Clinical trials are part of the research pipeline to treatment for Huntington's disease.
Before a compound can be prescribed for HD patients, it must go through three phases of clinical trials. In Phase I, a small number of volunteers are given the drug and closely monitored to see whether the drug is safe and well-tolerated.
Phase II involves more volunteers and focuses on finding the correct dose. Safety and tolerability continue to be monitored.
Phase III involves a still larger group - several hundred in HD research. Volunteers are randomly assigned to either the treatment group or a control group who receives a placebo (a non-active compound, sometimes a sugar pill). The study is double blinded - neither the subjects nor the researchers assessing them will know who received the compound and who received a placebo until the end of the study. Phase III takes much longer since enough time must pass for differences in disease progression to emerge between the treatment group and the control group, assuming the treatment is effective.
Observational trials involve collecting data on the natural course of a disease. Comparisons are made among gene carriers, patients at various stages of the disease, and those who do not have the Huntington's Disease gene.
Participants are needed for both clinical trials and observational trials.
Because the progression of a neurological disease like HD is gradual and difficult to measure, clinical trials follow a large number of participants be for years for thirty months or more.
Right now the research community is actively looking for chemical changes in the blood and changes in MR (magnetic resonance) and PET (positron emission tomography) scans that may be an early indicator that things are getting better or worse - long before the doctor can determine cahnges from a regular office examination. Such early indicators are called biomarkers, and when found can serve as surrogate (substitute) measures for disease progression. Surrogate measures will shorten the time needed for clinical trials and free up scarce resources for another trials. Observational trials are now including the goal of searching for and validating biomarkers.