Unexpected Death of a Duchenne Muscular Dystrophy Patient in an N-of-1 Trial of rAAV9-delivered CRISPR-transactivator

An N-of-1 trial was developed to deliver a dCas9-VP64 transgene designed to upregulate the cortical dystrophin as a custom therapy for a Duchenne muscular dystrophy (DMD) patient. After showing signs of mild cardiac dysfunction and pericardial effusion, the patient acutely decompensated and sustained cardiac arrest six-days after dosing and succumbed two-days later. Post-mortem examination revealed severe acute-respiratory distress syndrome with diffuse alveolar damage. Vector biodistribution data was obtained and revealed minimal expression of transgene in liver. There was no evidence of AAV9 antibodies nor of effector T cell reactivity. These findings demonstrate innate immune signaling with capillary leak as a form of toxicity in an advanced DMD case treated with high-dose rAAV gene therapy.