Efficacy and safety of leuprorelin in patients with spinal and bulbar muscular atrophy (JASMITT study): a multicentre, randomised, double-blind, placebo-controlled trial

Neurodegenerative diseases associated with the disruption of proteostasis and their therapeutic strategies using chemical chaperones

Aberrant proteostasis is thought to be involved in the pathogenesis of neurodegenerative diseases. Some proteostasis abnormalities are ameliorated by chaperones. Chaperones are divided into three groups: molecular, pharmacological and chemical. Chemical chaperones intended to alleviate stress in organelles, such as the endoplasmic reticulum (ER), are now being administered clinically. Of the chemical chaperones, 4-phenylbutyrate (4-PBA) has been used as a research reagent, and its mechanism of action includes chaperone effects and the inhibition of histone deacetylase. Moreover, it also binds to the B-site of SEC24 and regulates COPII-mediated transport from the ER. Although its therapeutic effect may not be strong, elucidating the mechanism of action of 4-PBA may contribute to the identification of novel therapeutic targets for neurodegenerative diseases.

Efficacy of leuprorelin in spinal and bulbar muscular atrophy: a 3-year observational study

OBJECTIVE

This study aimed to investigate the long-term effects and functional outcomes of androgen suppression therapy using leuprorelin among Korean patients with spinal and bulbar muscular atrophy (SBMA).

METHODS

This observational study enrolled patients with genetically confirmed SBMA who provided informed consent. Leuprorelin was administered via subcutaneous injection every 12 weeks. The primary outcome measure was the change in total Spinal and Bulbar Muscular Atrophy Functional Rating Scale (SBMAFRS) scores.

RESULTS

A total of 48 SBMA patients were evaluated in this study. Among them, 39 patients underwent androgen suppression therapy over a 3-year period. The total SBMAFRS score decreased from 41.72 ± 5.55 to 36.74 ± 7.74 (p < 0.001) in patients who completed their treatment. The subgroup with a baseline SBMAFRS score of ≥ 42 had a significantly lower decline in SBMAFRS score than did those with a baseline SBMAFRS score of ≤ 41. We determined that at a baseline, SBMAFRS cutoff value of 41.5 could predict good prognosis, with a corresponding area under the curve of 0.689.

CONCLUSION

Despite androgen suppression therapy, all enrolled participants exhibited a decrease in the overall SBMAFRS score. However, those with a baseline SBMAFRS of ≥ 42 showed a mild decrease in scores, indicating a more favorable prognosis. These findings suggest that a higher baseline motor function was a key prognostic indicator in SBMA treatment and that initiating early leuprorelin treatment in patients with high baseline function may lead to good clinical outcomes.

Mutant androgen receptor induces neurite loss and senescence independently of ARE binding in a neuronal model of SBMA

Spinal and bulbar muscular atrophy (SBMA) is a slowly progressing neuromuscular disease caused by a polyglutamine (polyQ)-encoding CAG trinucleotide repeat expansion in the androgen receptor (AR) gene, leading to AR aggregation, lower motor neuron death, and muscle atrophy. AR is a ligand-activated transcription factor that regulates neuronal architecture and promotes axon regeneration; however, whether AR transcriptional functions contribute to disease pathogenesis is not fully understood. Using a differentiated PC12 cell model of SBMA, we identified dysfunction of polyQ-expanded AR in its regulation of neurite growth and maintenance. Specifically, we found that in the presence of androgens, polyQ-expanded AR inhibited neurite outgrowth, induced neurite retraction, and inhibited neurite regrowth. This dysfunction was independent of polyQ-expanded AR transcriptional activity at androgen response elements (ARE). We further showed that the formation of polyQ-expanded AR intranuclear inclusions promoted neurite retraction, which coincided with reduced expression of the neuronal differentiation marker β-III-Tubulin. Finally, we revealed that cell death is not the primary outcome for cells undergoing neurite retraction; rather, these cells become senescent. Our findings reveal that mechanisms independent of AR canonical transcriptional activity underly neurite defects in a cell model of SBMA and identify senescence as a pathway implicated in this pathology. These findings suggest that in the absence of a role for AR canonical transcriptional activity in the SBMA pathologies described here, the development of SBMA therapeutics that preserve this activity may be desirable. This approach may be broadly applicable to other polyglutamine diseases such as Huntington's disease and spinocerebellar ataxias.

271st ENMC international workshop: Towards a unifying effort to fight Kennedy's disease. 20-22 October 2023, Hoofddorp, Netherlands

The workshop held in the Netherlands from October 20-22, 2023, united 27 scientists from academia, healthcare, and industry representing 11 countries, alongside four patient and charity representatives. Focused on Kennedy's Disease (KD), also known as spinal and bulbar muscular atrophy (SBMA), the workshop aimed to consolidate knowledge, align on clinical trial designs, and promote participative medicine for effective treatments. Discussions emphasized KD's molecular mechanisms, highlighting its status as a neuromuscular disorder with motor neuron degeneration. Strategies for therapeutic intervention, including AR activity modulation and targeting post-translational modifications, were proposed. The need for diagnostic, prognostic, and target engagement biomarkers was stressed. Challenges in patient stratification and clinical trial recruitment were acknowledged, with the International KD/SBMA Registry praised for its role. The workshop concluded with a patient-focused session, underscoring challenges in KD diagnosis and the vital support provided by patient associations.

Whole-Body Muscle Magnetic Resonance Imaging in 81 Patients with Spinal and Bulbar Muscular Atrophy: A Prospective Study

OBJECTIVE

Spinal and bulbar muscular atrophy (SBMA) is characterized by slow, progressive bulbar and limb muscle weakness; however, the pattern of progression of muscle fat infiltration remains unclear. We assessed the progression of muscle involvement in 81 patients with SBMA using whole-body muscle magnetic resonance imaging (MRI), alongside clinical and laboratory findings.

METHODS

This prospective study included patients with genetically confirmed SBMA who underwent whole-body muscle MRI. We analyzed muscle fat infiltration and the pattern of involved muscles using cluster analysis, visualizing the sequential progression of fat infiltration. Muscle clusters demonstrated correlation with clinical scales and laboratory findings. Additionally, linear regression analysis was performed to identify the MRI section most strongly associated with 6-minute walk test (6MWT).

