Acetylation turns leucine into a drug by membrane transporter switching

ORMDL mislocalization by impaired autophagy in Niemann-Pick type C disease leads to increased de novo sphingolipid biosynthesis

Niemann-Pick type C1 (NPC1) disease is a rare neurodegenerative cholesterol and sphingolipid storage disorder primarily due to mutations in the cholesterol-trafficking protein NPC1. In addition to catabolic-derived sphingolipids, NPC1 dysfunction also leads to an increase in de novo sphingolipid biosynthesis, yet little is known about the cellular mechanism involved. Although deletion of NPC1 or inhibition of the NPC1 sterol binding domain enhanced de novo sphingolipid biosynthesis, surprisingly levels of the ORMDLs, the regulatory subunits of serine palmitoyltransferase (SPT), the rate-limiting step in sphingolipid biosynthesis, were also greatly increased. Nevertheless, less ORMDL was bound in the SPT-ORMDL complex despite elevated ceramide levels. Instead, ORMDL colocalized with p62, the selective autophagy receptor, and accumulated in stalled autophagosomes due to defective autophagy in NPC1 disease cells. Restoration of autophagic flux with N-acetyl-L-leucine in NPC1 deleted cells decreased ORMDL accumulation in autophagosomes and reduced de novo sphingolipid biosynthesis and their accumulation. This study revealed a previously unknown link between de novo sphingolipid biosynthesis, ORMDL, and autophagic defects present in NCP1 disease. In addition, we provide further evidence and mechanistic insight for the beneficial role of N-acetyl-L-leucine treatment for NPC1 disease which is presently awaiting approval from the Food and Drug Administration and the European Medicines Agency.

[What's behind cerebellar dizziness? - News on diagnosis and therapy]

Vertigo and dizziness comprise a multisensory and multidisciplinary syndrome of different etiologies. The term "cerebellar vertigo and dizziness" comprises a heterogenous group of disorders with clinical signs of cerebellar dysfunction and is caused by vestibulo-cerebellar, vestibulo-spinal or cerebellar systems. About 10 % of patients in an outpatient clinic for vertigo and balance disorders suffer from cerebellar vertigo and dizziness. According to the course of the symptoms, one can considers 3 types: permanent complaints, recurrent episodes of vertigo and balance disorders, or an acute onset of complaints. The most common diagnoses in patients with cerebellar vertigo and dizziness were as follows: degenerative disease, hereditary forms and acquired forms. In a subgroup of patients with cerebellar vertigo, central cerebellar oculomotor dysfunction is indeed the only clinical correlate of the described symptoms. 81 % of patients with cerebellar vertigo suffer from permanent, persistent vertigo and dizziness, 31 % from vertigo attacks, and 21 % from both. Typical clinical cerebellar signs, including gait and limb ataxia or dysarthria, were found less frequently. Key to diagnosis is a focused history as well as a thorough clinical examination with particular attention to oculomotor function. Regarding oculomotor examination, the most common findings were saccadic smooth pursuit, gaze-evoked nystagmus, provocation nystagmus, rebound nystagmus, central fixation nystagmus, most commonly downbeat nystagmus, and disturbances of saccades. Thus, oculomotor examination is very sensitive in diagnosing cerebellar vertigo and dizziness, but not specific in distinguishing different etiologies. Laboratory examinations using posturography and a standardized gait analysis can support the diagnosis, but also help to estimate the risk of falls and to quantify the course and possible symptomatic treatment effects. Patients with cerebellar vertigo and dizziness should receive multimodal treatment.

Trial of N-Acetyl-l-Leucine in Niemann-Pick Disease Type C

BACKGROUND

Niemann-Pick disease type C is a rare lysosomal storage disorder. We evaluated the safety and efficacy of N-acetyl-l-leucine (NALL), an agent that potentially ameliorates lysosomal and metabolic dysfunction, for the treatment of Niemann-Pick disease type C.

