Almost 45 substances are being researched and developed preclinically for the treatment of polyglutamine diseases. The vast majority of these compounds are for the treatment of Huntington's disease (HD) but substances for the treatment of spinocerebellar ataxias (SCA) are also in the development pipeline (Table ). Table highlights drugs in preclinical development for the treatment of polyQ diseases, their class, mechanism of action, and the companies developing them. A wide range of therapies are being investigated including small molecules, protein degraders, RNA therapeutics, gene therapy, cell therapies, amongst others. The top five preclinical researched drug classes for the treatment of polyQ diseases include small molecule drugs followed by gene therapy, RNA interference agents, protein degraders, and stem cell therapy.