Real-world experience with Deutetrabenazine management in patients with Huntington's disease using video-based telemedicine

BACKGROUND

Huntington's disease (HD) is a rare progressive neurological disorder, and telemedicine has the potential to improve the quality of care for patients with HD. Deutetrabenazine (DTBZ) can reduce chorea symptoms in HD; however, there is limited experience with this medication in Asian countries.

METHODS

Retrospective and prospective studies were employed to explore the feasibility and reliability of a video-based telemedicine system for HD patient care. Reliability was demonstrated through consistency between selected-item scores (SIS) and total motor scores (TMS) and the agreement of scores obtained from hospital and home videos. Finally, a single-centre real-world DTBZ management study was conducted based on the telemedicine system to explore the efficacy of DTBZ in patients with HD.

RESULTS

There were 77 patients included in the retrospective study, and a strong correlation was found between SIS and TMS (r = 0.911, P < 0.0001), indicating good representativeness. There were 32 patients enrolled in the prospective study. The reliability was further confirmed, indicated by correlations between SIS and TMS (r = 0.964, P < 0.0001) and consistency of SIS derived from the in-person and virtual visits (r = 0.969, P < 0.0001). There were 17 patients included in the DTBZ study with a mean 1.41 (95% confidence interval, 0.37-2.46) improvement in chorea score and reported treatment success.

CONCLUSIONS

A video-based telemedicine system is a feasible and reliable option for HD patient care. It may also be used for drug management as a supplementary tool for clinical visits.

Safety of Deutetrabenazine for the Treatment of Tardive Dyskinesia and Chorea Associated with Huntington Disease

INTRODUCTION

Deutetrabenazine is a vesicular monoamine transporter 2 inhibitor used to treat tardive dyskinesia (TD) and chorea associated with Huntington disease (HD). To enhance detection of safety signals across individual trials, integrated safety analyses of deutetrabenazine in TD and HD chorea were conducted.

METHODS

For TD, safety data were integrated from two 12-week pivotal studies (ARM-TD and AIM-TD) and through week 15 of the open-label extension (OLE) study (RIM-TD). Data were analyzed by deutetrabenazine treatment group and placebo. For HD, safety data were integrated from the 12-week pivotal study (First-HD) and through week 15 of the OLE study (ARC-HD) for patients previously receiving placebo. Integrated deutetrabenazine data were compared with placebo from the pivotal study.

RESULTS

For TD, deutetrabenazine (n = 384) was generally well tolerated compared with placebo (n = 130). Adverse event (AE) incidence was numerically higher in the response-driven deutetrabenazine vs the fixed-dose deutetrabenazine and placebo groups, respectively (any AE, 59.5% vs 44.4-50.0% and 53.8%; treatment-related AE, 38.1% vs 18.1-25.0% and 30.8%). Serious AEs were reported for 2.8-8.3% of patients in the deutetrabenazine groups and 6.9% in the placebo group. Common AEs (≥ 4%) included headache, somnolence, nausea, anxiety, fatigue, dry mouth, and diarrhea. AE incidence was higher during the titration vs maintenance periods. For HD, AE incidence was numerically higher with deutetrabenazine (n = 84) vs placebo (n = 45; any AE, 64.3% vs 60.0%; treatment-related AE, 38.1% vs 26.7%); serious AEs were reported for similar proportions for the deutetrabenazine and placebo groups, 2.4% and 2.2%, respectively. Common AEs (≥ 4%) included irritability, fall, depression, dry mouth, and fatigue.

CONCLUSIONS

Data from an integrated analysis of studies in TD and an integrated analysis of studies of chorea in HD showed that deutetrabenazine has a favorable safety profile and is well tolerated across indications.

TRIAL REGISTRATION

ClinicalTrials.gov identifiers, NCT02291861, NCT02195700, NCT01795859, NCT02198794, NCT01897896.

