Annual severity increment score as a tool for stratifying patients with Niemann-Pick disease type C and for recruitment to clinical trials

Blood metabolites and chronic kidney disease: a Mendelian randomization study

BACKGROUND

Human blood metabolites have demonstrated close associations with chronic kidney disease (CKD) in observational studies. Nonetheless, the causal relationship between metabolites and CKD is still unclear. This study aimed to assess the associations between metabolites and CKD risk.

METHODS

We applied a two-sample Mendelian randomization (MR) analysis to evaluate relationships between 1400 blood metabolites and eight phenotypes (outcomes) (CKD, estimated glomerular filtration rate(eGFR), urine albumin to creatinine ratio, rapid progress to CKD, rapid decline of eGFR, membranous nephropathy, immunoglobulin A nephropathy, and diabetic nephropathy). The inverse variance weighted (IVW), MR-Egger, and weighted median were used to investigate the causal relationship. Sensitivity analyses were performed with Cochran's Q, MR-Egger intercept, MR-PRESSO Global test, and leave-one-out analysis. Bonferroni correction was used to test the strength of the causal relationship.

RESULTS

Through the MR analysis of 1400 metabolites and eight clinical phenotypes, a total of 48 metabolites were found to be associated with various outcomes. Among them, N-acetylleucine (OR = 0.923, 95%CI: 0.89-0.957, PIVW = 1.450 × 10-5) has a strong causal relationship with lower risk of CKD after the Bonferroni-corrected test, whereas Glycine to alanine ratio has a strong causal relationship with higher risk of CKD (OR = 1.106, 95%CI: 1.063-1.151, PIVW = 5.850 × 10-7). No horizontal pleiotropy and heterogeneity were detected.

CONCLUSION

Our study offers groundbreaking insights into the integration of metabolomics and genomics to reveal the pathogenesis of and therapeutic strategies for CKD. It underscores 48 metabolites as potential causal candidates, meriting further investigation.

Efficacy and safety of N-acetyl-L-leucine in patients with ataxia telangiectasia: A randomized, double-blind, placebo-controlled, crossover clinical trial

BACKGROUND

Ataxia telangiectasia (AT) is an autosomal recessive multisystem disorder. Most patients have progressive cerebellar ataxia, oculocutaneous telangiectasia, frequent pulmonary infection, and an increased risk of malignancies. Although N-acetyl-dl-leucine (ADLL) has shown some efficacy in patients with AT, its more pharmacologically active enantiomer, N-acetyl-l-leucine (NALL), has just recently been investigated in ataxic individuals. The current study assessed the efficacy of NALL in patients with AT.

METHODS

This 2 × 2 crossover, double-blind, randomized clinical trial was conducted on 20 patients with AT. After excluding four patients, 16 subjects (eight females, eight males; mean age 9.8 ± 3.5 years) with a definitive genetic diagnosis of AT were randomly assigned to one of two study groups, with one group receiving 1-4 g/day NALL or a placebo for six weeks. Subjects then had a 4-week washout before crossing over to the other treatment for an additional six weeks. The Spinocerebellar Ataxia Functional Index (SCAFI) and the Scale for Assessment and Rating of Ataxia (SARA) score assessed patients' motor function. Quality of life (QOL) was evaluated by a specialist using the PedsQL questionnaire. Fasting blood samples were taken from all subjects before and after each intervention to determine potential side effects.

RESULTS

Although patients' nausea and constipation were improved, the results failed to reveal any significant benefits of NALL treatment on ataxia symptoms. NALL treatment had no significant effects on SARA, SCAFI-9HPT (9-hole peg test) nondominant, SCAFI-9HPT dominant, or SCAFI-8WMT (8 m walking time) (p > 0.05). Our patient's Physical Health score in Child self-report and Parent proxy-report did not significantly change in the treatment group compared to the placebo (p > 0.05). Furthermore, there were no significant changes in energy and macronutrient intake after NALL treatment. None of the volunteers reported serious or moderate side effects.

CONCLUSIONS

To the best of our knowledge, this was the first placebo-controlled, randomized clinical trial exploring NALL's potential effects for treating AT. Despite improvements in some symptomss, NALL intervention failed to improve motor function significantly. However, patients' nausea and constipation were improved by NALL, which can be a relevant benefit clinically.

Sterol O-Acyltransferase 1 (SOAT1): A Genetic Modifier of Niemann-Pick Disease, Type C1

Niemann-Pick disease type C1 (NPC1) is a lysosomal disorder due to impaired intracellular cholesterol transport out of the endolysosomal compartment.. Marked heterogeneity has been observed in individuals with the same NPC1 genotype, thus suggesting a significant effect of modifier genes. Prior work demonstrated that decreased SOAT1 activity decreased disease severity in an NPC1 mouse model. Thus, we hypothesized that a polymorphism associated with decreased SOAT1 expression might influence the NPC1 phenotype. Phenotyping and genomic sequencing of 117 individuals with NPC1 was performed as part of a Natural History trial. Phenotyping included determination of disease severity and disease burden. Significant clinical heterogeneity is present in individuals homozygous for the NPC1I1061T variant and in siblings. Analysis of the SOAT1 polymorphism, rs1044925 (A>C), showed a significant association of the C-allele with earlier age of neurological onset. The C-allele may be associated with a higher Annualized Severity Index Score as well as increased frequency of liver disease and seizures. A polymorphism associated with decreased expression of SOAT1 appears to be a genetic modifier of the NPC1 phenotype. This finding is consistent with prior data showing decreased phenotypic severity in Npc1-/-:Soat1-/- mice and supports efforts to investigate the potential of SOAT1 inhibitors as a potential therapy for NPC1.

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.).

Elevated cerebrospinal fluid ubiquitin C-terminal hydrolase-L1 levels correlate with phenotypic severity and therapeutic response in Niemann-Pick disease, type C1

BACKGROUND

Niemann-Pick disease, type C1 (NPC1) is an ultrarare, recessive disorder due to pathological variants of NPC1. The NPC1 phenotype is characterized by progressive cerebellar ataxia and cognitive impairment. Although classically a childhood/adolescent disease, NPC1 is heterogeneous with respect to the age of onset of neurological signs and symptoms. While miglustat has shown to be clinically effective, there are currently no FDA approved drugs to treat NPC1. Identification and characterization of biomarkers may provide tools to facilitate therapeutic trials. Ubiquitin C-terminal hydrolase-L1 (UCHL1) is a protein which is highly expressed by neurons and is a biomarker of neuronal damage. We thus measured cerebrospinal fluid (CSF) levels of UCHL1 in individuals with NPC1.

