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Wolfgang Miesbach: Human Tissue Study Sheds Light on AAV Gene Therapy Safety

Wolfgang Miesbach/LinkedIn

Jul 24, 2026, 08:57

Wolfgang Miesbach: Human Tissue Study Sheds Light on AAV Gene Therapy Safety

Wolfgang Miesbach, Professor of Medicine at Frankfurt University Hospital, shared a post on LinkedIn:

“First human tissue data after cardiotoxicity from AAV gene therapy in Duchenne — a 17-year-old with DMD received delandistrogene moxeparvovec, the first commercially approved gene therapy for the disease.

Ben Samelson-Jones, Lindsey George, and colleagues (CHOP) now report the first cardiac and skeletal-muscle biopsy analysis after cardiotoxic effects:

Day 2: myocarditis, symptomatic atrial fibrillation, mild thrombotic microangiopathy.

Day 42: troponin I rising again, cardiac function deteriorating – intravenous methylprednisolone on top of prednisone and sirolimus. The delayed toxicity is attributed to an adaptive immune response against the AAV capsid.

Day 44: biopsies. Endomyocardium unremarkable, but taken after heavy glucocorticoid exposure; skeletal muscle dystrophic. Cardiac microdystrophin measured in a human for the first time:

vector copy number higher in heart than in skeletal muscle
transcripts skewed towards the 5′ end of the cassette, i.e. incomplete packaging — also demonstrable in the clinical vector lots
microdystrophin in 5 percent of cardiomyocytes and 10 percent of skeletal fibres, below 1 percent of normal dystrophin on Western blot
in skeletal muscle the dystrophin–glycoprotein complex was restored in positive fibres; in heart it was not

Such heterogeneity may limit long-term efficacy and could aggravate arrhythmogenic risk.

Sampling at six weeks precedes stable episome formation, so expression may still rise.

The packaging defect will not.

The events were captured by institutional monitoring more extensive than the label recommends, and the authors call for safety monitoring beyond label.

One patient: a larger cohort is needed before generalising.”

Other posts featuring Wolfgang Miesbach on Hemostasis Today.