RESULTS

We included 81 patients with SBMA (age = 54.3 years). After categorizing the patients into 6 clusters based on the pattern of muscle fat infiltration, we observed that muscle involvement began in the posterior calf and progressed to the posterior thigh, pelvis, trunk, anterior thigh, medial thigh, anterior calf, and upper extremity muscles. These muscle clusters correlated significantly with disease duration (τ = 0.47, p < 0.001), 6MWT (τ = -0.49, p < 0.001), and serum creatinine level (τ = -0.46, p < 0.001). The whole-body MRI indicated the thigh as the section most significantly correlated with 6MWT.

INTERPRETATION

We used whole-body muscle MRI to determine the sequential progression of the fat infiltration in SBMA. Our findings may enable the identification of objective and reliable imaging outcome measures in the study of the natural history or future clinical trials of SBMA. ANN NEUROL 2024;95:596-606.

Spinal and bulbar muscular atrophy: From molecular pathogenesis to pharmacological intervention targeting skeletal muscle

The clinical characteristics of SBMA, also known as Kennedy's disease (OMIM 313200), were initially documented by Dr. H Kawahara in the 18th century and a hundred years later by Dr. W. Kennedy. SBMA is a neuromuscular disease caused by expansions of a CAG microsatellite tandem repeat in exon 1 of the androgen receptor (AR) gene located on the X chromosome. These expansions result in the production of AR with an aberrantly expanded polyglutamine (polyQ) tract. In this review, we explore recent advancements in the significance of gene expression changes in skeletal muscle and discuss how pharmacological interventions targeting this aspect of disease pathogenesis can potentially be translated into therapies for SBMA patients.

Bicalutamide and Trehalose Ameliorate Spinal and Bulbar Muscular Atrophy Pathology in Mice

Spinal and bulbar muscular atrophy (SBMA) is characterized by motor neuron (MN) degeneration that leads to slowly progressive muscle weakness. It is considered a neuromuscular disease since muscle has a primary role in disease onset and progression. SBMA is caused by a CAG triplet repeat expansion in the androgen receptor (AR) gene. The translated poly-glutamine (polyQ) tract confers a toxic gain of function to the mutant AR altering its folding, causing its aggregation into intracellular inclusions, and impairing the autophagic flux. In an in vitro SBMA neuronal model, we previously showed that the antiandrogen bicalutamide and trehalose, a natural disaccharide stimulating autophagy, block ARpolyQ activation, reduce its nuclear translocation and toxicity and facilitate the autophagic degradation of cytoplasmic AR aggregates. Here, in a knock-in SBMA mouse model (KI AR113Q), we show that bicalutamide and trehalose ameliorated SBMA pathology. Bicalutamide reversed the formation of the AR insoluble forms in KI AR113Q muscle, preventing autophagic flux blockage. We demonstrated that apoptosis is activated in KI AR113Q muscle, and that both compounds prevented its activation. We detected a decrease of mtDNA and an increase of OXPHOS enzymes, already at early symptomatic stages; these alterations were reverted by trehalose. Overall, bicalutamide and/or trehalose led to a partial recovery of muscle morphology and function, and improved SBMA mouse motor behavior, inducing an extension of their survival. Thus, bicalutamide and trehalose, by counteracting ARpolyQ toxicity in skeletal muscle, are valuable candidates for future clinical trials in SBMA patients.

Ligand-free mitochondria-localized mutant AR-induced cytotoxicity in spinal bulbar muscular atrophy

Spinal bulbar muscular atrophy (SBMA), the first identified CAG-repeat expansion disorder, is an X-linked neuromuscular disorder involving CAG-repeat-expansion mutations in the androgen receptor (AR) gene. We utilized CRISPR-Cas9 gene editing to engineer novel isogenic human induced pluripotent stem cell (hiPSC) models, consisting of isogenic AR knockout, control and disease lines expressing mutant AR with distinct repeat lengths, as well as control and disease lines expressing FLAG-tagged wild-type and mutant AR, respectively. Adapting a small-molecule cocktail-directed approach, we differentiate the isogenic hiPSC models into motor neuron-like cells with a highly enriched population to uncover cell-type-specific mechanisms underlying SBMA and to distinguish gain- from loss-of-function properties of mutant AR in disease motor neurons. We demonstrate that ligand-free mutant AR causes drastic mitochondrial dysfunction in neurites of differentiated disease motor neurons due to gain-of-function mechanisms and such cytotoxicity can be amplified upon ligand (androgens) treatment. We further show that aberrant interaction between ligand-free, mitochondria-localized mutant AR and F-ATP synthase is associated with compromised mitochondrial respiration and multiple other mitochondrial impairments. These findings counter the established notion that androgens are requisite for mutant AR-induced cytotoxicity in SBMA, reveal a compelling mechanistic link between ligand-free mutant AR, F-ATP synthase and mitochondrial dysfunction, and provide innovative insights into motor neuron-specific therapeutic interventions for SBMA.

Development of a functional composite for the evaluation of spinal and bulbar muscular atrophy

This study aimed to develop a functional measurement that combines quantitative motor evaluation index of various body regions in patients with spinal and bulbar muscular atrophy (SBMA). We assessed subjects with SBMA and healthy controls with quantitative muscle strength measurements and functional scales. We selected tongue pressure, grip power, % peak expiratory flow (%PEF), timed walking test, and % forced vital capacity (%FVC) as components. By combining these values with Z-score, we created a functional composite (SBMA functional composite: SBMAFC). We also calculated the standardized response mean to compare the sensitivity of SBMAFC with that of existing measurements. A total of 97 genetically confirmed patients with SBMA and 36 age- and sex-matched healthy controls were enrolled. In the longitudinal analysis, the standardized response mean of SBMAFC was larger than that of existing rating scales. Receiver operating characteristic (ROC) analysis demonstrated that the SBMAFC is capable of distinguishing between subjects with early-stage SBMA and healthy controls. SBMAFC is more sensitive to disease progression than existing functional rating scales and is a potential outcome measure in clinical trials of SBMA.

Mexiletine in spinal and bulbar muscular atrophy: a randomized controlled trial

Objective

Patients with spinal and bulbar muscular atrophy (SBMA) often experience muscular weakness under cold exposure.

Methods

In our previously conducted observational study, we assessed nerve conduction and grip strength to examine the effect of cold exposure on motor function, based on which we conducted a randomized controlled trial to evaluate the efficacy and safety of mexiletine hydrochloride in SBMA (MEXPRESS).

