Mestre T.A.,Ottawa Hospital Research Institute |
Sampaio C.,CHDI Management CHDI Foundation |
Sampaio C.,University of Lisbon
Current Neurology and Neuroscience Reports | Year: 2017
Huntington disease (HD) is an autosomal dominant neurodegenerative condition caused by a CAG trinucleotide expansion in the huntingtin gene. At present, the HD field is experiencing exciting times with the assessment for the first time in human subjects of interventions aimed at core disease mechanisms. Out of a portfolio of interventions that claim a potential disease-modifying effect in HD, the target huntingtin has more robust validation. In this review, we discuss the spectrum of huntingtin-lowering therapies that are currently being considered. We provide a critical appraisal of the validation of huntingtin as a drug target, describing the advantages, challenges, and limitations of the proposed therapeutic interventions. The development of these new therapies relies strongly on the knowledge of HD pathogenesis and the ability to translate this knowledge into validated pharmacodynamic biomarkers. Altogether, the goal is to support a rational drug development that is ethical and cost-effective. Among the pharmacodynamic biomarkers under development, the quantification of mutant huntingtin in the cerebral spinal fluid and PET imaging targeting huntingtin or phosphodiesterase 10A deserve special attention. Huntingtin-lowering therapeutics are eagerly awaited as the first interventions that may be able to change the course of HD in a meaningful way. © 2017, Springer Science+Business Media New York.
Tabrizi S.J.,University College London |
Scahill R.I.,University College London |
Owen G.,University College London |
Durr A.,French Institute of Health and Medical Research |
And 9 more authors.
The Lancet Neurology | Year: 2013
Background: TRACK-HD is a multinational prospective observational study of Huntington's disease (HD) that examines clinical and biological findings of disease progression in individuals with premanifest HD (preHD) and early-stage HD. We aimed to describe phenotypic changes in these participants over 36 months and identify baseline predictors of progression. Methods: Individuals without HD but carrying the mutant huntingtin gene (classed as preHD-A if ≥10·8 years and preHD-B if <10·8 years from predicted onset), participants with early HD (classed as HD1 if they had a total functional capacity score of 11-13 and HD2 if they had a score of 7-10), and healthy control individuals were assessed at four study sites in the Netherlands, the UK, France, and Canada. We measured 36-month change for 3T MRI, clinical, cognitive, quantitative motor, and neuropsychiatric assessments and examined their prognostic value. We also assessed the relation between disease progression and the combined effect of CAG repeat length and age. All participants were analysed according to their baseline subgroups. Longitudinal results were analysed using a combination of repeated-measure weighted least squares models and, when examining risk of new diagnosis, survival analysis. Findings: At baseline, 366 participants were enrolled between Jan 17, and Aug 26, 2008, and of these 298 completed 36-month follow-up: 97 controls, 58 participants with preHD-A, 46 with preHD-B, 66 with HD1, and 31 with HD2. In the preHD-B group, several quantitative motor and cognitive tasks showed significantly increased rates of decline at 36 months, compared with controls, whereas few had at 24 months. Of the cognitive measures, the symbol digit modality test was especially sensitive (adjusted mean loss 4·11 points [95% CI 1·49-6·73] greater than controls; p = 0·003). Among psychiatric indicators, apathy ratings specifically showed significant increases (0·34 points [95% CI 0·02-0·66] greater than controls; p = 0·038). There was little evidence of reliable change in non-imaging measures in the preHD-A group, with the exception of the speeded tapping inter-tap interval (0·01 s [95% CI 0·01-0·02] longer than controls; p = 0·0001). Several baseline imaging, quantitative motor, and cognitive measures had prognostic value, independent of age and CAG repeat length, for predicting subsequent clinical diagnosis in preHD. Of these, grey-matter volume and inter-tap interval were particularly sensitive (p = 0·013 and 0·002, respectively). Longitudinal change in these two measures was also greater in participants with preHD who received a diagnosis of HD during the study compared with those who did not, after controlling for CAG repeat length and age-related risk (p = 0·006 and 0·0003, respectively). In early HD, imaging, quantitative motor, and cognitive measures were predictive of decline in total functional capacity and tracked longitudinal change; also, neuropsychiatric changes consistent with frontostriatal pathological abnormalities were associated with this loss of functional capacity (problem behaviours assessment composite behaviour score p<0·0001). Age and CAG repeat length explained variance in longitudinal change of multimodal measures, with the effect more prominent in preHD. Interpretation: We have shown changes in several outcome measures in individuals with preHD over 36 months. These findings further our understanding of HD progression and have implications for clinical trial design. Funding: CHDI Foundation. © 2013 Elsevier Ltd.
