Continuous Levodopa Delivery with an Intraoral Micropump System: An Open-Label Pharmacokinetics and Clinical Study.

BACKGROUND: Double-blind studies have demonstrated that motor complications in Parkinson's disease (PD) can be reduced with continuous delivery of levodopa. The DopaFuse system is a novel, intraoral micropump that attaches to a retainer and uses a propellant to deliver levodopa/carbidopa (LD/CD) continuously into the mouth. OBJECTIVES: Evaluate the safety, pharmacokinetics, and efficacy of LD/CD delivered via the DopaFuse system compared to treatment with intermittent doses of standard oral LD/CD in PD patients with motor fluctuations. METHODS: This was a 2-week, open-label study (NCT04778176) in 16 PD patients treated with ≥4 levodopa doses/day and experiencing motor fluctuations. On Day 1 (clinic setting) patients received their usual dose of standard LD/CD; DopaFuse therapy was initiated on Day 2, and on Day 3 patients received DopaFuse plus a morning oral LD/CD dose. Patients returned home on Days 4-14 and returned for in-clinic assessment on Day 15. RESULTS: Continuous DopaFuse delivery of LD/CD was associated with reduced variability in plasma levodopa levels compared to oral LD/CD (mean ± SD levodopa Fluctuation Index reduced from 2.15 ± 0.59 on Day1 to 1.50 ± 0.55 on Day 2 (P = 0.0129) and to 1.03 ± 0.53 on Day 3 (P < 0.0001)). This pharmacokinetic improvement translated into significantly reduced OFF time with DopaFuse therapy (reduction of -1.72 ± 0.37 h at Day 15; P = 0.0004) and increased ON time without severe dyskinesias (increase of 1.72 ± 0.37 h at Day 15; P = 0.0004) versus oral LD/CD administration. DopaFuse therapy was not associated with any clinically significant adverse events. CONCLUSIONS: Continuous delivery of LD/CD using the DopaFuse system was associated with significantly less variability in plasma levodopa concentrations and reductions in OFF time compared to treatment with standard oral LD/CD therapy and was well tolerated. © 2024 International Parkinson and Movement Disorder Society.

A Phase I, Randomized, SAD, MAD, and PK Study of Risvodetinib in Older Adults and Parkinson's Disease.

Background: Pre-clinical studies suggest that c-Abl activation may play an important role in the etiology of Parkinson's disease, making c-Abl an important target to evaluate for potential disease-modification. Objective: To assess safety, tolerability, and pharmacokinetics of the c-Abl inhibitor risvodetinib (IkT-148009) in healthy subjects and participants with Parkinson's disease. Methods: Part 1 (single ascending dose (SAD)) and Part 2 (7-day multiple ascending dose (MAD)) studies were in healthy volunteers. Participants were randomized 3 : 1 across 9 SAD doses and 3 MAD doses of risvodetinib (IkT-148009) or placebo. Part 3 was a MAD study conducted at two doses in 14 participants with mild-to-moderate PD (MAD-PD). Primary outcome measures were safety, tolerability and pharmacokinetics. Exploratory outcomes in PD participants included clinical measures of PD state, GI function, and cerebrospinal fluid (CSF) concentration. Results: 108 patients were treated with no dropouts. The SAD tested doses ranging from 12.5 to 325 mg, while the MAD tested 25 to 200 mg and MAD-PD tested 50 to 100 mg in Parkinson's participants. All active doses had a favorable safety profile with no clinically meaningful adverse events. Single dose pharmacokinetics were approximately linear between 12.5 mg and 200 mg for both Cmax and AUC0 - inf without distinction between healthy volunteers and participants with PD. Exposures at each dose were high relative to other drugs in the same kinase inhibitor class. Conclusions: Risvodetinib (IkT-148009) was well tolerated, had a favorable safety and pharmacology profile over 7-day dosing, did not induce serious adverse events and did not appear to induce deleterious side-effects in participants administered anti-PD medications.

An exploratory metabolomic comparison of participants with fast or absent functional progression from 2CARE, a randomized, double-blind clinical trial in Huntington's disease.