METHODS

In this double-blind, placebo-controlled, crossover trial, we randomly assigned patients 4 years of age or older with genetically confirmed Niemann-Pick disease type C in a 1:1 ratio to receive NALL for 12 weeks, followed by placebo for 12 weeks, or to receive placebo for 12 weeks, followed by NALL for 12 weeks. NALL or matching placebo was administered orally two to three times per day, with patients 4 to 12 years of age receiving weight-based doses (2 to 4 g per day) and those 13 years of age or older receiving a dose of 4 g per day. The primary end point was the total score on the Scale for the Assessment and Rating of Ataxia (SARA; range, 0 to 40, with lower scores indicating better neurologic status). Secondary end points included scores on the Clinical Global Impression of Improvement, the Spinocerebellar Ataxia Functional Index, and the Modified Disability Rating Scale. Crossover data from the two 12-week periods in each group were included in the comparisons of NALL with placebo.

RESULTS

A total of 60 patients 5 to 67 years of age were enrolled. The mean baseline SARA total scores used in the primary analysis were 15.88 before receipt of the first dose of NALL (60 patients) and 15.68 before receipt of the first dose of placebo (59 patients; 1 patient never received placebo). The mean (±SD) change from baseline in the SARA total score was -1.97±2.43 points after 12 weeks of receiving NALL and -0.60±2.39 points after 12 weeks of receiving placebo (least-squares mean difference, -1.28 points; 95% confidence interval, -1.91 to -0.65; P<0.001). The results for the secondary end points were generally supportive of the findings in the primary analysis, but these were not adjusted for multiple comparisons. The incidence of adverse events was similar with NALL and placebo, and no treatment-related serious adverse events occurred.

CONCLUSIONS

Among patients with Niemann-Pick disease type C, treatment with NALL for 12 weeks led to better neurologic status than placebo. A longer period is needed to determine the long-term effects of this agent in patients with Niemann-Pick disease type C. (Funded by IntraBio; ClinicalTrials.gov number, NCT05163288; EudraCT number, 2021-005356-10.).

Secretion of acetylated amino acids by drug-induced cancer cells: perspectives on metabolic-epigenetic alterations

The emerging understanding of the super-complex and heterogeneous nature of tumor is well supported by metabolic reprogramming, leading survival advantages. Metabolic reprogramming contributes to tumor responsiveness and resistance to various antitumor drugs. Among the numerous adaptations made by cancer cells in response to drug-induced perturbations, key metabolic alterations involving amino acids and acetylated derivatives of amino acids have received special attention. Considering these implications discussed, targeting cancer-associated metabolic pathways, particularly those involving acetylated amino acids, emerges as an important avenue in the pursuit of combinatorial anticancer strategies. As a result, the introduction of mimetic acetylated amino acids represents a promising new class of inhibitors that could be used alongside traditional chemotherapy agents.

Inborn Errors of Metabolism with Ataxia: Current and Future Treatment Options

A number of hereditary ataxias are caused by inborn errors of metabolism (IEM), most of which are highly heterogeneous in their clinical presentation. Prompt diagnosis is important because disease-specific therapies may be available. In this review, we offer a comprehensive overview of metabolic ataxias summarized by disease, highlighting novel clinical trials and emerging therapies with a particular emphasis on first-in-human gene therapies. We present disease-specific treatments if they exist and review the current evidence for symptomatic treatments of these highly heterogeneous diseases (where cerebellar ataxia is part of their phenotype) that aim to improve the disease burden and enhance quality of life. In general, a multimodal and holistic approach to the treatment of cerebellar ataxia, irrespective of etiology, is necessary to offer the best medical care. Physical therapy and speech and occupational therapy are obligatory. Genetic counseling is essential for making informed decisions about family planning.

