Safety and efficacy of valbenazine for the treatment of chorea associated with Huntington's disease (KINECT-HD): a phase 3, randomised, double-blind, placebo-controlled trial

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.

Factors Influencing Discharges to Hospice for Patients With Late-Stage Huntington's Disease

Background: Hospice services for patients with Huntington's disease (HD) are likely beneficial in relieving significant burdens and minimizing costly hospitalizations at the end of life, though there has been little study or clinical guidance on hospice enrollment for patients with HD. Objectives: The primary objective of this study was to identify clinical, sociodemographic, and system-level factors associated with discharges to hospice compared to other dispositions for hospitalized patients with late-stage HD. Methods: These analyses used data from the Nationwide Inpatient Sample between the years 2007 and 2011. Weighted logistic regression with a forward selection approach was performed to identify factors associated with discharge to hospice compared to discharge to home, facility, other locations, and death in hospital. Results: These analyses included 6544 hospitalizations of patients with late-stage HD. There was a significant increasing trend in discharges to hospice over the study period (P < 0.001). After adjustment, multiple clinical, sociodemographic, and system-level variables were identified as being associated with discharges to hospice. Patients with aspiration pneumonia and non-aspiration pneumonias had lower odds of being discharged to hospice compared to dying in the hospital. When comparing to discharges to facilities and home, weight loss and palliative care consultation were associated with greater odds of discharge to hospice. Conclusions: Our findings serve as a foundation for future studies on these factors, and thus help clinician decision-making on when to start advance care planning or end-of-life care for patients with HD. These results also support studies developing hospice referral criteria specific to patients with HD.

Huntington's Disease: Latest Frontiers in Therapeutics

PURPOSE OF REVIEW

Huntington's disease (HD) is an autosomal-dominant disorder caused by a pathological expansion of a trinucleotide repeat (CAG) on exon 1 of the huntingtin (HTT) gene. HD is characterized by the presence of chorea, alongside other hyperkinesia, parkinsonism and a combination of cognitive and behavioural features. Currently, there are no disease-modifying therapies (DMTs) for HD, and the only intervention(s) with approved indication target the treatment of chorea. This article reviews recent research on the clinical development of DMTs and newly developed tools that enhance clinical trial design towards a successful DMT in the future.

RECENT FINDINGS

HD is living in an era of target-specific drug development with emphasis on the mechanisms related to mutant Huntingtin (HTT) protein. Examples include antisense oligonucleotides (ASO), splicing modifiers and microRNA molecules that aim to reduce the levels of mutant HTT protein. After initial negative results with ASO molecules Tominersen and WVE-120101/ WVE-120102, the therapeutic landscape continues to expand, with various trials currently under development to document proof-of-concept and safety/tolerability. Immune-targeted therapies have also been evaluated in early-phase clinical trials, with promising preliminary findings. The possibility of quantifying mHTT in CSF, along with the development of an integrated biological staging system in HD are important innovations applicable to clinical trial design that enhance the drug development process. Although a future in HD with DMTs remains a hope for those living with HD, care partners and care providers, the therapeutic landscape is promising, with various drug development programs underway following a targeted approach supported by disease-specific biomarkers and staging frameworks.

Friedreich Ataxia Caregiver-Reported Health Index: Development of a Novel, Disease-Specific Caregiver-Reported Outcome Measure

Background and Objectives

The Friedreich ataxia (FRDA) scientific community needs access to patient-centered outcome measures that satisfy regulatory guidelines and are capable of tracking clinically meaningful changes in FRDA disease burden. The objective of this research was to develop a novel, disease-specific caregiver-reported outcome measure for use in FRDA research and clinical care.

Methods

In prior work, we conducted qualitative interviews and a cross-sectional study of FRDA caregivers and patients to determine the symptoms of greatest importance to individuals with FRDA. We designed the Friedreich Ataxia Caregiver-Reported Health Index (FACR-HI) to serially measure the symptoms of greatest importance to patients and utilized factor analysis, beta testing, reliability testing, and cross-sectional subgroup analysis to further evaluate and optimize this disease-specific outcome measure.

Results

The FACR-HI was designed to measure total disease burden and disease burden in 18 symptomatic domains. The FACR-HI total score demonstrated high internal consistency (Cronbach's α = 0.98) and test-retest reliability (intraclass correlation coefficient = 0.96). Beta interview participants found the FACR-HI to be highly relevant, comprehensive, and easy to use. FACR-HI total and subscale scores were associated with functional staging for ataxia scores and speech impairment.