Multiple therapies relieve long-term tardive dyskinesia in a patient with chronic schizophrenia: A case report

BACKGROUND

Tardive dyskinesia (TD) is a serious and disabling movement disorder; it impairs social function and quality of life and increases the mortality rate. TD is usually induced by the use of antipsychotic drugs; however, the underlying mechanism remains unclear. Pharmacotherapy of TD includes cholinergic drugs, benzodiazepines, ginkgo biloba extract (GBE), antioxidants, amantadine, propanolol, botulinum toxin, valbenazine, and deutetrabenazine, whereas the non-pharmacotherapy approach includes modified electroconvulsive therapy (MECT) and deep brain stimulation. We successfully treated a chronic schizophrenia patient with comorbid long-term severe TD using deutetrabenazine, clozapine, and MECT.

CASE SUMMARY

A 69-year-old woman who was diagnosed as having schizophrenia 16 years ago developed severe TD after 6-mo prescription of risperidone oral solution. Her TD symptoms did not resolve despite various treatments, such as GBE, vitamin E, trihexyphenidyl, promethazine, benzodiazepines, and switching to quetiapine and olanzapine. After admission, she was given deutetrabenazine 6 mg bid. Her buccal tremor was slightly resolved 3 d later; however, her tongue remained protruded and could not be retracted. Quetiapine was switched to clozapine on day 4, and the buccal tremor remarkably resolved, and the tongue could be retracted into the mouth from day 6 onward. After three sessions of MECT, the buccal tremor resolved further. Since then, she has been able to take a semifluid diet, and her quality of life improved remarkably during 6 mo of follow-up.

CONCLUSION

TD is a serious condition which could be caused by antipsychotic medications; however, the best strategy against TD is prevention and monitoring during using antipsychotics. For patients with TD caused by antipsychotic medication use, multiple measures should be considered like switching to clozapine, adjunction with deutetrabenazine, or even MECT.

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.

deutetrabenazine for the treatment of chorea associated with Huntington's disease

This is a comprehensive review of the literature regarding the use of Deutetrabenazine in treating chorea associated with Huntington's disease. Unfortunately, treatment has been limited for many aspects of this neurodegenerative disease. The present investigation presents the background, evidence, and indications for the use Deutetrabenazine in the setting of Huntington's disease. Huntington's disease is characterized by a variety of motor, psychiatric, and cognitive symptoms with chorea being one of the more notable ones. Chorea is a movement disorder present in multiple neurologic diseases that causes involuntary and irregular muscle movements theorized to be stemming from high dopamine levels. Deutetrabenazine is thought to function as an inhibitor of the VMAT2 vesicular monoamine transporter resulting in decreased monoamine release, including dopamine, in the synaptic cleft which has a therapeutic effect in management of chorea. This drug was approved by the FDA in 2017 with a specific indication for tardive dyskinesia and choreiform movement in Huntington's disease. Currently, there is no definitive treatment for Huntington's disease. Thus, management is primarily focused on symptom management with the use of a variety of pharmaceutical agents. Chorea is one of the many manifestations that significantly alter the quality of life of many patients. Deutetrabenazine is a promising new option for the treatment of chorea in the setting of Huntington's disease. Although studies so far have displayed mixed results, further research, including head-to-head studies, is necessary to elucidate the true potential of this drug.

Minimal clinically important change in Abnormal Involuntary Movement Scale score in tardive dyskinesia as assessed in pivotal trials of deutetrabenazine

INTRODUCTION

Deutetrabenazine is approved by the US Food and Drug Administration to treat tardive dyskinesia (TD) based on 2 pivotal, 12-week, placebo-controlled studies (ARM-TD and AIM-TD) evaluating safety and efficacy in patients with baseline total motor Abnormal Involuntary Movement Scale (AIMS) score ≥6. This analysis estimated the minimal clinically important change (MCIC) in total motor AIMS score in TD patients treated with deutetrabenazine.

