Safety, pharmacokinetics and pharmacodynamics of SBT-020 in patients with early stage Huntington's disease, a 2-part study.

AIMS: Huntington's disease (HD) is a neurodegenerative disease with cognitive, motor and psychiatric symptoms. Toxic accumulation of misfolded mutant huntingtin protein induces mitochondrial dysfunction, leading to a bioenergetic insufficiency in neuronal and muscle cells. We evaluated the safety, pharmacokinetics and pharmacodynamics of SBT-020, a novel compound to improve mitochondrial function, in a 2-part study in early stage HD patients. METHODS: Part 1 consisted of 7-day multiple ascending dose study to select the highest tolerable dose for Part 2, a 28-day multiple dose study. Mitochondrial function was measured in the visual cortex and calf muscle, using phosphorous magnetic resonance spectroscopy, and in circulating peripheral blood mononuclear cells. RESULTS: Treatment-emergent adverse events were mild and more present in the SBT-020 group. Injection site reactions occurred in 91% in Part 1 and 97% in Part 2. Mitochondrial function in calf muscle, peripheral blood mononuclear cells or visual cortex was not changed overall due to treatment with SBT-020. In a posthoc analysis, patients with a higher degree of mitochondrial dysfunction (below the median [∆Ψm < 3412 and τPCr > 42.5 s]) showed more improvement than patients with a relatively lower level of mitochondrial dysfunction. CONCLUSION: SBT-020 was safe at all doses, but no significant differences in any of the pharmacodynamic measurements between the treatment groups and placebo group could be demonstrated. The data suggest that the better than expected mitochondrial function in our patient population at baseline might explain the lack of effect of SBT-020.

Brain Bio-Energetic State Does Not Correlate to Muscle Mitochondrial Function in Huntington's Disease.

BACKGROUND: Huntington's disease (HD) is a neurodegenerative disease with cognitive, motor and psychiatric symptoms. A toxic accumulation of misfolded mutant huntingtin protein (Htt) induces mitochondrial dysfunction, leading to a bioenergetic insufficiency in neuronal and muscle cells. Improving mitochondrial function has been proposed as an opportunity to treat HD, but it is not known how mitochondrial function in different tissues relates. OBJECTIVE: We explored associations between central and peripheral mitochondrial function in a group of mild to moderate staged HD patients. METHODS: We used phosphorous magnetic resonance spectroscopy (31P-MRS) to measure mitochondrial function in vivo in the calf muscle (peripheral) and the bio-energetic state in the visual cortex (central). Mitochondrial function was also assessed ex vivo in circulating peripheral blood mononuclear cells (PBMCs). Clinical function was determined by the Unified Huntington's Disease Rating Scale (UHDRS) total motor score. Pearson correlation coefficients were computed to assess the correlation between the different variables. RESULTS: We included 23 manifest HD patients for analysis. There was no significant correlation between central bio-energetics and peripheral mitochondrial function. Central mitochondrial function at rest correlated significantly to the UHDRS total motor score (R = -0.45 and -0.48), which increased in a subgroup with the largest number of CAG repeats. DISCUSSION: We did not observe a correlation between peripheral and central mitochondrial function. Central, but not peripheral, mitochondrial function correlated to clinical function. Muscle mitochondrial function is a promising biomarker to evaluate disease-modifying compounds that improve mitochondrial function, but Huntington researchers should use central mitochondrial function to demonstrate proof-of-pharmacology of disease-modifying compounds.

Premanifest Huntington's disease: Examination of oculomotor abnormalities in clinical practice.

INTRODUCTION: Different oculomotor abnormalities have been reported to occur in premanifest Huntington's disease. The aim of this study is to investigate which oculomotor items of the Unified Huntington's Disease Rating Scale (UHDRS) are affected in premanifest individuals compared to healthy controls, and if CAG repeat length and age are correlated with oculomotor abnormalities in premanifest Huntington's disease gene carriers. METHODS: We compared baseline data of 70 premanifest individuals and 27 controls who participated in the Enroll-HD study at the Leiden University Medical Center, the Netherlands. Premanifest gene carriers were divided in individuals near to disease onset and individuals far from disease onset. RESULTS: Using a logistic regression model, only horizontal ocular pursuit of the six oculomotor items of the UHDRS was significantly more frequently affected in premanifest individuals close to disease onset compared to controls (p = 0.044, OR 13.100). Age was significantly higher in premanifest individuals with affected horizontal ocular pursuit (p = 0.016, OR 1.115) and with affected vertical ocular pursuit (p = 0.030, OR 1.065) compared to premanifest individuals without ocular pursuit deficits. CONCLUSIONS: Our results suggest that horizontal ocular pursuit is the only affected oculomotor item of the UHDRS in premanifest individuals and could be used to assess early clinical signs of Huntington's disease. Saccade initiation and saccade velocity do not seem useful for detecting differences between premanifest individuals and controls.