Results

In the observational study, 51 consecutive patients with SBMA and 18 healthy controls (HCs) were enrolled. Of the patients with SBMA, 88.0% experienced cold paresis. Patients with SBMA exhibited greater prolongation of ulnar nerve distal latency under cold (SBMA, 5.6 ± 1.1 msec; HC, 4.3 ± 0.6 msec; p <0.001); the change in the distal latencies between room temperature and cold exposure conditions correlated with the change in grip power. In the MEXPRESS trial, 20 participants took mexiletine or lactose, three times a day for 4 weeks with a crossover design. There was no difference in distal latencies at room temperature and under cold exposure between mexiletine and placebo groups as the primary endpoint. However, tongue pressure and 10‐sec grip and release test under cold exposure were improved in the mexiletine group. There were no serious adverse events throughout the study period.

Interpretation

Cold paresis is common and associated with prolongation of distal latency in SBMA. The results of the phase II clinical trial revealed that mexiletine showed short‐term safety, but it did not restore cold exposure‐induced prolongation of distal latency.

Hypogonadism in Males With Genetic Neurodevelopmental Syndromes

Genetic syndromes that affect the nervous system may also disrupt testicular function, and the mechanisms for these effects may be interrelated. Most often neurological signs and symptoms predominate and hypogonadism remains undetected and untreated, while in other cases, a thorough evaluation of a hypogonadal male reveals previously unrecognized ataxia, movement disorder, muscle weakness, tremor, or seizures, leading to a syndromic diagnosis. Androgen deficiency in patients with neurological diseases may aggravate muscle weakness and fatigue and predispose patients to osteoporosis and obesity. The purpose of this mini review is to provide a current understanding of the clinical, biochemical, histologic, and genetic features of syndromes in which male hypogonadism and neurological dysfunction may coexist and may be encountered by the clinical endocrinologist.

The Combined Efficacy of a Two-Year Period of Cybernic Treatment With a Wearable Cyborg Hybrid-Assistive Limb and Leuprorelin Therapy in a Patient With Spinal and Bulbar Muscular Atrophy: A Case Report

Spinal and bulbar muscular atrophy (SBMA), also known as Kennedy's disease, is a rare, slowly progressive, incurable, and hereditary neurodegenerative disease caused by the testosterone-dependent accumulation of pathogenic polyglutamine-expanded androgen receptor protein. After extensive review, two treatments for SBMA have recently been approved in Japan; this decision was based on the results of randomized controlled trials: First, anti-androgen therapy using leuprorelin acetate (leuprorelin), a disease-modifying drug that can inhibit the progression of dysphagia but has not yet been proved to improve gait function; second, cybernic treatment with a wearable cyborg hybrid assistive limb (HAL®) (Cyberdyne Inc. Tsukuba, Japan). The HAL is an innovative walking exercise system that has been shown to significantly improve gait function in eight neuromuscular diseases without reduction in muscle function, including SBMA. It is possible that the combination of these two approaches might yield better outcomes. However, the long-term effects of such a combined approach have yet to be clinically evaluated. Here, we describe the case of a 39-year-old male with SBMA who commenced anti-androgen therapy with leuprorelin 1 year previously; this was followed by cybernic treatment with HAL. The duration of walking exercise with HAL was 20–30 min a day in one session. Over 2 weeks, the patient underwent nine sessions (one course). The efficacy of HAL was evaluated by gait function tests before and after one course of cybernic treatment. Then, leuprorelin treatment was combined with cybernic sessions every 2 months for 2 years (13 courses in total). Walking ability, as evaluated by the 2-min walk test, improved by 20.3% in the first course and peaked 10 months after the commencement of combined therapy (a 59.0% improvement). Walking function was maintained throughout the period. Generally, SBMA is characterized by moderately increased serum levels of creatine kinase (CK), reflecting neuromuscular damage; interestingly, the patient's CK levels decreased dramatically with combined therapy, indicating remarkable functional improvement. Long-term combined therapy improved the patient's gait function with a steady reduction in CK levels. The combination of leuprorelin with cybernic treatment can, therefore, improve and maintain gait function without damaging the motor unit and may also suppress disease progression.

Label-free morphological sub-population cytometry for sensitive phenotypic screening of heterogenous neural disease model cells

Label-free image analysis has several advantages with respect to the development of drug screening platforms. However, the evaluation of drug-responsive cells based exclusively on morphological information is challenging, especially in cases of morphologically heterogeneous cells or a small subset of drug-responsive cells. We developed a novel label-free cell sub-population analysis method called “in silico FOCUS (in silico analysis of featured-objects concentrated by anomaly discrimination from unit space)” to enable robust phenotypic screening of morphologically heterogeneous spinal and bulbar muscular atrophy (SBMA) model cells. This method with the anomaly discrimination concept can sensitively evaluate drug-responsive cells as morphologically anomalous cells through in silico cytometric analysis. As this algorithm requires only morphological information of control cells for training, no labeling or drug administration experiments are needed. The responses of SBMA model cells to dihydrotestosterone revealed that in silico FOCUS can identify the characteristics of a small sub-population with drug-responsive phenotypes to facilitate robust drug response profiling. The phenotype classification model confirmed with high accuracy the SBMA-rescuing effect of pioglitazone using morphological information alone. In silico FOCUS enables the evaluation of delicate quality transitions in cells that are difficult to profile experimentally, including primary cells or cells with no known markers.

Kennedy disease in two sisters with biallelic CAG expansions of the androgen receptor gene

We present a retrospective 21-year follow-up of two sisters with X-linked biallelic CAG expansions in the androgen receptor (AR) gene causing Kennedy disease. Two sisters inherited CAG expansions from their mother who was a carrier and their father who had Kennedy disease. Genetic testing revealed alleles comprising 43/45, and 43/43 CAG repeats in the younger and older sister, respectively. They were referred to a neurologist for further evaluation. Both reported similar symptoms with chronic backache, pain and cramps in upper- and lower extremities, and fasciculations in their faces and extremities. Neurological examination demonstrated postural hand tremor in both and EMG revealed chronic neurogenic changes. Reevaluation of the patients at ages 74 and 83 showed slight progression of clinical manifestations. As opposed to male patients, these two females showed minimal disease progression and have maintained normal level of function into old age.

Gene therapy with AR isoform 2 rescues spinal and bulbar muscular atrophy phenotype by modulating AR transcriptional activity

Spinal and bulbar muscular atrophy (SBMA) is an X-linked, adult-onset neuromuscular condition caused by an abnormal polyglutamine (polyQ) tract expansion in androgen receptor (AR) protein. SBMA is a disease with high unmet clinical need. Recent studies have shown that mutant AR-altered transcriptional activity is key to disease pathogenesis. Restoring the transcriptional dysregulation without affecting other AR critical functions holds great promise for the treatment of SBMA and other AR-related conditions; however, how this targeted approach can be achieved and translated into a clinical application remains to be understood. Here, we characterized the role of AR isoform 2, a naturally occurring variant encoding a truncated AR lacking the polyQ-harboring domain, as a regulatory switch of AR genomic functions in androgen-responsive tissues. Delivery of this isoform using a recombinant adeno-associated virus vector type 9 resulted in amelioration of the disease phenotype in SBMA mice by restoring polyQ AR-dysregulated transcriptional activity.

