Experimental therapeutics in Huntington's disease: are models useful for therapeutic trials?

Research conducted over the past 10 years has uncovered molecular mechanisms that are likely to be important in the early stages of Huntington's disease pathogenesis. This review summarizes the resources and strategies that are in place in order to exploit these new findings and use them to develop novel Huntington's disease therapeutics. The role that disease models will play in this process is discussed. A wide variety of models of Huntington's disease have been developed including yeast, Caenorhabditis elegans, Drosophila melanogaster and mouse. These can be developed as screening assays for the identification of chemical compounds that show beneficial effects against a specific phenotype and for the cross validation of potential therapeutics. The first compounds arising through this drug development pipeline have been reported. Similarly, the preclinical screening of compounds in mouse models is being developed in a coordinated manner. Our understanding of the molecular basis of Huntington's disease is increasing at an exponential rate. Over the next few years an increasing number of potential therapeutic compounds will have been identified. It will only be possible to take a small number of these through to phase III clinical trials. The challenge will be to use the in-vivo models of Huntington's disease to best predict which of these compounds should be pursued in the clinic, to avoid depleting the patient population willing to enter into trials, and demoralizing them by conducting repeated unsuccessful trials.