell-free DNA using proprietary bioinformatics algorithms and machine-learning classifiers. When a cancer signal is detected, the system can predict one of 18 potential Cancer Signal Origin categories, including breast, lung, colon and rectum, prostate, liver and bile duct, pancreas and gallbladder, kidney, ovary, stomach and esophagus, and several hematologic categories.
There are currently no FDA-authorized devices indicated for screening for multiple types of cancer. Galleri received FDA Breakthrough Device Designation in August 2018, and an earlier version of the test became available by prescription in the U.S. in June 2021. However, Galleri has not previously received FDA marketing authorization in the U.S. or another country.
The FDA’s review draws heavily on two pivotal clinical studies, PATHFINDER 2 and NHS-Galleri. Both trials prospectively tested an earlier investigational version of the technology known as MCED-V2. GRAIL then conducted bridging analyses in which stored plasma samples from subsets of participants were retrospectively tested using the current Galleri assay.
In PATHFINDER 2, Galleri demonstrated 35.0% 12-month episode sensitivity and 99.85% specificity. Its positive predictive value was 77.0%, while its negative predictive value was 99.07%. The study produced a 0.15% false-positive rate and a cancer detection rate of 0.49%, corresponding to approximately 202 people screened for every cancer detected.
Results from NHS-Galleri were broadly similar but showed some differences. Galleri had 31.6% 12-month episode sensitivity, 99.74% specificity, a 66.2% positive predictive value, and a 98.89% negative predictive value in that analysis. Its cancer detection rate was 0.51%, and approximately 196 people needed to be screened for each cancer detected.
Galleri also showed a high ability to identify the likely location of cancers it detected. Cancer Signal Origin prediction accuracy reached 94.3% in PATHFINDER 2 and 91.9% in NHS-Galleri.
Performance varied substantially depending on cancer type. In PATHFINDER 2, Galleri’s 12-month episode sensitivity was 62.5% for colorectal cancer, 47.1% for lung cancer, 26.4% for breast cancer, and 10.7% for prostate cancer. Combined sensitivity among cancers covered by existing guideline-recommended screening programs was 22.9%.
Performance was higher for several cancers without established screening programs. PATHFINDER 2 reported 81.2% sensitivity for head and neck cancers and liver/intrahepatic bile duct cancers, 66.7% for pancreatic, extrahepatic bile duct and gallbladder cancers, and 63.0% for lymphoid-lineage cancers.
One issue receiving particular attention from the FDA is Galleri’s ability to identify cancers at earlier stages. In NHS-Galleri, 820 participants were diagnosed with new primary cancers and Galleri detected 259, or 31.6%. Among 474 stage I or II cancers, Galleri detected 97, or 20.5%. Detection increased at later stages, with sensitivity of 13.6% for stage I, 34.4% for stage II, 44.3% for stage III, and 60.0% for stage IV cancers.
Those findings are why the FDA is specifically asking the advisory panel whether the data support the proposed “early detection” language. If advisers determine that the evidence does not adequately support that characterization, the FDA has asked them to consider whether an alternative indication focused simply on multi-cancer detection would be appropriate.
Safety considerations center largely on what happens after a positive screening result. In PATHFINDER 2, 159 of 218 participants, or 72.9%, who underwent diagnostic evaluation following a positive investigational test result had at least one invasive procedure. The percentage was 90.6% among participants ultimately diagnosed with cancer and 47.8% among those who were not diagnosed with cancer.
The study recorded adverse events during diagnostic evaluation in 9 of 218 participants, or 4.1%. None of the study-related adverse events were serious, and the FDA said none were related to the device itself.
The NHS-Galleri safety analysis similarly found that most study-related adverse events were connected to blood draws and were mild or moderate. No serious study-procedure-related or device-related adverse events occurred in that analysis.
Galleri is intended to complement rather than replace existing cancer screening methods. Under GRAIL’s proposed labeling, patients receiving a negative Galleri result should continue guideline-recommended screening such as mammography, colorectal screening, and other established tests. A positive Galleri result also does not diagnose cancer and must be followed by appropriate diagnostic testing.
The FDA advisory committee will ultimately be asked to vote on three central questions: whether there is reasonable assurance that Galleri is safe, whether there is reasonable assurance that it is effective, and whether its benefits outweigh its risks for patients covered by the proposed indication. The advisory panel’s vote is not itself an FDA approval decision, but it will provide expert input as the agency continues evaluating GRAIL’s PMA application.
According to Reuters, Galleri generated $136.8 million in U.S. revenue in 2025. The test and Abbott Laboratories’ Cancerguard multi-cancer blood test are currently available under Clinical Laboratory Improvement Amendments regulations, but neither was FDA approved at the time of the report.