Molecular pathogenesis of spinal bulbar muscular atrophy (Kennedy's disease) and avenues for treatment

PURPOSE OF REVIEW

The aim of this study was to illustrate the current understanding and avenues for developing treatment in spinal and bulbar muscular atrophy (SBMA), an inherited neuromuscular disorder caused by a CAG trinucleotide repeat expansion in the androgen receptor (AR) gene.

RECENT FINDINGS

Important advances have been made in characterizing the molecular mechanism of the disease, including the disruption of protein homeostasis, intracellular trafficking and signalling pathways. Biomarkers such as MRI quantification of muscle volume and fat fraction have been used to track disease progression, and will be useful in future clinical studies. Therapies tested and under development have been based on diverse strategies, including targeting mutant AR gene expression, stability and activity, and pathways that mitigate disease toxicity.

SUMMARY

We provide an overview of the recent advances in understanding the SBMA disease mechanism and highlight efforts to translate these insights into well tolerated and effective therapy.

Late-onset hypogonadism: Clinical evidence, biological aspects and evolutionary considerations

The growing life expectancy in modern societies has raised scientific interest in identifying medical interventions to alleviate age-associated pathologies such as vascular calcification, cognitive decline, sarcopenia, osteoporosis and sexual dysfunction. Although no such single treatment has thus far been established in humans, some clinicians and patients have set their hopes on testosterone replacement therapy (TRT) as a potential "fountain of youth" for aging men. While TRT has proven effective in ameliorating distinct symptoms of late-onset hypogonadism (LOH), its safety remains to be demonstrated. Besides humans, multiple other species exhibit age-related reductions in circulating testosterone levels, raising the question whether such changes are an inherent, pathological feature of growing organismal age or rather reflect an adaptive response. In this manuscript, we apply key principles of evolutionary medicine to testosterone biology and LOH to provide a novel perspective on these two fields. Additionally, we discuss insightful data derived from the animal kingdom to illustrate the plasticity of individual testosterone trajectories across the lifespan, outline cost-benefit-considerations of TRT in LOH and highlight potential caveats of such therapies.

Effect of leuprorelin in bulbar function of spinal and bulbar muscular atrophy patients: observational study for 1 year

BACKGROUND

This study aimed to investigate the effect of androgen suppression therapy using leuprorelin focused on the bulbar function of patients with spinal and bulbar muscular atrophy (SBMA).

METHODS

Genetically confirmed SBMA patients who consented to participate in this observational study were enrolled. Leuprorelin was subcutaneously injected every 12 weeks. Videofluoroscopic swallowing study was performed at baseline and after androgen suppression therapy for 1 year. The primary outcome measures were the changes in the vallecular residue and pyriform sinus residue. The videofluoroscopic swallowing study data were analyzed and interpreted by two experienced physiatrists.

RESULTS

A total of 40 patients with SBMA were analyzed in this study. The inter-rater reliability testing showed good agreement for the pharyngeal residue (ICC = 0.84) and videofluoroscopic dysphagia scale (ICC = 0.75). The vallecular residue and pyriform sinus residue after swallowing 9 mL yogurt were significantly reduced (26.8 ± 22.6 to 14.6 ± 14.5, p < 0.001, 14.9 ± 16.9 to 7.6 ± 9.9, p < 0.001, respectively). The swallowing subscore of amyotrophic lateral sclerosis functional rating scale-revised improved after androgen suppression therapy (3.3 ± 0.5 to 3.5 ± 0.6, p = 0.041).

CONCLUSIONS

Leuprorelin significantly reduced the pharyngeal residue in patients with SBMA after 1 year of treatment without any serious adverse events and longitudinal studies are needed to confirm these results.

In silico designing of putative peptides for targeting pathological protein Htt in Huntington's disease

Huntington's disease is a neurodegenerative disease caused by CAG repeat in the first exon of HTT (Huntingtin) gene, leading to abnormal form of Htt protein containing enlarged polyglutamine strands of variable length that stick together to form aggregates and is toxic to brain causing brain damage. Complete reversal of brain damage is not possible till date but recovery may be possible by peptide therapy. The peptide-based therapy for Huntington's disease includes both poly Q peptide as well as non poly Q peptides like (QBP1)2, p42, Exendin 4, ED11, CaM, BiP, Leuprorelin peptide. The novel approach that is currently being tested in this article is the peptide-based therapy to target the mutated protein. This approach is based on the principle of preventing the aggregation of mutant Htt by blocking the potential sites responsible for protein aggregation and thereby ameliorating the disease symptoms. Herein, we have screened a variety of potential peptides that were known to prevent the protein aggregation, comparatively analyzed their binding affinity with homology modeled Htt protein, designed novel peptides based upon conservation analysis among screened potential peptides as a therapeutic agent, comparatively analyzed the therapeutic potential of novel peptides against modeled Htt protein for investigating the therapeutic prospects of Huntington's disease. We have designed a peptide for the therapy of Huntington's disease by comparing several peptides, which are already in use for Huntington's disease.

Kennedy's disease: an under-recognized motor neuron disorder

Kennedy's disease or spinal bulbar muscular atrophy is a rare, inherited and slowly progressive multisystem disease mostly manifesting with a motor neuron disease phenotype leading to disability. The slow progression, partial androgen insensitivity, electrophysiological evidence of sensory neuronopathy, and relatively spared central nervous system pathways help differentiate it from amyotrophic lateral sclerosis. To date, there is no treatment or cure with clinical care mainly focused on accurate diagnosis, symptom management, patient education, and genetic counselling.

Split hand and motor axonal hyperexcitability in spinal and bulbar muscular atrophy

OBJECTIVE

The 'split hand' sign refers to preferential wasting of the thenar and first dorsal interosseous muscles with relatively sparing of the hypothenar muscles in amyotrophic lateral sclerosis (ALS) and both cortical and spinal/peripheral excitotoxic mechanisms have been proposed. We aimed to study split hand and axonal excitability in spinal and bulbar muscular atrophy (SBMA) in which cortical motor neurons are intact.

