An expert panel advising the US Food and Drug Administration voted on September 23 in favor of the approval application for Galleri, a GRAIL blood test intended to support early detection of multiple cancers in adults aged 50 and older.
The panel voted 7 to 2, with one abstention, that Galleri's benefits outweigh its risks. It voted unanimously in support of safety and 6 to 4 in support of effectiveness. Those votes do not amount to FDA approval, and the agency is not required to follow the committee's recommendation.
How the test is intended to work
FDA materials describe Galleri as a next generation sequencing test that searches for cancer associated methylation patterns in cell free DNA isolated from blood. When it detects a signal, the test also attempts to predict where in the body that signal may have originated.
A positive result is not a cancer diagnosis. It is intended to trigger further diagnostic workup by medical professionals. The test is also not intended to replace established screening methods such as mammography or colonoscopy when those are recommended.
Why the evidence is still being examined
Blood tests designed to detect many cancers are attractive because they may identify tumors for which routine screening programs do not exist. But clinical benefit requires more than showing that a test can find a biological signal. Regulators also need to understand true diagnoses, unnecessary workups and whether use of the test improves health outcomes.
Earlier data from a large UK trial did not show a statistically significant improvement in the combined measure of stage III or IV cancers, although the company reported more encouraging findings in some analyses and aggressive cancer groups. That is one reason the regulatory assessment remains complex.
What happens next
The FDA will consider the committee vote, the full application and clinical data before deciding on premarket approval. The favorable vote does not establish that approval will be granted or when a decision will arrive.
If the test is approved, other practical questions would remain for consumers and health systems, including price, insurance coverage, incorporation into screening guidelines and how to manage positive signals that ultimately do not result in a cancer diagnosis.