PubMed | CHDI Management CHDI Foundation, Huntingtons Disease Drug Works, University of Oslo, Struthers Parkinsons Center and 7 more.
Type: Journal Article | Journal: Journal of Huntington's disease | Year: 2016
Little is known about the organization of clinical services for Huntingtons disease (HD).To describe how health care services are organized and delivered in HD-clinics taking part in or eligible for the Enroll-HD study.In 2014, a 69-item survey was administered to sites taking part in or eligible for the Enroll-HD study.Of 231 sites surveyed, 121 (52.2%) sites in Europe, North America, Latin America, and Oceania responded. Most sites in the sample serve large populations, with 61.1% serving more than 1.5 million people, and a further 33% serving >500,000. Almost all (86.0%) centers see patients from outside their region. The majority of centers (59.7%) follow 50-199 patients, 21.9% care for more than 200. Most centers provide care in all stages of HD, and nearly all review pre-symptomatic cases. Multidisciplinary case reviews are offered in 54.5% of sites, with outreach clinics offered by 48.1%. Videoconferencing and telemedicine are used by 23.6%. Separate consultations for caregivers are offered in more than half of the centers. Most centers (70.4%) report following published guidelines or local care pathways for HD.Most centers serve a large population and use a multidisciplinary approach. The survey gives insight into factors underpinning HD service delivery globally. There is a need for more in-depth studies of clinical practice to understand how services are organized and how such features may be associated with quality of care.
PubMed | Karolinska Institutet, 2CHDI Management CHDI Foundation and CHDI Management CHDI Foundation
Type: | Journal: Journal of nuclear medicine : official publication, Society of Nuclear Medicine | Year: 2016
Since the discovery of the HTT gene in 1993, numerous animal models have been developed to study the progression of Huntingtons disease, as well as to evaluate potential new therapeutics. In the present study we used small animal positron emission tomography (PET) to characterize the expression of molecular targets in the recently reported HD animal model, the zQ175 mouse model.Male heterozygous zQ175 (Htttm1Mfc/190JChdi, CHDI-81003003) and wild type (WT, C57BL/6J) animals were imaged with the dopamine DAt 6 months of age, the BPOur study indicates a marked reduction of ligand binding to D
Moumne L.,King's College London |
Campbell K.,Taconic |
Howland D.,CHDI Management CHDI Foundation |
Ouyang Y.,Taconic |
Bates G.P.,King's College London
PLoS ONE | Year: 2012
Huntington's disease (HD) is an autosomal dominant progressive neurodegenerative disorder caused by an expansion of a CAG/polyglutamine repeat for which there are no disease modifying treatments. In recent years, transcriptional dysregulation has emerged as a pathogenic process that appears early in disease progression and has been recapitulated across multiple HD models. Altered histone acetylation has been proposed to underlie this transcriptional dysregulation and histone deacetylase (HDAC) inhibitors, such as suberoylanilide hydroxamic acid (SAHA), have been shown to improve polyglutamine-dependent phenotypes in numerous HD models. However potent pan-HDAC inhibitors such as SAHA display toxic side-effects. To better understand the mechanism underlying this potential therapeutic benefit and to dissociate the beneficial and toxic effects of SAHA, we set out to identify the specific HDAC(s) involved in this process. For this purpose, we are exploring the effect of the genetic reduction of specific HDACs on HD-related phenotypes in the R6/2 mouse model of HD. The study presented here focuses on HDAC3, which, as a class I HDAC, is one of the preferred targets of SAHA and is directly involved in histone deacetylation. To evaluate a potential benefit of Hdac3 genetic reduction in R6/2, we generated a mouse carrying a critical deletion in the Hdac3 gene. We confirmed that the complete knock-out of Hdac3 is embryonic lethal. To test the effects of HDAC3 inhibition, we used Hdac3 +/- heterozygotes to reduce nuclear HDAC3 levels in R6/2 mice. We found that Hdac3 knock-down does not ameliorate physiological or behavioural phenotypes and has no effect on molecular changes including dysregulated transcripts. We conclude that HDAC3 should not be considered as the major mediator of the beneficial effect induced by SAHA and other HDAC inhibitors in HD. © 2012 Moumné et al.
