Phase III PROOF-HD clinical study of pridopidine reported on Huntington’s disease

Preliminary analysis of PROOF-HD indicated that the Phase III study did not meet its primary endpoint, change from baseline compared to placebo at 65 weeks, as measured by the Unified Huntington Disease Rating Scale-Total Functional Capacity score (TFC), or the key secondary endpoint, measured by the Composite Unified Huntington’s Disease Rating Scale (cUHDRS). Effects on both of these measures were reduced by the use of concomitant medications.

Pre-specified analyses that excluded participants taking neuroleptics and chorea medications showed clinically meaningful and nominally significant benefits for participants on pridopidine across multiple measures, including disease progression (cUHDRS) and cognition (Stroop Word Reading Test, SWR), at various timepoints. There were also positive trends in motor (TMS) and function (TFC). For many of these measures, this represented improvement from baseline values.

Additionally, important secondary endpoints measuring Q-Motor, a quantitative, objective, rater-bias independent, computerized assessment of motor function, showed robust and nominally significant beneficial effects for participants on pridopidine and improvement from baseline. The effect was further strengthened when excluding participants taking neuroleptics and chorea medications. Pridopidine was well-tolerated with no serious treatment-related adverse events, with a safety and tolerability profile similar to placebo and consistent with previous clinical studies. These initial results, along with recently announced findings from the pridopidine arm of the HEALEY ALS Platform Trial, were presented at the 75th American Academy of Neurology (AAN) Annual Meeting taking place in Boston, MA.