Grail reported that its large NHS-Galleri multicancer early detection trial failed to meet the study's primary endpoint of a statistically significant reduction in late-stage (Stage III–IV) cancers. The company disclosed topline results from the 142,000‑participant study alongside full‑year financials; shares plunged more than 45–50% in after‑hours trading after the announcement. Grail flagged favorable trends in a pre‑specified group of 12 lethal cancers and a reduction in stage IV diagnoses, and said it will extend follow‑up by 6–12 months to let effects mature. The trial result is a key datapoint for Grail’s commercial and regulatory strategy: the company said it still expects the FDA to review its premarket package and will continue discussions with payers and regulators. Critics and independent experts cautioned that favorable trends do not substitute for a missed primary endpoint and urged scrutiny of trial design and subgroup analyses.