QR-340

QR-340 is an experimental antisense oligonucleotide (ASO) developed by ProQR Therapeutics for the treatment of Fuchs' endothelial corneal dystrophy (FECD). FECD is a progressive eye disease characterized by the loss of corneal endothelial cells, often driven by a trinucleotide (CTG) repeat expansion in the *TCF4* gene. QR-340 is designed to specifically bind to the toxic expanded CUG repeats in the *TCF4* mRNA. By doing so, it aims to prevent the formation of RNA foci and the subsequent sequestration of RNA-binding proteins, such as Muscleblind-like 1 (MBNL1), thereby restoring normal cellular splicing and function. The program was part of ProQR's ophthalmology portfolio but was deprioritized as the company shifted its focus toward its Axiomer RNA editing technology.