** Shares of cancer test maker Grail GRAL.O fall 15.5% to $60.58 after detailed results from a large UK study of its Galleri multi-cancer blood test raised investor concerns

** Grail previously said at the American Society of Clinical Oncology meeting that the NHS-Galleri trial missed its primary goal of significantly reducing stage III and IV cancer diagnoses across 12 pre-specified cancer types

** The company highlighted signs of benefit, including fewer stage IV cancers and more early-stage diagnoses, but Guggenheim analysts questioned whether the data was strong enough to support broad use in average-risk patients

** Guggenheim said the ASCO presentation drew skepticism over whether Galleri may be better suited for high-risk groups

** The brokerage also noted concerns that many early-stage cancers detected were colorectal and lung cancers, which already have established screening options

** Including session's move, GRAL stock down 29.4% YTD