Effect of leuprorelin in bulbar function of spinal and bulbar muscular atrophy patients: observational study for 1 year

Functional Outcome Measures to Optimize Drug Development in Spinal and Bulbar Muscular Atrophy: Results From a Meta-Analysis of the Global SBMA Dataset

BACKGROUND AND OBJECTIVES

Spinal and bulbar muscular atrophy (SBMA) is a rare, slowly progressive, and debilitating disease without effective treatments available. Lack of reliable biomarkers and sensitive outcome measures makes clinical research conduct challenging. The primary objective of this study was to identify clinically meaningful and statistically sensitive outcome measures enabling the evaluation of therapeutic interventions in late-stage clinical trials.

METHODS

This study was a meta-analysis of SBMA patient-level data from 6 observational studies conducted in Italy, South Korea, Denmark, United Kingdom, Japan, and United States. Patients with confirmed SBMA genetic diagnosis and differing severity were enrolled following individual site protocols. Routine assessments were performed longitudinally for approximately 3 years, including one or more clinical outcomes, such as SBMA functional rating scale (SBMAFRS), 6-minute walk test (6MWT), quantitative muscle testing (QMT), and Adult Myopathy Assessment Tool (AMAT). A modified scale, m-SBMAFRS, was derived by including only lower limb and trunk subscales having lower variability and larger effect size compared with the others. Changes from baseline at follow-up time points were calculated for all measures, and percent changes using random slope models were calculated to compare clinical measure performances. A survey conducted on 196 patients by the Coordination of Rare Diseases at Sanford (CoRDS), elucidating the impact of specific disease aspects on patients' lives, was also evaluated to corroborate these research outcomes.

RESULTS

This global SBMA dataset analyzed data from 278 men (mean age = 59.7 ± 10.8 years, mean disease duration = 17.7 ± 11.9 years). Patients progressed on SBMAFRS (-4.7 ± 6.2 points after 38 months with 1-year standard response mean [SRM] = 0.6) and 6MWT (distance walked decreased by -53.2 ± 87.0 meters after 26 months with 1-year SRM = 0.5). These measures showed lower variability and larger effect size than AMAT and QMT (1-year SRM = 0.1 and -0.2, respectively) and confirmed SBMA linear progression across a range of disease stages. The m-SBMAFRS also showed a significant yearly decline of 0.9 ± 1.5 points (SRM = 0.6) and more consistent performance with less variability across clinical sites. The CoRDS survey confirmed the relevance of lower limb strength and mobility, which correlated with higher quality-of-life metrics and were reported by patients as predominant disease issues.

DISCUSSION

We generated a comprehensive global SBMA dataset, enabling the identification of sensitive functional end points for clinical trials. Possible limitations relate to data collection nuances across sites that a single study protocol could override.

Efficacy of leuprorelin in spinal and bulbar muscular atrophy: a 3-year observational study

OBJECTIVE

This study aimed to investigate the long-term effects and functional outcomes of androgen suppression therapy using leuprorelin among Korean patients with spinal and bulbar muscular atrophy (SBMA).

METHODS

This observational study enrolled patients with genetically confirmed SBMA who provided informed consent. Leuprorelin was administered via subcutaneous injection every 12 weeks. The primary outcome measure was the change in total Spinal and Bulbar Muscular Atrophy Functional Rating Scale (SBMAFRS) scores.

RESULTS

A total of 48 SBMA patients were evaluated in this study. Among them, 39 patients underwent androgen suppression therapy over a 3-year period. The total SBMAFRS score decreased from 41.72 ± 5.55 to 36.74 ± 7.74 (p < 0.001) in patients who completed their treatment. The subgroup with a baseline SBMAFRS score of ≥ 42 had a significantly lower decline in SBMAFRS score than did those with a baseline SBMAFRS score of ≤ 41. We determined that at a baseline, SBMAFRS cutoff value of 41.5 could predict good prognosis, with a corresponding area under the curve of 0.689.

CONCLUSION

Despite androgen suppression therapy, all enrolled participants exhibited a decrease in the overall SBMAFRS score. However, those with a baseline SBMAFRS of ≥ 42 showed a mild decrease in scores, indicating a more favorable prognosis. These findings suggest that a higher baseline motor function was a key prognostic indicator in SBMA treatment and that initiating early leuprorelin treatment in patients with high baseline function may lead to good clinical outcomes.

Whole-Body Muscle Magnetic Resonance Imaging in 81 Patients with Spinal and Bulbar Muscular Atrophy: A Prospective Study

OBJECTIVE

Spinal and bulbar muscular atrophy (SBMA) is characterized by slow, progressive bulbar and limb muscle weakness; however, the pattern of progression of muscle fat infiltration remains unclear. We assessed the progression of muscle involvement in 81 patients with SBMA using whole-body muscle magnetic resonance imaging (MRI), alongside clinical and laboratory findings.

METHODS

This prospective study included patients with genetically confirmed SBMA who underwent whole-body muscle MRI. We analyzed muscle fat infiltration and the pattern of involved muscles using cluster analysis, visualizing the sequential progression of fat infiltration. Muscle clusters demonstrated correlation with clinical scales and laboratory findings. Additionally, linear regression analysis was performed to identify the MRI section most strongly associated with 6-minute walk test (6MWT).