METHODS

The pooled analysis population included all patients in ARM-TD and AIM-TD who received study drug and had ≥1 postbaseline AIMS assessment. MCIC analyses were performed using Patient Global Impression of Change (PGIC) and Clinical Global Impression of Change (CGIC) as anchors. MCIC was defined as the mean change from baseline in total motor AIMS score in patients treated with deutetrabenazine who were rated minimally improved on PGIC or CGIC at Week 12.

RESULTS

This analysis included 295 patients (deutetrabenazine, n = 197; placebo, n = 98). At Week 12, the MCIC in deutetrabenazine-treated patients was -2.4 based on the PGIC and -2.1 based on the CGIC. Mean change from baseline in total motor AIMS score for placebo-treated patients rated minimally improved was -1.4 based on the PGIC and -1.5 based on the CGIC. The proportion of deutetrabenazine-treated patients who achieved improvement in total motor AIMS score by ≥2 and ≥3 points was 66% and 55%, respectively.

CONCLUSION

Using anchor-based methodology, the MCIC on the AIMS for deutetrabenazine in patients with TD was approximately -2, suggesting that a reduction in total motor AIMS score of ∼2 is associated with clinically meaningful improvement in TD symptoms.

Long-Term Safety and Efficacy of Deutetrabenazine in Younger and Older Patients With Tardive Dyskinesia

OBJECTIVES

To assess long-term safety and efficacy of deutetrabenazine in younger (<55 years) and older (≥55 years) adult participants with tardive dyskinesia (TD).

DESIGN

Three-year, single-arm, open-label extension (OLE) study enrolling participants who completed the 12-week, pivotal ARM-TD or AIM-TD studies.

SETTING

Seventy-six centers in the United States and Europe.

PARTICIPANTS

A total of 337 participants with TD (119 younger and 218 older).

INTERVENTION

Deutetrabenazine was initiated at 12 mg/day and titrated once weekly by 6 mg/day using a response-driven dosing regimen until adequate dyskinesia control was reached or a clinically significant adverse event occurred.

MEASUREMENTS

This post hoc analysis assessed change and percent change from baseline in total motor Abnormal Involuntary Movement Scale (AIMS) score, response rates for ≥50% AIMS improvement, Clinical Global Impression of Change (CGIC), Patient Global Impression of Change (PGIC), and safety in younger and older participants with TD.

RESULTS

After 3 years of open-label treatment, mean deutetrabenazine dose was ∼39.5 mg/day in both groups. Mean±SE changes from baseline in total motor AIMS score were -6.7 ± 0.62 and -6.5 ± 0.47 in younger and older participants, respectively (percent changes: -61.4% ± 4.10% and -54.6% ± 3.01%); 76% of younger and 62% of older participants achieved ≥50% AIMS response. Most younger and older participants achieved treatment success per CGIC (67% and 76%) and PGIC (64% and 63%). Deutetrabenazine was generally well tolerated in both groups.

CONCLUSIONS

Deutetrabenazine treatment was associated with sustained improvements in total motor AIMS score, treatment success, and improved quality of life, and was well tolerated in younger and older adults with TD in this 3-year OLE study.

Real-World Adherence to Tetrabenazine or Deutetrabenazine Among Patients With Huntington's Disease: A Retrospective Database Analysis

Introduction

Chorea, a common clinical manifestation of Huntington’s disease (HD), involves sudden, involuntary movements that interfere with daily functioning and contribute to the morbidity of HD. Tetrabenazine and deutetrabenazine are FDA-approved to treat chorea associated with HD. Compared to tetrabenazine, deutetrabenazine has a unique pharmacokinetic profile leading to more consistent systemic exposure, less frequent dosing, and a potentially more favorable safety/tolerability profile. Real-world adherence data for these medications are limited. Here, we evaluate real-world adherence patterns with the vesicular monoamine transporter 2 inhibitors, tetrabenazine and deutetrabenazine, among patients diagnosed with HD.

