Grail reported that its large NHS-Galleri multicancer early detection (MCED) trial did not meet the study’s primary endpoint, prompting a dramatic market reaction. The company disclosed top-line results showing no statistically significant reduction in late-stage (III–IV) combined cancers across the full study population; Grail said it saw favorable trends in a pre-specified group of 12 high-fatality cancers. The trial enrolled about 142,000 participants through England’s NHS and was designed to test whether annual Galleri screening shifts stage at diagnosis across a population. MCED tests analyze circulating tumor DNA methylation patterns to screen broadly for multiple cancer types in blood; regulators and payers are watching these outcome trials to judge clinical utility.