Advances in cerebellar disorders: pre-clinical models, therapeutic targets, and challenges

INTRODUCTION

Cerebellar ataxias (CAs) represent neurological disorders with multiple etiologies and a high phenotypic variability. Despite progress in the understanding of pathogenesis, few therapies are available so far. Closing the loop between preclinical studies and therapeutic trials is important, given the impact of CAs upon patients' health and the roles of the cerebellum in multiple domains. Because of a rapid advance in research on CAs, it is necessary to summarize the main findings and discuss future directions.

AREAS COVERED

We focus our discussion on preclinical models, cerebellar reserve, the therapeutic management of CAs, and suitable surrogate markers. We searched Web of Science and PubMed using keywords relevant to cerebellar diseases, therapy, and preclinical models.

EXPERT OPINION

There are many symptomatic and/or disease-modifying therapeutic approaches under investigation. For therapy development, preclinical studies, standardization of disease evaluation, safety assessment, and demonstration of clinical improvements are essential. Stage of the disease and the level of the cerebellar reserve determine the goals of the therapy. Deficits in multiple categories and heterogeneity of CAs may require disease-, stage-, and symptom-specific therapies. More research is needed to clarify how therapies targeting the cerebellum influence both basal ganglia and the cerebral cortex, poorly explored domains in CAs.

d-Glucose- and d-mannose-based antimetabolites. Part 4: Facile synthesis of mono- and di-acetates of 2-deoxy-d-glucose prodrugs as potentially useful antimetabolites

2-Deoxy-d-glucose (2-DG), a compound known to interfere with d-glucose and d-mannose metabolism, has been tested as a potential anticancer and antiviral agent. Preclinical and clinical studies focused on 2-DG have highlighted several limitations related to 2-DG drug-like properties, such as poor pharmacokinetic properties. To overcome this problem, we proposed design and synthesis of novel 2-DG prodrugs that subsequently could be tested using a variety of biochemical and molecular methods. We narrowed here our focus to esters of 2-DG as potential prodrugs based on the hypothesis that ubiquitous esterases will regenerate 2-DG, leading to increased circulation time of drug and adequate organ and tumor penetration. Testing this hypothesis in vitro and, especially, in vivo requires significant amounts of respective pure mono- and previously unknown di-acetylated water-soluble derivatives of 2-DG. Development of their efficient and practical method of synthesis was imperative. We describe novel facile and scalable syntheses of seven selectively acetylated water-soluble derivatives of 2-DG and present a detailed ¹H and ¹³C NMR analysis of all final products. X-ray diffraction analysis has been performed for compound WP1122 that was selected for detailed preclinical and subsequent clinical evaluation as potential anticancer or antiviral agent.

N-acetyl-L-leucine for Niemann-Pick type C: a multinational double-blind randomized placebo-controlled crossover study

BACKGROUND

Niemann-Pick disease type C (NPC) is a rare autosomal recessive neurodegenerative lysosomal disease characterized by multiple symptoms such as progressive cerebellar ataxia and cognitive decline. The modified amino acid N-acetyl-leucine has been associated with positive symptomatic and neuroprotective, disease-modifying effects in various studies, including animal models of NPC, observational clinical case studies, and a multinational, rater-blinded phase IIb clinical trial. Here, we describe the development of a study protocol (Sponsor Code "IB1001-301") for the chronic treatment of symptoms in adult and pediatric patients with NPC.

METHODS

This multinational double-blind randomized placebo-controlled crossover phase III study will enroll patients with a genetically confirmed diagnosis of NPC patients aged 4 years and older across 16 trial sites. Patients are assessed during a baseline period and then randomized (1:1) to one of two treatment sequences: IB1001 followed by placebo or vice versa. Each sequence consists of a 12-week treatment period. The primary efficacy endpoint is based on the Scale for the Assessment and Rating of Ataxia, and secondary outcomes include cerebellar functional rating scales, clinical global impression, and quality of life assessments.