Methods

Insurance claims data from the Symphony Health Solutions Integrated Dataverse (05/2017–05/2019) were retrospectively analyzed for patients diagnosed with HD (ICD-10-CM code G10). Patients were categorized into cohorts based on treatment. Outcomes included adherence, which was measured by proportion of days covered (PDC), adherence rate (PDC > 80%), and discontinuation rates during the 6-month follow-up period (after a 30-day dose stabilization period).

Results

Patient demographic characteristics between the deutetrabenazine (N = 281) and tetrabenazine (N = 101) cohorts were comparable at baseline. Mean ± SD PDC was significantly higher in the deutetrabenazine versus tetrabenazine cohort (78.5% ± 26.7% vs. 69.3% ± 31.4%; P < 0.01). Similarly, a higher adherence rate was observed in the deutetrabenazine versus tetrabenazine cohort, though the difference was not statistically significant (64.1% vs. 55.4%; P = 0.1518). Discontinuation rates were significantly lower in the deutetrabenazine versus tetrabenazine cohort during the 6-month follow-up period (1 month, 3.5% vs. 9.2%; 3 months, 14.7% vs. 23.3%; 6 months, 25.4% vs. 37.2%; P < 0.05).

Conclusions

Results from this real-world analysis indicate that patients treated with deutetrabenazine are more adherent to treatment and have lower discontinuation rates compared with patients in the tetrabenazine cohort. However, a potential limitation is overestimated adherence, as claims for prescription fills may not capture actual use. Additional research is warranted to explore the differences in adherence patterns between treatments, which may inform treatment decision-making.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40120-021-00309-5.

The effect of potent CYP2D6 inhibition on the pharmacokinetics and safety of deutetrabenazine in healthy volunteers

Purpose

Deutetrabenazine is a deuterated form of tetrabenazine with a confirmed lower rate of CYP2D6 metabolism of the active metabolites, α- and β-HTBZ. In this study, we assessed the effect of paroxetine, a potent CYP2D6 inhibitor, on the pharmacokinetics and safety of deutetrabenazine and its metabolites.

Methods

In this open-label sequential drug-drug-interaction study, 24 healthy adults who were CYP2D6 extensive or intermediate metabolizers received a single deutetrabenazine 22.5-mg oral dose on days 1 and 11 and a single paroxetine 20-mg oral daily dose on days 4–12. Pharmacokinetics of deutetrabenazine and its metabolites were assessed on days 1–4 and 11–14. Paroxetine trough concentrations were obtained pre-dose on days 9–13. Safety examinations occurred throughout the study.

Results

Paroxetine administered under steady-state conditions, increased exposure of the deuterated active metabolites, α-HTBZ (1.2-fold C_max and 1.8-fold AUC_0–∞) and β-HTBZ (2.1-fold C_max and 5.6-fold AUC_0–∞), and correspondingly, 1.6-fold C_max and threefold AUC_0–∞ for total (α + β)-HTBZ. Sixteen subjects reported 45 adverse events and most were mild. Headache was the most common AE reported 8 times by 7 subjects (5 following paroxetine alone; 2 following deutetrabenazine + paroxetine).

Conclusions

Paroxetine-induced increases in exposure to the active deutetrabenazine metabolites were less than those previously reported for tetrabenazine, a finding expected to reduce the burden of drug interaction. In addition, single doses of 22.5 mg deutetrabenazine, when given alone or in the presence of steady-state paroxetine (20 mg daily), were safe.

Supplementary information

The online version contains supplementary material available at 10.1007/s00228-021-03202-0.

Risk of Neuroleptic Malignant Syndrome with Vesicular Monoamine Transporter Inhibitors

Objective

Vesicular monoamine transporter-2 (VMAT2) inhibitors have been proven to be effective for the treatment of tardive dyskinesia and their use is likely to increase. The evidence base of published clinical reports was reviewed to evaluate the possible risk of neuroleptic malignant syndrome (NMS) with these drugs.