METHODS

CSF levels of UCHL1 were measured using a Quanterix Neuroplex 4 assay in 94 individuals with NPC1 and 35 age-appropriate comparison samples. Cross-sectional and longitudinal CSF UCHL1 levels were then evaluated for correlation with phenotypic measures and treatment status.

RESULTS

CSF UCHL1 levels were markedly elevated (3.3-fold) in individuals with NPC1 relative to comparison samples. The CSF UCHL1 levels showed statistically significant (adj p < 0.0001), moderate, positive correlations with both the 17- and 5-domain NPC Neurological Severity Scores and the Annual Severity Increment Scores. Miglustat treatment significantly decreased (adj p < 0.0001) CSF UCHL1 levels by 30% (95% CI 17-40%).

CONCLUSIONS

CSF UCHL1 levels are elevated in NPC1, increase with increasing clinical severity and decrease in response to therapy with miglustat. Based on these data, UCHL1 may be a useful biomarker to monitor disease progression and therapeutic response in individuals with NPC1.

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.

Ataxia-telangiectasia clinical trial landscape and the obstacles to overcome

INTRODUCTION

Ataxia telangiectasia (A-T) is a life-limiting autosomal recessive disease characterized by cerebellar degeneration, ocular telangiectasias, and sinopulmonary disease. Since there is no cure for A-T, the standard of care is primarily supportive.

AREAS COVERED

We review clinical trials available in PubMed from 1990 to 2023 focused on lessening A-T disease burden. These approaches include genetic interventions, such as antisense oligonucleotides, designed to ameliorate disease progression in patients with select mutations. These approaches also include pharmacologic treatments that target oxidative stress, inflammation, and mitochondrial exhaustion, to attenuate neurological progression in A-T. Finally, we discuss the use of biological immunotherapies for the treatment of malignancies and granulomatous disease, along with other supportive therapies being used for the treatment of pulmonary disease and metabolic syndrome.

EXPERT OPINION

Barriers to successful genetic and pharmacologic interventions in A-T include the need for personalized treatment approaches based on patient-specific ATM mutations and phenotypes, lack of an animal model for the neurologic phenotype, and extreme rarity of disease making large-scale randomized trials difficult to perform. Ongoing efforts are needed to diagnose patients earlier, discover more effective therapies, and include more individuals in clinical trials, with the goal to lessen disease burden and to find a cure for patients with A-T.

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.

Neutral theory: applicability and neutrality of clinical study endpoints where a disease-specific instrument is available

BACKGROUND

There is a pressing need to improve the accuracy of rare disease clinical study endpoints. Neutral theory, first described here, can be used to assess the accuracy of endpoints and improve their selection in rare disease clinical studies, reducing the risk of patient misclassification.

METHODS

Neutral theory was used to assess the accuracy of rare disease clinical study endpoints and the resulting probability of false positive and false negative classifications at different disease prevalence rates. Search strings were extracted from the Orphanet Register of Rare Diseases using a proprietary algorithm to conduct a systematic review of studies published until January 2021. Overall, 11 rare diseases with one disease-specific disease severity scale (133 studies) and 12 rare diseases with more than one disease-specific disease severity scale (483 studies) were included. All indicators from clinical studies were extracted, and Neutral theory was used to calculate their match to disease-specific disease severity scales, which were used as surrogates for the disease phenotype. For those with more than one disease-severity scale, endpoints were compared with the first disease-specific disease severity scale and a composite of all later scales. A Neutrality score of > 1.50 was considered acceptable.

RESULTS

Around half the clinical studies for half the rare diseases with one disease-specific disease severity score (palmoplantar psoriasis, achalasia, systemic lupus erythematosus, systemic sclerosis and Fournier's gangrene) met the threshold for an acceptable match to the disease phenotype, one rare disease (Guillain-Barré syndrome) had one study with an acceptable match, and four diseases (Behcet's syndrome, Creutzfeldt-Jakob disease, atypical hemolytic uremic syndrome and Prader-Willi syndrome) had no studies. Clinical study endpoints in almost half the rare diseases with more than one disease-specific DSS (acromegaly, amyotrophic lateral sclerosis, cystic fibrosis, Fabry disease and juvenile rheumatoid arthritis) were a better match to the composite, while endpoints in the remaining rare diseases (Charcot Marie Tooth disease, Gaucher disease Type I, Huntington's disease, Sjogren's syndrome and Tourette syndrome) were a worse match. Misclassifications varied with increasing disease prevalence.

CONCLUSIONS

Neutral theory confirmed that disease-severity measurement needs improvement in rare disease clinical studies, especially for some diseases, and suggested that the potential for accuracy increases as the body of knowledge on a disease increases. Using Neutral theory to benchmark disease-severity measurement in rare disease clinical studies may reduce the risk of misclassification, ensuring that recruitment and treatment effect assessment optimise medicine adoption and benefit patients.

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.

Neurofilament light chain in cerebrospinal fluid as a novel biomarker in evaluating both clinical severity and therapeutic response in Niemann-Pick disease type C1

PURPOSE

Niemann-Pick disease type C1 (NPC1) is a neurodegenerative lysosomal disorder caused by pathogenic variants in NPC1. Disease progression is monitored using the NPC Neurological Severity Scale, but there are currently no established validated or qualified biomarkers. Neurofilament light chain (NfL) is being investigated as a biomarker in multiple neurodegenerative diseases.

METHODS

Cross-sectional and longitudinal cerebrospinal fluid (CSF) samples were obtained from 116 individuals with NPC1. NfL levels were measured using a solid-phase sandwich enzyme-linked immunosorbent assay and compared with age-appropriate non-NPC1 comparison samples.

RESULTS

Median levels of NfL were elevated at baseline (1152 [680-1840] pg/mL) in NPC1 compared with controls (167 [82-372] pg/mL; P < .001). Elevated NfL levels were associated with more severe disease as assessed by both the 17-domain and 5-domain NPC Neurological Severity Score. Associations were also observed with ambulation, fine motor, speech, and swallowing scores. Although treatment with the investigational drug 2-hydroxypropyl-β-cyclodextrin (adrabetadex) did not decrease CSF NfL levels, miglustat therapy over time was associated with a decrease (odds ratio = 0.77, 95% CI = 0.62-0.96).

CONCLUSION

CSF NfL levels are increased in individuals with NPC1, associated with clinical disease severity, and decreased with miglustat therapy. These data suggest that NfL is a biomarker that may have utility in future therapeutic trials.

