Satellos Bioscience (NASDAQ:MSLE) said interim six-month data from its ongoing TRAILHEAD study showed encouraging safety and efficacy signals for SAT-3247, its investigational therapy for Duchenne muscular dystrophy, in a small cohort of adult participants.
The company reported results from four adults with Duchenne muscular dystrophy, or DMD, ages 21 to 28, who had previously completed the 28-day CL-101 study and then enrolled in TRAILHEAD. Chief Medical Officer Dr. Wildon Farwell said the data through day 140 of TRAILHEAD, representing roughly six months of overall exposure across CL-101 and TRAILHEAD, showed stability or improvement across several measures, including muscle fat fraction, upper limb activity, strength, biomarkers and patient-reported fatigue.
Safety Profile Remained Clean in Interim Data
In TRAILHEAD, participants received 60 milligrams of SAT-3247 orally on a five-days-on, two-days-off schedule. Farwell said that as of May 18, 2026, all reported adverse events were mild or moderate. The company reported no serious adverse events, no adverse events leading to withdrawal or discontinuation, and 100% treatment compliance.
Participants had achieved more than 186 days of mean drug exposure across CL-101 and TRAILHEAD. Farwell said the safety and tolerability findings were consistent with previously reported data and “continue to strongly support the clinical development of SAT-3247 in DMD and other indications with serious muscle disease.”
Company Reports Improvement in Muscle Fat Fraction
Satellos said all four participants showed a decline, or improvement, in biceps brachii muscle fat fraction as measured by MRI from TRAILHEAD baseline to day 140. The mean fat fraction improved by 3.7 percentage points, from 49.7% at baseline to 46.0% at day 140, with individual changes ranging from 0.9% to 6.2%.
Farwell said published natural history data show that muscle fat fraction in adults with DMD typically worsens by about 5.9% per year without treatment. He characterized the observed improvement across all four participants as “a meaningful and encouraging objective signal of biologic activity” in a difficult-to-treat adult DMD population.
The company also reported improvement in an upper limb activity measure known as TE99c, or total effort at the 99th percentile, which is collected using the Sysnav ActiMyo wearable device. Farwell said all four participants showed an increase from CL-101 baseline to TRAILHEAD month six, with mean improvement of approximately 5.5 joules per kilogram, or about 34%.
Strength, Function and Biomarker Measures
Across dynamometry measures, including handgrip strength and strength measured at the elbow and shoulder, Satellos said participants demonstrated stability through month six of TRAILHEAD. Farwell noted that a near doubling of handgrip strength first reported in the earlier CL-101 study was maintained through month six, despite a roughly seven- to 11-month treatment gap between CL-101 and TRAILHEAD.
The company also reported that mean creatine kinase, a biomarker of muscle damage, declined 38% from CL-101 baseline, falling from 2,130 units per liter to 1,315 units per liter at month six of TRAILHEAD.
On the Performance of the Upper Limb assessment, two participants improved by one point and two remained stable from TRAILHEAD baseline through day 140. On the PedsQL Multidimensional Fatigue Scale, adapted for adults in the study, the mean score increased by 6.94 points, from 71.53 to 78.47, which Farwell said may suggest less fatigue and improved quality of life.
BASECAMP Readout Expected in Fourth Quarter
Chief Executive Officer Frank Gleeson said the company’s strategy is to first evaluate SAT-3247 in adults with DMD, then move into a pediatric population through its placebo-controlled BASECAMP study. Farwell said boys with DMD generally have more muscle mass than adults, which could provide a greater opportunity to demonstrate clinical potential.
Satellos said it remains on track to complete BASECAMP enrollment in the third quarter and to initiate U.S. clinical trial sites for TRAILHEAD. In the fourth quarter, the company expects initial top-line data from BASECAMP and the 12-month primary readout from TRAILHEAD among the first four participants.
During the question-and-answer session, Farwell said BASECAMP currently uses dynamometry as the primary endpoint and also includes muscle biopsy, muscle MRI, SB95c, the North Star Ambulatory Assessment, other functional assessments and patient-reported outcomes. He said the company believes BASECAMP could provide a dataset to support discussions with the U.S. Food and Drug Administration about accelerated approval if the data are supportive.
Gleeson closed the call by saying the consistency of the data across patients and measures increased the company’s confidence in SAT-3247 and its development plans. He also said Satellos is “fully cashed up” to execute its plans through the end of 2027 and is increasing its engagement with the FDA based on the data it is generating.
About Satellos Bioscience (NASDAQ:MSLE)
Satellos Bioscience Inc is a regenerative medicine company dedicated to developing novel therapeutics which stimulate or restore muscle regeneration in severe disorders. The company’s lead program is focused on developing an oral therapeutic drug for Duchenne muscular dystrophy. Satellos Bioscience Inc, formerly known as iCo Therapeutics Inc, is based in Toronto, Ontario.