METHODS

In 35 patients with genetically confirmed SBMA, 55 with ALS, 158 with other neuromuscular diseases and 90 normal controls; split hand was strictly determined by amplitudes of compound muscle action potentials. Nerve excitability testing of median motor axons was performed in 35 SBMA and 55 patients with ALS and 45 normal controls.

RESULTS

Split hand was as frequently found for patients with SBMA (57%) and ALS (62%), compared with disease (20%) and normal (0%) controls. Excitability testing showed that in both SBMA and ALS, strength-duration time constant was longer, and threshold changes in depolarising threshold electrotonus and superexcitability in the recovery cycle were greater than in normal controls (p<0.01).

CONCLUSIONS

Split hand is not specific to ALS and can be caused by the peripheral mechanism alone in SBMA, whereas the effect of upper motor neuron lesion cannot be excluded in ALS. Our results also suggest that SBMA and ALS share common axonal excitability changes; increased nodal persistent sodium and reduced potassium currents that may accelerate motor neuronal death and differently affect axons-innervating different muscles. Ion channel modulators could be a therapeutic option for both SBMA and ALS.

Reliability and Validity of the Korean Version of the Spinal and Bulbar Muscular Atrophy Functional Rating Scale

Background and Purpose

The Spinal and Bulbar Muscular Atrophy Functional Rating Scale (SBMAFRS) is a reliable and valid instrument for evaluating the functional status of patients with spinal and bulbar muscular atrophy (SBMA). This study aimed to validate a Korean version of the SBMAFRS in an SBMA population.

Methods

We applied the SBMAFRS to 64 SBMA patients at their regular follow-up clinical visits. The patients underwent clinical evaluations that included the 6-minute walking test (6MWT), forced vital capacity (FVC), manual muscle test, and the Penetration-Aspiration Scale (PAS). To estimate the stability of the SBMAFRS, the scale was reapplied to a subset of 31 randomly selected patients within 4 weeks of the initial test. The convergent validity was evaluated, and correlations were examined between SBMAFRS items and the muscular force, the total and subscores on the Revised Amyotrophic Lateral Sclerosis Functional Rating Scale (ALSFRS-R), FVC, PAS score, age at onset, disease duration, and 6MWT results.

Results

The internal consistency of the scale was confirmed by a high Cronbach's alpha (total raw alpha=0.867, total standardized alpha=0.863). The test-retest reliability as assessed by Spearman's rho was also high. The total score and subscores of the SBMAFRS were strongly correlated with the respective items and subscores of the ALSFRS-R, respiratory function, and the 6MWT.

Conclusions

We have performed a validation study of the Korean version of a disease-specific functional rating scale for SBMA patients. The SBMAFRS is a useful tool for clinical practice and as a potential outcome measure for Korean SBMA patients.

Disease mechanism, biomarker and therapeutics for spinal and bulbar muscular atrophy (SBMA)

Spinal and bulbar muscular atrophy (SBMA) is a hereditary neuromuscular disorder caused by CAG trinucleotide expansion in the gene encoding the androgen receptor (AR). In the central nervous system, lower motor neurons are selectively affected, whereas pathology of patients and animal models also indicates involvement of skeletal muscle including loss of fast-twitch type 2 fibres and increased slow-twitch type 1 fibres, together with a glycolytic-to-oxidative metabolic switch. Evaluation of muscle and fat using MRI, in addition to biochemical indices such as serum creatinine level, are promising biomarkers to track the disease progression. The serum level of creatinine starts to decrease before the onset of muscle weakness, followed by the emergence of hand tremor, a prodromal sign of the disease. Androgen-dependent nuclear accumulation of the polyglutamine-expanded AR is an essential step in the pathogenesis, providing therapeutic opportunities via hormonal manipulation and gene silencing with antisense oligonucleotides. Animal studies also suggest that hyperactivation of Src, alteration of autophagy and a mitochondrial deficit underlie the neuromuscular degeneration in SBMA and provide alternative therapeutic targets.

Androgen Therapy in Neurodegenerative Diseases

Neurodegenerative diseases, including Alzheimer disease (AD), Parkinson disease (PD), multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS), and Huntington disease, are characterized by the loss of neurons as well as neuronal function in multiple regions of the central and peripheral nervous systems. Several studies in animal models have shown that androgens have neuroprotective effects in the brain and stimulate axonal regeneration. The presence of neuronal androgen receptors in the peripheral and central nervous system suggests that androgen therapy might be useful in the treatment of neurodegenerative diseases. To illustrate, androgen therapy reduced inflammation, amyloid-β deposition, and cognitive impairment in patients with AD. As well, improvements in remyelination in MS have been reported; by comparison, only variable results are observed in androgen treatment of PD. In ALS, androgen administration stimulated motoneuron recovery from progressive damage and regenerated both axons and dendrites. Only a few clinical studies are available in human individuals despite the safety and low cost of androgen therapy. Clinical evaluations of the effects of androgen therapy on these devastating diseases using large populations of patients are strongly needed.

The French national protocol for Kennedy's disease (SBMA): consensus diagnostic and management recommendations

Background

Kennedy’s disease (KD), also known as spinal and bulbar muscular atrophy (SBMA), is a rare, adult-onset, X-linked recessive neuromuscular disease caused by CAG expansions in exon 1 of the androgen receptor gene (AR). The objective of the French national diagnostic and management protocol is to provide evidence-based best practice recommendations and outline an optimised care pathway for patients with KD, based on a systematic literature review and consensus multidisciplinary observations.

Results

The initial evaluation, confirmation of the diagnosis, and management should ideally take place in a tertiary referral centre for motor neuron diseases, and involve an experienced multidisciplinary team of neurologists, endocrinologists, cardiologists and allied healthcare professionals. The diagnosis should be suspected in an adult male presenting with slowly progressive lower motor neuron symptoms, typically affecting the lower limbs at onset. Bulbar involvement (dysarthria and dysphagia) is often a later manifestation of the disease. Gynecomastia is not a constant feature, but is suggestive of a suspected diagnosis, which is further supported by electromyography showing diffuse motor neuron involvement often with asymptomatic sensory changes. A suspected diagnosis is confirmed by genetic testing. The multidisciplinary assessment should ascertain extra-neurological involvement such as cardiac repolarisation abnormalities (Brugada syndrome), signs of androgen resistance, genitourinary abnormalities, endocrine and metabolic changes (glucose intolerance, hyperlipidemia). In the absence of effective disease modifying therapies, the mainstay of management is symptomatic support using rehabilitation strategies (physiotherapy and speech therapy). Nutritional evaluation by an expert dietician is essential, and enteral nutrition (gastrostomy) may be required. Respiratory management centres on the detection and treatment of bronchial obstructions, as well as screening for aspiration pneumonia (chest physiotherapy, drainage, positioning, breath stacking, mechanical insufflation-exsufflation, cough assist machnie, antibiotics). Non-invasive mechanical ventilation is seldom needed. Symptomatic pharmaceutical therapy includes pain management, endocrine and metabolic interventions. There is no evidence for androgen substitution therapy.

