Efficacy and Safety of Fixed-Dose Deutetrabenazine in Children and Adolescents for Tics Associated With Tourette Syndrome: A Randomized Clinical Trial

An update on the pharmacological management of Tourette syndrome and emerging treatment paradigms

INTRODUCTION

Tourette syndrome (TS) is a childhood-onset neurobehavioral disorder characterized by tics. Pharmacotherapy is advised for patients whose symptoms affect their quality of life.

AREAS COVERED

The authors review the tic phenomenology and TS diagnostic criteria. The bulk of this article focuses on pharmacotherapeutic options for treating tics. They also highlight pharmacotherapies in the research pipeline.

EXPERT OPINION

Tic treatment must be tailored to individual needs. Behavioral therapy is the first line of treatment. Most with bothersome tics need pharmacotherapy and rarely, for medication-refractory cases, surgical therapy is indicated. Alpha-2 agonists are considered in patients with mild tics, especially in those with attention deficit with or without hyperactivity. Second-generation antipsychotics like aripiprazole and tiapride may be considered for severe tics. However, prescribers should be mindful of potential side effects, especially drug-induced movement disorders. Botulinum toxin injections may be considered for focal motor tics. Topiramate can be considered when other treatments are ineffective, and its benefits outweigh the risks. The same holds true for vesicular monoamine transporter-2 inhibitors, as they are deemed to be safe and effective in real-world use and open-label trials despite not meeting primary endpoints in placebo-controlled trials. Cannabinoids may be considered in adults if the approaches above do not control tics.

Profiling deutetrabenazine extended-release tablets for tardive dyskinesia and chorea associated with Huntington's disease

INTRODUCTION

Tardive dyskinesia (TD) and Huntington's disease (HD)-associated chorea are persistent and disabling hyperkinetic disorders that can be treated with vesicular monoamine transporter type 2 (VMAT2) inhibitors, including the recently approved once-daily (QD) formulation of deutetrabenazine (DTBZ ER). While its efficacy and safety profile have not been directly investigated, currently available data confirms bioequivalence and similar bioavailability to the twice-daily formulation (DTBZ BID).

AREAS COVERED

The authors briefly review the pivotal trials establishing efficacy of DTBZ for TD and HD-associated chorea, the pharmacokinetic data for bioequivalence between QD and BID dosing of DTBZ, as well as dose proportionality evidence, titration recommendations, and safety profile for DTBZ ER.

EXPERT OPINION

Long-term data show that DTBZ is efficacious and well tolerated for the treatment of TD and HD-associated chorea. DTBZ ER likely demonstrates therapeutic equivalence with no new safety signals. Due to the lack of comparative clinical trial data, no evidence-based recommendation about choice of VMAT2 inhibitor or switching between VMAT2 inhibitors can be made about best practice. Ultimately, QD dosing may offer the chance of improved medication adherence, an important consideration in patients with complex treatment regimens and/or patients with cognitive decline.

Pharmacological Treatment of Tourette Disorder in Children

Background: Tourette disorder (TD) is a neurodevelopmental disorder characterized by childhood onset of tics lasting more than one year, with multiple motor tics and at least one phonic tic at some point during the course of the symptoms. Treatment of tics may include psychoeducation, non-pharmacologic treatment, or pharmacologic treatment. We review pharmacologic treatment here. Methods: We performed a literature review on pharmacologic treatments for TD. Results: There is no current evidence to suggest that medications impact the prognosis of tic disorders, so current clinical guidelines recommend reassurance of the patient and family and monitoring if there is no change in function or quality of life due to tics. If treatment is indicated, it must be chosen based on the needs of each individual patient. Comprehensive behavioral intervention for tics (CBIT) is considered first-line management for most individuals with bothersome tics, especially if they are mild to moderate in severity. Pharmacotherapy should be considered when tics are impairing daily functioning, causing social problems, accompanied by other neuropsychiatric symptoms, or when the patient is not likely to benefit from CBIT. Current recommended pharmacotherapy options include alpha-2 adrenergic agonists, dopamine modulators, GABAergic medications, dopamine depleters, and botulinum toxin injections. Additionally, there are other novel medications that are being studied in ongoing clinical trials. Conclusions: This review summarizes available pharmacotherapy options for TD in children. It provides an overview of new medications and offers guidance to physicians when selecting appropriate treatments. If medications are indicated for tic management, treatment should be chosen based on the needs of the individual patient.

