Definition

An orally bioavailable, small molecule diacylhydrazine-based activator ligand, that can be used to activate certain genes using the ecdysone receptor (EcR)-based inducible gene regulation system, the RheoSwitch Therapeutic System (RTS). Upon administration of veledimex, this agent specifically binds to the EcR located on the separately administered RTS, which includes two fusions proteins: Gal4-EcR, which contains a modified ecdysone receptor (EcR) fused with the DNA binding domain of the yeast Gal4 transcription factor, and VP16-RXR, which contains a chimeric retinoid X receptor (RXR) fused with the transcription activation domain of the viral protein VP16 of herpes simplex virus type 1 (HSV1). The fusion proteins form inactive, unstable and unproductive heterodimers in the absence of veledimex. In the presence of veledimex, the protein heterodimer changes to a stable conformation, forming an active transcription factor complex, which can bind to the inducible promoter, thereby allowing the induction of controlled transcription of the target gene.