Discovery of Imidazo[1,2-]pyrazines and Pyrazolo[1,5-]pyrimidines as TARP γ-8 Selective AMPAR Negative Modulators.

This report discloses the discovery and characterization of imidazo[1,2-]pyrazines and pyrazolo[1,5-]pyrimidines as selective negative modulators of α-amino-3-hydroxy-5-methylisoxazole-4-propionate receptors (AMPARs) associated with transmembrane AMPAR regulatory protein γ-8. Imidazopyrazine was initially identified as a promising γ-8 selective high-throughput screening hit, and subsequent structure-activity relationship optimization yielded subnanomolar, brain penetrant leads. Replacement of the imidazopyrazine core with an isosteric pyrazolopyrimidine scaffold improved microsomal stability and efflux liabilities to provide , JNJ-61432059. Following oral administration, exhibited time- and dose-dependent AMPAR/γ-8 receptor occupancy in mouse hippocampus, which resulted in robust seizure protection in corneal kindling and pentylenetetrazole (PTZ) anticonvulsant models.