Discussion

Initial evaluation of the FACR-HI supports its content validity, test-retest reliability, and construct validity as a caregiver-reported outcome measure for assessing how pediatric individuals with FRDA feel and function. The FACR-HI provides a potential mechanism to quantify changes in multifactorial FRDA disease burden during future clinical trials.

Mining and analysis of security alert signals of valbenazine based on the Food and Drug Administration Adverse Event Reporting System database

BACKGROUND

Valbenazine is used for tardive movement disorders in adults. Current studies on its safety are mostly from clinical trials and small case reports, limiting information on rare adverse reactions. This study investigated valbenazine-related adverse event (AE) risk signals using the U.S. Food and Drug Administration Adverse Event Reporting System (FAERS) database.

METHODS

Valbenazine AEs data were collected from the FAERS database from 2017 Q2 to 2023 Q1, employing methods like reporting odds ratio (ROR), proportional reporting ratio (PRR), Bayesian confidence propagation neural network, and empirical Bayesian geometric mean.

RESULTS

After data cleaning and drug screening, there were 20,837 AEs primarily suspecting valbenazine, involving 26 system organ classes and 125 AEs related to valbenazine at the preferred terms level. AEs related to valbenazine were mainly concentrated in nervous system disorders, general disorders and administration site conditions, and psychiatric disorders. Eye disorders and gastrointestinal disorders are new AEs not labeled in the valbenazine instructions. In addition, some new potential AE signals were found, such as Tardive dyskinesia and eyelid function disorder.

CONCLUSION

The common AEs of valbenazine in the real world are consistent with the instructions, but there are some newly discovered suspicious AEs.

Influence of anosognosia on patient-reported outcomes for psychiatric symptoms and quality of life in Huntington's disease

INTRODUCTION

Anosognosia, defined as reduced awareness of one's deficit or symptom, is common in Huntington's disease (HD) and detectable at each disease stage. The impact of anosognosia on self-reporting in HD populations is critical to understand given growing use of patient-reported outcomes in HD clinical care and research. We aimed to determine the influence of anosognosia on patient-reported outcome measures assessing psychiatric symptoms and quality of life in HD.

METHODS

We enrolled HD patients to complete a battery of patient-reported and rater-administered measures, including the Anosognosia Scale, at baseline and 6 months later. Patient-reported outcome measures included NeuroQoL short forms for depression, anxiety, satisfaction with social roles and activities, and positive affect and well-being and Patient-Reported Outcomes Measurement Information System short forms for emotional distress-anger and sleep-related impairment. Anosognosia Scale-Difference Score indexed patient-clinician agreement on patient motor, cognitive, and behavioral abilities. We conducted multivariable linear regression analyses to quantify the association of baseline anosognosia with 6-month patient-reported outcomes.

RESULTS

Of 79 patients with complete Anosognosia Scale data at baseline, 25 (31.6 %) met the scale's criterion for anosognosia. In the regression analyses, baseline Difference Score improved prediction of 6-month patient-reported outcomes for depression, anxiety, anger, and positive affect and well-being (χ2(1) value range for likelihood ratio tests contrasting models with and without Difference Score: 13.1-20.9, p-values <0.001). Patients with more anosognosia self-reported less severe psychiatric symptoms and more positive affect and well-being.

CONCLUSION

Study results suggest that anosognosia influences patient-reported outcomes for psychiatric symptoms and quality of life in HD populations.

Exploring molecular mechanisms, therapeutic strategies, and clinical manifestations of Huntington's disease

Huntington's disease (HD) is a paradigm of a genetic neurodegenerative disorder characterized by the expansion of CAG repeats in the HTT gene. This extensive review investigates the molecular complexities of HD by highlighting the pathogenic mechanisms initiated by the mutant huntingtin protein. Adverse outcomes of HD include mitochondrial dysfunction, compromised protein clearance, and disruption of intracellular signaling, consequently contributing to the gradual deterioration of neurons. Numerous therapeutic strategies, particularly precision medicine, are currently used for HD management. Antisense oligonucleotides, such as Tominersen, play a leading role in targeting and modulating the expression of mutant huntingtin. Despite the promise of these therapies, challenges persist, particularly in improving delivery systems and the necessity for long-term safety assessments. Considering the future landscape, the review delineates promising directions for HD research and treatment. Innovations such as Clustered regularly interspaced short palindromic repeats associated system therapies (CRISPR)-based genome editing and emerging neuroprotective approaches present unprecedented opportunities for intervention. Collaborative interdisciplinary endeavors and a more insightful understanding of HD pathogenesis are on the verge of reshaping the therapeutic landscape. As we navigate the intricate landscape of HD, this review serves as a guide for unraveling the intricacies of this disease and progressing toward transformative treatments.

