RAP-199

RAP-199 is a small molecule drug developed by Rapport Therapeutics. It is designed to selectively target TARPγ8 (transmembrane AMPA receptor regulatory protein gamma-8), a receptor-associated protein that modulates the neuronal AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid) receptor. The mechanism of action involves negative allosteric modulation of the AMPA receptor via selective binding to TARPγ8, which is expressed in discrete brain regions such as the hippocampus—an area implicated in focal epilepsy. This neuroanatomical specificity aims to provide improved efficacy and tolerability compared to traditional anti-seizure medications by limiting off-target effects elsewhere in the central nervous system. As of mid-2025, development for RAP-199 has been deprioritized in favor of Rapport’s lead candidate (RAP-219), with further investment deferred[3][4][9].