Background:
Delandistrogene moxeparvovec (Elevidys), approved by the U.S. Food and Drug Administration (FDA) for ambulatory Duchenne muscular dystrophy (DMD), has limited real-world evidence outside of clinical trials. We evaluated short-term functional outcomes and laboratory safety in ambulant boys treated at an international center serving cross-border families.
Methods:
Fourteen ambulant boys with DMD from Russia, Turkey, India, Ukraine and Hungary (mean age 8.2 years; range 4.6–14.3) received Elevidys; thirteen had serial laboratory monitoring for ≥8 weeks. Thirteen were on deflazocort. Prednisolone was initiated one day pre-infusion, continued for 60 days, and tapered over 4–6 weeks before returning to maintenance deflazacort. None had received exon-skipping therapy or givinostat. Monthly functional assessments included the North Star Ambulatory Assessment (NSAA), Time-to-Rise (TTR), and 6-Minute Walk Distance (6MWD).
Results:
NSAA increased from a mean baseline of 23.4 to 24.7 (+1.3) at Month 1 and 26.1 (+2.7) at Month 2. By Month 3 (n=4), the mean cumulative NSAA gain was +6.0 points (range +4 to +9). Across three months, the mean monthly NSAA increase was 1.6 points (range: 0 to +3.1), with several boys achieving improvements of +6 to +13 points. TTR improved in nearly all patients, with prolonged baseline times (16–24 s) decreasing by 2–6 s within 1–2 months. 6MWD increased in most boys, with several achieving +100 to +180 m by Month 2. No functional decline was observed.
Mean AST and ALT declined through Week 2 (AST 183.9 U/L; ALT 246.1 U/L) before rising at Week 3. Mean creatine kinase decreased initially (5,726.9 U/L) and rose thereafter (10,753.5 U/L). Biomarker variability was high; regression showed net reductions in AST (–16.1 U/L/week) and ALT (–24.8 U/L/week), and a CK increase (+154.4 U/L/week), with R² <0.02. Conclusions: Elevidys was well tolerated and associated with rapid, clinically meaningful functional gains. Laboratory fluctuations remained within expected DMD ranges without treatment-limiting toxicity.