Latest advances on new promising molecular-based therapeutic approaches for Huntington's disease

Huntington's disease (HD) is a devastating, autosomal-dominant inherited, neurodegenerative disorder characterized by progressive motor deficits, cognitive impairments, and neuropsychiatric symptoms. It is caused by excessive cytosine-adenine-guanine (CAG) trinucleotide repeats within the huntingtin gene (HTT). Presently, therapeutic interventions capable of altering the trajectory of HD are lacking, while medications for abnormal movement and psychiatric symptoms are limited. Numerous pre-clinical and clinical studies have been conducted and are currently underway to test the efficacy of therapeutic approaches targeting some of these mechanisms with varying degrees of success. In this review, we update the latest advances on new promising molecular-based therapeutic strategies for this disorder, including DNA-targeting techniques such as zinc-finger proteins, transcription activator-like effector nucleases, and CRISPR/Cas9; post-transcriptional huntingtin-lowering approaches such as RNAi, antisense oligonucleotides, and small-molecule splicing modulators; and novel methods to clear the mHTT protein, such as proteolysis-targeting chimeras. We mainly focus on the ongoing clinical trials and the latest pre-clinical studies to explore the progress of emerging potential HD therapeutics.

Huntington's Disease: Complex Pathogenesis and Therapeutic Strategies

Huntington's disease (HD) arises from the abnormal expansion of CAG repeats in the huntingtin gene (HTT), resulting in the production of the mutant huntingtin protein (mHTT) with a polyglutamine stretch in its N-terminus. The pathogenic mechanisms underlying HD are complex and not yet fully elucidated. However, mHTT forms aggregates and accumulates abnormally in neuronal nuclei and processes, leading to disruptions in multiple cellular functions. Although there is currently no effective curative treatment for HD, significant progress has been made in developing various therapeutic strategies to treat HD. In addition to drugs targeting the neuronal toxicity of mHTT, gene therapy approaches that aim to reduce the expression of the mutant HTT gene hold great promise for effective HD therapy. This review provides an overview of current HD treatments, discusses different therapeutic strategies, and aims to facilitate future therapeutic advancements in the field.

What Huntington's Disease Patients Say About Their Illness: An Online Direct-to-Participant Pilot Study

Background

Direct-to-participant online reporting facilitates the conduct of clinical research by increasing access and clinically meaningful patient engagement.

Objective

We assessed feasibility of online data collection from adults with diagnosed Huntington's disease (HD) who directly reported their problems and impact in their own words.

Methods

Data were collected online from consenting United States residents who self-identified as 1) having been diagnosed with Huntington's disease, 2) able to ambulate independently, and 3) self-sufficient for most daily needs. Data for this pilot study were collected using the Huntington Study Group myHDstory online research platform. The Huntington Disease Patient Report of Problems (HD-PROP), an open-ended questionnaire, was used to capture verbatim bothersome problems and functional impact. Natural language processing, human-in-the-loop curation of verbatim reports involving clinical and experience experts, and machine learning classified verbatim-reports into clinically meaningful symptoms.

Results

All 8 questionnaires in the online pilot study were completed by 345 participants who were 60.9% men, 34.5±9.9 (mean±SD) years old, and 9.5±8.4 years since HD diagnosis. Racial self-identification was 46.4% Caucasian, 28.7% African American, 15.4% American Indian/Alaska Native, and 9.5% other. Accuracy of verbatim classification was 99%. Non-motor problems were the most frequently reported symptoms; depression and cognitive impairment were the most common.

Conclusions

Online research participation was feasible for a diverse cohort of adults who self-reported an HD diagnosis and predominantly non-motor symptoms related to mood and cognition. Online research tools can help inform what bothers HD patients, identify clinically meaningful outcomes, and facilitate participation by diverse and under-represented populations.

Crushing the Contents of Valbenazine Capsules for Potential Addition to Soft Foods or Administration via Gastrostomy Tube

PURPOSE

One-capsule, once-daily valbenazine is approved for tardive dyskinesia and under evaluation for chorea associated with Huntington's disease, conditions in which patients often experience dysphagia. In vitro studies were conducted to assess the suitability of crushing the contents of valbenazine capsules (40 and 80 mg) for mixing with soft foods or liquids or administration via a gastrostomy tube (G-tube).

