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.).

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.

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.

Effects of Acetyl-DL-Leucine on Ataxia and Downbeat-Nystagmus in Six Patients With Ataxia Telangiectasia

BACKGROUND

There is no authorized treatment for ataxia telangiectasia (AT). As cerebellar symptoms of storage diseases were improved by acetyl-DL-leucine (ADLL), the authors hypothesized a symptomatic and disease-modifying effect in AT upon supplementation with ADLL.

METHODS

Six patients were treated with ADLL 3 g/day for 1 week followed by 5g/day for 3 weeks to 1 year. Cerebellar ataxia was evaluated by validated scales. Gaze-holding, saccades and smooth pursuit were examined by video-oculography. Measurements took place at baseline, at 1 month of therapy in 5 patients, and after 6 and 12 months in 1 patient.

RESULTS

The Scale for Assessment and Rating of Ataxia changed from the baseline, mean, (SD, min-max) of 22.1 (5.88, 11-28.5) to 18 points (5.39, 8.5-23.5) after 1 month on medication (P = .0028). All patients demonstrated gaze-holding deficits; 3 patients had central-position downbeat-nystagmus. Mean slow-phase velocity of this nystagmus with the gaze straight-ahead changed from 5.57°/s (1.8, 3.53-6.99) to 4.7°/s (0.79, 3.97-5.56) after 1 month on treatment (1.35, -2.56-4.17) (P = .046).

INTERPRETATION

ADLL may improve ataxia and ocular stability in AT patients, while the molecular basis still remains to be elucidated. A multicentric, rater-blinded, phase II trial currently investigates the effects of acetyl-L-leucine in AT (NCT03759678).

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.

A cross-sectional, prospective ocular motor study in 72 patients with Niemann-Pick disease type C

Objective

To characterize ocular motor function in patients with Niemann‐Pick disease type C (NPC).

Methods

In a multicontinental, cross‐sectional study we characterized ocular‐motor function in 72 patients from 12 countries by video‐oculography. Interlinking with disease severity, we also searched for ocular motor biomarkers. Our study protocol comprised reflexive and self‐paced saccades, smooth pursuit, and gaze‐holding in horizontal and vertical planes. Data were compared with those of 158 healthy controls (HC).

Results

Some 98.2% of patients generated vertical saccades below the 95% CI of the controls’ peak velocity. Only 46.9% of patients had smooth pursuit gain lower than that of 95% CI of HC. The involvement in both downward and upward directions was similar (51°/s (68.9, [32.7–69.3]) downward versus 78.8°/s (65.9, [60.8–96.8]) upward). Horizontal saccadic peak velocity and latency, vertical saccadic duration and amplitude, and horizontal position smooth pursuit correlated best to disease severity. Compensating strategies such as blinks to elicit saccades, and head and upper body movements to overcome the gaze palsy, were observed. Vertical reflexive saccades were more impaired and slower than self‐paced ones. Gaze‐holding was normal. Ocular‐motor performance depended on the age of onset and disease duration.

Conclusions

This is the largest cohort of NPC patients investigated for ocular‐motor function. Vertical supranuclear saccade palsy is the hallmark of NPC. Vertical upward and downward saccades are equally impaired. Horizontal saccadic peak velocity and latency, vertical saccadic duration and amplitude, and horizontal position smooth pursuit can be used as surrogate parameters for clinical trials. Compensating strategies can contribute to establishing a diagnosis.

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, ocular motor, and imaging profile of Niemann-Pick type C heterozygosity

Objective

To characterize subclinical abnormalities in asymptomatic heterozygote NPC1 mutation carriers as markers of neurodegeneration.

Methods

Motor function, cognition, mood, sleep, and smell function were assessed in 20 first-degree heterozygous relatives of patients with Niemann-Pick disease type C (NPC) (13 male, age 52.7 ± 9.9 years). Video-oculography and abdominal ultrasound with volumetry were performed to assess oculomotor function and size of liver and spleen. NPC biomarkers in blood were analyzed. 18F-fluorodesoxyglucose PET was performed (n = 16) to detect patterns of brain hypometabolism.

Results

NPC heterozygotes recapitulated characteristic features of symptomatic NPC disease and demonstrated the oculomotor abnormalities typical of NPC. Hepatosplenomegaly (71%) and increased cholestantriol (33%) and plasma chitotriosidase (17%) levels were present. The patients also showed signs seen in other neurodegenerative diseases, including hyposmia (20%) or pathologic screening for REM sleep behavior disorder (24%). Cognitive function was frequently impaired, especially affecting visuoconstructive function, verbal fluency, and executive function. PET imaging revealed significantly decreased glucose metabolic rates in 50% of participants, affecting cerebellar, anterior cingulate, parieto-occipital, and temporal regions, including 1 with bilateral abnormalities.

