Characteristics of a newly diagnosed Polish cohort of patients with neurological manifestations of Wilson disease evaluated with the Unified Wilson's Disease Rating Scale.

BACKGROUND: Wilson disease is a rare genetic disorder in which impaired copper excretion results in toxic copper levels and tissue damage. Manifestations are primarily hepatic and/or neuropsychiatric, with a variety of neurological phenotypes. The aim of this study was to characterize neurological signs of Wilson disease in newly diagnosed patients and to determine whether they correlated with disability, liver function, and copper metabolism. METHODS: Fifty-three treatment-naïve patients recently diagnosed with Wilson disease who exhibited neurological symptoms were included. Neurological manifestations were characterized by examination in terms of symptom type and degree of neurological impairment (Unified Wilson's Disease Rating Scale [UWDRS] Part III) and correlated with degree of disability (UWDRS Part II), abnormalities in copper parameters and hepatic status. RESULTS: Most patients (62.3%) exhibited tremor and ataxia, whereas 15.1% were dystonic, and 11.3% had parkinsonism. Discrete or unclassified signs only were observed in 11.3% of patients. A good correlation between disability (UWDRS Part II) and neurological impairment (UWDRS Part III) was observed (Pearson r = 0.84). However, there was a lack of correlation when either disability or neurological impairment were analyzed with copper parameters or liver impairment. CONCLUSIONS: The predominant neurological manifestations in this cohort of newly diagnosed Wilson disease patients were ataxia and tremor. Neurological impairment measured was highly correlated with the level of disability. However, hepatic manifestations of Wilson disease and copper levels did not appear to be correlated with neurological status and disability. These results highlight the challenges faced when assessing Wilson disease with its highly variable symptomatology.

Prospective exploratory muscle biopsy, imaging, and functional assessment in patients with late-onset Pompe disease treated with alglucosidase alfa: The EMBASSY Study.

BACKGROUND: Late-onset Pompe disease is characterized by progressive skeletal myopathy followed by respiratory muscle weakness, typically leading to loss of ambulation and respiratory failure. In this population, enzyme replacement therapy (ERT) with alglucosidase alfa has been shown to stabilize respiratory function and improve mobility and muscle strength. Muscle pathology and glycogen clearance from skeletal muscle in treatment-naïve adults after ERT have not been extensively examined. METHODS: This exploratory, open-label, multicenter study evaluated glycogen clearance in muscle tissue samples collected pre- and post- alglucosidase alfa treatment in treatment-naïve adults with late-onset Pompe disease. The primary endpoint was the quantitative reduction in percent tissue area occupied by glycogen in muscle biopsies from baseline to 6months. Secondary endpoints included qualitative histologic assessment of tissue glycogen distribution, secondary pathology changes, assessment of magnetic resonance images (MRIs) for intact muscle and fatty replacement, and functional assessments. RESULTS: Sixteen patients completed the study. After 6months of ERT, the percent tissue area occupied by glycogen in quadriceps and deltoid muscles decreased in 10 and 8 patients, respectively. No changes were detected on MRI from baseline to 6months. A majority of patients showed improvements on functional assessments after 6months of treatment. All treatment-related adverse events were mild or moderate. CONCLUSIONS: This exploratory study provides novel insights into the histopathologic effects of ERT in late-onset Pompe disease patients. Ultrastructural examination of muscle biopsies demonstrated reduced lysosomal glycogen after ERT. Findings are consistent with stabilization of disease by ERT in treatment-naïve patients with late-onset Pompe disease.

Bis-choline tetrathiomolybdate in patients with Wilson's disease: an open-label, multicentre, phase 2 study.

