An independent advisory committee to the U.S. Food and Drug Administration gave conditional support to Galleri, a blood test developed by Grail that aims to detect signals associated with multiple types of cancer. The committee voted 7 members to 2, with one member abstaining, that the test’s potential benefits outweigh its risks.
The vote followed a full-day meeting focused on the test’s accuracy and the likelihood of false results, as well as the risk that a negative result could give some patients false confidence and lead them to ignore guideline-recommended cancer screenings. The committee unanimously concluded that the test is safe, but it was more divided over its effectiveness, with 6 members supporting it and 4 opposing it.
What does Galleri do?
Galleri uses a single blood sample to analyze methylation patterns in cell-free DNA, looking for a signal that may indicate the presence of cancer. If a signal appears, the test attempts to identify the tissue or organ associated with it. The importance of this approach lies in targeting cancers for which routine screening tests are not currently available.
There are no FDA-approved devices for screening for multiple types of cancer in this way. The basic idea behind multi-cancer screening is to detect disease before symptoms appear, when treatment options are generally broader, but the committee emphasized that this goal alone does not establish the test’s ability to improve health outcomes for every type of cancer.
No replacement for existing screenings
Committee members emphasized that Galleri should not replace screenings recommended by current guidelines, including screenings for breast, cervical, colorectal, and lung cancer. Deborah Armstrong, a professor of oncology at Johns Hopkins School of Medicine, said the greatest concerns involve false reassurance among those who receive a negative result, along with the follow-up tests that a small number of people with false-positive results may undergo.
Grail says the test is intended for use in addition to recommended screenings, not as a replacement for them. The company also began selling Galleri in 2021 as a laboratory-developed test, a pathway that did not require FDA approval.
The evidence remains under debate
Despite the committee’s support, the vote did not resolve questions about the test’s ability to detect certain types of cancer. Charity Morgan, a professor of biostatistics at the University of Alabama, noted that the evidence presented was not sufficient to establish Galleri’s ability to detect those types.
The Galleri test also did not meet the primary endpoint in the NHS-Galleri trial, while Grail said its data showed a shift toward detecting cancer at earlier stages and that the test detected approximately four to seven times more cancers compared with usual care alone. These results remain part of the company’s premarket approval application submitted to the FDA, while the committee’s vote is expected to be an important indication of the final decision’s direction, although the agency is not required to follow its recommendation.
Why does this news matter?
The vote represents an important regulatory step, not final approval. If the FDA approves it, the first multi-cancer blood test will receive a clear U.S. regulatory pathway, but its use will remain tied to the limitations of the evidence and the need to continue existing screening programs. Therefore, the test’s practical value will depend not only on its ability to find cancer signals, but also on reducing missed diagnoses and misleading results and identifying appropriate follow-up tests.