Pharmacological treatment of Tourette's syndrome: from the past to the future

Tourette's syndrome (TS) is a neuropsychiatric disease featuring tics and vocal tics, with a prevalence of approximately 1%, including 75% of the total number of male patients. TS seriously disturbs the patients' career, education, and life and brings a serious and unbearable psychological burden to the patients themselves and their families. At present, there are no specific clinical medications recommended for treating TS. Therefore, it is necessary to select the appropriate medication for symptomatic treatment based on the doctor's personal experience and the patient's symptoms, with the main goal of relieving symptoms, thus improving the patient's social skills and psychological problems. Here we conducted a comprehensive search on PubMed to review and organize the history and current status of the development of drug therapy for TS through a timeline format. We also systematically evaluated the effects of each drug for TS treatment to summarize the current problems and new research directions and to provide some ideas for clinical treatment.

In Memoriam: Professor Joseph Biederman's Contributions to Child and Adolescent Psychiatry

OBJECTIVE

To provide an overview of Joe Biederman's contributions to child and adolescent psychiatry.

METHOD

Nine colleagues described his contributions to: psychopharmacology, comorbidity and genetics, pediatric bipolar disorder, autism spectrum disorders, Tourette's and tic disorders, clinical and neuro biomarkers for pediatric mood disorders, executive functioning, and adult ADHD.

RESULTS

Joe Biederman left us with many concrete indicators of his contributions to child and adolescent psychiatry. He set up the world's first pediatric psychopharmacology clinic and clinical research program in child adolescent psychiatry. As a young faculty member he began a research program that led to many awards and eventual promotion to full professor at Harvard Medical School. He was for many years the most highly cited researcher in ADHD. He achieved this while maintaining a full clinical load and was widely respected for his clinical acumen.

CONCLUSION

The world is a better place because Joe Biederman was here.

Placebo and Nocebo Responses in Pharmacological Trials of Tic Disorders: A Meta-Analysis

BACKGROUND

Clinical trials of new drugs for tic disorders (TD) often fail to yield positive results. Placebo and nocebo responses play a vital role in interpreting the outcomes of randomized controlled trials (RCTs), yet these responses in RCTs of TD remain unexplored.

OBJECTIVE

The aim was to assess the magnitude of placebo and nocebo responses in RCTs of pharmacological interventions for TD and identify influencing factors.

METHODS

A systematic search of the Embase, Medline, Cochrane Central Register of Controlled Trials, and PsycINFO databases was conducted. Eligible studies were RCTs that compared active pharmacological agents with placebos. Placebo response was defined as the change from baseline in TD symptom severity in the placebo group, and nocebo response as the proportion experiencing adverse events (AEs) in this group. Subgroup analysis and meta-regression were performed to explore modifying factors.

RESULTS

Twenty-four trials involving 2222 participants were included in this study. A substantial placebo response in TD symptom severity was identified, with a pooled effect size of -0.79 (95% confidence interval [CI] -0.99 to -0.59; I2 = 67%). Forty-four percent (95% CI 27% to 63%; I2 = 92%) of patients experienced AEs while taking inert pills. Sample size, study design, and randomization ratio were correlated with changes in placebo and nocebo responses.