Huntington's disease (HD) is increasingly recognized for diverse pathology outside of the nervous system. To describe the biology of HD in relation to functional progression, we previously analyzed the plasma and CSF metabolome in a cross-sectional study of participants who had various degrees of functional impairment. Here, we carried out an exploratory study in plasma from HD individuals over a 3-year time frame to assess whether differences exist between those with fast or absent clinical progression. There were more differences in circulating metabolite levels for fast progressors compared to absent progressors (111 vs 20, nominal p < 0.05). All metabolite changes in faster progressors were decreases, whereas some metabolite concentrations increased in absent progressors. Many of the metabolite levels that decreased in the fast progressors were higher at Screening compared to absent progressors but ended up lower by Year 3. Changes in faster progression suggest greater oxidative stress and inflammation (kynurenine, diacylglycerides, cysteine), disturbances in nitric oxide and urea metabolism (arginine, citrulline, ornithine, GABR), lower polyamines (putrescine and spermine), elevated glucose, and deficient AMPK signaling. Metabolomic differences between fast and absent progressors suggest the possibility of predicting functional decline in HD, and possibly delaying it with interventions to augment arginine, polyamines, and glucose regulation.

A Randomized Phase 3 Study Comparing P2B001 to its Components (Low-Dose Extended-Release Rasagiline and Pramipexole) and to Optimized Doses of Marketed Extended-Release Pramipexole in Early Parkinson's Disease.

BACKGROUND: There remains uncertainty as to the optimal way to initiate therapy for Parkinson's disease (PD) to maximize benefit and minimize adversity. OBJECTIVES: The objective was to determine if P2B001 (a fixed, low-dose, extended-release [ER] combination of pramipexole 0.6 mg and rasagiline 0.75 mg) is superior to each of its components and compare its safety and efficacy to optimized treatment with marketed doses of pramipexole-ER. METHODS: This was a 12-week, double-blind study (NCT03329508). Total of 544 untreated patients with PD were randomized (2:2:2:1) to treatment with P2B001, its individual components (pramipexole-ER 0.6 mg or rasagiline-ER 0.75 mg), or commercial doses of pramipexole-ER titrated to optimal dose (1.5-4.5 mg). The primary endpoint was change from baseline to week 12 in Unified Parkinson's Disease Rating Scale (UPDRS) parts II and III. The key secondary endpoint was the change from baseline in the Epworth Sleepiness Scale (ESS) for P2B001 versus the titrated dose of pramipexole-ER. RESULTS: P2B001 provided superior efficacy compared to each of its components; mean (95% CI) treatment differences in UPDRS II + III scores were -2.66 (95% CI, -4.33 to -1.00) versus pramipexole-ER 0.6 mg (P = 0.0018) and - 3.30 (95% CI, -4.96 to -1.63) versus rasagiline-ER 0.75 mg (P < 0.0001). P2B001 had comparable efficacy with the titrated dose of pramipexole-ER (mean, 3.2 mg), but significantly less worsening in daytime-sleepiness (ESS treatment difference: -2.66 [95% CI, -3.50 to -1.81]; P < 0.0001). P2B001 was well-tolerated with fewer sleep-related and dopaminergic adverse events than titrated doses of pramipexole-ER including somnolence, orthostatic hypotension, and neuropsychiatric side effects. CONCLUSIONS: P2B001 had superior efficacy to its individual components and was comparable with commercially used doses of pramipexole-ER with less worsening of sleepiness and fewer dopaminergic adverse events. These findings support considering once-daily P2B001 as initial therapy for patients with early PD. © 2023 International Parkinson and Movement Disorder Society.

Safety, tolerability, and efficacy of NLY01 in early untreated Parkinson's disease: a randomised, double-blind, placebo-controlled trial.

