Grail reported that its large UK NHS‑Galleri multicancer early detection (MCED) trial did not meet the primary endpoint of a statistically significant reduction in Stage III–IV cancers. The company highlighted favorable trends in a pre‑specified subgroup but confirmed the study missed its main goal, triggering a near‑50% aftermarket stock decline. Grail executives said they expect the result will not necessarily derail FDA review or Medicare discussions and emphasized secondary signals and broader evidence packages. External experts including Eric Topol criticized the trial design and underscored that favorable subgroup trends do not substitute for a positive primary outcome. The result raises questions about MCED trial design, regulatory paths and commercial expectations for multi‑cancer blood tests.