GRAIL's (GRAL) stock fell 11% in Monday's premarket session after the company said over the weekend that the NHS-Galleri trial of its Galleri multi-cancer early detection test missed its primary endpoint.

The NHS-Galleri trial evaluated a primary endpoint of Stage III and IV diagnoses in a group of 12 cancers. The company said that when the Galleri test was added to standard of care screening in England, there was no statistically significant difference one year following the participants' last appointment.

"The NHS-Galleri trial tested whether adding the Galleri blood test to NHS screening could reduce the combined number of cancers diagnosed at Stage III or IV over three years," Charles Swanton, one of the trial's chief investigators, said in a statement. "The primary endpoint was not met."