Conclusion

The French national Kennedy’s disease protocol provides management recommendations for patients with KD. In a low-incidence condition, sharing and integrating regional expertise, multidisciplinary experience and defining consensus best-practice recommendations is particularly important. Well-coordinated collaborative efforts will ultimately pave the way to the development of evidence-based international guidelines.

Genetic approaches to the treatment of inherited neuromuscular diseases

Inherited neuromuscular diseases are a heterogeneous group of developmental and degenerative disorders that affect motor unit function. Major challenges toward developing therapies for these diseases include heterogeneity with respect to clinical severity, age of onset and the primary cell type that is affected (e.g. motor neurons, skeletal muscle and Schwann cells). Here, we review recent progress toward the establishment of genetic therapies to treat inherited neuromuscular disorders that affect both children and adults with a focus on spinal muscular atrophy, Charcot-Marie-Tooth disease and spinal and bulbar muscular atrophy. We discuss clinical features, causative mutations and emerging approaches that are undergoing testing in preclinical models and in patients or that have received recent approval for clinical use. Many of these efforts employ antisense oligonucleotides to alter pre-mRNA splicing or diminish target gene expression and use viral vectors to replace expression of mutant genes. Finally, we discuss remaining challenges for optimizing the delivery and effectiveness of these approaches. In sum, therapeutic strategies for neuromuscular diseases have shown encouraging results, raising hope that recent strides will translate into significant clinical benefits for patients with these disorders.

Unveiling synapse pathology in spinal bulbar muscular atrophy by genome-wide transcriptome analysis of purified motor neurons derived from disease specific iPSCs

Spinal bulbar muscular atrophy (SBMA) is an adult-onset, slowly progressive motor neuron disease caused by abnormal CAG repeat expansion in the androgen receptor (AR) gene. Although ligand (testosterone)-dependent mutant AR aggregation has been shown to play important roles in motor neuronal degeneration by the analyses of transgenic mice models and in vitro cell culture models, the underlying disease mechanisms remain to be fully elucidated because of the discrepancy between model mice and SBMA patients. Thus, novel human disease models that recapitulate SBMA patients’ pathology more accurately are required for more precise pathophysiological analysis and the development of novel therapeutics. Here, we established disease specific iPSCs from four SBMA patients, and differentiated them into spinal motor neurons. To investigate motor neuron specific pathology, we purified iPSC-derived motor neurons using flow cytometry and cell sorting based on the motor neuron specific reporter, HB9^e438::Venus, and proceeded to the genome-wide transcriptome analysis by RNA sequences. The results revealed the involvement of the pathology associated with synapses, epigenetics, and endoplasmic reticulum (ER) in SBMA. Notably, we demonstrated the involvement of the neuromuscular synapse via significant upregulation of Synaptotagmin, R-Spondin2 (RSPO2), and WNT ligands in motor neurons derived from SBMA patients, which are known to be associated with neuromuscular junction (NMJ) formation and acetylcholine receptor (AChR) clustering. These aberrant gene expression in neuromuscular synapses might represent a novel therapeutic target for SBMA.

Molecular Mechanisms and Therapeutics for SBMA/Kennedy's Disease

Spinal and bulbar muscular atrophy (SBMA) is a neuromuscular disease caused by a polyglutamine (polyQ) expansion in the androgen receptor (AR). Despite the fact that the monogenic cause of SBMA has been known for nearly 3 decades, there is no effective treatment for this disease, underscoring the complexity of the pathogenic mechanisms that lead to a loss of motor neurons and muscle in SBMA patients. In the current review, we provide an overview of the system-wide clinical features of SBMA, summarize the structure and function of the AR, discuss both gain-of-function and loss-of-function mechanisms of toxicity caused by polyQ-expanded AR, and describe the cell and animal models utilized in the study of SBMA. Additionally, we summarize previously conducted clinical trials which, despite being based on positive results from preclinical studies, proved to be largely ineffective in the treatment of SBMA; nonetheless, these studies provide important insights as researchers develop the next generation of therapies.

Src inhibition attenuates polyglutamine-mediated neuromuscular degeneration in spinal and bulbar muscular atrophy

Spinal and bulbar muscular atrophy (SBMA) is a neuromuscular disease caused by an expanded CAG repeat in the androgen receptor (AR) gene. Here, we perform a comprehensive analysis of signaling pathways in a mouse model of SBMA (AR-97Q mice) utilizing a phosphoprotein assay. We measure the levels of 17 phosphorylated proteins in spinal cord and skeletal muscle of AR-97Q mice at three stages. The level of phosphorylated Src (p-Src) is markedly increased in the spinal cords and skeletal muscles of AR-97Q mice prior to the onset. Intraperitoneal administration of a Src kinase inhibitor improves the behavioral and histopathological phenotypes of the transgenic mice. We identify p130Cas as an effector molecule of Src and show that the phosphorylated p130Cas is elevated in murine and cellular models of SBMA. These results suggest that Src kinase inhibition is a potential therapy for SBMA.

Long-term Effects of Androgen Deprivation in a Patient with Spinal and Bulbar Muscular Atrophy - A Case Report with 14 Years of Follow-up

Spinal and bulbar muscular atrophy (SBMA) is a progressive hereditary neuromuscular disease caused by the testosterone-dependent accumulation of pathogenic polyglutamine-expanded androgen receptor protein. A 41-year-old man with SBMA received the androgen deprivation agent leuprorelin acetate for 7 years in clinical trials and underwent castration following the trial. Suppression of testosterone levels for 14 years resulted in a slower disease progression, as measured prospectively with quantitative measurements, than the historical control data reported in previous studies. This suggests that long-term androgen deprivation delays disease progression in SBMA.

