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.
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.
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
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.
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