LX6171 is an orally-delivered, small molecule inhibitor of SLC6A7, a high-affinity L-proline transporter found in the brain. SLC6A7 is a member of the gamma-aminobutyric acid (GABA) neurotransmitter transporter family, and is expressed in regions of the brain that are known to be involved in learning and memory. In preclinical studies, mice treated with LX6171 displayed improved performance in tests of learning and memory, corroborating observations in knockout mice lacking SLC6A7. In the completed Phase 2a clinical trial, daily doses of LX6171 or placebo were given to 121 healthy elderly subjects with age-associated memory impairment (AAMI). The study evaluated safety, tolerability, and cognitive effects of LX6171 over four weeks. Although LX6171 was well tolerated at all doses evaluated, the trial did not result in significant effects on parameters of attention or memory that would justify further studies in therapeutic indications prioritized by the company.