CONCLUSION

There were considerable placebo and nocebo responses in TD clinical trials. These results are of great relevance for the design of future trials and for clinical practice in TD.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration ID CRD42023388397. © 2024 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Dopamine in the Regulation of Glucose Homeostasis, Pathogenesis of Type 2 Diabetes, and Chronic Conditions of Impaired Dopamine Activity/Metabolism: Implication for Pathophysiological and Therapeutic Purposes

Dopamine regulates several functions, such as voluntary movements, spatial memory, motivation, sleep, arousal, feeding, immune function, maternal behaviors, and lactation. Less clear is the role of dopamine in the pathophysiology of type 2 diabetes mellitus (T2D) and chronic complications and conditions frequently associated with it. This review summarizes recent evidence on the role of dopamine in regulating insular metabolism and activity, the pathophysiology of traditional chronic complications associated with T2D, the pathophysiological interconnection between T2D and chronic neurological and psychiatric disorders characterized by impaired dopamine activity/metabolism, and therapeutic implications. Reinforcing dopamine signaling is therapeutic in T2D, especially in patients with dopamine-related disorders, such as Parkinson's and Huntington's diseases, addictions, and attention-deficit/hyperactivity disorder. On the other hand, although specific trials are probably needed, certain medications approved for T2D (e.g., metformin, pioglitazone, incretin-based therapy, and gliflozins) may have a therapeutic role in such dopamine-related disorders due to anti-inflammatory and anti-oxidative effects, improvement in insulin signaling, neuroinflammation, mitochondrial dysfunction, autophagy, and apoptosis, restoration of striatal dopamine synthesis, and modulation of dopamine signaling associated with reward and hedonic eating. Last, targeting dopamine metabolism could have the potential for diagnostic and therapeutic purposes in chronic diabetes-related complications, such as diabetic retinopathy.

Real-world experience with VMAT2 inhibitors in Tourette syndrome

OBJECTIVES

We aimed to review our "real-world" experience with the vesicular monoamine transporter 2 (VMAT2) inhibitors tetrabenazine, deutetrabenazine, and valbenazine for treatment of Tourette syndrome, focusing on therapeutic benefits, side effect profile, and accessibility for the off-label use of these drugs.

METHODS

We performed a retrospective chart review, supplemented with a telephone survey, of all our patients treated for their tics with VMAT2 inhibitors over a period of 4 years from January 2017 until January 2021.

RESULTS

We identified 164 patients treated with the various VMAT2 inhibitors (tetrabenazine, n = 135; deutetrabenazine, n = 71; valbenazine, n = 20). Data on the mean treatment duration and daily dosages were collected. The response to VMAT2 inhibitors was assessed by a Likert scale by comparing the symptom severity before initiation and while on treatment. Side effects were mild and mostly consisted of depression as the major side effect but there was no suicidality reported.

CONCLUSION

VMAT2 inhibitors are effective and safe in the treatment of tics associated with Tourette syndrome but are not readily accessible by patients in the United States, partly because of lack of approval by the Food and Drug Administration.

Safety and Efficacy of Long-Term Deutetrabenazine Use in Children and Adolescents with Tics Associated with Tourette Syndrome: An Open-Label Extension Study

Background

Tourette syndrome (TS) is a neurodevelopmental disorder characterized by motor and phonic tics.

Objective

To assess the safety and efficacy of deutetrabenazine (Teva Neuroscience, Inc, Parsippany, NJ), a vesicular monoamine transporter 2 inhibitor, in children and adolescents with TS.

Methods

Alternatives for Reducing Tics in TS (ARTISTS) open-label extension (OLE) (NCT03567291) was a 54-week, global, phase 3, open-label extension study of deutetrabenazine (6-48 mg daily) conducted May 28, 2018 to April 3, 2020 with a 2-week randomized withdrawal period. Participants (6-16 years of age) had TS and active tics causing distress or impairment. Safety (primary outcome) was assessed by treatment-emergent adverse events (TEAEs) and clinical laboratory testing. Efficacy was measured by the Yale Global Tic Severity Scale-Total Tic Score (YGTSS-TTS).