Eine Kinderkrankheit wird erwachsen

Zusammenfassung: Die Untersuchung von seltenen Erkrankungen ist aufgrund der geringen Anzahl an Patient_innen sowie einem häufig heterogenen, multisymptomatischen Erscheinungsbild deutlich erschwert. Als Beispiel für eine solche seltene Krankheit dient im Folgenden die progrediente, neurodegenerative Erbkrankheit Niemann-Pick Typ C (NPC), die lange Zeit als „Kinderkrankheit“ galt. Im Verlauf des letzten Jahrzehnts wurde jedoch auch ein substanzieller Anteil an erwachsenen NPC-Patient_innen diagnostiziert. Da zum klinischen Erscheinungsbild von erwachsenen NPC-Patient_innen wenig Umfassendes bekannt ist, widmet sich der Artikel diesem Thema und zeigt, inwieweit die Erkenntnisse zu Manifestationen sowie zur Krankheitsentwicklung von pädiatrischen auf erwachsene NPC-Patient_innen übertragbar sind. Die Darstellung von Erkrankungsmerkmalen der Subpopulationen pädiatrischer gegenüber jugendlicher bzw. erwachsener NPC-Patient_innen basiert auf der verfügbaren Literatur sowie Expertenmeinungen hinsichtlich der Epidemiologie, des genetischen Mutationsmusters, des klinischen Bildes einschließlich der Prodromalsymptome, der Progressionsrate, dem allgemeinen Behandlungsregime und den Therapieeffekten. Insgesamt erweist sich NPC als ein Krankheitskontinuum, basierend auf weitestgehend ähnlichen genetischen Mutationsmustern sowie einer sich in den Altersgruppen entsprechenden Pathophysiologie. Pädiatrische und jugendliche bzw. erwachsene Patient_innen sind durch diverse Facetten fortschreitender neuropsychologischer Manifestationen wie bspw. kognitive Defizite und deutliche Einschränkungen ihrer motorischen Fähigkeiten (einschließlich der Berücksichtigung von prodromalen Symptomen) gekennzeichnet. NPC verläuft bei Kindern sowie bei jugendlichen bzw. erwachsenen Patient_innen auf die ähnliche Weise – jedoch mit einer beschleunigten Progressionsrate und einer somit verkürzten Lebenserwartung, je jünger die Patient_innen bei erstmaligem Auftreten neurologischer Symptome sind. Jedoch weist die hohe Krankheitslast aller NPC-Patient_innen auf die Schwere dieser seltenen Stoffwechselkrankheit hin. Die Behandlung von NPC erfolgt altersunabhängig interdisziplinär. Es besteht bisher keine kausale Therapieoption.

Identification of cerebral spinal fluid protein biomarkers in Niemann-Pick disease, type C1

BACKGROUND

Niemann-Pick disease, type C1 (NPC1) is an ultrarare, recessive, lethal, lysosomal disease characterized by progressive cerebellar ataxia and cognitive impairment. Although the NPC1 phenotype is heterogeneous with variable age of onset, classical NPC1 is a pediatric disorder. Currently there are no therapies approved by the FDA and therapeutics trials for NPC1 are complicated by disease rarity, heterogeneity, and the relatively slow rate of neurological decline. Thus, identification of disease relevant biomarkers is necessary to provide tools that can support drug development efforts for this devastating neurological disease.

METHODS

Proximal extension assays (O-link® Explore 1536) were used to compare cerebrospinal fluid (CSF) samples from individuals with NPC1 enrolled in a natural history study and non-NPC1 comparison samples. Relative expression levels of 1467 proteins were determined, and candidate protein biomarkers were identified by evaluating fold-change and adjusted Kruskal-Wallis test p-values. Selected proteins were orthogonally confirmed using ELISA. To gain insight into disease progression and severity we evaluated the altered protein expression with respect to clinically relevant phenotypic aspects: NPC Neurological Severity Score (NPC1 NSS), Annual Severity Increment Score (ASIS) and age of neurological onset.

RESULTS

This study identified multiple proteins with altered levels in CSF from individuals with NPC1 compared to non-NPC1 samples. These included proteins previously shown to be elevated in NPC1 (NEFL, MAPT, CHIT1, CALB1) and additional proteins confirmed by orthogonal assays (PARK7, CALB2/calretinin, CHI3L1/YKL-40, MIF, CCL18 and ENO2). Correlations with clinically relevant phenotypic parameters demonstrated moderate negative (p = 0.0210, r = -0.41) and possible moderate positive (p = 0.0631, r = 0.33) correlation of CSF CALB2 levels with age of neurological onset and ASIS, respectively. CSF CHI3L1 levels showed a moderate positive (p = 0.0183, r = 0.40) correlation with the concurrent NPC1 NSS. A strong negative correlation (p = 0.0016, r = -0.648) was observed between CSF CCL18 and age of neurological onset for childhood/adolescent cases. CSF CCL18 levels also showed a strong positive correlation (p = 0.0017, r = 0.61) with ASIS.

CONCLUSION

Our study identified and validated multiple proteins in CSF from individuals with NPC1 that are candidates for further investigation in a larger cohort. These analytes may prove to be useful as supportive data in therapeutic trials.

TRIAL REGISTRATIONS

NCT00344331, NCT00001721, NCT02931682.

Phenotypic expression of swallowing function in Niemann-Pick disease type C1

Background

Niemann–Pick disease type C1 (NPC1) is a rare autosomal recessive disease characterized by endolysosomal accumulation of unesterified cholesterol with progressive deterioration in swallowing, often leading to premature death. Although documented, the natural history of NPC1 swallowing dysfunction has yet to be delineated systematically. This manuscript aims to provide a comprehensive characterization of the phenotypic spectrum and progression of swallowing dysfunction in NPC1.

Methodology

The National Institutes of Health (NIH) NPC1 natural history study (NCT00344331) enrolled 120 patients, who underwent comprehensive interpretative swallow assessments for swallowing safety, dietary modifications, and aspiration risk. Longitudinal statistical modeling accounted for all outcomes with NPC1 disease covariates (first symptom onset, age at neurological symptom onset, seizure history, duration of neurological symptoms) as well as miglustat use (a glucosylceramide synthase inhibitor) and NIH study duration (NIHSD; the length of time an individual participated in the NIH study). Probabilities for disease progression and time to swallowing decline were conducted for the entire cohort.

Results

Time to swallowing decline with American Speech-Language-Hearing Association National Outcome Measure (ASHA-NOMS) and the NIH-adapted Penetration Aspiration Scale (NIH-PAS) were identified: \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\frac{7.7}{100}$$\end{document}7.7100 person-years and \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\frac{9.8}{100}$$\end{document}9.8100 person-years, respectively. NIHSD and seizure history consistently and significantly were associated with decline (OR_NIHSD = 1.34–2.10, 95% CI 1.04–3.4, p = 0.001–0.026; OR_Seizure = 3.26–18.22, 1.03–167.79; p = 0.001–0.046), while miglustat use revealed protection (OR_Miglustat = 0.01–0.43, 0.007–0.98; p = 0.001–0.044). The probability of decline with NPC1 neurological severity scale and annual severity increment scale were established with the aforementioned covariates, varying amongst subgroups.