Methods

Pubmed, Embase, Web of Science and PsycINFO databases were queried for all years using terms for “neuroleptic malignant syndrome”, “hyperthermia” AND “vesicular monoamine transporter inhibitors”, “reserpine”, “tetrabenazine”, “valbenazine” or “deutetrabenazine”

Results

Thirteen clinical cases, ten of which involved tetrabenazine, were identified in which VMAT2 inhibitors were prescribed in patients with current or past NMS episodes. In most cases, the association was confounded by limited reporting of clinical data, variable temporal correlation with VMAT2 inhibitors, polypharmacy with antipsychotics, and uncertain differential diagnoses.

Conclusion

While rare cases of NMS meeting consensus criteria have been reported primarily with tetrabenazine, the risk with recently developed VMAT2 inhibitors may be even less. Evidence of causality of NMS with VMAT2 inhibitors is confounded by concomitant treatment with antipsychotics and diagnostic uncertainties in patients susceptible to basal ganglia dysfunction. Nevertheless, clinicians should remain vigilant for early signs of NMS in all patients treated with any drugs that affect brain dopamine activity.

VMAT2 inhibitors for the treatment of hyperkinetic movement disorders

Hyperkinetic movement disorders comprise a variety of conditions characterized by involuntary movements, which include but are not limited to tardive dyskinesia, chorea associated with Huntington's Disease, and tic disorders. The class of medications that have been used to treat these conditions includes Vesicular Monoamine Transporter-2 (VMAT2) inhibitors. In 2008, the FDA approved tetrabenazine as a treatment for chorea associated with Huntington's Disease. Optimization of the pharmacology of tetrabenazine has since led to the approval of two new VMAT2 inhibitors, deutetrabenazine and valbenazine. The objective of this review is to provide background on the role of VMAT in monoamine neurotransmission, the mechanism of VMAT2 inhibition on the treatment of hyperkinetic disorders (specifically tardive dyskinesia and chorea associated with Huntington's Disease), the pharmacology and pharmacokinetics of the commercially available VMAT2 inhibitors, and a summary of the clinical data to support application of these medications.

Treatment of tics associated with Tourette syndrome

Motor and phonic tics associated with Tourette syndrome (TS) can range in severity from barely perceptible to disabling and most patients have a variety of behavioral co-morbidities, particularly, attention deficit disorder and obsessive compulsive disorder. Therefore, therapy must be tailored to the individual needs of the patients. In addition to behavioral therapy, oral medications such as alpha agonists, dopamine depletors, anti-psychotics, and topiramate are used to control the involuntary movements and noises. Botulinum toxin injections are particularly effective in patients with troublesome focal motor and phonic tics, including coprolalia. Deep brain stimulation may be considered for patients with "malignant" TS, that is, refractory to medical therapy. When appropriate therapy is selected and implemented, most patients with TS can achieve their full potential and lead essentially normal life.

Current treatment of tardive dyskinesia

Tardive dyskinesia (TD) is a common, iatrogenic movement disorder affecting many individuals treated with dopamine-receptor blocking agents (DRBAs). Studying treatment of TD can be complex, as the symptoms can be affected by changes in either dosage or type of DRBA, as well as by the variable natural course of the disease. Historically many pharmacological therapies have been studied in TD, finding varying degrees of treatment success. Most recently, the VMAT2 inhibitors valbenazine and deutetrabenazine were rigorously studied in TD in large, phase III clinical trials, and were shown to be beneficial in this population. In this article, we will review various treatments of TD, including manipulation of the offending agent, VMAT2 inhibitors, other non-VMAT2-inhibiting medications, and non-pharmacological approaches.

