Treatment of tardive dyskinesia with VMAT-2 inhibitors: a systematic review and meta-analysis of randomized controlled trials

Abstract

Aim: The aim of this study was to summarize the characteristics, efficacy, and safety of vesicular monoamine transporter-2 (VMAT-2) inhibitors for treating tardive dyskinesia (TD).

Materials and methods: We conducted a literature search in PubMed, Cochrane Database, and ClinicalTrials.gov, screening for systematic reviews, meta-analyses or double-blind, randomized, placebo-controlled trials (DBRPCTs) reporting efficacy or safety data of VMAT-2 inhibitors (tetrabenazine, deutetrabenazine, and valbenazine) in patients with TD. A random effects meta-analysis of efficacy and safety data from DBRPCTs was performed.

Results: Two acute, 12-week DBRPCTs with deutetrabenazine 12-48 mg/day (n=413) and 4 acute, 4-6-week double-blind trials with valbenazine 12.5-100 mg/day (n=488) were meta-analyzable, without meta-analyzable, high-quality data for tetrabenazine. Regarding reduction in total Abnormal Involuntary Movement Scale (AIMS) scores (primary outcome), both deutetrabenazine (k=2, n=413, standardized mean difference [SMD] =-0.40, 95% confidence interval [CI] =-0.19, -0.62, p<0.001; weighted mean difference (WMD) =-1.44, 95% CI =-0.67, -2.19, p<0.001) and valbenazine (k=4, n=421, SMD =-0.58, 95% CI =-0.26, -0.91, p<0.001; WMD =-2.07, 95% CI =-1.08, -3.05, p<0.001) significantly outperformed placebo. Results were confirmed regarding responder rates (≥50% AIMS total score reduction; deutetrabenazine: risk ratio [RR] =2.13, 95% CI =1.10, 4.12, p=0.024, number-needed-to-treat [NNT] =7, 95% CI =3, 333, p=0.046; valbenazine: RR =3.05, 95% CI =1.81, 5.11, p<0.001, NNT =4, 95% CI =3, 6, p<0.001). Less consistent results emerged from patient-rated global impression-based response (p=0.15) and clinical global impression for deutetrabenazine (p=0.088), and for clinical global impression change for valbenazine (p=0.67). In an open-label extension (OLE) study of deutetrabenazine (≤54 weeks) and a dose-blinded valbenazine study (≤48 weeks), responder rates increased over time. With valbenazine, discontinuation effects were studied, showing TD symptom recurrence towards baseline severity levels within 4 weeks after valbenazine withdrawal. No increased cumulative or specific adverse (AEs) events versus placebo (acute trials) in extension versus acute trial data were observed.

Conclusion: The 2 VMAT-2 inhibitors, valbenazine and deutetrabenazine, are effective in treating TD, both acutely and long-term, without concerns about increased risk of depression or suicide in the TD population. No head-to-head comparison among VMAT-2 inhibitors and no high-quality, meta-analyzable data are available for tetrabenazine in patients with TD.

Keywords: VMAT-2; deutetrabenazine; tardive dyskinesia; tetrabenazine; valbenazine.

Figure 1

PRISMA flowchart of study selection process.^* Notes: ^*Different information from the same trial were retrieved from different sources (articles and result section of ClinicalTrials.gov for each trial). Hence, record selection flow diagram goes in parallel (articles and trials) with final merging of information from different sources in the present manuscript. Article represents published manuscript; study represents trial with design other than DBRPCT, or retrospective data collection; trial represents DBRPCT. Abbreviation: DBRPCT, double-blind randomized placebo-controlled trial.

Figure 2

Forest plot of AIMS change after treatment with deutetrabenazine and valbenazine. Abbreviation: AIMS, Abnormal Involuntary Movement Scale.