Top Line: Yesterday the FDA’s Molecular and Clinical Genetics Devices Panel advisory board voted in favor of approval of GRAIL’s Galleri multi‑cancer early detection (MCED) test based on both the UK’s NHS‑Galleri trial and the US’s PATHFINDER 2 trial.
The Study: The single-arm prospective PATHFINDER 2 trial evaluated a newer, single-round Galleri assay (MCED-V2) primarily for test performance across 35,878 adults age 50+ without clinical suspicion of cancer. This newer version still relies on the basic principle of measuring cell-free DNA methylation but somewhat streamlines results by decreasing possible sites of origin from 21 to 18 and decreasing reported possible primary sites from 2 to 1. With a single screening MCED-V2 test, a cancer signal was detected in 0.54% (n=287) of patients with a 60% positive predictive value (n=173). The predicted cancer origin was correct in 91% of these true positives. Of 287 patients with a positive MCED test, 213 had a total of 295 invasive procedures thereafter–including four surgeries yielding no evidence of cancer–with a median time to diagnostic resolution of 48 days. Finally, 267 patients with a negative test went on to develop cancer within a year, over a third comprising early-stage breast and prostate cancers.
TBL: This data supports the Galleri MCED test as a potential complement to (not replacement for) guideline-recommended cancer population screening with a continued need for upfront patient education on its expected utility versus pitfalls. | Nabavizadeh, Nat Med 2026
The Study: The single-arm prospective PATHFINDER 2 trial evaluated a newer, single-round Galleri assay (MCED-V2) primarily for test performance across 35,878 adults age 50+ without clinical suspicion of cancer. This newer version still relies on the basic principle of measuring cell-free DNA methylation but somewhat streamlines results by decreasing possible sites of origin from 21 to 18 and decreasing reported possible primary sites from 2 to 1. With a single screening MCED-V2 test, a cancer signal was detected in 0.54% (n=287) of patients with a 60% positive predictive value (n=173). The predicted cancer origin was correct in 91% of these true positives. Of 287 patients with a positive MCED test, 213 had a total of 295 invasive procedures thereafter–including four surgeries yielding no evidence of cancer–with a median time to diagnostic resolution of 48 days. Finally, 267 patients with a negative test went on to develop cancer within a year, over a third comprising early-stage breast and prostate cancers.
TBL: This data supports the Galleri MCED test as a potential complement to (not replacement for) guideline-recommended cancer population screening with a continued need for upfront patient education on its expected utility versus pitfalls. | Nabavizadeh, Nat Med 2026