The HD Pipeline

Research and Drug Development for Huntington's Disease

Clinical Trials: Phase III

Phase III trials serve as the definitive experiment to determine if a potential drug is effective and should be available for routine use in patients. If there is no treatment available for the disease in question, a phase III trials tests the effectiveness of a new drug against a placebo or no treatment. When there are established treatments, the point of a phase III trial is not to test the effectiveness of a potential treatment, but to test if it is more effective than the established treatment. This is always done by comparing two treatments- usually, the new treatment with a standard one. Sometimes trials use the same type of drug for both categories, but compare a new dosage regiment with an old one. Like phase II trials, all participants have the relevant disease. Phase III trials typically enroll large participant groups, anywhere from 1000-7000 people. It is important to have a large group so that researchers can identify any benefits or side-effects, no matter how small they are. Like phase II trial, phase III trials are randomized.

Designing and conducting a phase III clinical trial is very difficult. It is very time-consuming and costly, and it must be done carefully to ensure valid results. Data analysis is very complex, especially when researchers are not simply looking for changes and effects that are very concrete and easily measurable, like the number of people who survived. Researchers often look for changes that can be measured on a scale, like the improvement of symptoms. These can be difficult to judge and compare between patients being treated with the potential new drug and those patients treated with an existing drug. However they are important to analyze and understand so that the benefits of the new potential treatment can be determined. It is also important that researchers recognize any significant differences in response between genders or ethnic groups.

HD and Phase III Clinical Trials

As of April 2007, several phase III clinical trials are in progress, testing new treatments for HD. Enrollment was completed in August 2006 for a trial sponsored by the Huntington Study Group testing the effects of ethyl-eicosapentaenoate (ethyl-EPA) on HD chorea. Ethyl-EPA is thought to keep nerve cells healthy, inhibit apoptosis, and reduce free radical damage. The trial itself is underway, and is composed of at least two 6-month phases, and is slated for completion in September 2007. For more information on this study, please click here

A phase III trial has just finished recruiting participants for a three year study on the long term effects of the drug riluzole. Riluzole has been used to slow the progress of amyotrophic lateral sclerosis, a related neurodegenerative disorder. This study is sponsored by Sanofi-Aventis, and is testing whether riluzole has long term effects on HD chorea and on total functional capacity (TFC) of affected patients. For more information on riluzole, click hereand for more information on this clinical trial, please click here

Prestwick Pharmaceuticals has recently completed a phase III trial using tetrabenazine to treat HD chorea. Tetrabenazine is thought to reduce the amount of dopamine in nerve cells, and this may reduce the severity of chorea. Tetrabenazine is also used to treat chorea in other neurodegenerative disorders. Initial results have shown that it is better than a placebo. Prestwick filed an application with the FDA to market tetrabenezine, and in April 2006 received a letter from the FDA stipulating the conditions which they must meet to make it an available treatment. The FDA also designated tetrabenazine a fast track product because there are no other drugs available in the U.S. to treat chorea. However, Prestwick's formulation is already marketed in at least 8 countries outside of the US, including Canada.

Last Modified: 07/07/2007

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