RESULTS

We included 81 patients with SBMA (age = 54.3 years). After categorizing the patients into 6 clusters based on the pattern of muscle fat infiltration, we observed that muscle involvement began in the posterior calf and progressed to the posterior thigh, pelvis, trunk, anterior thigh, medial thigh, anterior calf, and upper extremity muscles. These muscle clusters correlated significantly with disease duration (τ = 0.47, p < 0.001), 6MWT (τ = -0.49, p < 0.001), and serum creatinine level (τ = -0.46, p < 0.001). The whole-body MRI indicated the thigh as the section most significantly correlated with 6MWT.

INTERPRETATION

We used whole-body muscle MRI to determine the sequential progression of the fat infiltration in SBMA. Our findings may enable the identification of objective and reliable imaging outcome measures in the study of the natural history or future clinical trials of SBMA. ANN NEUROL 2024;95:596-606.

Incidence and prevalence of Spinal and bulbar muscular atrophy in South Korea: a nationwide population-based study

Spinal and bulbar muscular atrophy (SBMA), or Kennedy's disease, is a rare X-linked neuromuscular disorder predominantly affecting males and caused by a mutation in the androgen receptor gene. The epidemiology and comorbidities associated with SBMA in different ethnicities remain poorly understood. This study investigated the prevalence, incidence, and comorbidities associated with SBMA in the South Korean population using the Health Insurance Review and Assessment Service (HIRA) database. We retrospectively reviewed diagnosed cases of SBMA (G12.25 code of the Korean Classification of Diseases-7th edition) registered from January 1, 2016, to December 31, 2019, to calculate incidence and prevalence rates and concomitant comorbidities. Additionally, we surveyed SBMA patients (questionnaire group) visiting our clinic in 2022 to compare comorbidities with the HIRA data. The mean incidence rate of SBMA in the Korean population was 0.36/100,000 males from 2018 to 2019, while the prevalence rate was approximately 0.46/100,000 males from 2016 to 2019. The most common comorbidities identified in HIRA were gastritis and duodenitis (99.7%), gastroesophageal reflux (90.5%), hyperlipidemia (88.4%), and liver disorders (75.2%), which showed similar results in the questionnaire group. Additionally, gastric cancer was the most common type of cancer reported in SBMA in South Korea; although indeterminate, age-related factors may contribute to the development of cancer in these patients. Our findings provide valuable insights into the epidemiology and associated comorbidities of SBMA within the Korean population, which could inform clinical practice and future clinical research.

Bicalutamide and Trehalose Ameliorate Spinal and Bulbar Muscular Atrophy Pathology in Mice

Spinal and bulbar muscular atrophy (SBMA) is characterized by motor neuron (MN) degeneration that leads to slowly progressive muscle weakness. It is considered a neuromuscular disease since muscle has a primary role in disease onset and progression. SBMA is caused by a CAG triplet repeat expansion in the androgen receptor (AR) gene. The translated poly-glutamine (polyQ) tract confers a toxic gain of function to the mutant AR altering its folding, causing its aggregation into intracellular inclusions, and impairing the autophagic flux. In an in vitro SBMA neuronal model, we previously showed that the antiandrogen bicalutamide and trehalose, a natural disaccharide stimulating autophagy, block ARpolyQ activation, reduce its nuclear translocation and toxicity and facilitate the autophagic degradation of cytoplasmic AR aggregates. Here, in a knock-in SBMA mouse model (KI AR113Q), we show that bicalutamide and trehalose ameliorated SBMA pathology. Bicalutamide reversed the formation of the AR insoluble forms in KI AR113Q muscle, preventing autophagic flux blockage. We demonstrated that apoptosis is activated in KI AR113Q muscle, and that both compounds prevented its activation. We detected a decrease of mtDNA and an increase of OXPHOS enzymes, already at early symptomatic stages; these alterations were reverted by trehalose. Overall, bicalutamide and/or trehalose led to a partial recovery of muscle morphology and function, and improved SBMA mouse motor behavior, inducing an extension of their survival. Thus, bicalutamide and trehalose, by counteracting ARpolyQ toxicity in skeletal muscle, are valuable candidates for future clinical trials in SBMA patients.

Diffuse Leukoplakia of the Bladder Ostium-Sparing in Patient Treated with Leuprorelin for Breast Cancer

Case

A 55-year-old woman came to our attention in April 2020 referring haematuria, frequency and urgency. The patient referred previous treatment with leuprorelin 3.75 mg/2 ml for breast cancer three years ago. Urine culture was performed and resulted always negative for pathogens. Cystoscopy revealed a whitish plaque lesion on the fundus, dome, trigone, and left lateral wall of the bladder. Histology of the biopsy confirmed the diagnosis of leukoplakia of the bladder. The plan is to follow her up repeating a cystoscopy every three months and biopsy in 6 months. Literature search revealed very little information on pathogenesis and prognosis of this condition due to its rare occurrence. The main objective of our case study was to describe individual situation of a woman affected by diffuse leukoplakia of the bladder ostium-sparing with a previous treatment with leuprorelin 3.75 mg/2 ml for breast cancer and to show safety of follow-up by cystoscopy and biopsy.

Conclusions

We showed a case of a woman treated with leuprorelin and with diffuse leukoplakia of the bladder. We support the recommended long-term follow-up and surveillance based on the literature review by cystoscopy with or without biopsy.