Modeling disease progression and placebo response in Huntington's Disease: Insights from Enroll-HD and GENERATION HD1 cohorts

ObjectiveThe objective of this study was to quantify longitudinal changes in Unified Huntingtons Disease Rating Scale (UHDRS) clinical scores and evaluate their susceptibility to placebo response, improving our understanding of disease progression and the ability to optimize clinical trials in Huntingtons disease. MethodsWe utilized data from the Enroll-HD and GENERATION HD1 placebo arm cohorts to model the natural history of the disease and placebo response for functional, motor and cognitive clinical scores. Baseline patient characteristics available in both cohorts were analyzed as potential predictors of progression rate. ResultsWe identified distinct trajectories for each clinical measurement throughout the course of the disease, with baseline characteristics serving as strong predictors of progression rate. Interestingly, we observed a weak correlation between progression rates among different endpoints, highlighting the need for careful selection of endpoints, as they may not have the same relevance for different patient populations. To quantify placebo response, we compared disease progression in the largest Huntingtons clinical trial to date (GENERATION HD1 placebo arm) to the Enroll-HD cohort. We found a strong initial improvement in motor and cognitive scores in GENERATION HD1, which remained constant during the dosing period of the trial. We show that this initial improvement in motor and cognitive scores can be quantified, enabling the simulation of changes in endpoints in a placebo arm for distinct subpopulations. InterpretationOur model successfully captures essential aspects of disease progression and placebo response in Huntingtons disease, providing valuable guidance for the design and analysis of upcoming clinical trials.