Deuterium Tetrabenazine for Tardive Dyskinesia

Tardive dyskinesia remains a significant, potentially stigmatizing or crippling adverse effect for any patient treated with an antipsychotic medication. While second- and third-generation antipsychotics have exhibited lower annual incidence rates for tardive dyskinesia than classic or first-generation agents, 3.9% versus 5.5%, the estimated incidence rate is only modestly lower. When coupled with the fact that second- and third-generation antipsychotic medications have come to be employed in treating a wider range of disorders (e.g., autism spectrum disorders, mood disorders, personality disorders, etc.), it is clear that the population of patients exposed to the risk of tardive dyskinesia has expanded. On April 3, 2017, the U.S. Food and Drug Administration (FDA) approved a deuterated version of tetrabenazine (Xenozine®) for the treatment of the involuntary choreic movements associated with Huntington's disease. More recent data, however, have indicated that deuterium tetrabenazine or deutetrabenazine (Austedo®) is effective in treating tardive dyskinesia. Moreover, like the other derivative of tetrabenazine, valbenazine (Ingrezza®), deutetrabenazine offers less frequent dosing and a better short-term adverse effect profile than that of tetrabenazine. Longer use in a broader range of patients, however, will be required to identify risks and benefits not found in short-term trials, as well as optimal use parameters for treatment of tardive dyskinesia.

Reprint of: Clinical management of tardive dyskinesia: Five steps to success

Tardive dyskinesia (TD) has long been thought to be a generally irreversible consequence of the use of dopamine receptor blocking agents. There is now an opportunity to successfully manage this condition with agents approved by the US Food and Drug Administration. This is important because TD has not been eliminated with the use of second-generation antipsychotics, and the expansion of antipsychotics to treat conditions other than schizophrenia has resulted in millions of additional individuals at risk for developing TD. Recognition of TD requires careful observation; a structured approach using the Abnormal Involuntary Movement Scale is encouraged. Harm reduction can be achieved by using antipsychotics judiciously when possible and by paying attention to other modifiable risk factors such as drug-induced parkinsonian symptoms and the use of anticholinergic medication. Once TD has emerged and is associated with dysfunction or distress, treatment with a VMAT2 inhibitor such as deutetrabenazine or valbenazine is well supported by several controlled clinical trials.

Tardive dyskinesia: Out of the shadows

The approvals of the first two medications, valbenazine and deutetrabenazine, to treat tardive dyskinesia have ushered in a new era in neuropsychiatric care. Tardive syndromes are defined as delayed onset, persistent movement disorders or sensory phenomena that occur in association with exposure to dopamine receptor blocking agents (DRBAs). Their underlying pathophysiology remains to be fully elucidated, but clinicians can conceptualize tardive syndromes as persistent dopamine supersensitivity states. Tardive syndromes can potentially cause distress, disfigurement, embarrassment, and dysfunction, and are often permanent. Therefore, practitioners who prescribe DRBAs should be aware of this potential, carefully assess the risk/benefit ratio when considering the use of these medications, and be sure that patients are appropriately informed. Patients on DRBAs should be monitored for the development of tardive syndromes, including through the use of regularly scheduled Abnormal Involuntary Movement Scale (AIMS) (or similar) examinations. Clinicians prescribing DRBAs should be familiar with the diagnosis and management of tardive syndromes, and be able to institute treatment or refer patients when treatment is appropriate. Future research may focus on the potential benefit of earlier introduction of VMAT2 inhibitors to delay onset or progression of tardive syndromes. More effective treatments are still needed, as are effective, well-tolerated antipsychotics that do not cause tardive syndromes.

Deutetrabenazine: Treatment of hyperkinetic aspects of Huntington's disease, tardive dyskinesia and Tourette syndrome

Deutetrabenazine is a derivative of tetrabenazine in which two trideuteromethoxy groups substitute two methoxy groups. The active metabolites of deutetrabenazine have a longer half-life than those of tetrabenazine, together with a greater overall absorption. However, the peak plasma concentrations are lower. Because of these pharmacokinetic differences, deutetrabenazine can be given twice daily, thus improving compliance. The lower peak concentrations may account for a lower incidence of some unwanted adverse effects. Unlike tetrabenazine, deutetrabenazine has no effect on the QT interval. Treatment with deutetrabenazine significantly improved chorea in Huntington's disease, the hyperkinetic features of tardive dyskinesia, and tics in Tourette syndrome. In all three conditions, deutetrabenazine produced an acceptable level of overall adverse effects without causing any severe adverse effects.