DNA methylation inhibitor attenuates polyglutamine-induced neurodegeneration by regulating Hes5

Spinal and bulbar muscular atrophy (SBMA) is a polyglutamine-mediated neuromuscular disease caused by a CAG repeat expansion in the androgen receptor (AR) gene. While transcriptional dysregulation is known to play a critical role in the pathogenesis of SBMA, the underlying molecular pathomechanisms remain unclear. DNA methylation is a fundamental epigenetic modification that silences the transcription of various genes that have a CpG-rich promoter. Here, we showed that DNA methyltransferase 1 (Dnmt1) is highly expressed in the spinal motor neurons of an SBMA mouse model and in patients with SBMA. Both genetic Dnmt1 depletion and treatment with RG108, a DNA methylation inhibitor, ameliorated the viability of SBMA model cells. Furthermore, a continuous intracerebroventricular injection of RG108 mitigated the phenotype of SBMA mice. DNA methylation array analysis identified hairy and enhancer of split 5 (Hes5) as having a CpG island with hyper-methylation in the promoter region, and the Hes5 expression was strongly silenced in SBMA. Moreover, Hes5 over-expression rescued the SBMA cells possibly by inducing Smad2 phosphorylation. Our findings suggest DNA hyper-methylation underlies the neurodegeneration in SBMA.

Efficacy and safety of leuprorelin acetate for subjects with spinal and bulbar muscular atrophy: pooled analyses of two randomized-controlled trials

BACKGROUND

Spinal and bulbar muscular atrophy (SBMA) is an adult-onset, hereditary neuromuscular disease characterized by muscle atrophy, weakness, contraction fasciculation, and bulbar involvement. Although the causative gene, androgen receptor, has been identified, the development of novel therapeutics for SBMA is incomplete. In this study, the efficacy and safety of leuprorelin acetate administration for patients with SBMA, using the pooled data of two randomized-controlled trials, was studied.

METHODS

Two randomized double-blinded studies (JASMITT-06DB and JASMITT-11DB) were done as multicentric, investigator-initiated clinical trials in Japan. In both studies, eligible patients were randomly assigned 1:1 to receive leuprorelin acetate administration once per 12 weeks for 48 weeks. The primary endpoint was the longitudinal change of pharyngeal barium residues from the baseline data measured with videofluorographic swallowing analyses. The pooled analysis plan was decided upon after the 06B study was finished and before the 11DB study began.

RESULTS

The primary endpoint difference between the leuprorelin group and the placebo group was pharyngeal barium residue after initial swallowing, - 4.12% (95% CI, - 8.40-0.15; p = 0.058). The primary endpoint of this study does not reach significant results, although inter-group differences of pharyngeal barium residues after the initial swallowing indicated that leuprorelin acetate may be effective at each assessment point in both study groups.

CONCLUSIONS

The efficacy of leuprorelin acetate for patients with SBMA was statistically similar in two randomized-controlled trials, and suggested that leuprorelin acetate may be effective and safe. Further investigations are needed to clarify the promising efficacy of the drug.

Impaired Nuclear Export of Polyglutamine-Expanded Androgen Receptor in Spinal and Bulbar Muscular Atrophy

Spinal and bulbar muscular atrophy (SBMA) is a neuromuscular disease caused by polyglutamine (polyQ) expansion in the androgen receptor (AR). Prior studies have highlighted the importance of AR nuclear localization in SBMA pathogenesis; therefore, in this study, we sought to determine the role of AR nuclear export in the pathological manifestations of SBMA. We demonstrate here that the nuclear export of polyQ-expanded AR is impaired, even prior to the formation of intranuclear inclusions of aggregated AR. Additionally, we find that promoting AR export with an exogenous nuclear export signal substantially reduces its aggregation and blocks hormone-induced toxicity. Moreover, we show that these protective effects are conferred by destabilization of the mutant protein due to an increase in proteasomal degradation of the cytoplasmic AR. Despite a growing body of evidence that global disruption of nucleo/cytoplasmic transport occurs in ALS and HD, our data suggest that no such global disruption occurs in models of SBMA; rather, AR-specific mechanisms, including reduced phosphorylation at Serine 650, are likely responsible for the impaired nuclear export of polyQ-expanded AR.

Safety, tolerability, and preliminary efficacy of an IGF-1 mimetic in patients with spinal and bulbar muscular atrophy: a randomised, placebo-controlled trial

BACKGROUND

Spinal and bulbar muscular atrophy is an X-linked neuromuscular disease caused by CAG repeat expansion in the androgen receptor gene. Patients with this disease have low concentrations of insulin-like growth factor-1 (IGF-1), and studies of overexpression and administration of IGF-1 showed benefit in a transgenic model; thus the IGF-1 pathway presents as a potential treatment target. We assessed safety, tolerability, and preliminary efficacy of BVS857, an IGF-1 mimetic, in patients with spinal and bulbar muscular atrophy.

METHODS

In this randomised, double-blind, placebo-controlled trial, we recruited patients from neuromuscular centres in Denmark (Copenhagen), Germany (Ulm), Italy (Padova), and three sites within the USA (Bethesda, MD; Irvine, CA; and Columbus, OH). Eligible patients were 18 years or older with a confirmed genetic diagnosis of spinal and bulbar muscular atrophy, were ambulatory, had symptomatic weakness, and had serum IGF-1 concentrations of 170 ng/mL or lower. Patients were randomly assigned (2:1) to study drug or placebo by a number scheme. Patients, investigators, and study personnel were masked to treatment assignment. After a safety and tolerability assessment with eight patients, BVS857 was administered once a week (0·06 mg/kg intravenously) for 12 weeks. Primary outcome measures were safety, tolerability, and the effects of BVS857 on thigh muscle volume (TMV) measured by MRI. The ratio of TMV at day 85 to baseline was analysed with ANCOVA per protocol. Secondary outcomes of muscle strength and function were measured with the Adult Myopathy Assessment Tool, lean body mass through dual energy x-ray absorptiometry, and BVS857 pharmacokinetics. This trial was registered with ClinicalTrials.gov, NCT02024932.

FINDINGS

31 patients were assessed for eligibility, 27 of whom were randomly assigned to either BVS857 treatment (n=18) or placebo (n=9), and 24 were included in the preliminary efficacy analysis (BVS857 group, n=15; placebo group, n=9). BVS857 was generally safe with no serious adverse events. No significant differences were found in adverse events between the BVS857 and placebo groups. Immunogenicity was detected in 13 (72%) of 18 patients in the BVS857 group, including crossreacting antibodies with neutralising capacity to endogenous IGF-1 in five patients. TMV decreased from baseline to day 85 in the placebo group (-3·4% [-110 cm³]) but not in the BVS857 group (0% [2 cm³]). A significant difference in change in TMV was observed in the BVS857 group versus the placebo group (geometric-mean ratio 1·04 [90% CI 1·01-1·07]; p=0·02). There were no differences between groups in measures of muscle strength and function.

