SA17. Response to Treatment With Valbenazine (NBI-98854) in Subjects With Tardive Dyskinesia

Abstract

Abstract Background: Tardive dyskinesia (TD) is a persistent and potentially disabling movement disorder resulting from exposure to dopamine receptor-blocking agents (DRBAs), such as antipsychotics. Valbenazine is a novel and highly selective vesicular monoamine transporter 2 (VMAT2) inhibitor that is being evaluated for the treatment of TD and other movement disorders. Clinical studies include a Phase 3 trial of valbenazine in adults who had TD and underlying schizophrenia/schizoaffective disorder or mood disorder (KINECT 3; NCT02274558). The primary end point of this trial was met as demonstrated by a significant difference between valbenazine 80 mg/day and placebo for the Abnormal Involuntary Movement Scale (AIMS) dyskinesia total score (Items 1–7) change from baseline. Additional analyses of AIMS data from this trial were conducted to assess treatment response in subjects with TD. Methods: In this 6-week, double-blind, placebo-controlled trial, subjects were randomized 1:1:1 to once-daily treatment with valbenazine 80 mg, valbenazine 40 mg, or placebo. Treatment response was defined as ≥50% reduction in the AIMS total score. AIMS responders were analyzed by study visit (Weeks 2, 4, and 6) in the intent-to-treat (ITT) population and in subgroups categorized by underlying psychiatric diagnosis (schizophrenia/schizoaffective disorder or mood disorder). Numbers needed to treat (NNTs) were calculated for AIMS responders (valbenazine vs placebo) at Week 6. Significance testing was not conducted in the subgroups. Results: At Week 6 in the ITT population (N = 225), AIMS responder rates were significantly higher with valbenazine than with placebo: 80 mg, 40.0% (P < .0001; NNT = 4); 40 mg, 23.8% (P = .0200; NNT=7); placebo, 8.7%. Treatment with valbenazine 80 mg versus placebo also resulted in significantly higher responder rates at Week 2 (23.4% vs 5.3%, P = .0016) and Week 4 (28.8% vs 9.7%, P = 0.0039). Subjects treated with valbenazine 40 mg also had higher response rates at Week 2 (14.3% vs 5.3%) and Week 4 (15.6% vs 9.7%) relative to placebo-treated subjects, but the differences were not statistically significant. In subjects with schizophrenia/schizoaffective disorder (n = 148) or mood disorder (n = 77), AIMS responder rates were higher with valbenazine than placebo at all study visits. The highest responder rates were found at Week 6 and similar in the schizophrenia subgroup (80 mg, 40.9%, NNT = 4; 40 mg, 26.2%, NNT = 6; placebo, 9.3%) and mood subgroup (80 mg, 38.5%, NNT = 4; 40 mg, 19.0%, NNT=9; placebo, 7.7%). Conclusion: These study results, based on a rigorous definition of treatment response, indicate that substantial TD improvements occurred more frequently with valbenazine than placebo in adults diagnosed with schizophrenia/schizoaffective disorder or mood disorder. A significant difference between the 80-mg dose and placebo for the AIMS response was observed as early as 2 weeks of treatment.