Gabriele Nunes Souza

A Randomized, Phase 2 Clinical Trial of Lithium Carbonate in Machado-Joseph Disease

Because lithium exerts neuroprotective effects in preclinical models of polyglutamine disorders, our objective was to assess the safety and efficacy of lithium carbonate (0.5‐0.8 milliequivalents per liter) in patients with Machado‐Joseph disease (spinocerebellar ataxia type 3 [MJD/SCA3]).

Body mass index is inversely correlated with the expanded CAG repeat length in SCA3/MJD patients.

Spinocerebellar ataxia type 3, also known as Machado–Joseph disease (SCA3/MJD), is an autosomal dominant neurodegenerative disorder with no current treatment. We aimed to evaluate the body mass index (BMI) of patients with SCA3/MJD and to assess the correlations with clinical, molecular, biochemical, and neuroimaging findings. A case–control study with 46 SCA3/MJD patients and 42 healthy, non-related control individuals with similar age and sex was performed. Clinical evaluation was done with the ataxia scales SARA and NESSCA. Serum insulin, insulin-like growth factor 1 (IGF-1) and magnetic resonance imaging normalized volumetries of cerebellum and brain stem were also assessed. BMI was lower in SCA3/MJD patients when compared to controls (p = 0.01). BMI was associated with NESSCA, expanded CAG repeat number (CAG)n, age of onset, age, disease duration, and serum insulin levels; however, in the linear regression model, (CAG)n was the only variable independently associated with BMI, in an inverse manner (R = −0.396, p = 0.015). In this report, we present evidence that low BMI is not only present in SCA3/MJD, but is also directly related to the length of the expanded CAG repeats, which is the causative mutation of the disease. This association points that weight loss might be a primary disturbance of SCA3/MJD, although further detailed analyses are necessary for a better understanding of the nutritional deficit and its role in the pathophysiology of SCA3/MJD.

Planning future clinical trials in Machado Joseph disease: Lessons from a phase 2 trial

BACKGROUND In a recent phase 2 clinical trial in spinocerebellar ataxia type 3/Machado Joseph disease (SCA3/MJD), a neurogenetic disorder without specific therapy, benefits of lithium carbonate were found only on secondary efficacy outcomes, all related to ataxic features. In order to help designing future studies, we further analyzed the trial data searching for treatment response modifiers and metric properties of spinocerebellar ataxia (SCA) scales. METHODS Efficacy analysis was performed with the Neurological Examination Score for the Assessment of Spinocerebellar Ataxia (NESSCA) and the Scale for the Assessment and Rating of Ataxia (SARA) subscores and with the subgroup of patients with independent gait according to the 8-meter walking-time (8MW). Interactions of clinical/molecular findings with treatment response, minimally important differences (MIDs), and sample size estimations for NESSCA, SARA, Spinocerebellar Ataxia Functional Index (SCAFI) and Composite Cerebellar Functional Score (CCFS) were evaluated. RESULTS 62 SCA3/MJD patients had been randomly assigned (1:1) for the double-blind, placebo-controlled trial. While cerebellar NESSCA (range: 0-7 points) differed between groups 0.64 points (95% CI 0.23 to 1.05, p<0.001) over the whole 48weeks of study, favoring lithium, no effect was found on non-ataxia subscores. Among patients able to perform the 8MW on baseline, NESSCA (p=0.010) and SCAFI (p=0.015) differed between groups favoring lithium. Finally, estimated sample sizes for the scales were provided. CONCLUSION Lithium efficacy on cerebellar NESSCA, and on SCAFI and CCFS in the primary analysis, together with the lack of effect on non-ataxia features suggests that lithium should be tested in phase 3 trials in SCA3/MJD and that ataxia scales should be preferred to multisystem neurological instruments as the primary outcome. The inclusion of early stage patients is advisable in future clinical trials in SCA3/MJD. TRIAL REGISTRATION clinicaltrials.gov identifier: NCT01096082.

Spinocerebellar ataxia type 3/Machado-Joseph disease: segregation patterns and factors influencing instability of expanded CAG transmissions.

Controversies about Mendelian segregation and CAG expansion (CAGexp) instabilities during meiosis in spinocerebellar ataxia type 3/Machado–Joseph disease (SCA3/MJD) need clarification. Additional evidence about these issues was obtained from the cohort of all SCA3/MJD individuals living in South Brazil. A survey was carried out to update information registered since 2001. Deaths were checked with the Public Information System, and data was made anonymous. Anticipation and delta‐CAGexp from parent–offspring pairs, and delta‐CAGexp between siblings were obtained. One hundred and fifty‐nine families (94% of the entire registry) were retrieved, comprising 3725 living individuals as of 2015, 625 of these being symptomatic. Minimal prevalence was 6:100,000. Carriers of a CAGexp represented 65.6% of sibs in the genotyped offspring (p < 0.001). Median instability was larger among paternal than maternal transmissions, and instabilities correlated with anticipation (r = 0.38; p = 0.001). Age of the parent correlated to delta‐CAGexp among 115 direct parent–offspring CAGexp transmissions (ρ = 0.23, p = 0.014). In 98 additional kindreds, the delta‐CAGexp between 269 siblings correlated with their delta‐of‐age (ρ = 0.27, p < 0.0001). SCA3/MJD was associated with a segregation distortion favoring the expanded allele in our cohort. Instability of expansion during meiosis was weakly influenced by the age of the transmitting parent at the time of conception.