BACKGROUND: Converging lines of evidence suggest that microglia are relevant to Parkinson's disease pathogenesis, justifying exploration of therapeutic agents thought to attenuate pathogenic microglial function. We sought to test the safety and efficacy of NLY01-a brain-penetrant, pegylated, longer-lasting version of exenatide (a glucagon-like peptide-1 receptor agonist) that is believed to be anti-inflammatory via reduction of microglia activation-in Parkinson's disease. METHODS: We report a 36-week, randomised, double-blind, placebo-controlled study of NLY01 in participants with early untreated Parkinson's disease conducted at 58 movement disorder clinics in the USA. Participants meeting UK Brain Bank or Movement Disorder Society research criteria for Parkinson's disease were randomly allocated (1:1:1) to one of two active treatment groups (2·5 mg or 5·0 mg NLY01) or matching placebo, based on a central computer-generated randomisation scheme using permuted block randomisation with varying block sizes. All participants, investigators, coordinators, study staff, and sponsor personnel were masked to treatment assignments throughout the study. The primary efficacy endpoint for the primary analysis population (defined as all randomly assigned participants who received at least one dose of study drug) was change from baseline to week 36 in the sum of Movement Disorder Society Unified Parkinson's Disease Rating Scale (MDS-UPDRS) parts II and III. Safety was assessed in the safety population (all randomly allocated participants who received at least one dose of the study drug) with documentation of adverse events, vital signs, electrocardiograms, clinical laboratory assessments, physical examination, and scales for suicidality, sleepiness, impulsivity, and depression. This trial is complete and registered at ClinicalTrials.gov, NCT04154072. FINDINGS: The study took place between Jan 28, 2020, and Feb 16, 2023. 447 individuals were screened, of whom 255 eligible participants were randomly assigned (85 to each study group). One patient assigned to placebo did not receive study treatment and was not included in the primary analysis. At 36 weeks, 2·5 mg and 5·0 mg NLY01 did not differ from placebo with respect to change in sum scores on MDS-UPDRS parts II and III: difference versus placebo -0·39 (95% CI -2·96 to 2·18; p=0·77) for 2·5 mg and 0·36 (-2·28 to 3·00; p=0·79) for 5·0 mg. Treatment-emergent adverse events were similar across groups (reported in 71 [84%] of 85 patients on 2·5 mg NLY01, 79 [93%] of 85 on 5·0 mg, and 73 [87%] of 84 on placebo), with gastrointestinal disorders the most commonly observed class in active groups (52 [61%] for 2·5 mg, 64 [75%] for 5·0 mg, and 30 [36%] for placebo) and nausea the most common event overall (33 [39%] for 2·5 mg, 49 [58%] for 5·0 mg, and 16 [19%] for placebo). No deaths occurred during the study. INTERPRETATION: NLY01 at 2·5 and 5·0 mg was not associated with any improvement in Parkinson's disease motor or non-motor features compared with placebo. A subgroup analysis raised the possibility of motor benefit in younger participants. Further study is needed to determine whether these exploratory observations are replicable. FUNDING: D&D Pharmatech-Neuraly.

Adaptive clinical trials and master protocols.

Methodologies for randomized, double-blind, placebo-controlled clinical trials continue to develop in concert with evolving scientific and translational knowledge. Adaptive trial designs, in which data generated during the study are used to modify subsequent study activity (i.e., sample sizes, entry criteria, or outcomes), can optimize flexibility and expedite the safety and efficacy assessments for interventions of interest. This chapter will summarize general designs, advantages, and pitfalls associated with adaptive clinical trials and compare their features with those of conventional trial designs. It will also review novel ways for which seamless designs and master protocols may improve trial efficiency while offering interpretable data.

Suicidality Risk Factors Across the CARE-HD, 2CARE, and CREST-E Clinical Trials in Huntington Disease.

Background and Objectives: Suicidality is a common concern in the routine care of persons with Huntington disease (HD) and for the many participants in HD clinical trials. In a previous analysis, we identified baseline and time-dependent factors associated with suicidal ideation and attempts from 2CARE, a large, randomized, double-blind clinical trial. Methods: The present analysis extends our prior methodology to 2 other large interventional HD clinical trials, CARE-HD and CREST-E. Results: We observed relationships across studies between suicidality events and prior suicidal ideation at baseline, antidepressant/anxiolytic use, chorea, increasing age, and several domains in the Unified Huntington Disease Rating Scale (UHDRS) Behavioral Assessment (depressed mood, low self-esteem, aggression, and active suicidality). Discussion: These data may form the basis for a subscale of demographic and UHDRS items with the potential for prospectively identifying suicidality risk in HD clinics and clinical trials. Trial Registration Information: 2CARE and CREST are registered at clinicaltrials.gov. 2CARE NCT00608881, registered February 6, 2008; first enrollment March 2008. CREST-E NCT00712426, registered July 10, 2008; first enrollment September 2009. CARE-HD, not registered; first enrollment July 1997.

