Roche said its Alzheimer’s drug candidate could not clearly be shown to slow dementia progression in two drug trials, failing to draw level with a recent development success by rivals Biogen and Eisai . The Swiss drugmaker said in a statement on Monday that twin studies known as Graduate 1 and 2 had not reached the primary goal of showing that the drug gantenerumab could preserve abilities such as remembering, solving problems, orientation and personal care in patients suffering from early stages of Alzheimer’s disease.