INTERPRETATION

TMV remained stable in patients with spinal and bulbar muscular atrophy after being given BVS857 for 12 weeks. The intervention was associated with high incidence of immunogenicity and did not improve muscle strength or function. Additional studies might be needed to assess the efficacy of activating the IGF-1 pathway in this disease.

FUNDING

Novartis Pharmaceuticals and the US National Institutes of Health.

Biomarkers of Spinal and Bulbar Muscle Atrophy (SBMA): A Comprehensive Review

Spinal and bulbar muscular atrophy (SBMA), also known as Kennedy's disease, is a rare, X-linked, late onset neuromuscular disorder. The disease is caused by a CAG trinucleotide repeat expansion in the first exon of the androgen receptor gene. It is characterized by slowly progressive lower motor neurons degeneration, primary myopathy and widespread multisystem involvement. Respiratory involvement is rare, and the condition is associated with a normal life expectancy. Despite a plethora of therapeutic studies in mouse models, no effective disease-modifying therapy has been licensed for clinical use to date. The development of sensitive monitoring markers for the particularly slowly progressing pathology of SBMA is urgently required to aid future clinical trials. A small number of outcome measures have been proposed recently, including promising biochemical markers, which show correlation with clinical disability and disease-stage and progression. Nevertheless, a paucity of SBMA-specific biomarker studies persists, delaying the development of monitoring markers for pharmaceutical trials. Collaborative efforts through international consortia and multicenter registries are likely to contribute to the characterization of the natural history of the condition, the establishment of disease-specific biomarker panels and ultimately contribute to the development of disease-modifying drugs.

Study protocol for the MEXiletine hydrochloride administration trial: a placebo-controlled, randomised, double-blind, multicentre, crossover study of its efficacy and safety in spinal and bulbar muscular atrophy (MEXPRESS)

INTRODUCTION

Spinal and bulbar muscular atrophy (SBMA) is a slowly progressive neuromuscular disease. Cold exposure often leads to worsening of motor symptoms including paresis. Although mexiletine hydrochloride administration has been shown to be effective for the treatment of several muscular diseases, its effectiveness in SBMA has not been validated to date. The trial will test it as a symptomatic drug for cold paresis. This study is the first trial to evaluate the efficacy and safety of mexiletine hydrochloride administration in patients with SBMA.

METHODS AND ANALYSIS

A placebo-controlled, randomised, double-blind, multicentre, crossover clinical trial will be conducted to assess the safety and efficacy of mexiletine hydrochloride in patients with SBMA. The eligible patients will be assigned randomly in a 1:1 ratio to two groups in a double-blind manner. Participants will take mexiletine hydrochloride (300 mg/day) or a placebo orally three times a day for 4 weeks (period 1). After a 1-week washout period, participants will take the other drug for 4 weeks (period 2). The primary endpoint is the difference in distal latencies between room temperature and cold exposure conditions.

ETHICS AND DISSEMINATION

This study will be conducted in compliance with the Helsinki Declaration and the Ethical Guidelines for Medical and Health Research Involving Human Subjects by the Japanese government and has been approved by the ethics committee of Nagoya University Graduate School of Medicine, as a central institutional review board, and by each facility. The results will be disseminated in peer-reviewed journals and at scientific conferences.

TRIAL REGISTRATION NUMBER

UMIN000026150; Pre-results.

Selective modulation of the androgen receptor AF2 domain rescues degeneration in spinal bulbar muscular atrophy

Spinal bulbar muscular atrophy (SBMA) is a motor neuron disease caused by toxic gain of function of the androgen receptor (AR). Previously, we found that co-regulator binding through the activation function-2 (AF2) domain of AR is essential for pathogenesis, suggesting that AF2 may be a potential drug target for selective modulation of toxic AR activity. We screened previously identified AF2 modulators for their ability to rescue toxicity in a Drosophila model of SBMA. We identified two compounds, tolfenamic acid (TA) and 1-[2-(4-methylphenoxy)ethyl]-2-[(2-phenoxyethyl)sulfanyl]-1H-benzimidazole (MEPB), as top candidates for rescuing lethality, locomotor function and neuromuscular junction defects in SBMA flies. Pharmacokinetic analyses in mice revealed a more favorable bioavailability and tissue retention of MEPB compared with TA in muscle, brain and spinal cord. In a preclinical trial in a new mouse model of SBMA, MEPB treatment yielded a dose-dependent rescue from loss of body weight, rotarod activity and grip strength. In addition, MEPB ameliorated neuronal loss, neurogenic atrophy and testicular atrophy, validating AF2 modulation as a potent androgen-sparing strategy for SBMA therapy.

From gene to therapy in spinal and bulbar muscular atrophy: Are we there yet?

Abnormal polyglutamine expansions in the androgen receptor (AR) cause a muscular condition, known as Kennedy's disease or spinal and bulbar muscular atrophy (SBMA). The disease is transmitted in an X-linked fashion and is clinically characterized by weakness, atrophy and fasciculations of the limb and bulbar muscles as a result of a toxic gain-of-function of the mutant protein. Notably, affected males also show signs of androgen insensitivity, such as gynaecomastia and reduced fertility. The characterization of the natural history of the disease, the increasing understanding of the mechanism of pathogenesis and the elucidation of the functions of normal and mutant AR have offered a momentum for developing a rational therapeutic strategy for this disease. In this special issue on androgens and AR functions, we will review the molecular, biochemical, and cellular mechanisms underlying the pathogenesis of SBMA. We will discuss recent advances on therapeutic approaches and opportunities for this yet incurable disease, ranging from androgen deprivation, to gene silencing, to an expanding repertoire of peripheral targets, including muscle. With the advancement of these strategies into the clinic, it can be reasonably anticipated that the landscape of treatment options for SBMA and other neuromuscular conditions will change rapidly in the near future.

[An early history of Japanese amyotrophic lateral sclerosis (ALS)-related diseases and the current development]

The present review focuses an early history of Japanese amyotrophic lateral sclerosis (ALS)-related diseases and the current development. In relation to foreign previous reports, five topics are introduced and discussed on ALS with dementia, ALS/Parkinsonism dementia complex (ALS/PDC), familial ALS (FALS), spinal bulbar muscular atrophy (SBMA), and multisystem involvement especially in cerebellar system of ALS including ALS/SCA (spinocerebellar ataxia) crossroad mutation Asidan. This review found the great contribution of Japanese reports on the above five topics, and confirmed the great development of ALS-related diseases over the past 120 years.