BACKGROUND: Wilson's disease is a genetic disorder in which copper accumulates in the liver, brain, and other tissues. Therapies are limited by efficacy, safety concerns, and multiple daily dosing. Bis-choline tetrathiomolybdate (WTX101) is an oral first-in-class copper-protein-binding molecule that targets hepatic intracellular copper and reduces plasma non-ceruloplasmin-bound copper (NCC) by forming tripartite complexes with albumin and increasing biliary copper excretion. We aimed to assess the efficacy and safety of WTX101 in the initial or early treatment of patients with Wilson's disease. METHODS: We did this open-label, phase 2 study at 11 hospitals in the USA and Europe. We enrolled patients (≥18 years) with Wilson's disease who were untreated or had received no more than 24 months of treatment with chelators or zinc, had a Leipzig score of 4 or more, and had NCC concentrations above the lower limit of the normal reference range (≥0·8 µmol/L). Eligible patients received WTX101 monotherapy at a starting dose of 15-60 mg/day on the basis of baseline NCC concentrations for the first 4-8 weeks, with response-guided individualised dosing for the remaining weeks up to week 24. Investigators, other hospital personnel, and patients were aware of the identity of the treatment. The primary endpoint was change in baseline NCC concentrations corrected for copper in tetrathiomolybdate-copper-albumin complexes (NCCcorrected) at 24 weeks, with treatment success defined as achievement or maintenance of normalised NCCcorrected (≤2·3 µmol/L [upper limit of normal]) or achievement of at least a 25% reduction in NCCcorrected from baseline at 24 weeks. This study is registered with ClinicalTrials.gov, number NCT02273596. FINDINGS: Between Nov 24, 2014, and April 27, 2016, 28 patients were enrolled and received WTX101; 22 (79%) patients completed the study up to week 24. At 24 weeks, 20 (71%, 95% CI 51·3-86·8; p<0·0001) of 28 patients met the criteria for treatment success: 16 (57%) treated with WTX101 either achieved or maintained normalised NCCcorrected concentrations and 4 (14%) had at least a 25% reduction from baseline NCCcorrected. Mean NCCcorrected was reduced by 72% from baseline to week 24 (least squares mean difference -2·4 µmol/L [SE 0·4], 95% CI -3·2 to -1·6; p<0·0001). No cases of paradoxical drug-related neurological worsening were recorded. Liver function was stable in all patients, although reversible increased concentrations of asymptomatic alanine or aspartate aminotransferase, or γ-glutamyltransferase, without increased bilirubin, occurred in 11 (39%) of 28 patients who received at least 30 mg/day. 11 serious adverse events were reported in seven (25%) patients and included psychiatric disorders (six events in four patients), gait disturbance (one event), elevated liver aminotransferases (two events in two patients, one with agranulocytosis), and decline in neurological functioning (one event, likely due to natural disease progression although causality could not be ruled out). The seven serious adverse events categorised as psychiatric disorders and as gait disturbance were assessed as unlikely to be related to the study drug, whereas the remaining four events were possibly or probably related. INTERPRETATION: Our findings indicate that WTX101 might be a promising new therapeutic approach for Wilson's disease, with a unique mode of action. In view of its once-daily dose and favourable safety profile, WTX101 could improve the treatment of patients with this debilitating condition. FUNDING: Wilson Therapeutics AB.

Safety and efficacy of alternative alglucosidase alfa regimens in Pompe disease.

Emerging phenotypes in long-term survivors with Pompe disease on standard enzyme replacement therapy (ERT) (alglucosidase alfa 20 mg/kg/2 weeks) can include patients with worsening motor function. Whether higher doses of ERT improve skeletal function in these patients has not been systematically studied. This exploratory, randomized, open-label, 52-week study examined the safety and efficacy of 2 ERT regimens of alglucosidase alfa (20 mg/kg/week or 40 mg/kg/2 weeks) in 13 patients with Pompe disease and clinical decline or a lack of improvement on standard ERT: late-onset (n = 4), infantile-onset (n = 9). Cross-reactive immunologic material assay-negative patients were excluded. Eleven of 13 patients completed the study. Trends for improvement were seen in total gross motor function, but not mobility; however, 6 (late-onset, 2; infantile-onset, 4) of 11 patients (55%) who met the entry criteria of motor decline (late-onset, 4; infantile-onset, 7) showed improvement in motor and/or mobility skills. No between-regimen differences in efficacy emerged. Two case studies highlight the benefits of increased ERT dose in patients with Pompe disease experiencing clinical decline. Both alternative regimens were generally well tolerated. This study was limited by the small sample size, which is not uncommon for small clinical studies of rare diseases. Additionally, the study did not include direct assessment of muscle pathology, which may have identified potential causes of decreased response to ERT. Results were inconclusive but suggest that increased ERT dose may be beneficial in some patients with Pompe disease experiencing motor decline. Controlled studies are needed to clarify the benefits and risks of this strategy.