Results

The intent-to-treat population (228 participants; mean age, 12.0 years; 79.8% male; 86.4% white) had a median (range) duration of exposure of 28.4 (0.3-52.9) weeks. Of 227 participants in the safety analysis, 161 (70.9%) reported ≥1 TEAE (exposure-adjusted incidence rate, 2.77/patient-year), of which 95 (41.9%) were treatment related. The most frequently reported TEAEs were headaches, somnolence, nasopharyngitis, weight increases, and anxiety. No additional safety signals were observed. Worsening of YGTSS-TTS after the 2-week randomized withdrawal was not statistically significant (least squares mean difference, -0.4; P = 0.78). Several exploratory measures showed sustained improvement throughout the treatment periods.

Conclusions

In this long-term, open-label trial, deutetrabenazine was well tolerated with low frequency of TEAEs. There was no significant difference in tics between treatment arms during the 2-week randomized withdrawal period, however, descriptive statistics and comparison with baseline showed a numeric improvement in tics, quality of life, and other measures.

Deuterium in drug discovery: progress, opportunities and challenges

Substitution of a hydrogen atom with its heavy isotope deuterium entails the addition of one neutron to a molecule. Despite being a subtle change, this structural modification, known as deuteration, may improve the pharmacokinetic and/or toxicity profile of drugs, potentially translating into improvements in efficacy and safety compared with the non-deuterated counterparts. Initially, efforts to exploit this potential primarily led to the development of deuterated analogues of marketed drugs through a 'deuterium switch' approach, such as deutetrabenazine, which became the first deuterated drug to receive FDA approval in 2017. In the past few years, the focus has shifted to applying deuteration in novel drug discovery, and the FDA approved the pioneering de novo deuterated drug deucravacitinib in 2022. In this Review, we highlight key milestones in the field of deuteration in drug discovery and development, emphasizing recent and instructive medicinal chemistry programmes and discussing the opportunities and hurdles for drug developers, as well as the questions that remain to be addressed.

Comparative efficacy, tolerability, and acceptability of pharmacological interventions for the treatment of children, adolescents, and young adults with Tourette's syndrome: a systematic review and network meta-analysis

BACKGROUND

In clinical practice guidelines there is no consensus about the medications that should be initially offered to children and young people with Tourette's syndrome. To provide a rigorous evidence base that could help guide decision making and guideline development, we aimed to compare the efficacy, tolerability, and acceptability of pharmacological interventions for Tourette's syndrome.

METHODS

For this systematic review and network meta-analysis, we searched the Cochrane Central Register of Controlled Trials, Embase, PsycINFO, PubMed, Web of Science, the WHO International Clinical Trials Registry Platform, and ClinicalTrials.gov, for published and unpublished studies from database inception to Nov 19, 2021. We included double-blind randomised controlled trials of any medication administered as a monotherapy for at least 1 week against another medication or placebo in children and adolescents (aged ≥4 years and ≤18 years), adults (>18 years), or both, diagnosed with Tourette's syndrome according to standardised criteria. We excluded studies that exclusively recruited participants with comorbid attention-deficit hyperactivity disorder or obsessive-compulsive disorder. The primary outcome was change in severity of tic symptoms (efficacy). Secondary outcomes were treatment discontinuations due to adverse events (tolerability) and for any reason (acceptability). Pharmacological interventions were examined considering medication categories and medications individually in separate analyses. Summary data were extracted and pooled with a random-effects network meta-analysis to calculate standardised mean differences for efficacy and odds ratios for tolerability and acceptability, with 95% CIs. The Confidence in Network Meta-Analysis (CINeMA) framework was used to assess the certainty of evidence. The protocol was pre-registered in PROSPERO (CRD42022296975).

