Clinical development of valbenazine for tics associated with Tourette syndrome

Introduction: Significant need exists for effective, well-tolerated pharmacologic treatments for Tourette syndrome (TS). Medications that inhibit vesicular monoamine transporters (i.e. VMAT2 inhibitors) downregulate presynaptic packaging and release of dopamine into the neuronal synapse and are effective in treating hyperkinetic movement disorders such as Huntington's chorea and tardive dyskinesia (TD); thus, they may be useful in treating TS.Areas covered: This review describes the clinical program evaluating the safety and efficacy of valbenazine in the treatment of involuntary tics associated with TS in adult and pediatric subjects. While there was a trend in the 6 completed trials toward greater improvement in valbenazine-treated versus placebo subjects on the primary efficacy endpoint (Yale Global Tic Severity Scale Total Tic Score), this difference did not reach statistical significance. Valbenazine was generally well-tolerated in the studies, and treatment-emergent adverse events were consistent with valbenazine studies in TD.Expert opinion: Due to the failure to meet the primary endpoint in these trials, further investigation of valbenazine for TS is unlikely. Given the need for safe and effective TS therapies and the key role of VMAT2 in modulating dopaminergic activity, it is reasonable for future studies to investigate other VMAT2 inhibitors as potential treatments for TS.