KEY TAKEAWAYSCassava Sciences shares are plunging in premarket trading and are losing most of their value after the biotech firm said its experimental Simufilam drug aimed at treating Alzheimer’s disease failed a late-stage study.The drug was aimed at treating patients with mild-to-moderate Alzheimer’s.A second late-stage trial for the drug Simufilam has also been discontinued. Cassava Sciences (SAVA) shares are plunging in premarket trading and are losing most of their value after the biotech firm said its ...