A New Approach to the Development of Disease-Modifying Therapies for PD; Fighting Another Pandemic.

A disease-modifying therapy that slows disease progression and development of disability is the major unmet need in the treatment of Parkinson's disease. Recent scientific advances suggest many promising and exciting new interventions. However, despite these opportunities, the cost, time and uncertainty of being able to receive an indication as a disease-modifying therapy has caused many pharmaceutical companies to abandon development of potentially disease-modifying drugs. We propose a new approach to development of these agents that will reduce the cost and facilitate approval of putative disease-modifying drugs that should prove acceptable to pharmaceutical companies and regulatory agencies. © 2020 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Safety and Tolerability of SRX246, a Vasopressin 1a Antagonist, in Irritable Huntington's Disease Patients-A Randomized Phase 2 Clinical Trial.

SRX246 is a vasopressin (AVP) 1a receptor antagonist that crosses the blood-brain barrier. It reduced impulsive aggression, fear, depression and anxiety in animal models, blocked the actions of intranasal AVP on aggression/fear circuits in an experimental medicine fMRI study and demonstrated excellent safety in Phase 1 multiple-ascending dose clinical trials. The present study was a 3-arm, multicenter, randomized, placebo-controlled, double-blind, 12-week, dose escalation study of SRX246 in early symptomatic Huntington's disease (HD) patients with irritability. Our goal was to determine whether SRX246 was safe and well tolerated in these HD patients given its potential use for the treatment of problematic neuropsychiatric symptoms. Participants were randomized to receive placebo or to escalate to 120 mg twice daily or 160 mg twice daily doses of SRX246. Assessments included standard safety tests, the Unified Huntington's Disease Rating Scale (UHDRS), and exploratory measures of problem behaviors. The groups had comparable demographics, features of HD and baseline irritability. Eighty-two out of 106 subjects randomized completed the trial on their assigned dose of drug. One-sided exact-method confidence interval tests were used to reject the null hypothesis of inferior tolerability or safety for each dose group vs. placebo. Apathy and suicidality were not affected by SRX246. Most adverse events in the active arms were considered unlikely to be related to SRX246. The compound was safe and well tolerated in HD patients and can be moved forward as a candidate to treat irritability and aggression.

Effects of Pridopidine on Functional Capacity in Early-Stage Participants from the PRIDE-HD Study.

BACKGROUND: No pharmacological treatment has been demonstrated to provide a functional benefit for persons with Huntington's disease (HD). Pridopidine is a sigma-1-receptor agonist shown to have beneficial effects in preclinical models of HD. OBJECTIVE: To further explore the effect of pridopidine on Total Functional Capacity (TFC) in the recent double-blind, placebo-controlled PRIDE-HD study. METHODS: We performed post-hoc analyses to evaluate the effect of pridopidine on TFC at 26 and 52 weeks. Participants were stratified according to baseline TFC score and analyzed using repeated measures (MMRM) and multiple imputation assuming missing not-at-random (MNAR) and worst-case scenarios. RESULTS: The pridopidine 45 mg bid dosage demonstrated a beneficial effect on TFC for the entire population at week 52 of 0.87 (nominal p = 0.0032). The effect was more pronounced for early HD participants (HD1/HD2, TFC = 7-13), with a change from placebo of 1.16 (nominal p = 0.0003). This effect remained nominally significant using multiple imputation with missing not at random assumption as a sensitivity analysis. Responder analyses showed pridopidine 45 mg bid reduced the probability of TFC decline in early HD patients at Week 52 (nominal p = 0.02). CONCLUSION: Pridopidine 45 mg bid results in a nominally significant reduction in TFC decline at 52 weeks compared to placebo, particularly in patients with early-stage HD.

