Satellos Reports Interim Phase 2 TRAILHEAD Data: SAT‑3247 Shows Muscle Composition Gains in Adults with DMD

Satellos Bioscience reported six-month interim data from the ongoing Phase 2 TRAILHEAD trial showing that its investigational therapy SAT-3247 demonstrated encouraging improvements in muscle composition, upper-limb function, biomarkers of muscle damage, and patient-reported outcomes in adults with Duchenne muscular dystrophy (DMD), while maintaining a favourable safety profile. The findings were presented at the 18th International Congress on Neuromuscular Diseases (ICNMD 2026).

The interim analysis included four adults aged 21–28 years who had previously completed the Phase 1a/b CL-101 study (NCT06565208). Although limited by the small sample size, the results demonstrated consistent stability or improvement across multiple clinically relevant measures in a patient population that typically experiences progressive muscle deterioration.

Clinical Trial Design

The TRAILHEAD study (NCT06867107) is an ongoing multicentre, open-label Phase 2 trial evaluating the long-term safety, tolerability, and preliminary efficacy of SAT-3247 in up to 30 males aged 16 years and older with genetically confirmed DMD across Australia and the United States. Participants receive 60 mg of oral SAT-3247 on a 5-days-on/2-days-off schedule for up to 12 months. The primary endpoint is change in biceps brachii muscle fat fraction measured by magnetic resonance imaging (MRI), while secondary and exploratory endpoints include muscle strength, upper-limb function, physical activity, pulmonary function, quality of life, and biomarkers of muscle regeneration.

Interim Efficacy Findings

All four participants experienced reductions in MRI-measured muscle fat fraction, with mean fat fraction improving by 3.7%, from 49.7% at baseline to 46.0% after six months, suggesting improved muscle composition.

Participants also showed improvements in TE99C, a wearable sensor-based measure of maximum upper-limb effort assessed using the SYSNAV Syde® system. Mean TE99C increased by approximately 34%, from 16.1 joules/kg at CL-101 baseline to 21.6 joules/kg after six months.

Upper-extremity muscle strength, including handgrip strength and handheld dynamometry of the elbow and shoulder, remained stable throughout treatment. Notably, the near-doubling of handgrip strength achieved during the earlier CL-101 study was maintained through six months of TRAILHEAD. Mean creatine kinase (CK), a biomarker of muscle damage, declined 38%, from 2,130 U/L at CL-101 baseline to 1,315 U/L after six months.

Additional findings showed one-point improvements in Performance of the Upper Limb (PUL) 2.0 scores in two participants, while scores remained stable in the other two. Mean PedsQL-MFS fatigue-related quality-of-life scores increased by 6.94 points, from 71.53 to 78.47.

Safety Findings

SAT-3247 maintained a favourable safety and tolerability profile. No serious treatment-emergent adverse events or treatment discontinuations were reported, and participants achieved 100% treatment compliance over an average of 186 days, consistent with findings from the CL-101 study.

Clinical Significance

Dr. Perry Shieh, Professor of Neurology and Paediatrics at the David Geffen School of Medicine at UCLA, noted that evaluating therapies in adults with DMD is particularly challenging because of advanced muscle loss and limited regenerative capacity. Despite the small study size, he said the consistent improvements across muscle composition, strength, effort, quality of life, and safety support continued evaluation of SAT-3247 in both the TRAILHEAD and BASECAMP studies.

Frank Gleeson, Co-founder and Chief Executive Officer of Satellos Bioscience, said the interim results further support the biological activity of SAT-3247. The company remains on track to complete enrolment in the paediatric BASECAMP Phase 2 study and initiate U.S. clinical sites for TRAILHEAD during the third quarter of 2026.

 About SAT-3247

SAT-3247 is an investigational oral small-molecule therapy designed to restore skeletal muscle regeneration through AAK1 inhibition. Because it acts through a dystrophin-independent mechanism, it has the potential to treat patients with DMD regardless of mutation subtype.

Although based on only four participants, the interim TRAILHEAD results provide encouraging early evidence that SAT-3247 may improve muscle composition, reduce biomarkers of muscle injury, and maintain upper-limb strength in adults with DMD. Confirmation in the full TRAILHEAD study and the ongoing randomized BASECAMP trial will be important to determine its potential as a mutation-independent, disease-modifying therapy.

Reference

Satellos Bioscience Inc. – Satellos Reports Six-Month Interim TRAILHEAD Data Showing Reduced Muscle Fat Fraction, Increased Effort, Stable Strength, Lower CK and Favorable Safety Profile in DMD Adults Treated with SAT-3247