FINDINGS

Of the 12 088 records identified through the database search, 88 records representing 39 randomised controlled trials were included in the network meta-analysis; these 39 randomised controlled trials comprised 4578 participants (mean age 11·8 [SD 4·5] years; 3676 [80·8%] male participants) and evaluated 23 individual medications distributed across six medication categories. When considering medication categories, first-generation (standardised mean difference [SMD] -0·65 [95% CI -0·79 to -0·51]; low certainty of evidence) and second-generation (-0·71 [-0·88 to -0·54]; moderate certainty of evidence) antipsychotic drugs, as well as α-2 agonists (-0·21 [-0·39 to -0·03]; moderate certainty of evidence), were more efficacious than placebo. First-generation and second-generation antipsychotic drugs did not differ from each other (SMD 0·06 [95% CI -0·14 to 0·25]; low certainty of evidence). However, both first-generation (SMD 0·44 [95% CI 0·21 to 0·66]) and second-generation (0·49 [0·25 to 0·74]) antipsychotic drugs outperformed α-2 agonists, with moderate certainty of evidence. Similar findings were observed when individual medications were considered: aripiprazole (SMD -0·60 [95% CI -0·83 to -0·38]), haloperidol (-0·51 [-0·88 to -0·14]), olanzapine (-0·83 [-1·49 to -0·18]), pimozide (-0·48 [-0·84 to -0·12]), risperidone (-0·66 [-0·98 to -0·34]), and clonidine (-0·20 [-0·37 to -0·02]) all outperformed placebo, with moderate certainty of evidence. Antipsychotic medications did not differ from each other, but there was low to very low certainty of evidence for these comparisons. However, aripiprazole (SMD -0·40 [95% CI -0·69 to -0·12]) and risperidone (-0·46 [-0·82 to -0·11]) outperformed clonidine, with moderate certainty of evidence. Heterogeneity or inconsistency only emerged for a few comparisons. In terms of tolerability and acceptability, there were no relevant findings for any of the efficacious medication categories or individual medications against each other or placebo, but there was low to very low certainty of evidence associated with these comparisons.

INTERPRETATION

Our analyses show that antipsychotic drugs are the most efficacious intervention for Tourette's syndrome, while α-2 agonists are also more efficacious than placebo and could be chosen by those who elect not to take antipsychotic drugs. Shared decision making about the degree of tic-related severity and distress or impairment, the trade-offs of efficacy and safety between antipsychotic drugs and α-2 agonists, and other highly relevant individual factors that could not be addressed in the present analysis, should guide the choice of medication for children and young people with Tourette's syndrome.

FUNDING

None.

Emerging therapies and recent advances for Tourette syndrome

Tourette syndrome is the most prevalent hyperkinetic movement disorder in children and can be highly disabling. While the pathomechanism of Tourette syndrome remains largely obscure, recent studies have greatly improved our knowledge about this disease, providing a new perspective in our understanding of this condition. Advances in electrophysiology and neuroimaging have elucidated that there is a reduction in frontal cortical volume and reduction of long rage connectivity to the frontal lobe from other parts of the brain. Several genes have also been identified to be associated with Tourette syndrome. Treatment of Tourette syndrome requires a multidisciplinary approach which includes behavioral and pharmacological therapy. In severe cases surgical therapy with deep brain stimulation may be warranted, though the optimal location for stimulation is still being investigated. Studies on alternative therapies including traditional Chinese medicine and neuromodulation, such as transcranial magnetic stimulation have shown promising results, but still are being used in an experimental basis. Several new therapies have also recently been tested in clinical trials. This review provides an overview of the latest findings with regards to genetics and neuroimaging for Tourette syndrome as well as an update on advanced therapeutics.

Sleep Dysfunction in Huntington's Disease: Impacts of Current Medications and Prospects for Treatment

Sleep dysfunction is highly prevalent in Huntington's disease (HD). Increasing evidence suggests that such dysfunction not only impairs quality of life and exacerbates symptoms but may even accelerate the underlying disease process. Despite this, current HD treatment approaches neither consider the impact of commonly used medications on sleep, nor directly tackle sleep dysfunction. In this review, we discuss approaches to these two areas, evaluating not only literature from clinical studies in HD, but also that from parallel neurodegenerative conditions and preclinical models of HD. We conclude by summarizing a hierarchical framework of current medications with regard to their impact on sleep, and by outlining key emerging sleep therapies.