Cross-sectional analysis of plasma and CSF metabolomic markers in Huntington's disease for participants of varying functional disability: a pilot study.

Huntington's Disease (HD) is a progressive, fatal neurodegenerative condition. While generally considered for its devastating neurological phenotype, disturbances in other organ systems and metabolic pathways outside the brain have attracted attention for possible relevance to HD pathology, potential as therapeutic targets, or use as biomarkers of progression. In addition, it is not established how metabolic changes in the HD brain correlate to progression across the full spectrum of early to late-stage disease. In this pilot study, we sought to explore the metabolic profile across manifest HD from early to advanced clinical staging through metabolomic analysis by mass spectrometry in plasma and cerebrospinal fluid (CSF). With disease progression, we observed nominally significant increases in plasma arginine, citrulline, and glycine, with decreases in total and D-serine, cholesterol esters, diacylglycerides, triacylglycerides, phosphatidylcholines, phosphatidylethanolamines, and sphingomyelins. In CSF, worsening disease was associated with nominally significant increases in NAD+, arginine, saturated long chain free fatty acids, diacylglycerides, triacylglycerides, and sphingomyelins. Notably, diacylglycerides and triacylglyceride species associated with clinical progression were different between plasma and CSF, suggesting different metabolic preferences for these compartments. Increasing NAD+ levels strongly correlating with disease progression was an unexpected finding. Our data suggest that defects in the urea cycle, glycine, and serine metabolism may be underrecognized in the progression HD pathology, and merit further study for possible therapeutic relevance.

Additional Safety and Exploratory Efficacy Data at 48 and 60 Months from Open-HART, an Open-Label Extension Study of Pridopidine in Huntington Disease.

BACKGROUND: Open-HART was an open-label extension of HART, a randomized, double-blind, placebo-controlled study of pridopidine in Huntington disease (HD). Previously, we reported safety and exploratory efficacy data after 36 months of treatment with pridopidine 45 mg twice daily. In the interim, emerging data suggests pridopidine may have neuroprotective effects mediated by sigma-1 receptor agonism. OBJECTIVE: To report additional safety and exploratory efficacy data for continued open-label use of 45 mg BID pridopidine at 48 and 60 months. METHODS: Patients in Open-HART were followed up to or greater than 60 months. Adverse events, concomitant medications, vital signs, laboratory values, and ECG data were monitored. Rates of decline in total functional capacity (TFC) and total motor score (TMS) over 60 months were evaluated in an exploratory analysis and compared between Open-HART and placebo recipients from the 2CARE trial. To account for missing data, sensitivity analyses were performed. RESULTS: Of the original Open-HART baseline cohort (N = 118), 40 remained in the study at 48 months and 33 at 60 months. Pridopidine remained safe and well tolerated over the 60-month interval. TFC and TMS at 48 and 60 months remained stable, showing less decline at these timepoints compared to historical placebo controls from the 2CARE trial. TFC differences at 48 and 60 months observed remained nominally significant after sensitivity analysis. CONCLUSION: The 45 mg BID pridopidine dosage remained safe and tolerable over 60 months. Exploratory analyses show TFC and TMS stability at 48 and 60 months, in contrast to placebo historical controls from the 2CARE trial. Results are consistent with data reported from the recent Phase 2 PRIDE-HD trial showing less functional decline in the pridopidine 45 mg BID treated group at 52 weeks.

Baseline Variables Associated with Functional Decline in 2CARE, A Randomized Clinical Trial in Huntington's Disease.