Conclusion

This study represents the most extensive collection of prospective, instrumental swallowing assessments in NPC1 to date with an interpretive analysis providing an improved understanding of NPC1 disease progression with swallowing function—serving as a foundation for clinical management and future NPC1 therapeutics.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13023-022-02472-w.

Epilepsy Course and Developmental Trajectories in STXBP1-DEE

Background and Objectives

Clinical manifestations in STXBP1 developmental and epileptic encephalopathy (DEE) vary in severity and outcome, and the genotypic spectrum is diverse. We aim to trace the neurodevelopmental trajectories in individuals with STXBP1-DEE and dissect the relationship between neurodevelopment and epilepsy.

Methods

Retrospective standardized clinical data were collected through international collaboration. A composite neurodevelopmental score system compared the developmental trajectories in STXBP1-DEE.

Results

Forty-eight patients with de novo STXBP1 variants and a history of epilepsy were included (age range at the time of the study: 10 months to 35 years, mean 8.5 years). At the time of inclusion, 65% of individuals (31/48) had active epilepsy, whereas 35% (17/48) were seizure free, and 76% of those (13/17) achieved remission within the first year of life. Twenty-two individuals (46%) showed signs of developmental impairment and/or neurologic abnormalities before epilepsy onset. Age at seizure onset correlated with severity of developmental outcome and the developmental milestones achieved, with a later seizure onset associated with better developmental outcome. In contrast, age at seizure remission and epilepsy duration did not affect neurodevelopmental outcomes. Overall, we did not observe a clear genotype-phenotype correlation, but monozygotic twins with de novo STXBP1 variant showed similar phenotype and parallel disease course.

Discussion

The disease course in STXBP1-DEE presents with 2 main trajectories, with either early seizure remission or drug-resistant epilepsy, and a range of neurodevelopmental outcomes from mild to profound intellectual disability. Age at seizure onset is the only epilepsy-related feature associated with neurodevelopment outcome. These findings can inform future dedicated natural history studies and trial design.

Consistently High Agreement Between Independent Raters of Niemann-Pick Type C1 Clinical Severity Scale in Phase 2/3 Trial

BACKGROUND

Niemann-Pick disease, type C1 (NPC1) is a rare neurodegenerative genetic disorder characterized by impaired intracellular transport of cholesterol and other lipids. The Niemann-Pick Disease, type C1 Severity Scale (NPC-SS) was developed to quantify neurological progression of NPC; it is used to monitor the natural history of disease progression and assess response to treatment. The objective of the study was to examine the interrater reliability of the NPC-SS in a phase 2/3 trial.

METHODS

Study data were from a multicenter, prospective, randomized, double-blind trial of adrabetadex in 56 subjects with NPC1. Clinical data recorded at each study site were distributed to two independent blinded central raters to generate a severity score. A composite four-item score was utilized as the primary clinical study end point, whereas a five-item focused score has been utilized in other NPC1 trials. Interrater reliability was assessed using two-way mixed models for instrument stability, Cohen kappa, weighted kappa, and percent agreement for the four- and five-item scores.

RESULTS

The frequency distribution and mean (S.D.) of the NPC-SS domain assessments by the raters were almost identical. Evaluation at the patient visit level showed wide variability between visits; however, weighted kappa calculation provided a lower variability between visits. The average kappa coefficients ranged between 0.69 and 0.89, indicating good to very good agreement between raters.

CONCLUSIONS

These results support the NPC-SS, including derived four- and five-item composite scores, as reliable measures for use in a clinical trial setting.

Impacts and Burden of Niemann pick Type-C: a patient and caregiver perspective

Background

Niemann-Pick disease type C (NPC) is a debilitating condition that impacts patients’ and caregivers’ quality of life (QOL) and reduces the patient’s life expectancy. Since there is little qualitative research from the perspective of patients and family caregivers, this study explored the impact of NPC on patients’ and caregivers’ daily lives to understand the burden of disease.

Results

A survey of caregivers for patients with NPC and adult patients with NPC (n = 49; patient age: 13 months–65 years) assessed NPC severity, importance of NPC symptoms, and how symptoms impacted patients’ and caregivers’ activities of daily living (ADLs) and health-related QOL (HRQOL). Follow-up interviews with a subset of survey participants (n = 28) explored the ranking of NPC symptom importance and impact on ADLs and HRQOL. Findings indicated that the most important manifestations of NPC were ambulation, swallowing, speech, fine motor skills, and cognition, which were those that had the most significant impact on ADLs and HRQOL. A wide range of ADLs were affected by NPC, mainly eating/drinking and the ability to perform daily tasks, including self-care, communicating, participating in school or work, and moving indoors as well as outside the home. Along with these impacts, there was an increased risk of experiencing dangerous or life-threatening situations leading to loss of patient independence and additional caregiver burden, often requiring changes in lifestyle such as giving up work. All aspects of patients’ and caregivers’ HRQOL were affected. Participants reported feelings of social isolation, loss of enjoyment in activities (patients), and feelings of sadness or worry (caregivers).

Conclusions

Ambulation, swallowing, speech, fine motor skills, and cognition are important manifestations of NPC. ADLs and HRQOL were impaired in the majority of patients as well as their caregivers. The findings were independent of current age, age of onset of symptoms, and level of NPC disease-related disability; however, the impact increased at higher levels of disease disability. Knowing the impact of NPC on patients and caregivers is important for understanding the lived experience of NPC and for identifying potential areas of support.

International consensus on clinical severity scale use in evaluating Niemann-Pick disease Type C in paediatric and adult patients: results from a Delphi Study

Background

Several scales have been developed in the past two decades to evaluate Niemann–Pick disease Type C (NPC) severity in clinical practice and trials. However, a lack of clarity concerning which scale to use in each setting is preventing the use of standardised assessments across the world, resulting in incomparable data sets and clinical trial outcome measures. This study aimed to establish agreed approaches for the use of NPC severity scales in clinical practice and research.

Methods

A Delphi method of consensus development was used, comprising three survey rounds. In Round 1, participants were asked nine multiple-choice and open-ended questions to gather opinions on the six severity scales and domains. In Rounds 2 and 3, questions aimed to gain consensus on the opinions revealed in Round 1 using a typical Likert scale.

