Protein biomarker signature in patients with spinal and bulbar muscular atrophy.

Spinal and bulbar muscular atrophy (SBMA) is a slowly progressing disease with limited sensitive biomarkers that support clinical research. We analyzed plasma and serum samples from patients with SBMA and matched healthy controls in multiple cohorts, identifying 40 highly reproducible SBMA-associated proteins out of nearly 3,000 measured. These proteins were robustly enriched in gene sets of skeletal muscle expression and processes related to mitochondria and calcium signaling. Many proteins outperformed currently used clinical laboratory tests (e.g., creatine kinase [CK]) in distinguishing patients from controls and in their correlations with clinical and functional traits in patients. Two of the 40 proteins, Ectodysplasin A2 receptor (EDA2R) and Repulsive guidance molecule A (RGMA), were found to be associated with decreased survival and body weight in a mouse model of SBMA. In summary, we identified what we believe to be a robust and novel set of fluid protein biomarkers in SBMA that are linked with relevant disease features in patients and in a mouse model of disease. Changes in these SBMA-associated proteins could be used as an early predictor of treatment effects in clinical trials.

Rycal S48168 (ARM210) for RYR1-related myopathies: a phase one, open-label, dose-escalation trial.

Background: RYR1-related myopathies (RYR1-RM) are caused by pathogenic variants in the RYR1 gene which encodes the type 1 ryanodine receptor (RyR1). RyR1 is the sarcoplasmic reticulum (SR) calcium release channel that mediates excitation-contraction coupling in skeletal muscle. RyR1 sub-conductance, SR calcium leak, reduced RyR1 expression, and oxidative stress often contribute to RYR1-RM pathogenesis. Loss of RyR1-calstabin1 association, SR calcium leak, and increased RyR1 open probability were observed in 17 RYR1-RM patient skeletal muscle biopsies and improved following ex vivo treatment with Rycal compounds. Thus, we initiated a first-in-patient trial of Rycal S48168 (ARM210) in ambulatory adults with genetically confirmed RYR1-RM. Methods: Participants received 120 mg (n = 3) or 200 mg (n = 4) S48168 (ARM210) daily for 29 days. The primary endpoint was safety and tolerability. Exploratory endpoints included S48168 (ARM210) pharmacokinetics (PK), target engagement, motor function measure (MFM)-32, hand grip and pinch strength, timed functional tests, PROMIS fatigue scale, semi-quantitative physical exam strength measurements, and oxidative stress biomarkers. The trial was registered with clinicaltrials.gov (NCT04141670) and was conducted at the National Institutes of Health Clinical Center between October 28, 2019 and December 12, 2021. Findings: S48168 (ARM210) was well-tolerated, did not cause any serious adverse events, and exhibited a dose-dependent PK profile. Three of four participants who received the 200 mg/day dose reported improvements in PROMIS-fatigue at 28 days post-dosing, and also demonstrated improved proximal muscle strength on physical examination. Interpretation: S48168 (ARM210) demonstrated favorable safety, tolerability, and PK, in RYR1-RM affected individuals. Most participants who received 200 mg/day S48168 (ARM210) reported decreased fatigue, a key symptom of RYR1-RM. These results set the foundation for a randomized, double-blind, placebo-controlled proof of concept trial to determine efficacy of S48168 (ARM210) in RYR1-RM. Funding: NINDS and NINR Intramural Research Programs, NIH Clinical Center Bench to Bedside Award (2017-551673), ARMGO Pharma Inc., and its development partner Les Laboratoires Servier.

Patient-Reported Impact of Symptoms in Spinal and Bulbar Muscular Atrophy.

Background and Objectives: The aim of this study was to determine the frequency and relative importance of symptoms experienced by patients with spinal and bulbar muscular atrophy (SBMA). Methods: We conducted a cross-sectional study of 232 participants with SBMA. Participants provided input regarding 18 themes and 208 symptoms that affect patients with SBMA. Participants were asked about the relative importance of each symptom, and analysis was conducted to determine how age, education, disease duration, CAG repeat length, and ambulation status relate to symptom prevalence. Results: Hip, thigh, or knee weakness (96.5%), fatigue (96.5%), problems with hands and fingers (95.7%), and limitations with walking (95.7%) were the themes with the highest prevalence in the study population. Ambulatory status was associated with the prevalence of 9 of the 14 themes, and CAG repeat length and education were each associated with 4 of 14 themes. The prevalence of fatigue was reduced in those with a lower CAG repeat length and increased with a longer disease duration. Younger patients reported a higher prevalence of emotional issues. Discussion: There are a diversity of themes that are important to patients with SBMA. These themes have a variable level of importance to the population with SBMA and represent clinically meaningful outcome measures for future therapeutic interventions.