DISCUSSION

Pre-clinical as well as observational and phase IIb clinical trials have previously demonstrated that IB1001 rapidly improved symptoms, functioning, and quality of life for pediatric and adult NPC patients and is safe and well tolerated. In this placebo-controlled cross-over trial, the risk/benefit profile of IB1001 for NPC will be evaluated. It will also give information about the applicability of IB1001 as a therapeutic paradigm for other rare and common neurological disorders.

TRIAL REGISTRATIONS

The trial (IB1001-301) has been registered at www.

CLINICALTRIALS

gov (NCT05163288) and www.clinicaltrialsregister.eu (EudraCT: 2021-005356-10). Registered on 20 December 2021.

Current advancements in therapy for Niemann-Pick disease: progress and pitfalls

INTRODUCTION

Niemann-Pick disease type C (NPC) is a rare, autosomal recessive, lysosomal storage disorder. To combat the progressive neurodegeneration in NPC, disease-modifying treatment needs to be introduced early in the course of the disease. The only approved, disease-modifying treatment is a substrate-reduction treatment, miglustat. Given miglustat's limited efficacy, new compounds are under development, including gene therapy; however, many are still far from clinical use. Moreover, the phenotypic heterogeneity and variable course of the disease can impede the development and approval of new agents.

AREAS COVERED

Here, we offer an expert review of these therapeutic candidates, with a broad scope not only on the main pharmacotherapies, but also on experimental approaches, gene therapies, and symptomatic strategies. The National Institute of Health (NIH) database PubMed has been searched for the combination of the words 'Niemann-Pick type C'+ 'treatment' or 'therapy' or 'trial.' The website clinicaltrials.gov has also been consulted.

EXPERT OPINION

We conclude a combination of treatment strategies should be sought, with a holistic approach, to improve the quality of life of affected individuals and their families.

Efficacy and Safety of N-Acetyl-l-Leucine in Children and Adults With GM2 Gangliosidoses

BACKGROUND AND OBJECTIVES

GM2 gangliosidoses (Tay-Sachs and Sandhoff diseases) are rare, autosomal recessive, neurodegenerative diseases with no available symptomatic or disease-modifying treatments. This clinical trial investigated N-acetyl-l-leucine (NALL), an orally administered, modified amino acid in pediatric (≥6 years) and adult patients with GM2 gangliosidoses.

METHODS

In this phase IIb, multinational, open-label, rater-blinded study (IB1001-202), male and female patients aged ≥6 years with a genetically confirmed diagnosis of GM2 gangliosidoses received orally administered NALL for a 6-week treatment period (4 g/d in patients ≥13 years, weight-tiered doses for patients 6-12 years), followed by a 6-week posttreatment washout period. For the primary Clinical Impression of Change in Severity analysis, patient performance on a predetermined primary anchor test (the 8-Meter Walk Test or the 9-Hole Peg Test) at baseline, after 6 weeks on NALL, and again after a 6-week washout period was videoed and evaluated centrally by blinded raters. Secondary outcomes included assessments of ataxia, clinical global impression, and quality of life.

RESULTS

Thirty patients between the age of 6 and 55 years were enrolled. Twenty-nine had an on-treatment assessment and were included in the primary modified intention-to-treat analysis. The study met its CI-CS primary end point (mean difference 0.71, SD = 2.09, 90% CI 0.00, 1.50, p = 0.039), as well as secondary measures of ataxia and global impression. NALL was safe and well tolerated, with no serious adverse reactions.

DISCUSSION

Treatment with NALL was associated with statistically significant and clinically relevant changes in functioning and quality of life in patients with GM2 gangliosidosis. NALL was safe and well tolerated, contributing to an overall favorable risk:benefit profile. NALL is a promising, easily administered (oral) therapeutic option for these rare, debilitating diseases with immense unmet medical needs.

TRIAL REGISTRATION INFORMATION

The trial is registered with ClinicalTrials.gov (NCT03759665; registered on November 30, 2018), EudraCT (2018-004406-25), and DRKS (DRKS00017539). The first patient was enrolled on June 7, 2019.

