A Multi-Cancer Blood Test Reaches a Critical FDA Review: Galleri to Face Dual Scrutiny Over Benefits and Misclassification

Can a single tube of blood identify multiple cancers before symptoms appear? That question is moving from technological possibility toward a regulatory decision. The U.S. Food and Drug Administration (FDA) has scheduled a public expert meeting for September 23 to review the premarket approval application for GRAIL’s Galleri multi-cancer early detection test. For multi-cancer blood screening, which still lacks a mature review framework, this will be a consequential test of the evidence.

The FDA’s Molecular and Clinical Genetics Panel will meet from 9 a.m. to 6 p.m. Eastern Time to discuss, make recommendations, and vote. Galleri is being reviewed through the premarket approval (PMA) pathway, the FDA’s most stringent review process for medical devices. Although the panel’s conclusions are not legally binding, they typically have a significant influence on subsequent decisions.

According to the FDA, Galleri is a prescription-use, next-generation sequencing in vitro diagnostic that analyzes cancer-specific methylation patterns in cell-free DNA from peripheral blood. The proposed indication is multi-cancer early screening in adults aged 50 and older. If a cancer signal is detected, the system also predicts the most likely tissue of origin, but the person tested must still undergo diagnostic procedures such as imaging, endoscopy, or biopsy for confirmation.

The real difficulty is that the clinical benefit can be interpreted in more than one way. The three-year, randomized UK NHS-Galleri trial, involving approximately 142,000 participants, failed to significantly reduce the combined number of stage III and stage IV cancer diagnoses at its primary endpoint and did not demonstrate a significant overall improvement in early detection. On the other hand, a secondary analysis released by GRAIL showed that, among 12 prespecified aggressive cancers, there were 26% fewer stage IV cases in the third screening round than in the standard-care group. With Galleri added, the number of cancers detected through screening increased approximately fourfold.

These results create the central tension in the FDA review: detecting more cancer signals does not necessarily mean reducing late-stage disease or deaths. Experts must assess whether positive results reliably lead to actual cancers, how many follow-up examinations and how much harm false alarms may cause, and whether tissue-of-origin predictions are sufficient to shorten the diagnostic pathway. Favorable findings from the third round and for specific cancer types also cannot substitute for the unmet primary endpoint, and a mortality benefit has not yet been established.

Galleri is currently available in the United States as a laboratory-developed test, but it has not yet received FDA approval. The FDA has opened public docket FDA-2026-N-8004 for the meeting, with submissions due by September 16; comments received by September 8 will be provided to the committee for consideration. The September vote will not immediately determine the product’s fate, but it may draw the first clear boundary for how multi-cancer early detection tests must demonstrate safety and real-world benefit in the future.