Conclusion

NPC heterozygosity, which has a carrier frequency of 1:200 in the general population, is associated with abnormal brain metabolism and functional consequences. Clinically silent heterozygous gene variations in NPC1 may be a risk factor for late-onset neurodegeneration, similar to the concept of heterozygous GBA mutations underlying Parkinson disease.

Do heterozygous mutations of Niemann-Pick type C predispose to late-onset neurodegeneration: a review of the literature

BACKGROUND/METHODS

Monogenic diseases are important models for the study of neurodegenerative diseases, such as Parkinson's disease (PD) and dementia. Notably, for some disorders, homozygosity is associated with a complex metabolic disease, while heterozygosity predisposes to late-onset neurodegeneration. For instance, biallelic glucocerebrosidase gene mutations cause Gaucher's disease, while heterozygous mutations are a common genetic risk factor for late-onset PD. Little is known about similar risks of related diseases, such as Niemann-Pick type C (NPC). Given that both conditions map into related, i.e., lysosomal, pathways, we hypothesize a similar risk of single-NPC gene mutations. Indeed, there is increasing evidence based on clinical observations in humans and animal studies. Here we review the current knowledge of NPC heterozygosity.

RESULTS

Family history studies suggest a high proportion of late-onset neurodegenerative diseases in NPC families. We identified 19 cases with heterozygous NPC mutations in the literature who presented with a neurodegenerative disease, including levodopa-responsive PD, atypical parkinsonism (PSP, CBD), dystonia or dementia with a mean age at onset of about 57 years (range 8-87). Consistent splenomegaly and mildly abnormal filipin staining results have also been reported in heterozygous gene mutation carriers. Imaging and pathological data support this notion.

DISCUSSION/CONCLUSION

This finding has wider implications in so far as NPC-related forms of Parkinsonian syndromes, dementia, motor neuron disease and other neurodegenerative disorders may benefit from NPC-mechanistic therapies, in particular related to lysosomal dysfunction. Further research is warranted to generate systematic data of heterozygous mutation carriers, including longitudinal data.

An algorithm as a diagnostic tool for central ocular motor disorders, also to diagnose rare disorders

Background

Recently an increasing number of digital tools to aid clinical work have been published. This study’s aim was to create an algorithm which can assist physicians as a “digital expert” with the differential diagnosis of central ocular motor disorders, in particular in rare diseases.

Results

The algorithm’s input consists of a maximum of 60 neurological and oculomotor signs and symptoms. The output is a list of the most probable diagnoses out of 14 alternatives and the most likely topographical anatomical localizations out of eight alternatives. Positive points are given for disease-associated symptoms, negative points for symptoms unlikely to occur with a disease. The accuracy of the algorithm was evaluated using the two diagnoses and two brain zones with the highest scores. In a first step, a dataset of 102 patients (56 males, 48.0 ± 22 yrs) with various central ocular motor disorders and underlying diseases, with a particular focus on rare diseases, was used as the basis for developing the algorithm iteratively. In a second step, the algorithm was validated with a dataset of 104 patients (59 males, 46.0 ± 23 yrs). For 12/14 diseases, the algorithm showed a sensitivity of between 80 and 100% and the specificity of 9/14 diseases was between 82 and 95% (e.g., 100% sensitivity and 75.5% specificity for Niemann Pick type C, and 80% specificity and 91.5% sensitivity for Gaucher’s disease). In terms of a topographic anatomical diagnosis, the sensitivity was between 77 and 100% for 4/8 brain zones, and the specificity of 5/8 zones ranged between 79 and 99%.

Conclusion

This algorithm using our knowledge of the functional anatomy of the ocular motor system and possible underlying diseases is a useful tool, in particular for the diagnosis of rare diseases associated with typical central ocular motor disorders, which are often overlooked.

Electronic supplementary material

The online version of this article (10.1186/s13023-019-1164-8) contains supplementary material, which is available to authorized users.

No Evidence of a Contribution of the Vestibular System to Frequent Falls in Progressive Supranuclear Palsy

Background and Purpose

Conflicting results about vestibular function in progressive supranuclear palsy (PSP) prompted a systematic examination of the semicircular canal function, otolith function, and postural stability.

