Enthusiasm for the clinical potential of EX-527 in neurodegenerative diseases was sparked in part by a study demonstrating that EX-527 attenuated functional motor deficits and decreased striatal huntingtin protein inclusions in a mouse model of Huntington’s disease [144]; however, a phase II clinical trial demonstrated that EX-527, while a pharmacologically safe drug, did not improve Huntington’s disease patient outcomes within the timeframe of the study [145]. This evidence concerns the gene HTT and Huntington disease.