Marriage as Protector for Nursing Home Admission in Huntington's Disease.

BACKGROUND: Huntington's disease is a progressive, incurable neurodegenerative disorder and it is not possible to delay onset or progression of the disease. Consequently, the disease leads to functional decline and loss of independency and finally to institutionalization. OBJECTIVE: The aim of this study is to identify factors which are associated with nursing home admission in patients with Huntington's disease. METHODS: The Unified Huntington's Disease Rating Scale (UHDRS) and the UHDRS-For Advanced Patients (UHDRS-FAP) were administered in 28 nursing home residents and 12 patients receiving day-care. Comparisons between the two groups were performed using Mann-Whitney U tests and Chi-square tests. The significantly different findings were fitted in individual univariate logistic regression models to determine which components were most predictive of institutionalization. RESULTS: Day-care participants were more often married than nursing home residents (p = 0.006) and were functionally more independent: the Functional Assessment Scale (p = 0.022) of the UHDRS was significantly higher. Not being married was more predictive for nursing home admission than functional capacity in the regression models. CONCLUSIONS: Our results suggest that being married is protective for nursing home placement. Possibly, a caregiver living with a patient can assist with activities of daily living which the patient could not have done independently, resulting in being able to live at home longer. Providing support to unmarried patients, who do not have a caregiver living with them, by home care services specialized in Huntington's disease might increase the chance of the best possible care before institutionalization and postpone nursing home admission.

Interrater Reliability of the Unified Huntington's Disease Rating Scale-Total Motor Score Certification.

BACKGROUND: The clinical assessment of motor symptoms in Huntington's disease is usually performed with the Unified Huntington's Disease Rating Scale-Total Motor Score (UHDRS-TMS). A high interrater reliability is desirable to monitor symptom progression. Therefore, a teaching video and a system for annual online certification has been developed and implemented. OBJECTIVES: The aim of this study is to investigate the interrater reliability of the UHDRS-TMS and of its subitems, and to examine the performance of raters in consecutive years. METHODS: Data from the online UHDRS-TMS certification were used. The interrater reliability was assessed for all first-time participants (n = 944) between 2009 and 2016. Intraclass correlation coefficients (ICC) were calculated for each year separately and the mean was taken as the total ICC. RESULTS: The UHDRS-TMS (ICC = 0.847), tandem walking (0.824), pronate/supinate hands left (0.713), and retropulsion pull test (0.706) showed good interrater reliability. Poor interrater reliability was found for maximal dystonia of the left and right upper extremity (0.187 and 0.322, respectively), maximal dystonia of the left and right lower extremity (0.200 and 0.256, respectively), and maximal dystonia of the trunk (0.389), tongue protrusion (0.266), and rigidity arms left (0.390). Raters performed significantly worse on follow-up certification compared to their first certification. CONCLUSIONS: Our results suggest that the rating of dystonia (absent, slight, mild, moderate, or marked) is subjective and difficult to interpret, especially on video. Therefore, changing the dystonia items of the UHDRS-TMS should be explored. We also recommend that raters should watch the UHDRS-TMS teaching video before each certification.

Assessment Scales for Patients with Advanced Huntington's Disease: Comparison of the UHDRS and UHDRS-FAP.

BACKGROUND: The standard clinical assessment tool in Huntington's disease is the Unified Huntington's Disease Rating Scale (UHDRS). In patients with advanced Huntington's disease ceiling and floor effects of the UHDRS hamper the detection of changes. Therefore, the UHDRS-For Advanced Patients (UHDRS-FAP) has been designed for patients with late-stage Huntington's disease. OBJECTIVES: This cross-sectional study aims to examine if the UHDRS-FAP can differentiate better between patients with advanced Huntington's disease than the UHDRS. METHODS: Forty patients, who were institutionalized or received day-care, were assessed with the UHDRS, UHDRS-FAP, and Care Dependency Scale (CDS). The severity of Huntington's disease was defined by the Total Functional Capacity (TFC). Comparisons between consecutive TFC stages were performed for all domains of the UHDRS, UHDRS-FAP, and CDS using Mann-Whitney U tests. RESULTS: The motor scores of the UHDRS-FAP and UHDRS were the only subscales with significantly worse scores in TFC stage 5 compared to stage 4. In TFC stages 4-5, the range of the UHDRS-FAP motor score was broader, the standard error of measurement was lower, and the effect size r was higher than for the UHDRS motor score. The CDS declined significantly across all TFC stages. CONCLUSIONS: Our results suggest that the UHDRS-FAP motor score might differentiate better between patients with severe Huntington's disease than the UHDRS motor score. Therefore, the UHDRS-FAP motor score is potentially a better instrument than the UHDRS motor score to improve disease monitoring and, subsequently, care in patients with advanced Huntington's disease in long-term care facilities.