Results

Nineteen experts, active in NPC paediatric and adult research and treatment, participated in this study. Of these, 16/19 completed Rounds 1 and 2 and 19/19 completed Round 3. Consensus (defined as ≥ 70% agreement or neutrality, given the study aim to identify the severity scales that the clinical community would accept for international consistency) was achieved for 66.7% of the multiple-choice questions in Round 2 and 83% of the multiple-choice questions in Round 3. Consensus was almost reached (68%) on the use of the 5-domain NPCCSS scale as the first choice in clinical practice. Consensus was reached (74%) for the 17-domain NPCCSS scale as the first choice in clinical trial settings, but the domains measured in the 5-domain scale should be prioritised as the primary endpoints. Experts called for educational and training materials on how to apply the NPCCSS (17- and 5-domains) for clinicians working in NPC.

Conclusions

In achieving a consensus on the use of the 17-domain NPCCSS scale as the first choice for assessing clinical severity of NPC in clinical trial settings but prioritising the domains in the 5-domain NPCCSS scale for routine clinical practice, this study can help to inform future discussion around the use of the existing NPC clinical severity scales. For routine clinical practice, the study helps provide clarity on which scale is favoured by a significant proportion of a representative body of experts, in this case, the 5-domain NPCCSS scale.

Efficacy and safety of arimoclomol in Niemann-Pick disease type C: Results from a double-blind, randomised, placebo-controlled, multinational phase 2/3 trial of a novel treatment

Niemann-Pick disease type C (NPC) is a rare, genetic, progressive neurodegenerative disorder with high unmet medical need. We investigated the safety and efficacy of arimoclomol, which amplifies the heat shock response to target NPC protein misfolding and improve lysosomal function, in patients with NPC. In a 12-month, prospective, randomised, double-blind, placebo-controlled, phase 2/3 trial (ClinicalTrials.gov identifier: NCT02612129), patients (2-18 years) were randomised 2:1 to arimoclomol:placebo, stratified by miglustat use. Routine clinical care was maintained. Arimoclomol was administered orally three times daily. The primary endpoint was change in 5-domain NPC Clinical Severity Scale (NPCCSS) score from baseline to 12 months. Fifty patients enrolled; 42 completed. At month 12, the mean progression from baseline in the 5-domain NPCCSS was 0.76 with arimoclomol vs 2.15 with placebo. A statistically significant treatment difference in favour of arimoclomol of -1.40 (95% confidence interval: -2.76, -0.03; P = .046) was observed, corresponding to a 65% reduction in annual disease progression. In the prespecified subgroup of patients receiving miglustat as routine care, arimoclomol resulted in stabilisation of disease severity over 12 months with a treatment difference of -2.06 in favour of arimoclomol (P = .006). Adverse events occurred in 30/34 patients (88.2%) receiving arimoclomol and 12/16 (75.0%) receiving placebo. Fewer patients had serious adverse events with arimoclomol (5/34, 14.7%) vs placebo (5/16, 31.3%). Treatment-related serious adverse events (n = 2) included urticaria and angioedema. Arimoclomol provided a significant and clinically meaningful treatment effect in NPC and was well tolerated.

Efficacy and safety of N-acetyl-L-leucine in Niemann-Pick disease type C

OBJECTIVE

To investigate the safety and efficacy of N-acetyl-L-leucine (NALL) on symptoms, functioning, and quality of life in pediatric (≥ 6 years) and adult Niemann-Pick disease type C (NPC) patients.

METHODS

In this multi-national, open-label, rater-blinded Phase II study, patients were assessed during a baseline period, a 6-week treatment period (orally administered NALL 4 g/day in patients ≥ 13 years, weight-tiered doses for patients 6-12 years), and a 6-week post-treatment washout period. The primary Clinical Impression of Change in Severity (CI-CS) endpoint (based on a 7-point Likert scale) was assessed by blinded, centralized raters who compared randomized video pairs of each patient performing a pre-defined primary anchor test (8-Meter Walk Test or 9-Hole Peg Test) during each study periods. Secondary outcomes included cerebellar functional rating scales, clinical global impression, and quality of life assessments.

RESULTS

33 subjects aged 7-64 years with a confirmed diagnosis of NPC were enrolled. 32 patients were included in the primary modified intention-to-treat analysis. NALL met the CI-CS primary endpoint (mean difference 0.86, SD = 2.52, 90% CI 0.25, 1.75, p = 0.029), as well as secondary endpoints. No treatment-related serious adverse events occurred.

CONCLUSIONS

NALL demonstrated a statistically significant and clinical meaningfully improvement in symptoms, functioning, and quality of life in 6 weeks, the clinical effect of which was lost after the 6-week washout period. NALL was safe and well-tolerated, informing a favorable benefit-risk profile for the treatment of NPC. CLINICALTRIALS.

GOV IDENTIFIER

NCT03759639.

Acetylation turns leucine into a drug by membrane transporter switching

Small changes to molecules can have profound effects on their pharmacological activity as exemplified by the addition of the two-carbon acetyl group to make drugs more effective by enhancing their pharmacokinetic or pharmacodynamic properties. N-acetyl-D,L-leucine is approved in France for vertigo and its L-enantiomer is being developed as a drug for rare and common neurological disorders. However, the precise mechanistic details of how acetylation converts leucine into a drug are unknown. Here we show that acetylation of leucine switches its uptake into cells from the L-type amino acid transporter (LAT1) used by leucine to organic anion transporters (OAT1 and OAT3) and the monocarboxylate transporter type 1 (MCT1). Both the kinetics of MCT1 (lower affinity compared to LAT1) and the ubiquitous tissue expression of MCT1 make it well suited for uptake and distribution of N-acetyl-L-leucine. MCT1-mediated uptake of a N-acetyl-L-leucine as a prodrug of leucine bypasses LAT1, the rate-limiting step in activation of leucine-mediated signalling and metabolic process inside cells such as mTOR. Converting an amino acid into an anion through acetylation reveals a way for the rational design of drugs to target anion transporters.

N-Acetyl-L-leucine improves functional recovery and attenuates cortical cell death and neuroinflammation after traumatic brain injury in mice

Traumatic brain injury (TBI) is a major cause of mortality and long-term disability around the world. Even mild to moderate TBI can lead to lifelong neurological impairment due to acute and progressive neurodegeneration and neuroinflammation induced by the injury. Thus, the discovery of novel treatments which can be used as early therapeutic interventions following TBI is essential to restrict neuronal cell death and neuroinflammation. We demonstrate that orally administered N-acetyl-l-leucine (NALL) significantly improved motor and cognitive outcomes in the injured mice, led to the attenuation of cell death, and reduced the expression of neuroinflammatory markers after controlled cortical impact (CCI) induced experimental TBI in mice. Our data indicate that partial restoration of autophagy flux mediated by NALL may account for the positive effect of treatment in the injured mouse brain. Taken together, our study indicates that treatment with NALL would be expected to improve neurological function after injury by restricting cortical cell death and neuroinflammation. Therefore, NALL is a promising novel, neuroprotective drug candidate for the treatment of TBI.