Ross C.A.,Johns Hopkins University |
Aylward E.H.,Seattle Childrens Research Institute |
Wild E.J.,University College London |
Langbehn D.R.,University of Iowa |
And 11 more authors.
Nature Reviews Neurology | Year: 2014
Huntington disease (HD) can be seen as a model neurodegenerative disorder, in that it is caused by a single genetic mutation and is amenable to predictive genetic testing, with estimation of years to predicted onset, enabling the entire range of disease natural history to be studied. Structural neuroimaging biomarkers show that progressive regional brain atrophy begins many years before the emergence of diagnosable signs and symptoms of HD, and continues steadily during the symptomatic or 'manifest' period. The continued development of functional, neurochemical and other biomarkers raises hopes that these biomarkers might be useful for future trials of disease-modifying therapeutics to delay the onset and slow the progression of HD. Such advances could herald a new era of personalized preventive therapeutics. We describe the natural history of HD, including the timing of emergence of motor, cognitive and emotional impairments, and the techniques that are used to assess these features. Building on this information, we review recent progress in the development of biomarkers for HD, and potential future roles of these biomarkers in clinical trials. © 2014 Macmillan Publishers Limited.
Yu-Taeger L.,University of Tübingen |
Petrasch-Parwez E.,Ruhr University Bochum |
Osmand A.P.,University of Tennessee at Knoxville |
Redensek A.,University of Tübingen |
And 10 more authors.
Journal of Neuroscience | Year: 2012
Huntington disease (HD) is an inherited progressive neurodegenerative disorder, characterized by motor, cognitive, and psychiatric deficits as well as neurodegeneration and brain atrophy beginning in the striatum and the cortex and extending to other subcortical brain regions. The genetic cause is an expansion of the CAG repeat stretch in the HTT gene encoding huntingtin protein (htt). Here, we generated an HD transgenic rat model using a human bacterial artificial chromosome (BAC), which contains the full-length HTT genomic sequence with 97 CAG/CAA repeats and all regulatory elements. BACHD transgenic rats display a robust, early onset and progressive HD-like phenotype including motor deficits and anxiety-related symptoms. In contrast to BAC and yeast artificial chromosome HD mouse models that express full-length mutant huntingtin, BACHD rats do not exhibit an increased body weight. Neuropathologically, the distribution of neuropil aggregates and nuclear accumulation of N-terminal mutant huntingtin in BACHD rats is similar to the observations in human HD brains. Aggregates occur more frequently in the cortex than in the striatum and neuropil aggregates appear earlier than mutant htt accumulation in the nucleus. Furthermore, we found an imbalance in the striatal striosome and matrix compartments in early stages of the disease. In addition, reduced dopamine receptor binding was detectable by in vivo imaging. Our data demonstrate that this transgenic BACHD rat line may be a valuable model for further understanding the disease mechanisms and for preclinical pharmacological studies. © 2012 the authors.
Rossin F.,University of Rome Tor Vergata |
D'Eletto M.,University of Rome Tor Vergata |
MacDonald D.,CHDI Management CHDI Foundation |
Farrace M.G.,University of Rome Tor Vergata |
And 2 more authors.