Methods

Sixteen patients with probable PSP [9 females, age=72±6 years (mean±SD), mean disease duration=3.6 years, and mean PSP Rating Scale score=31] and 17 age-matched controls were examined using the video head impulse test, caloric testing, ocular and cervical vestibular evoked myogenic potentials (o- and cVEMPs), video-oculography, and posturography.

Results

There was no evidence of impaired function of the angular vestibulo-ocular reflex (gain=1.0±0.1), and caloric testing also produced normal findings. In terms of otolith function, there was no significant difference between PSP patients and controls in the absolute peakto-peak amplitude of the oVEMP (13.5±7.2 µV and 12.5±5.6 µV, respectively; p=0.8) or the corrected peak-to-peak amplitude of the cVEMP (0.6±0.3 µV and 0.5±0.2 µV, p=0.3). The total root-mean-square body sway was significantly increased in patients with PSP compared to controls (eyes open/head straight/hard platform: 9.3±3.7 m/min and 6.9±2.1 m/min, respectively; p=0.032). As expected, the saccade velocities were significantly lower in PSP patients than in controls: horizontal, 234±92°/sec and 442±66°/sec, respectively; downward, 109±105°/sec and 344±72°/sec; and upward, 121±110°/sec and 348±78°/sec (all p<0.01).

Conclusions

We found no evidence of impairment of either high- or low-frequency semicircular function or otolith organ function in the examined PSP patients. It therefore appears that other causes such as degeneration of supratentorial pathways lead to postural imbalance and falls in patients with PSP.

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

BACKGROUND

Niemann-Pick disease type C (NPC) is a lysosomal storage disease with a heterogeneous neurodegenerative clinical course. Multiple therapies are in clinical trials and inclusion criteria are currently mainly based on age and neurological signs, not taking into consideration differential individual rates of disease progression.

RESULTS

In this study, we have evaluated a simple metric, denoted annual severity increment score (ASIS), that measures rate of disease progression and could easily be used in clinical practice. We show that ASIS is stable over several years and can be used to stratify patients for clinical trials. It achieves greater homogeneity of the study cohort relative to age-based inclusion and provides an evidence-based approach for establishing inclusion/exclusion criteria. In addition, we show that ASIS has prognostic value and demonstrate that treatment with an experimental therapy - acetyl-DL-leucine - is associated with a reduction in ASIS scores.

CONCLUSION

ASIS has the potential to be a useful metric for clinical monitoring, trial recruitment, for prognosis and measuring response to therapy.

Oculomotor and Vestibular Findings in Gaucher Disease Type 3 and Their Correlation with Neurological Findings

Objectives

To evaluate the function of the oculomotor and vestibular systems and to correlate these findings with the clinical status of patients with Gaucher disease type 3 (GD3). The goal of this cross-sectional and longitudinal study was to find oculomotor biomarkers for future clinical trials.

Methods

Twenty-six patients with GD3 were assessed for eligibility and 21 were able to perform at least one task. Horizontal and vertical reflexive saccades, smooth pursuit, gaze-holding, optokinetic nystagmus, and horizontal vestibulo-ocular reflex (VOR) were examined by video-oculography/video-head impulse test and compared concurrently with 33 healthy controls. The Scale for the Assessment and Rating of Ataxia (SARA), the modified Severity Scoring Tool (mSST), and Grooved Pegboard Test (GPT) were administered to assess overall neurological function. Eleven patients were also re-assessed after 1 year.

Results

Nine out of 17 patients exhibited gaze-holding deficits. One patient had upbeat nystagmus. Three patients presented with bilateral abducens palsy in combination with central oculomotor disorders, suggesting a bilateral involvement of the abducens nucleus. Horizontal angular VOR gain was reduced in all patients (0.66 ± 0.37) compared with controls (1.1 ± 0.11, p < 0.001). Most strongly correlated with clinical rating scales were peak velocity of downward saccades (SARA: ρ = −0.752, p < 0.0005; mSST: ρ = −0.611, p = 0.003; GPT: ρ = −0.649, p = 0.005) and duration of vertical saccades (SARA: ρ = 0.806, p < 0.001; mSST: ρ = 0.700, p < 0.0005; GPT: ρ = 0.558, p = 0.02) together with the VOR gain (SARA: ρ = −0.63, p = 0.016; mSST: ρ = −0.725, p = 0.003; GPT: ρ = −0.666, p = 0.004). Vertical smooth pursuit gain decreased significantly at follow-up.

Interpretation

This study shows neuronal degeneration of the brainstem and cerebellum with combined involvement of both supranuclear and nuclear oculomotor structures and the vestibular system in GD3. We also identified oculomotor parameters that correlate with the neurological status and can be used as biomarkers in future clinical trials.