Central Maryland Affiliate
Once a drug is ready to test in people, it must go through three stages of clinical trials.
Phase One 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 Two Trials
Phase II involves more volunteers and focuses on finding the correct dose. Safety and tolerability continue to be monitored.
Phase Three Trials
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. 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.
If the results show that a compound is safe, well tolerated and effective, the FDA will be requested to approve the compound for clinical use. Because HD is a serious disease without a cure, the FDA may fast track its evaluation, taking about six months to review and make a decision.
Observational trials are critical to the effort to get effective treatments to patients. Huntington's Disease proceeds slowly; it may take two or more years for differences to be observed clinically between the treatment group and the control group. Observational trials are underway to discover more sensitive outcomes measures such as a biomarker or cognitive test that could serve as surrogate endpoints to shorten clinical trials and make treatments available to patients more quickly.