Axon loss in the spinal cord determines permanent neurological disability in an animal model of multiple sclerosis.

Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system (CNS). Most patients undergo an initial relapsing-remitting (RR-MS) course that transforms into a relentless neurodegenerative disorder, termed secondary progressive (SP)-MS. Reversible inflammation and demyelination account readily for the pattern of RR-MS but provide an unsatisfactory explanation for irrevocable decline in SP-MS. Axon loss is thought to be responsible for progressive, non-remitting neurological disability during SP-MS. There is considerable potential for neuroprotective therapies in MS, but their application awaits animal models in which axonal loss correlates with permanent neurological disability. In this report, we describe quantitative immunohistochemical methods that correlate inflammation and axonal loss with neurological disability in chronic-relapsing experimental autoimmune encephalomyelitis (EAE). At first attack, CNS inflammation, but not axon loss, correlated with the degree of neurological disability. In contrast, fixed neurological impairment in chronic EAE correlated with axon loss that, in turn, correlated with the number of symptomatic attacks. As proposed for MS, these observations imply a causal relationship between inflammation, axon loss, and irreversible neurological disability. This chronic-relapsing EAE model provides an excellent platform for 2 critical objectives: investigating mechanisms of axon loss and evaluating efficacy of neuroprotective therapies.

Axonal degeneration and progressive neurologic disability in multiple sclerosis.

Accumulating data support axonal degeneration as the major determinant of irreversible neurological disability in patients with multiple sclerosis (MS). The extent of axonal injury correlates with the degree of inflammation in active MS lesions and occurs at early stages of disease, indicating that inflammatory demyelination is an important factor behind axon pathology at the relapsing-remitting stage of MS. Axonal loss from disease onset can remain clinically silent for many years, and permanent neurological disability develops when a threshold of axonal loss is reached and the CNS compensatory resources are exhausted. Lack of myelin-derived trophic support due to long term demyelination may cause continuous axonal degeneration in chronic inactive lesions at the secondary-progressive stage of MS. Axonal pathology is not limited to demyelinated lesions, but also extends into normal appearing white matter. The concept of MS as a neurodegenerative disorder has important clinical implications: First, proactive anti-inflammatory and immunomodulatory treatment should prevent or delay chronic disability since inflammation influences axonal injury. Second, the pathophysiological mechanisms underlying axonal degeneration in MS need to be clarified in order to develop novel neuroprotective therapeutics. Finally, surrogate markers of axonal pathology, such as N-acetyl aspartate, can be used to monitor axonal dysfunction, axonal loss and treatment efficiency in patients with MS.

Beta IV tubulin is selectively expressed by oligodendrocytes in the central nervous system.

Oligodendrocyte differentiation and myelination involve dramatic changes in cell signaling pathways, gene expression patterns, cell shape, and cytoskeletal organization. In a pilot study investigating CNS angiogenesis, oligodendrocytes were intensely labeled by antisera directed against the C-terminal of Tie-2, a 140-kDa transmembrane receptor for angiopoietin. Immunoprecipitation of rat brain proteins with Tie-2 C-terminal antisera, however, produced a single spot of approximately 55-kDa pI approximately 5 by two-dimensional (2D) electrophoresis, which was identified as beta-tubulin by mass spectrometry. Isotype-specific antibodies for beta(IV) tubulin selectively labeled oligodendrocytes. First detected in premyelinating oligodendrocytes, beta(IV) tubulin was abundant in myelinating oligodendrocyte perinuclear cytoplasm and processes extending to and along developing myelin internodes. Beta(IV) tubulin-positive MTs were diffusely distributed in oligodendrocyte perinuclear cytoplasm and not organized around the centrosome. Beta(IV) tubulin may play a role in establishing the oligodendrocyte MT network, which is essential for the transport of myelin proteins, lipids, and RNA during myelination.

