A panel of independent experts advising the U.S. Food and Drug Administration (FDA) backed the safety of Grail’s Galleri blood-based cancer detection test but was divided on its effectiveness. All ten panel members unanimously supported Galleri’s safety, while only six voted in favor of its effectiveness, with four opposing. The panel also voted seven to two, with one abstention, that the test's benefits outweigh its risks. The FDA is not bound by these votes but heavily considers them in its final decisions, with a decision on nationwide sales expected in the coming months.
Galleri is designed to screen for multiple types of cancer simultaneously in adults aged 50 and older through a single blood draw, a capability currently unique among approved tests in the United States. GRAIL, the developer, proposes the test for early detection of cancer and prediction of cancer signal origin. However, the test is not intended to replace existing recommended single-cancer screenings and may produce false positive or negative results. The benefits and risks of programmatic screening with Galleri are still under study.
The test's efficacy was evaluated in two large studies: PATHFINDER 2 in the U.S. and NHS-Galleri in Britain. The U.S. study showed the test detected 35% of cancers within 12 months with a high specificity of 99.85%, indicating a low rate of false alarms. Similar results were observed in the British trial. When added to existing screening methods, Galleri significantly increased the number of detected cancers. For instance, in the PATHFINDER 2 study, the detection rate was 0.54% among participants aged 50 or older, with a positive predictive value of 60.3% and a 12-month episode sensitivity of 39.3% for all cancers.
Regarding safety, adverse events (AEs) were minimal and not considered serious. Device-related AEs occurred in 0.04% of patients. Common trial-related AEs included vessel bruises, syncope, dizziness, and anxiety. Patient anxiety increased temporarily for those with true-positive results but returned to baseline. False-positive results led to invasive procedures in a small proportion of patients (0.6%), with four false positives leading to surgical procedures where benign neoplasms were found. GRAIL's CEO, Josh Ofman, emphasized that the test is designed to improve cancer screening by detecting more cancers earlier, when they are potentially curable.
The FDA's advisory committee's recommendation reaffirms the rigorous evidence standards GRAIL has met for a multi-cancer early detection test. GRAIL is committed to working with the FDA as it completes its review of Galleri, which is the first Premarket Approval (PMA) submission for such a test. The company highlighted strong public support for Galleri, noting over 200 physicians, nurses, and patient advocates who shared their backing through written comments and during the open comment period.
