Neuroimaging biomarkers in Huntington's disease: Preparing for a new era of therapeutic development

Background: A critical challenge for Huntington's disease (HD) clinical trials in disease modification is the definition of endpoints that can capture change when clinical signs are subtle/non-existent. Reliable biomarkers are therefore urgently needed to facilitate drug development by allowing the enrichment of clinical trial populations and providing measures of benefit that can support the establishment of efficacy. Methods: By systematically examining the published literature on HD neuroimaging biomarker studies, we sought to advance knowledge to guide the validation of neuroimaging biomarkers. We started by reviewing both crosssectional and longitudinal studies and then conducted an in-depth review to make quantitative comparisons between biomarkers using data only from longitudinal studies with samples sizes larger than ten participants in PET studies or 30 participants in MRI studies. Results: From a total of 2202 publications initially identified, we included 32 studies, 19 of which underwent indepth comparative review. The majority of included studies used various MRI-based methods (manual to automatic) to longitudinally assess either the volume of the putamen or the caudate, which have been shown to undergo significant structural change during HD natural history. Conclusion: Despite the impressively large number of neuroimaging biomarker studies, only a small number of adequately designed studies met our criteria. Among these various biomarkers, MRI-based volumetric analyses of the caudate and putamen are currently the best validated for use in the disease phase before clinical motor diagnosis. A biomarker that can be used to demonstrate a disease-modifying effect is still missing.

Automated summary

Neuroimaging biomarkers play an important role in Huntington's disease clinical trials, but reliable biomarkers are still relatively scarce. The results of the study show that MRI-based volumetric analysis of the caudate and putamen is currently the most feasible biomarker for early disease stages.