ABSTRACT: Abstract Background: Valbenazine is a novel and highly selective vesicular monoamine transporter 2 (VMAT2) inhibitor that is being evaluated for the treatment of tardive dyskinesia (TD), a persistent movement disorder resulting from exposure to antipsychotics or other dopamine receptor blocking agents (DRBAs). The efficacy of valbenazine in treating TD was demonstrated in a Phase 3 clinical trial (KINECT 3; NCT02274558), which included subjects with underlying schizophrenia/schizoaffective disorder or mood disorder. Further analyses of data from that trial were conducted to explore the efficacy of valbenazine across diagnostic subgroups. Methods: Subjects in this 6-week, double-blind, placebo-controlled trial were randomized 1:1:1 to once-daily valbenazine 80?mg, valbenazine 40?mg, or placebo. The primary endpoint was change from baseline to Week 6 on the Abnormal Involuntary Movement Scale (AIMS) total score (items 1–7) for valbenazine 80?mg vs placebo in the intent-to-treat (ITT) population. AIMs were videotaped and ratings were conducted by central raters blind to study visit and group. Additional outcomes included AIMS total score change (40?mg vs placebo) and Clinical Global Impression of Change-Tardive Dyskinesia (CGI TD) score (80 and 40?mg vs placebo) at Week 6. In addition to being evaluated in the ITT population, these outcomes were analyzed in subgroups categorized by underlying psychiatric diagnosis (schizophrenia/schizoaffective disorder or mood disorder). Results: At Week 6 in the ITT population (N = 225), AIMS score improvement was significantly greater with valbenazine 80?mg than placebo (least squares [LS] mean change from baseline: 80?mg, 3.2; placebo, ?0.1; P < .0001). AIMS score change at Week 6 for valbenazine 40?mg (1.9) was also greater than placebo (P = .0021). Statistical testing was not conducted in the subgroups, but the magnitude of AIMS improvement in these patients was comparable to results in the overall ITT population: schizophrenia/schizoaffective disorder (n = 148; mean change from baseline: 80?mg, ?3.1; 40?mg, ?1.5; placebo, +0.4); mood disorder (n = 77; 80?mg, 3.6; 40?mg, ?2.5; placebo, ?0.7). CGI-TD scores at Week 6 in the ITT population indicated greater global improvement with valbenazine than placebo, but between-group differences were not statistically significant (LS mean scores: 80?mg, 2.9; 40?mg, 2.9; placebo, 3.2). CGI-TD outcomes in the subgroups were as follows: schizophrenia/schizoaffective disorder (mean scores: 80?mg, 3.0; 40?mg, 2.9; placebo, 3.1); mood disorder (80?mg, 2.7; 40?mg, 2.9; placebo, 3.2). Psychiatric status remained stable during the 6-week double-blind treatment period. Conclusion: Once-daily treatment with valbenazine improved TD regardless of underlying psychiatric diagnosis.