Indirect tolerability comparison of Deutetrabenazine and Tetrabenazine for Huntington disease

Background

Vesicular monoamine transporter 2 (VMAT2) inhibitors can improve hyperkinetic movements, and are effective treatment options for chorea of Huntington disease (HD). Tetrabenazine was assessed for treating chorea in the TETRA-HD trial, and while efficacious, there are tolerability concerns possibly due to its pharmacokinetic properties. Deutetrabenazine is a novel VMAT2 inhibitor that contains deuterium, which extends active metabolite half-lives and minimizes drug concentration fluctuations. In the First-HD trial, deutetrabenazine was efficacious in treating chorea and was generally well tolerated. In the absence of a head-to-head trial, we performed an indirect treatment comparison (ITC) of the tolerability of deutetrabenazine and tetrabenazine for the treatment of HD-associated chorea, as observed in the First-HD and TETRA-HD trials, using well-established comparison methods.

Methods

Data from the Phase III, 12-week, parallel-group, clinical trials First-HD (N = 90) and TETRA-HD (N = 84) were used to conduct an ITC of the tolerability of deutetrabenazine versus tetrabenazine using two anchor-based methods: Bucher comparison for unadjusted ITCs, and matching indirect comparison for adjusted ITCs. Overall adverse events (AEs; mild, moderate, and severe), serious AEs, specific AEs occurring in ≥10% of patients, and discontinuations (all-cause and AE-related) were included in the analysis. The risk differences of these outcomes for deutetrabenazine and tetrabenazine were estimated by subtracting the applicable placebo-adjusted risk in First-HD from that of TETRA-HD. Sensitivity analyses were performed to address differences between trials, and p-values were obtained from z-tests.

Results

Compared with tetrabenazine, deutetrabenazine was associated with a significantly lower risk of moderate to severe AEs and neuropsychiatric AEs including agitation, akathisia, depression, depression/agitated depression, drowsiness/somnolence, insomnia, and parkinsonism in both adjusted and unadjusted analyses (p < 0.05 for each). Deutetrabenazine had a significantly lower rate of dose reduction or dose reduction/suspension in the unadjusted and adjusted analyses (p < 0.001 for each). Deutetrabenazine resulted in numerically more mild AEs, such as diarrhea and coughing; however, these results were not statistically significant.

Conclusions

This indirect treatment comparison demonstrates that for the treatment of HD chorea, deutetrabenazine has a favorable tolerability profile compared to tetrabenazine.

Trial registration

ClinicalTrials.gov NCT01795859 and NCT00219804.

Dopamine depleters in the treatment of hyperkinetic movement disorders

INTRODUCTION

Abnormal involuntary movements often improve in response to anti-dopaminergic drugs. In contrast to classic neuroleptics that block dopamine receptors, drugs that deplete presynaptic dopamine by blocking vesicular monoamine transporter type 2 (VMAT2) seem to be safer and have little or no risk of tardive dyskinesia. This is one reason why there has been a recent emergence of novel VMAT2 inhibitors. Areas covered: Since the approval of tetrabenazine, the classic VMAT2 inhibitor, in the treatment of chorea associated with Huntington disease (HD), other VMAT2 inhibitors (e.g. deutetrabenazine and valbenazine) have been studied in the treatment of HD-related chorea, tardive dyskinesia and tics associated with Tourette syndrome. This review, based largely on a detailed search of PubMed, will summarize the pharmacology and clinical experience with the various VMAT2 inhibitors. Expert commentary: Because of differences in pharmacology and pharmacokinetics these new VMAT2 inhibitors promise to be at least as effective as tetrabenazine but with a lower risk of adverse effects, such as sedation, insomnia, depression, parkinsonism, and akathisia.