Satellos recently attended the International Congress on Neuromuscular Diseases (ICNMD) in Florence, Italy (July 7–11), where they presented six-month interim data from their ongoing TRAILHEAD clinical study evaluating SAT-3247 in young adults with DMD. Read their community letter below or visit their website for more information.
July 23, 2026
Dear Duchenne Muscular Dystrophy (DMD) Community Leaders:
We are writing in response to your request for medical updates from Satellos. Our team at Satellos recently attended the International Congress on Neuromuscular Diseases (ICNMD) held in Florence, Italy between July 7 and 11. During the congress, we shared six-month interim results from our ongoing TRAILHEAD clinical study evaluating SAT-3247 in young adults living with DMD. While we recognize that this is an ongoing study with a small number of participants (n = 4), we believe it is important to share these early findings with transparency, and to speak directly to all of you in the DMD community. It is important to note that SAT-3247 is an investigational therapy that has not been approved by any regulatory authority in any country, and its safety and effectiveness have not yet been established.
What the TRAILHEAD study is and what we observed
TRAILHEAD is an open-label (no placebo) study evaluating our investigational oral small molecule SAT-3247 at a dose of 60 mg, taken once per day on a 5-days-on/2-days-off schedule for up to 12 months, in up to 30 adult males age >16 years who are living with DMD. The four adults (ages 21-28) currently participating in TRAILHEAD are those who had previously completed 28 days of SAT-3247 dosing in our Phase 1a/b CL-101 trial, and who have now been exposed to SAT-3247 for an average of 186 days in total. Across these four participants, the safety and tolerability profile was consistent with prior reports. Changes from baseline in muscle composition, strength, and function were observed and described below.
Safety
Safety and tolerability of SAT-3247 remained consistent with our previous reports. Throughout six months in TRAILHEAD (representing an average of 186 days exposure to SAT-3247), no serious treatment-related adverse events were reported, no participants discontinued treatment because of side effects, and compliance with the SAT-3247 dosing regimen in the study was 100%.
Magnetic resonance imaging (MRI) of muscle composition
MRI showed that all four participants experienced a reduction in muscle fat fraction ranging from -0.9% to -6.2% during five months of SAT-3247 dosing in TRAILHEAD. On average, fat fraction of biceps brachii muscles was reduced from 49.7% at the beginning of TRAILHEAD to 46.0% after five months of treatment, representing an average change of -3.7 percentage points.
Upper limb physical effort
All four TRAILHEAD participants demonstrated an increase in a physical performance measure called TE99C, which uses wearable wrist and ankle sensors called SYSNAV™ Syde devices to measure maximum effort generated during at-home daily activities. Using these limb sensors, we observed that total effort achieved by all four current participants was increased from the beginning of the CL-101 Phase 1a/b study to the six-month observation of the TRAILHEAD study. On average, total physical effort increased from 16.1 joules/kg at the beginning of the CL-101 study to 21.6 joules/kg after six months in TRAILHEAD, representing a change of 34%.
Muscle strength
Consistent with what we have previously reported, participants maintained stable upper extremity strength throughout six months of follow-up in TRAILHEAD, as indicated by dynamometry assessments of hand grip, elbow, and shoulder strength. The stability of muscle strength includes the near-doubling of handgrip strength that we previously reported from our initial 28-day CL-101 Phase 1a/b study of SAT-3247 (accompanying figure provided).
Blood markers of muscle damage
Previously, we have shared observations that several proteins in blood samples obtained from our CL-101 Phase 1a/b participants that indicate muscle damage (proteins released from the damaged muscle into the blood), including some that are recognized in the context of DMD, were reduced during 15-days of SAT-3247 dosing. Last week during ICNMD, we also reported new findings that blood levels of creatine kinase (CK), which is another common assessment of muscle damage in DMD, were also reduced over five months of SAT-3247 dosing in TRAILHEAD by an average of 38% compared to levels observed in the CL-101 study. The significance of blood CK levels in these participants is an active area of exploration for us.
Additional upper-limb assessment and quality-of-life
Like many clinical trials in DMD, we also used the Performance of the Upper Limb (PUL 2.0) to evaluate upper-limb function of TRAILHEAD participants. Overall, average PUL 2.0 scores remained stable between TRAILHEAD baseline (score = 21.8) and 6-month (score = 22.3) assessments, with two participants experiencing one-point improvements and two participants maintaining stable scores. In the natural history of DMD, PUL 2.0 scores are expected to decline over time.
Additionally, we reported for the first time our ongoing assessment of participant-reported fatigue and quality of life using the adapted Pediatric Quality of Life Multidimensional Fatigue Scale (PedsQL-MFS). Mean PedsQL-MFS scores increased 6.94 points from CL-101 baseline (score = 71.53) to month 6 in TRAILHEAD (score = 78.47). PedsQL-MFS scoring ranges from 0-100 points, with higher scores reflecting less fatigue and greater quality of life.
Looking ahead
Our observations to date in the CL-101 and TRAILHEAD studies are based on only four participants and should be interpreted cautiously. Our team at Satellos Bioscience remains committed to the DMD community. We recognize that every advance in research, treatment, and care is only possible because of the strength, courage, and commitment of individuals and families who selflessly share their experience and volunteer to participate in clinical research. As such, we wish to thank every person living with DMD, every family member, every caregiver, every advocate, every investigator, every healthcare professional, and every advisor for your partnership, resilience, and support during this journey. We are committed to advancing our science responsibly and we encourage anyone who is interested to review the study information posted on ClinicalTrials.gov (NCT06867107). As you requested, we will share updates with openness and transparency as our program progresses.
Sincerely on behalf of the Satellos Bioscience Team,
Bill Aschenbach, Head of Medical Affairs and Patient Advocacy
ABOUT SAT-3247
SAT-3247 is an investigational, proprietary, oral, small molecule drug candidate being developed by Satellos as a novel approach to regenerating skeletal muscle lost in DMD and other degenerative muscle diseases or injury conditions. Satellos is advancing SAT-3247 as a potential treatment for DMD that is independent of dystrophin regardless of exon mutation status, with ongoing Phase 2 clinical studies, including TRAILHEAD, an openlabel study in adult participants, and BASECAMP, a global, randomized, placebo-controlled study in pediatric participants.
ABOUT SATELLOS BIOSCIENCE INC.
Satellos is a clinical-stage drug development company advancing SAT-3247, a first-of-itskind, orally administered small molecule therapy designed to enhance the body’s natural muscle repair and regeneration process in degenerative muscle diseases. SAT-3247 is being evaluated as a potentially disease-modifying treatment, initially for DMD, in two Phase 2 clinical trials: BASECAMP in pediatrics and TRAILHEAD in adults. SAT-3247 targets AAK1, a protein that is a key regulator of the body’s natural muscle repair and regeneration biology, which Satellos discovered is disrupted in DMD and other degenerative conditions. By inhibiting AAK1, SAT-3247 is designed to re-establish a critical biochemical signal needed to guide this process, in a dystrophin-independent manner. This mechanistic feature offers SAT-3247 the potential for broad applicability as either a stand-alone treatment to potentially enhance muscle and function, or as adjunctive therapy alongside other approaches. Satellos has identified additional degenerative muscle diseases where enhancing muscle repair and regeneration may have therapeutic benefit and plans to pursue these opportunities in future clinical development. For more information, visit www.satellos.com.