METHODS

In study 1, the dissolution of whole valbenazine capsules and crushed capsule contents were measured serially for 1 hour. In study 2, valbenazine recovery was evaluated after crushed contents were mixed with soft foods, buffer solutions (pH range, 1.2-6.8), and fed-state simulated gastric fluid. In study 3, valbenazine recovery was evaluated after crushed contents were dispersed in water and delivered via a G-tube. In studies 2 and 3, acceptable valbenazine recovery was 90% to 110%.

FINDINGS

Study 1 indicated rapid and complete drug release for whole valbenazine capsules and crushed capsule contents, with similar release at 10 minutes (whole, 94%-99%; crushed, 98%-100%) and 60 minutes (whole, 101%-103%; crushed, 101%-102%). Study 2 found acceptable valbenazine recovery within 2 hours of adding crushed capsule contents to tested foods, buffers, or fed-state simulated gastric fluid (recovery, 92%-102%). Study 3 found acceptable valbenazine recovery when crushed contents were added to cold or hot water and delivered via G-tube, with a water cup rinse to capture residual contents (recovery, 91%-97%).

IMPLICATIONS

These studies indicate the potential viability of valbenazine formulation(s) that can be added to soft foods or liquids or delivered via G-tube. Such formulations will be important for individuals who require treatment with a vesicular monoamine transporter 2 inhibitor but cannot swallow whole pills.

Mutant-Huntingtin Molecular Pathways Elucidate New Targets for Drug Repurposing

The spectrum of neurodegenerative diseases known today is quite extensive. The complexities of their research and treatment lie not only in their diversity. Even many years of struggle and narrowly focused research on common pathologies such as Alzheimer's, Parkinson's, and other brain diseases have not brought cures for these illnesses. What can be said about orphan diseases? In particular, Huntington's disease (HD), despite affecting a smaller part of the human population, still attracts many researchers. This disorder is known to result from a mutation in the HTT gene, but having this information still does not simplify the task of drug development and studying the mechanisms of disease progression. Nonetheless, the data accumulated over the years and their analysis provide a good basis for further research. Here, we review studies devoted to understanding the mechanisms of HD. We analyze genes and molecular pathways involved in HD pathogenesis to describe the action of repurposed drugs and try to find new therapeutic targets.

Huntington's Disease Drug Development: A Phase 3 Pipeline Analysis

Huntington's Disease (HD) is a severely debilitating neurodegenerative disorder in which sufferers exhibit different combinations of movement disorders, dementia, and behavioral or psychiatric abnormalities. The disorder is a result of a trinucleotide repeat expansion mutation that is inherited in an autosomal dominant manner. While there is currently no treatment to alter the course of HD, there are medications that lessen abnormal movement and psychiatric symptoms. ClinicalTrials.gov was searched to identify drugs that are currently in or have completed phase III drug trials for the treatment of HD. The described phase III trials were further limited to interventional studies that were recruiting, active not recruiting, or completed. In addition, all studies must have posted an update within the past year. PubMed was used to gather further information on these interventional studies. Of the nine clinical trials that met these criteria, eight involved the following drugs: metformin, dextromethorphan/quinidine, deutetrabenazine, valbenazine, Cellavita HD, pridopidine, SAGE-718, and RO7234292 (RG6042). Of these drug treatments, four are already FDA approved. This systematic review provides a resource that summarizes the present therapies for treating this devastating condition that are currently in phase III clinical trials in the United States.

From Pathogenesis to Therapeutics: A Review of 150 Years of Huntington's Disease Research

Huntington's disease (HD) is a debilitating neurodegenerative genetic disorder caused by an expanded polyglutamine-coding (CAG) trinucleotide repeat in the huntingtin (HTT) gene. HD behaves as a highly penetrant dominant disorder likely acting through a toxic gain of function by the mutant huntingtin protein. Widespread cellular degeneration of the medium spiny neurons of the caudate nucleus and putamen are responsible for the onset of symptomology that encompasses motor, cognitive, and behavioural abnormalities. Over the past 150 years of HD research since George Huntington published his description, a plethora of pathogenic mechanisms have been proposed with key themes including excitotoxicity, dopaminergic imbalance, mitochondrial dysfunction, metabolic defects, disruption of proteostasis, transcriptional dysregulation, and neuroinflammation. Despite the identification and characterisation of the causative gene and mutation and significant advances in our understanding of the cellular pathology in recent years, a disease-modifying intervention has not yet been clinically approved. This review includes an overview of Huntington's disease, from its genetic aetiology to clinical presentation and its pathogenic manifestation. An updated view of molecular mechanisms and the latest therapeutic developments will also be discussed.