Peripheral Oxidative Stress Biomarkers in Spinocerebellar Ataxia Type 3/Machado–Joseph Disease

Objectives Spinocerebellar ataxia type 3/Machado–Joseph disease (SCA3/MJD) is a polyglutamine disorder with no current disease-modifying treatment. Conformational changes in mutant ataxin-3 trigger different pathogenic cascades, including reactive oxygen species (ROS) generation; however, the clinical relevance of oxidative stress elements as peripheral biomarkers of SCA3/MJD remains unknown. We aimed to evaluate ROS production and antioxidant defense capacity in symptomatic and presymptomatic SCA3/MJD individuals and correlate these markers with clinical and molecular data with the goal of assessing their properties as disease biomarkers. Methods Molecularly confirmed SCA3/MJD carriers and controls were included in an exploratory case–control study. Serum ROS, measured by 2′,7′-dichlorofluorescein diacetate (DCFH-DA) as well as superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) antioxidant enzyme activities, levels were assessed. Results Fifty-eight early/moderate stage symptomatic SCA3/MJD, 12 presymptomatic SCA3/MJD, and 47 control individuals were assessed. The DCFH-DA levels in the symptomatic group were 152.82 nmol/mg of protein [95% confidence interval (CI), 82.57–223.08, p < 0.001] higher than in the control and 243.80 nmol/mg of protein (95% CI, 130.64–356.96, p < 0.001) higher than in the presymptomatic group. The SOD activity in the symptomatic group was 3 U/mg of protein (95% CI, 0.015–6.00, p = 0.048) lower than in the presymptomatic group. The GSH-Px activity in the symptomatic group was 13.96 U/mg of protein (95% CI, 5.90–22.03, p < 0.001) lower than in the control group and 20.52 U/mg of protein (95% CI, 6.79–34.24, p < 0.001) lower than in the presymptomatic group and was inversely correlated with the neurological examination score for spinocerebellar ataxias (R = −0.309, p = 0.049). Conclusion Early/moderate stage SCA3/MJD patients presented a decreased antioxidant capacity and increased ROS generation. GSH-Px activity was the most promising oxidative stress disease biomarker in SCA3/MJD. Further longitudinal studies are necessary to identify both the roles of redox parameters in SCA3/MJD pathophysiology and as surrogate outcomes for clinical trials.

Cancer in Machado–Joseph disease patients—low frequency as a cause of death

Since polyglutamine diseases have been related to a reduced risk of cancer, we aimed to study the 15 years cumulative incidence of cancer (CIC) (arm 1) and the proportion of cancer as a cause of death (arm 2) in symptomatic carriers of spinocerebellar ataxia type 3/Machado-Joseph disease (SCA3/MJD). SCA3/MJD and control individuals from our state were invited to participate. A structured interview was performed. CIC as published by the Brazilian National Institute of Cancer, was used as populational control. Causes of death were obtained from the Public Information System on Mortality. We interviewed 154 SCA3/MJD patients and 80 unrelated controls: CIC was 7/154 (4.5%) and 5/80 (6.3%), respectively. The interim analysis for futility showed that the number of individuals required to detect a significant difference between groups (1938) would be three times larger than the existing local SCA3/MJD population (625), for an absolute risk reduction of 1.8%. Then this study arm was discontinued due to lack of power. In the same period, cancer was a cause of death in 9/101 (8.9%) SCA3/MJD and in 52/202 (26.2%) controls, with an absolute reduction risk of 17.3% (OR 0.27, 95%CI 0.13 to 0.58, p = 0.01). A significant reduction of cancer as cause of death was observed in SCA3/MJD, suggesting a common effect to all polyglutamine diseases.

Age at onset prediction in spinocerebellar ataxia type 3 changes according to population of origin

In spinocerebellar ataxia type 3/Machado–Joseph disease (SCA3/MJD), the length of CAG repeat expansions in ATXN3 shows an inverse correlation with age at onset (AO). Recently, a formula for predicting AO based on CAG expansion was developed for European carriers. We tested this formula in SCA3/MJD carriers from distinct origins and developed population‐specific models to predict AO.