Brain hypometabolic changes in 14 adolescent-adult patients with Niemann-Pick disease type C assessed by 18F-fluorodeoxyglucose positron emission tomography

OBJECTIVE

Niemann Pick disease type C (NPC) is a rare progressive neurovisceral lysosomal disorder caused by autosomal recessive mutations in the NPC1 or NPC2 genes. 18F-fluorodeoxyglucose (FDG) is a positron-emitting glucose analogue for non-invasive imaging of brain metabolism. FDG PET is commonly used for dementia imaging but its specific application to NPC is rarely described.

METHODS

This is a retrospective study of all baseline brain FDG PET performed for NPC patients. Images were assessed using a normal database statistical comparison of metabolic changes expressed in standard deviations and three-dimensional Stereotactic Surface Projection maps. Typical hypometabolic patterns in NPC were identified. We further investigated any correlation between the degree of regional brain hypometabolism and the Iturriaga clinical severity scale.

RESULTS

Brain FDG PET images of 14 adolescent-adult NPC patients were analysed, with mean age of 35 years. We found significant frontal lobe hypometabolism in 12 patients (86%), thalamic hypometabolism in eight patients (57%) and variable parietal lobe hypometabolism in 13 patients (93%). Hypometabolic changes were usually bilateral and symmetric. Ten out of 13 ataxic patients showed cerebellar or thalamic hypometabolism (sensitivity 77%, specificity 100%). Linear regression analysis showed frontal lobe hypometabolism to have the best correlation with the Iturriaga clinical scale (R² = 0.439; p = 0.01).

CONCLUSIONS

We found bilateral symmetric hypometabolism of the frontal lobes, thalami and parietal lobes (especially posterior cingulate gyrus) to be typical of adolescent-adult NPC. Ataxia was commonly associated with cerebellar or thalamic hypometabolism. Frontal lobe hypometabolism showed the best inverse correlation with clinical severity.

Niemann-Pick Disease, Type C: Diagnosis, Management and Disease-Targeted Therapies in Development

Niemann-Pick disease, type C (NPC) is a highly heterogeneous rare neurovisceral storage disease with early infantile, late infantile, juvenile and adult onset forms, and relentlessly progressive neurodegeneration leading to death. Vertical supranuclear gaze palsy is a hallmark symptom, and ataxia, dysarthria, dysphagia, dystonia, cognitive decline, seizures, cataplexy, hearing loss and visceromegaly are also characteristic. Diagnosis is made by gene sequencing, metabolic measures, or more recently through gene panels and exome sequencing. Management involves multidisciplinary supportive care. Disease-directed treatments are in development, raising hope that with combination therapy, disease progression will be stalled, and NPC will become a treatable disease.

Validation of the 5-domain Niemann-Pick type C Clinical Severity Scale

Background

Niemann-Pick disease type C (NPC) is an ultra-rare, progressive, genetic disease leading to impaired lysosomal function and neurodegeneration causing serious morbidity and shortened life expectancy.

The Niemann-Pick type C Clinical Severity Scale (NPCCSS) is a 17 domain, disease-specific, clinician-reported outcome measure of disease severity and progression. An abbreviated 5-domain NPCCSS scale has been developed (measuring Ambulation, Swallow, Cognition, Speech, and Fine Motor Skills) and the scale reliability has been established. Additional psychometric properties and meaningful change of the scale need, however, to be assessed.

Methods

Mixed method studies were conducted to ascertain which NPCCSS domains were most important, as well as to explore meaningful change: 1) surveys in caregivers/patients (n = 49) and 2) interviews with clinicians (n = 5) as well as caregivers/patients (n = 28). Clinical trial data (n = 43) assessed construct validity and meaningful change through an anchor-based approach.

Results

Domains identified as most important by clinicians, caregivers, and patients (independent of current age, age of onset, and disease severity) were Ambulation, Swallow, Cognition, Speech, and Fine Motor Skills, indicating content validity of the 5-domain NPCCSS.

Criterion validity was shown with the 5-domain NPCCSS being highly correlated with the 17-item NPCCSS total score (excluding hearing domains), r² = 0.97. Convergent validity was demonstrated against the 9 Hole Peg Test, r² = 0.65 (n = 31 patients), and the Scale for Assessment and Rating of Ataxia (SARA), r² = 0.86 (n = 49 patients). Any change was seen as meaningful by patients/caregivers across domains. Meaningful change using trial data and interviews with NPC experts (n = 5) and patients/caregivers (n = 28) suggested that a 1-category change on a domain is equivalent to 1-point change or greater in the 5-domain NPCCSS total score.

Conclusions

Qualitative and quantitative data support content and construct validity of the 5-domain NPCCSS score as a valid endpoint in NPC trials. A 1-category change on any domain is equivalent to 1-point change or greater in the 5 domain NPCCSS total score, representing a clinically meaningful transition and reflecting loss of complex function and increased disability.

Trial registration NCT02612129. Registered 23 November 2015, https://clinicaltrials.gov/ct2/show/NCT02612129

A master protocol to investigate a novel therapy acetyl-L-leucine for three ultra-rare neurodegenerative diseases: Niemann-Pick type C, the GM2 gangliosidoses, and ataxia telangiectasia

BACKGROUND

The lack of approved treatments for the majority of rare diseases is reflective of the unique challenges of orphan drug development. Novel methodologies, including new functionally relevant endpoints, are needed to render the development process more feasible and appropriate for these rare populations and thereby expedite the approval of promising treatments to address patients' high unmet medical need. Here, we describe the development of an innovative master protocol and primary outcome assessment to investigate the modified amino acid N-acetyl-L-leucine (Sponsor Code: IB1001) in three separate, multinational, phase II trials for three ultra-rare, autosomal-recessive, neurodegenerative disorders: Niemann-Pick disease type C (NPC), GM2 gangliosidoses (Tay-Sachs and Sandhoff disease; "GM2"), and ataxia telangiectasia (A-T).

