ABT-354

ABT-354 is an investigational small molecule drug developed by AbbVie as a selective antagonist of the serotonin 5-HT6 receptor (HTR6). The drug was primarily investigated for the treatment of cognitive disorders, especially mild-to-moderate Alzheimer’s disease. By antagonizing the 5-HT6 receptor—a G protein-coupled receptor predominantly expressed in the central nervous system—ABT-354 modulates neurotransmitter systems including acetylcholine, glutamate, dopamine, and norepinephrine. This blockade is believed to enhance cholinergic and glutamatergic neurotransmission, potentially improving cognitive performance and memory. Despite promising preclinical results and early-phase clinical trials focused on safety, tolerability, and pharmacokinetics in Alzheimer’s patients (often as adjunct therapy with acetylcholinesterase inhibitors), development for this indication was discontinued after phase 1[1][3][4][5][6].