BACKGROUND: Despite the clearly recognized progressive functional decline of Huntington's disease (HD), detailed investigations of factors associated with the rate of functional progression are limited. OBJECTIVE: Understanding factors associated with functional decline through examination of existing HD clinical databases may improve efforts to mitigate it. METHODS: We analyzed data from 2CARE, a randomized clinical trial with up to 5 years of follow-up, to assess potential risk factors for more rapid functional decline in HD. RESULTS: Variables associated with faster functional decline included worse motor performance, worse cognitive test scores, female sex, lower weight and body mass index, and a higher CAG repeat length, especially in younger people. CONCLUSION: While our data are limited to the structured environment and homogeneity of a clinical trial, attention to several of the identified risk factors may be useful towards managing functional decline over time. The observation that women progress faster than men, while potentially confounded by an association between sex and weight, deserves further study.

Risk factors for suicidality in Huntington disease: An analysis of the 2CARE clinical trial.

OBJECTIVE: Most suicidality literature in Huntington disease (HD) is based on natural history studies or retrospective reviews, but reports on risk factors from clinical trials are limited. METHODS: We analyzed 609 participants from 2CARE, a randomized, double-blind, placebo-controlled clinical trial with up to 5 years of follow-up, for risk factors related to suicidality. The primary outcome variable was the time from randomization until the first occurrence of either suicidal ideation or attempt. We also considered time from randomization until the first suicide attempt as a secondary outcome variable. RESULTS: Depression, anxiety, bipolar disorder, antidepressant or anxiolytic use, and prior suicide attempt at baseline were associated with time to ideation or attempt. Baseline employment status, marital status, CAG repeat length, tetrabenazine use, and treatment assignment (coenzyme Q10 or placebo) were not associated with suicidality. Time-dependent variables from the Unified Huntington's Disease Rating Scale Behavioral Assessment were associated with time to suicidal ideation or attempt, driven mainly by items related to depressed mood, low self-esteem/guilt, anxiety, suicidal thoughts, irritability, and compulsions. Variables associated with time to suicide attempt alone were generally similar. CONCLUSION: These data suggest psychiatric comorbidities in HD are predictive of suicidal behavior while participating in clinical trials, reinforcing the importance of clinical surveillance and treatment towards lessening risk during participation and perhaps beyond. Designing a composite algorithm for early prediction of suicide attempts in HD may be of value, particularly given anticipated trials aimed at disease modification are likely to be long-term. CLINICALTRIALSGOV IDENTIFIER: NCT00608881.

Safety and efficacy of pridopidine in patients with Huntington's disease (PRIDE-HD): a phase 2, randomised, placebo-controlled, multicentre, dose-ranging study.

BACKGROUND: Previous trials have shown that pridopidine might reduce motor impairment in patients with Huntington's disease. The aim of this study was to ascertain whether higher doses of pridopidine than previously tested reduce motor symptoms in a dose-dependent manner while maintaining acceptable safety and tolerability. METHODS: PRIDE-HD was a randomised, placebo-controlled, phase 2, dose-ranging study in adults (aged ≥21 years) with Huntington's disease at outpatient clinics in 53 sites across 12 countries (Australia, Austria, Canada, Denmark, France, Germany, Italy, Poland, Russia, the Netherlands, the UK, and the USA). Eligible patients had clinical onset after age 18 years, 36 or more cytosine-adenine-guanine repeats in the huntingtin gene, motor symptoms (Unified Huntington's Disease Rating Scale total motor score [UHDRS-TMS] ≥25 points), and reduced independence (UHDRS independence score ≤90%). Patients were randomly assigned (1:1:1:1:1) with centralised interactive-response technology to receive one of four doses of pridopidine (45, 67·5, 90, or 112·5 mg) or placebo orally twice a day for 52 weeks. Randomisation was stratified within centres by neuroleptic drug use. The primary efficacy endpoint was change in the UHDRS-TMS from baseline to 26 weeks, which was assessed in all randomised patients who received at least one dose of study drug and had at least one post-baseline efficacy assessment (full analysis set). Participants and investigators were masked to treatment assignment. This trial is registered with EudraCT (2013-001888-23) and ClinicalTrials.gov (NCT02006472). FINDINGS: Between Feb 13, 2014, and July 5, 2016, 408 patients were enrolled and randomly assigned to receive placebo (n=82) or pridopidine 45 mg (n=81), 67·5 mg (n=82), 90 mg (n=81), or 112·5 mg (n=82) twice daily for 26 weeks. The full analysis set included 397 patients (81 in the placebo group, 75 in the 45 mg group, 79 in the 67·5 mg group, 81 in the 90 mg group, and 81 in the 112·5 mg group). Pridopidine did not significantly change the UHDRS-TMS at 26 weeks compared with placebo at any dose. The most frequent adverse events across all groups were diarrhoea, vomiting, nasopharyngitis, falls, headache, insomnia, and anxiety. The most common treatment-related adverse events were insomnia, diarrhoea, nausea, and dizziness. Serious adverse events occurred in the pridopidine groups only and were most frequently falls (n=5), suicide attempt (n=4), suicidal ideation (n=3), head injury (n=3), and aspiration pneumonia (n=3). No new safety or tolerability concerns emerged in this study. One death in the pridopidine 112·5 mg group due to aspiration pneumonia was considered to be possibly related to the study drug. INTERPRETATION: Pridopidine did not improve the UHDRS-TMS at week 26 compared with placebo and, thus, the results of secondary or tertiary analyses in previous trials were not replicated. A potentially strong placebo effect needs to be ruled out in future studies. FUNDING: Teva Pharmaceutical Industries.