METHODS/DESIGN

The innovative IB1001 master protocol and novel CI-CS primary endpoints were developed through a close collaboration between the Industry Sponsor, Key Opinion Leaders, representatives of the Patient Communities, and National Regulatory Authorities. As a result, the open-label, rater-blinded study design is considerate of the practical limitations of recruitment and retention of subjects in these ultra-orphan populations. The novel primary endpoint, the Clinical Impression of Change in Severity© (CI-CS), accommodates the heterogenous clinical presentation of NPC, GM2, and A-T: at screening, the principal investigator appoints for each patient a primary anchor test (either the 8-m walk test (8MWT) or 9-hole peg test of the dominant hand (9HPT-D)) based on his/her unique clinical symptoms. The anchor tests are videoed in a standardized manner at each visit to capture all aspects related to the patient's functional performance. The CI-CS assessment is ultimately performed by independent, blinded raters who compare videos of the primary anchor test from three periods: baseline, the end of treatment, and the end of a post-treatment washout. Blinded to the time point of each video, the raters make an objective comparison scored on a 7-point Likert scale of the change in the severity of the patient's neurological signs and symptoms from video A to video B. To investigate both the symptomatic and disease-modifying effects of treatment, N-acetyl-L-leucine is assessed during two treatment sequences: a 6-week parent study and 1-year extension phase.

DISCUSSION

The novel CI-CS assessment, developed through a collaboration of all stakeholders, is advantageous in that it better ensures the primary endpoint is functionally relevant for each patient, is able to capture small but meaningful clinical changes critical to the patients' quality of life (fine-motor skills; gait), and blinds the primary outcome assessment. The results of these three trials will inform whether N-acetyl-L-leucine is an effective treatment for NPC, GM2, and A-T and can also serve as a new therapeutic paradigm for the development of future treatments for other orphan diseases.

TRIAL REGISTRATION

The three trials (IB1001-201 for Niemann-Pick disease type C (NPC), IB1001-202 for GM2 gangliosidoses (Tay-Sachs and Sandhoff), IB1001-203 for ataxia telangiectasia (A-T)) have been registered at www.clinicaltrials.gov (NCT03759639; NCT03759665; NCT03759678), www.clinicaltrialsregister.eu (EudraCT: 2018-004331-71; 2018-004406-25; 2018-004407-39), and https://www.germanctr.de (DR KS-ID: DRKS00016567; DRKS00017539; DRKS00020511).

Acetyl-leucine slows disease progression in lysosomal storage disorders

Acetyl-dl-leucine is a derivative of the branched chain amino acid leucine. In observational clinical studies, acetyl-dl-leucine improved symptoms of ataxia, in particular in patients with the lysosomal storage disorder, Niemann-Pick disease type C1. Here, we investigated acetyl-dl-leucine and its enantiomers acetyl-l-leucine and acetyl-d-leucine in symptomatic Npc1^-/- mice and observed improvement in ataxia with both individual enantiomers and acetyl-dl-leucine. When acetyl-dl-leucine and acetyl-l-leucine were administered pre-symptomatically to Npc1^-/- mice, both treatments delayed disease progression and extended life span, whereas acetyl-d-leucine did not. These data are consistent with acetyl-l-leucine being the neuroprotective enantiomer. Altered glucose and antioxidant metabolism were implicated as one of the potential mechanisms of action of the l-enantiomer in Npc1^-/- mice. When the standard of care drug miglustat and acetyl-dl-leucine were used in combination significant synergy resulted. In agreement with these pre-clinical data, when Niemann-Pick disease type C1 patients were evaluated after 12 months of acetyl-dl-leucine treatment, rates of disease progression were slowed, with stabilization or improvement in multiple neurological domains. A beneficial effect of acetyl-dl-leucine on gait was also observed in this study in a mouse model of GM2 gangliosidosis (Sandhoff disease) and in Tay-Sachs and Sandhoff disease patients in individual-cases of off-label-use. Taken together, we have identified an unanticipated neuroprotective effect of acetyl-l-leucine and underlying mechanisms of action in lysosomal storage diseases, supporting its further evaluation in clinical trials in lysosomal disorders.

Clinical disease progression and biomarkers in Niemann-Pick disease type C: a prospective cohort study

Background

Niemann–Pick disease type C (NPC) is a rare, progressive, neurodegenerative disease associated with neurovisceral manifestations resulting from lysosomal dysfunction and aberrant lipid accumulation. A multicentre, prospective observational study (Clinical Trials.gov ID: NCT02435030) of individuals with genetically confirmed NPC1 or NPC2 receiving routine clinical care was conducted, to prospectively characterize and measure NPC disease progression and to investigate potential NPC-related biomarkers versus healthy individuals. Progression was measured using the abbreviated 5-domain NPC Clinical Severity Scale (NPCCSS), 17-domain NPCCSS and NPC clinical database (NPC-cdb) score. Cholesterol esterification and heat shock protein 70 (HSP70) levels were assessed from peripheral blood mononuclear cells (PBMCs), cholestane-3β,5α-,6β-triol (cholestane-triol) from serum, and unesterified cholesterol from both PBMCs and skin biopsy samples. The inter- and intra-rater reliability of the 5-domain NPCCSS was assessed by 13 expert clinicians’ rating of four participants via video recordings, repeated after ≥ 3 weeks. Intraclass correlation coefficients (ICCs) were calculated.

Results

Of the 36 individuals with NPC (2–18 years) enrolled, 31 (86.1%) completed the 6–14-month observation period; 30/36 (83.3%) were receiving miglustat as part of routine clinical care. A mean (± SD) increase in 5-domain NPCCSS scores of 1.4 (± 2.9) was observed, corresponding to an annualized progression rate of 1.5. On the 17-domain NPCCSS, a mean (± SD) progression of 2.7 (± 4.0) was reported. Compared with healthy individuals, the NPC population had significantly lower levels of cholesterol esterification (p < 0.0001), HSP70 (p < 0.0001) and skin unesterified cholesterol (p = 0.0006). Cholestane-triol levels were significantly higher in individuals with NPC versus healthy individuals (p = 0.008) and correlated with the 5-domain NPCCSS (Spearman’s correlation coefficient = 0.265, p = 0.0411). The 5-domain NPCCSS showed high ICC agreement in inter-rater reliability (ICC = 0.995) and intra-rater reliability (ICC = 0.937).

Conclusions

Progression rates observed were consistent with other reports on disease progression in NPC. The 5-domain NPCCSS reliability study supports its use as an abbreviated alternative to the 17-domain NPCCSS that focuses on the most relevant domains of the disease. The data support the use of cholestane-triol as a disease monitoring biomarker and the novel methods of measuring unesterified cholesterol could be applicable to support NPC diagnosis. Levels of HSP70 in individuals with NPC were significantly decreased compared with healthy individuals.