The French version of the Gilles de la Tourette Syndrome Quality of Life Scale for adolescents (GTS-QOL-French-Ado): Adaptation and psychometric evaluation

INTRODUCTION

The aim of this study was to create a new version of the French GTS-QOL adapted to adolescents with GTS aged 12-16 years (GTS-QOL-French-Ado) and to evaluate its psychometric properties.

METHODS

We assessed the psychometric properties of the GTS-QOL-French-Ado in 84 adolescents (mean age 13.6 years, standard deviation 1.2) in terms of factor structure, internal consistency, reliability and convergent validity with the Child Depression Inventory (CDI), the Multidimensional Anxiety Scale for Children (MASC), the Motor tic, Obsessions and compulsions, Vocal tic Evaluation Survey (MOVES) and the French "Vécu et Santé Perçue de l'Adolescent" (VSP-A), a generic self-administered measure of health-related quality of life (HRQoL) in adolescents.

RESULTS

Exploratory factor analysis of the GTS-QOL-French-Ado resulted in a 5-factor solution. The GTS-QOL-French-Ado demonstrated good acceptability with missing values per subscale ranging from 0% to 1.2%, good internal consistency for four of the five subscales with Cronbach's alpha ranging from 0.56 to 0.87 and good test-retest reliability with intraclass correlation coefficients ranging from 0.74 (95% CI: 0.52-0.86) to 0.82 (95% CI: 0.66-0.91). Convergent validity was supported by correlations with CDI, MASC, MOVES, VSP-A and clinical variables.

DISCUSSION

The GTS-QOL-French-Ado is the first disease-specific HRQoL tool for French-speaking adolescents with GTS aged 12-16 years, and shows good psychometric properties. Further psychometric testing on responsiveness to change would be of great interest.

Tourette syndrome research highlights from 2021

We summarize selected research reports from 2021 relevant to Tourette syndrome that the authors consider most important or interesting. The authors welcome article suggestions and thoughtful feedback from readers.

Meta-Analysis: Efficacy and Tolerability of Vesicular Monoamine Transporter Type 2 Inhibitors in the Treatment of Tic Disorders

Vesicular monoamine transporter type 2 (VMAT2) inhibitors may be an effective therapy for chronic tic disorders (CTD), including Tourette syndrome (TS), but there has not been a meta-analysis compiling available evidence from randomized controlled trials (RCTs). We performed a systematic review and meta-analysis to evaluate the efficacy, acceptability, and tolerability of VMAT2 inhibitors for CTD/TS. PubMed, CENTRAL, and Embase were searched for double-blinded RCTs of VMAT2 inhibitors versus placebo for the treatment of CTD/TS. Change in tic severity measured by the Yale Global Tic Severity Scale (efficacy) and rates of discontinuation attributed to adverse effects (tolerability) or all causes (acceptability) were extracted closest to 12 weeks. Mean difference (MD) and odds ratio (OR) were the effect size indexes for efficacy and acceptability/tolerability, respectively. Data were pooled through random-effects meta-analysis weighted by inverse variance. Five RCTs involving eight comparisons were included. Meta-analysis found a nonsignificant effect on efficacy (k = 8; N = 583; MD = -0.71; 95% confidence interval [CI], -1.93 to 0.50; P = 0.24), and there was certainty that the true effect is nonclinically meaningful (high quality of evidence). Meta-analysis found decreased tolerability (k = 7; N = 626; OR = 2.67; 95% CI, 1.21-5.92; P = 0.01) and decreased acceptability (k = 8; N = 626; OR = 1.90; 95% CI, 1.14-3.18; P = 0.01), although those comparisons were limited because of the relatively small number of events across trials. Meta-analyses did not support the efficacy of VMAT2 inhibitors in the short-term treatment of tic disorders and suggested no clinically meaningful effect of these agents on tic symptoms. © 2022 International Parkinson and Movement Disorder Society.