Amino Acids | Year: 2012
Tissue transglutaminase (TG2) activity has been implicated in inflammatory disease processes such as Celiac disease, infectious diseases, cancer, and neurodegenerative diseases, such as Huntington's disease. Furthermore, four distinct biochemical activities have been described for TG2 including protein crosslinking via transamidation, GTPase, kinase and protein disulfide isomerase activities. Although the enzyme plays a complex role in the regulation of cell death and autophagy, the molecular mechanisms and the putative biochemical activity involved in each is unclear. Therefore, the goal of the present study was to determine how TG2 modulates autophagy and/or apoptosis and which of its biochemical activities is involved in those processes. To address this question, immortalized embryonic fibroblasts obtained from TG2 knock-out mice were reconstituted with either wild-type TG2 or TG2 lacking its transamidating activity and these were subjected to different treatments to induce autophagy or apoptosis. We found that knock out of the endogenous TG2 resulted in a significant exacerbation of caspase 3 activity and PARP cleavage in MEF cells subjected to apoptotic stimuli. Interestingly, the same cells showed the accumulation of LC3 II isoform following autophagy induction. These findings strongly suggest that TG2 transamidating activity plays a protective role in the response of MEF cells to death stimuli, because the expression of the wild-type TG2, but not its transamidation inactive C277S mutant, resulted in a suppression of caspase 3 as well as PARP cleavage upon apoptosis induction. Additionally, the same mutant was unable to catalyze the final steps in autophagosome formation during autophagy. Our findings clearly indicate that the TG2 transamidating activity is the primary biochemical function involved in the physiological regulation of both apoptosis and autophagy. These data also indicate that TG2 is a key regulator of cross-talk between autophagy and apoptosis. © Springer-Verlag 2011.
Sampaio C.,CHDI Management CHDI Foundation |
Borowsky B.,CHDI Management CHDI Foundation |
Reilmann R.,George Huntington Institute |
Reilmann R.,University of Tübingen
Movement Disorders | Year: 2014
Since the identification of the Huntington's disease (HD) gene, knowledge has accumulated about mechanisms directly or indirectly affected by the mutated Huntingtin protein. Transgenic and knock-in animal models of HD facilitate the preclinical evaluation of these targets. Several treatment approaches with varying, but growing, preclinical evidence have been translated into clinical trials. We review major landmarks in clinical development and report on the main clinical trials that are ongoing or have been recently completed. We also review clinical trial settings and designs that influence drug-development decisions, particularly given that HD is an orphan disease. In addition, we provide a critical analysis of the evolution of the methodology of HD clinical trials to identify trends toward new processes and endpoints. Biomarker studies, such as TRACK-HD and PREDICT-HD, have generated evidence for the potential usefulness of novel outcome measures for HD clinical trials, such as volumetric imaging, quantitative motor (Q-Motor) measures, and novel cognitive endpoints. All of these endpoints are currently applied in ongoing clinical trials, which will provide insight into their reliability, sensitivity, and validity, and their use may expedite proof-of-concept studies. We also outline the specific opportunities that could provide a framework for a successful avenue toward identifying and efficiently testing and translating novel mechanisms of action in the HD field. © 2014 International Parkinson and Movement Disorder Society.
Howland D.S.,CHDI Management CHDI Foundation |
Munoz-Sanjuan I.,CHDI Management CHDI Foundation
Movement Disorders | Year: 2014
Unraveling the pathophysiology and testing candidate therapeutics in neurodegenerative disorders is, necessarily, highly dependent on model systems. Because Huntington's disease (HD) is caused by a single (expanded CAG tract) mutation in the huntingtin (HTT) gene, a richness of model systems, particularly mice, have been engineered to both dissect disease mechanisms and test potential therapeutics. Even so, as with other neurodegenerative diseases, very little success has been achieved in translating HD mouse model drug testing results to the clinic. Because of the considerable costs-human, opportunity, and financial-there is a pressing need to improve the use of existing HD models and also to develop models in higher species beyond rodent, such as sheep, minipig, and nonhuman primate, to bridge the translational gap from preclinical to clinical testing of candidate therapeutics. © 2014 International Parkinson and Movement Disorder Society.