Rational Design of the First Dual Agonist at Trace Amine-Associated Receptor 1 and 5-HT2C Receptors Based on Binding Pocket Similarity for the Treatment of Schizophrenia and Alzheimer’s Disease-Related Psychosis

The clinical-stage agonists for trace amine-associated receptor 1 (TAAR1) show insufficient clinical efficacy, requiring the design of new compounds beyond the TAAR1 receptor alone. Here, we provide evidence for the feasibility of designing TAAR1/5-HT2CR dual agonists based on structural basis of these two targets and similarities of their agonists. Three series of novel agonists were discovered, leading to a potent compound named 21b. 21b exhibits submicromolar potency on both TAAR1 and 5-HT2CR targets with high specificity confirmed by site-directed mutagenesis. Preclinical proof-of-concept studies showed that 21b was highly efficacious against the positive and negative symptoms of schizophrenia in mice models. 21b also alleviated cognitive deficits and psychoactive symptoms in Alzheimer's disease (AD) model mice. Four week repeated dosing of 21b is exceptionally well tolerated in rats and beagle dogs without hyperglycemia commonly seen with antipsychotics. Thus, the favorable druggability of compound 21b warrants further clinical development for the treatment of schizophrenia and AD-related psychosis.