In two separate reports, researchers from the University of Indiana and Imperial College in England report promising results on a potential new biomarker for Huntington's. With more work, this could lead to shorter clinical trials for HD drugs. Summary by Dr. LaVonne Veatch Goodman.

The Goal

To discover better methods than the Unified Huntington's Disease Rating Scale (UHDRS) to measure HD progression. If successful, this could shorten the time and reduce the number of patients needed for clinical trials which would help get drugs to HD people more quickly.

The Method

High-resolution, video-based eye tracking systems were used to observe the coordination and control of particular eye movements, called saccades, in more than 200 volunteers. Researchers were hoping to find particular eye movements that could serve as biomarkers of disease progression.

The Results

Huntington's causes slowing of several types of saccade eye movements. Automated tracking systems can measure saccade differences earlier than doctors can observe them. Saccade abnormalities increase in Huntington's in a manner that parallels predicted disease progression, at least in individuals with early disease.

Why is it Important?

Eye movement abnormalities are potentially good biomarkers, because they are physical traits of disease progression. Saccades appear to be more sensitive biomarkers than UHDRS in early symptomatic stages of HD. This means that fewer people will be needed for clinical trials and that drugs can be tested more quickly.

Comment

We applaud and are indebted to all trial participants and researchers who contributed to these trials. Their combined work brings us a big step closer to better clinical trials for HD drugs. They have described a biomarker that is looking good.
This is just the first step in demonstrating that saccades are a useful way to measure HD progression. The next step is a longer term study of volunteers in which saccades are measured at several time points, perhaps weekly or monthly, over a period of half a year to a year or two. This is the only way to know whether changes in saccade measurements occur quickly enough to be useful in short clinical trials.
Further, because it is doubtful that a single test measure will be sufficient for use in drug approval, other measures will need to be identified. Those familiar with FDA requirements should provide focus for this effort to ensure that the measures being developed will be acceptable to the FDA.

The Reports

Blekher T, Johnson SA, Marshall J, White K, Hui S, Weaver M, Gray J, Yee R, Stout JC, Beristain X, Wojcieszek J, Foroud T. Saccades in presymptomatic and early stages of Huntington disease. Neurology. 2006 Aug 8;67(3):394-9. PubMed abstract

Golding CV, Danchaivijitr C, Hodgson TL, Tabrizi SJ, Kennard C. Identification of an oculomotor biomarker of preclinical Huntington disease. Neurology. 2006 Aug 8;67(3):485-7. PubMed abstract