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The following is a summary of “Functional Outcome Measures to Optimize Drug Development in Spinal and Bulbar Muscular Atrophy: Results From a Meta-Analysis of the Global SBMA Dataset,” published in the November 2024 issue of Neurology by Huggett et al.    

Spinal and Bulbar Muscular Atrophy (SBMA) is a rare, progressive disease that affects individuals’ mobility and strength, with limited treatment options available. The need for reliable biomarkers and outcome measures complicates clinical research.  

Researchers conducted a retrospective study identifying sensitive outcome measures for evaluating therapeutic interventions in late-stage clinical trials for people living with SBMA.  

They analyzed data from 278 men with SBMA across 6 countries (Italy, South Korea, Denmark, United Kingdom, Japan, United States) who underwent longitudinal assessments over approximately 3 years. The measures included the SBMA Functional Rating Scale (SBMAFRS), 6-minute walk test (6MWT), quantitative muscle testing (QMT), and Adult Myopathy Assessment Tool (AMAT). Random slope models were used to assess changes and percent changes from baseline at follow-up. A survey was also reviewed on 196 individuals with SBMA to assess the disease’s impact on QoL.  

The results showed that individuals with SBMA experienced progression on the SBMAFRS (−4.7 ± 6.2 points after 38 months, 1-year standard response mean [SRM] = 0.6) and 6MWT (distance decreased by −53.2 ± 87.0 meters after 26 months, 1-year SRM = 0.5). The measures showed lower variability and larger effect size than AMAT and QMT (1-year SRM = 0.1 and −0.2, respectively), confirming linear disease progression. The modified SBMAFRS (m-SBMAFRS) showed a yearly decline of 0.9 ± 1.5 points (SRM = 0.6) with consistent performance across clinical sites. The Coordination of Rare Diseases at Sanford (CoRDS) survey confirmed that lower limb strength and mobility were critical for individuals’ QoL.  

They concluded that the global SBMA dataset identified sensitive functional endpoints for clinical trials for people living with SBMA, though variations in data collection across sites may affect results.  

Source: neurology.org/doi/10.1212/WNL.0000000000210088