Preclinical motor manifestations of Huntington disease.

Huntington disease (HD) is an autosomal-dominant, progressive neurodegenerative condition characterized by multiple movement disorders, psychiatric disturbances, and cognitive decline. As an insidious, progressive disorder, clinical phenoconversion in HD can be quite subtle and difficult to pinpoint. In light of this ambiguity, substantial interest has developed in HD research for biomarker identification, with the intent of establishing specific changes or "stages" of disease progression. Presumably, earlier stages of dysfunction offer greater chance for intervention or modification of disease mechanisms. As such, identifying disease processes as early as possible, in a prediagnostic period if possible, has been of paramount interest. Emerging evidence suggests motor dysfunction in HD long precedes clinical diagnosis, raising questions about the initiation of HD pathology and in turn our understanding of disease progression. This chapter summarizes advances in characterizing and understanding preclinical motor manifestations in HD, including changes in eye movements, gait, and fine motor performance. Development of the most sensitive and specific outcome measures for trial design is a rapidly evolving field in HD experimental therapeutics, with exciting implications for the study and treatment of this challenging disorder.

Safety and Exploratory Efficacy at 36 Months in Open-HART, an Open-Label Extension Study of Pridopidine in Huntington's Disease.

BACKGROUND: Open-HART is an open-label extension of HART, a randomized, placebo-controlled, dose-ranging, parallel-group study. OBJECTIVE: To evaluate safety and exploratory efficacy of open-label pridopidine over 36 months in subjects with Huntington's disease (HD). METHODS: Open-HART subjects were treated with pridopidine 45 mg twice daily (BID). After initial evaluation by telephone (Week 1) and in person (Month 1), in-person visits occurred every 3 months, alternating between safety and clinical visits (safety plus Unified Huntington's Disease Rating Scale [UHDRS] assessment). The UHDRS was performed for pre-specified analysis as a secondary outcome measure. Adverse events (AEs), laboratory values, and electrocardiography were monitored throughout. RESULTS: Most subjects (89%) reported at least one AE, with 30% experiencing treatment-related AEs. The most common AEs during the first year were falls (12.7%), anxiety (9.3%), insomnia (8.5%), irritability (6.8%), and depression (5.9%). Ninety-nine percent of subjects took concomitant medications. Two seizures were reported as AEs. No arrhythmias or suicide attempts were reported. Five deaths occurred, all considered treatment unrelated. Secondary exploratory analyses of subjects on pridopidine demonstrated motor deterioration (as measured by the UHDRS total motor score) consistent with HD's natural history, as shown in large observational studies. A post-hoc, exploratory analysis of TFC performance compared to placebo groups from other long-term HD studies demonstrated no significant effect for pridopidine on TFC progression after correction for multiple comparisons. CONCLUSIONS: Pridopidine 45 mg BID was generally safe and tolerable in HD subjects over 36 months. TMS declined in a manner consistent with the known natural history of HD.