New FDA breakthrough therapy designations awarded for two investigational Alzheimer's disease (AD) candidates, Eli Lilly and Co.'s donanemab and the Bioarctic AB-Eisai Co. Ltd.-developed asset lecanemab (BAN-2401) underline ongoing willingness at the U.S. regulator to invest deeper attention in the potential of amyloid plaque reduction to slow progress of the disease, a critical and costly challenge estimated to affect more than 6 million Americans.