CLASSIFICATION OF EVIDENCE

This study provides Class IV evidence that NALL improves outcomes for patients with GM2 gangliosidoses.

Urine Metabolome Dynamics Discriminate Influenza Vaccination Response

Influenza represents a major and ongoing public health hazard. Current collaborative efforts are aimed toward creating a universal flu vaccine with the goals of both improving responses to vaccination and increasing the breadth of protection against multiple strains and clades from a single vaccine. As an intermediate step toward these goals, the current work is focused on evaluating the systemic host response to vaccination in both normal and high-risk populations, such as the obese and geriatric populations, which have been linked to poor responses to vaccination. We therefore employed a metabolomics approach using a time-course (n = 5 time points) of the response to human vaccination against influenza from the time before vaccination (pre) to 90 days following vaccination. We analyzed the urinary profiles of a cohort of subjects (n = 179) designed to evenly sample across age, sex, BMI, and other demographic factors, stratifying their responses to vaccination as “High”, “Low”, or “None” based on the seroconversion measured by hemagglutination inhibition assay (HAI) from plasma samples at day 28 post-vaccination. Overall, we putatively identified 15,903 distinct, named, small-molecule structures (4473 at 10% FDR) among the 895 samples analyzed, with the aim of identifying metabolite correlates of the vaccine response, as well as prognostic and diagnostic markers from the periods before and after vaccination, respectively. Notably, we found that the metabolic profiles could unbiasedly separate the high-risk High-responders from the high-risk None-responders (obese/geriatric) within 3 days post-vaccination. The purine metabolites Guanine and Hypoxanthine were negatively associated with high seroconversion (p = 0.0032, p < 0.0001, respectively), while Acetyl-Leucine and 5-Aminovaleric acid were positively associated. Further changes in Cystine, Glutamic acid, Kynurenine and other metabolites implicated early oxidative stress (3 days) after vaccination as a hallmark of the High-responders. Ongoing efforts are aimed toward validating these putative markers using a ferret model of influenza infection, as well as an independent cohort of human seasonal vaccination and human challenge studies with live virus.

Acetyl-DL-leucine in cerebellar ataxia ([18F]-FDG-PET study): how does a cerebellar disorder influence cortical sensorimotor networks?

OBJECTIVE

The aim of the study was to deepen our insights into central compensatory processes of brain networks in patients with cerebellar ataxia (CA) before and with treatment with acetyl-DL-leucine (AL) by means of resting-state [¹⁸F]-FDG-PET brain imaging.

METHODS

Retrospective analyses of [¹⁸F]-FDG-PET data in 22 patients with CA (with vestibular and ocular motor disturbances) of different etiologies who were scanned before (PET A) and on AL treatment (PET B). Group subtraction analyses, e.g., for responders and non-responders, comparisons with healthy controls and correlation analyses of regional cerebral glucose metabolism (rCGM) with symptom duration, ataxia (SARA) and quality of life (QoL) scores were calculated.

RESULTS

Prior to treatment rCGM was consistently downregulated at the cerebellar level and increased in multisensory cortical areas, e.g., somatosensory, primary and secondary visual (including V5, precuneus), secondary vestibular (temporal gyrus, anterior insula), and premotor/supplementary motor areas. With AL (PET B vs. A) cerebellar hypometabolism was deepened and sensorimotor hypermetabolism increased only in responders with clinical benefit, but not for the non-responders and the whole CA group. A positive correlation of ataxia improvement with rCGM was found in visual and vestibular cortices, a negative correlation in cerebellar and brainstem areas. QoL showed a positive correlation with rCGM in the cerebellum and symptom duration in premotor and somatosensory areas.

CONCLUSIONS

Central compensatory processes in CA mainly involve multisensory visual, vestibular, and somatosensory networks as well as premotor/primary motor areas at the cortical level. The enhanced divergence of cortical sensorimotor up- and cerebellar downregulation with AL in responders could reflect amplification of inhibitory cerebellar mechanisms.