N-acetylaspartate is an axon-specific marker of mature white matter in vivo: a biochemical and immunohistochemical study on the rat optic nerve.

Axonal pathology is a major cause of neurological disability in multiple sclerosis. Axonal transection begins at disease onset but remains clinically silent because of compensatory brain mechanisms. Noninvasive surrogate markers for axonal injury are therefore essential to monitor cumulative disease burden in vivo. The neuronal compound N-acetylaspartate, as measured by magnetic resonance spectroscopy, is currently the best and most specific noninvasive marker of axonal pathology in multiple sclerosis. The possibility has been raised, however, that N-acetylaspartate is expressed also by oligodendroglial lineage cells. In order to investigate N-acetylaspartate specificity for white matter axons, transected rat optic nerves were analyzed by high-performance liquid chromatography and immunohistochemistry. In transected adult nerves, N-acetylaspartate and N-acetyl aspartylglutamate decreased in concordance with axonal degeneration and were undetectable 24 days posttransection. Nonproliferating oligodendrocyte progenitor cells, oligodendrocytes, and myelin were abundant in these axon-free nerves. At 24 days posttransection, N-acetylaspartate was increased (42%; p = 0.02) in nontransected contralateral nerves. After transection at postnatal day 4, total N-acetylaspartate decreased by 80% (P14; p = 0.002) and 94% (P20; p = 0.003). In these developing axon-free nerves, 25 to 33% of oligodendrocyte progenitor cells were proliferating. These data validate magnetic resonance spectroscopy measurements of N-acetylaspartate as an axon-specific monitor of central nervous system white matter in vivo. In addition, the results indicate that neuronal adaptation can increase N-acetylaspartate levels, and that 5 to 20% of the N-acetylaspartate in developing white matter is synthesized by proliferating oligodendrocyte progenitor cells.

The tetraspanin protein, CD9, is expressed by progenitor cells committed to oligodendrogenesis and is linked to beta1 integrin, CD81, and Tspan-2.

Previous studies identified the tetraspanin protein CD9 in myelinating oligodendrocytes. The present report extends these observations by identifying CD9 in a subpopulation of oligodendrocyte progenitor cells (OPCs) and in premyelinating oligodendrocytes in rodents. NG2-positive cells expressed CD9 in a temporal and spatial pattern during development that was consistent with CD9 expression in OPCs just prior to their differentiation into premyelinating oligodendrocytes. NG2-positive cells in mature brains were CD9-negative. CD9 expression during oligodendrocyte development in vitro supported this hypothesis, as all CD9-positive cells became O4-positive when switched to oligodendrocyte differentiating media. CD9 immunoreactivity was enriched in myelinating oligodendrocytes and their processes, and the outer aspects of myelin internodes. Immunoprecipitation of CD9 from postnatal rat cerebrum coprecipitated beta1 integrin, CD81, and Tspan-2, another tetraspanin protein recently identified in oligodendrocytes. Following surface biotinylation of oligodendrocytes in vitro, biotinylated beta1 integrin was identified in a CD9 immunoprecipitate. These data support a molecular link between surface integrins and a CD9, Tspan-2 molecular web during the differentiation of oligodendrocytes. Oligodendrocyte production and myelination appears to be normal in CD9-deficient mice. These data support the hypothesis that CD9 helps form the tetraspanin web beneath the plasma membranes of progenitor cells committed to oligodendrogenesis, but that CD9 is not essential for oligodendrogenesis and myelination.