Trial registration

CT-ORZY-NPC-001: ClincalTrials.gov NCT02435030, Registered 6 May 2015, https://clinicaltrials.gov/ct2/show/NCT02435030; EudraCT 2014–005,194-37, Registered 28 April 2015, https://www.clinicaltrialsregister.eu/ctr-search/trial/2014-005194-37/DE. OR-REL-NPC-01: Unregistered.

Beneficial Effects of Acetyl-DL-Leucine (ADLL) in a Mouse Model of Sandhoff Disease

Sandhoff disease is a rare neurodegenerative lysosomal storage disease associated with the storage of GM2 ganglioside in late endosomes/lysosomes. Here, we explored the efficacy of acetyl-DL-leucine (ADLL), which has been shown to improve ataxia in observational studies in patients with Niemann-Pick Type C1 and other cerebellar ataxias. We treated a mouse model of Sandhoff disease (Hexb^-/-) (0.1 g/kg/day) from 3 weeks of age with this orally available drug. ADLL produced a modest but significant increase in life span, accompanied by improved motor function and reduced glycosphingolipid (GSL) storage in the forebrain and cerebellum, in particular GA2. ADLL was also found to normalize altered glucose and glutamate metabolism, as well as increasing autophagy and the reactive oxygen species (ROS) scavenger, superoxide dismutase (SOD1). Our findings provide new insights into metabolic abnormalities in Sandhoff disease, which could be targeted with new therapeutic approaches, including ADLL.

Unexpected differences in the pharmacokinetics of N-acetyl-DL-leucine enantiomers after oral dosing and their clinical relevance

The enantiomers of many chiral drugs not only exhibit different pharmacological effects in regard to targets that dictate therapeutic and toxic effects, but are also handled differently in the body due to pharmacokinetic effects. We investigated the pharmacokinetics of the enantiomers of N-acetyl-leucine after administration of the racemate (N-acetyl-DL-leucine) or purified, pharmacologically active L-enantiomer (N-acetyl-L-leucine). The results suggest that during chronic administration of the racemate, the D-enantiomer would accumulate, which could have negative effects. Compounds were administered orally to mice. Plasma and tissue samples were collected at predetermined time points (0.25 to 8 h), quantified with liquid chromatography/mass spectrometry, and pharmacokinetic constants were calculated using a noncompartmental model. When administered as the racemate, both the maximum plasma concentration (Cmax) and the area under the plasma drug concentration over time curve (AUC) were much greater for the D-enantiomer relative to the L-enantiomer. When administered as the L-enantiomer, the dose proportionality was greater than unity compared to the racemate, suggesting saturable processes affecting uptake and/or metabolism. Elimination (ke and T1/2) was similar for both enantiomers. These results are most readily explained by inhibition of uptake at an intestinal carrier of the L-enantiomer by the D-enantiomer, and by first-pass metabolism of the L-, but not D-enantiomer, likely by deacetylation. In brain and muscle, N-acetyl-L-leucine levels were lower than N-acetyl-D-leucine, consistent with rapid conversion into L-leucine and utilization by normal leucine metabolism. In summary, the enantiomers of N-acetyl-leucine exhibit large, unexpected differences in pharmacokinetics due to both unique handling and/or inhibition of uptake and metabolism of the L-enantiomer by the D-enantiomer. Taken together, these results have clinical implications supporting the use of N-acetyl-L-leucine instead of the racemate or N-acetyl-D-leucine, and support the research and development of only N-acetyl-L-leucine.

Treating lysosomal storage disorders: What have we learnt?

The first enzyme replacement therapy (ERT) for a lysosomal storage disorder (LSD) was approved in 1991 and we now have more than 25 years of experience of treating patients with type 1 Gaucher disease. Because of the remarkable success of this therapy, enormous effort and resource has gone into developing other ERTs, for Gaucher (where three different enzyme preparations have now been approved) and for other LSDs. We now have more than 10 years of clinical experience in using ERT to treat Gaucher, Fabry, Pompe and MPS I, II, and VI. This article aims to assess the real-life experience of a selection of these innovative and expensive treatments to see if they have met the high expectations which were set for them when they launched.

Expanded access with intravenous hydroxypropyl-β-cyclodextrin to treat children and young adults with Niemann-Pick disease type C1: a case report analysis

Background

Niemann-Pick Disease Type C (NPC) is an inherited, often fatal neurovisceral lysosomal storage disease characterized by cholesterol accumulation in every cell with few known treatments. Defects in cholesterol transport cause sequestration of unesterified cholesterol within the endolysosomal system. The discovery that systemic administration of hydroxypropyl-beta cyclodextrin (HPβPD) to NPC mice could release trapped cholesterol from lysosomes, normalize cholesterol levels in the liver, and prolong life, led to expanded access use in NPC patients. HPβCD has been administered to NPC patients with approved INDs globally since 2009.

Results

Here we present safety, tolerability and efficacy data from 12 patients treated intravenously (IV) for over 7 years with HPβCD in the US and Brazil. Some patients subsequently received intrathecal (IT) treatment with HPβCD following on average 13 months of IV HPβCD. Several patients transitioned to an alternate HPβCD. Moderately affected NPC patients treated with HPβCD showed slowing of disease progression. Severely affected patients demonstrated periods of stability but eventually showed progression of disease. Neurologic and neurocognitive benefits were seen in most patients with IV alone, independent of the addition of IT administration. Physicians and caregivers reported improvements in quality of life for the patients on IV therapy. There were no safety issues, and the drug was well tolerated and easy to administer.

Conclusions

These expanded access data support the safety and potential benefit of systemic IV administration of HPβCD and provide a platform for two clinical trials to study the effect of intravenous administration of HPβCD in NPC patients.

Animal models for Niemann-Pick type C: implications for drug discovery & development

INTRODUCTION

Niemann-Pick type C (NPC) is a neurovisceral, progressively detrimental lysosomal storage disease with very limited therapeutic options and no approved treatment available in the US. Despite its rarity, NPC has seen increased drug developmental efforts over the past decade, culminating in the completion of two potential registration trials in 2018. Areas covered: This review highlights the many available animal models that have been developed in the field and briefly covers classical and new cell technologies. This review provides a high-level evaluation and prioritization of the various models with regard to efficient and clinically translatable drug development, and briefly discusses the relevant developments and opportunities pertaining to this. Expert opinion: With a number of in vitro and in vivo models available, and with having several drugs, all with various mechanisms of action, either approved or in late stage development, the NPC field is in an exciting time. One of the challenges for researchers and developers will be the ability to make use of the lessons learnt from existing late-stage programs as well as the incorporation not only of the opportunities but also the limitations of the many models into successful drug discovery and translational development programs.