After an unexpected fatality in a gene-editing study for an investigative Duchenne muscular dystrophy therapy, researchers attributed the death to a virus used in delivering the drug instead of CRISPR, according to a preprint published May 30 in MedRxiv.
The patient, who was in his 20s, "had severe muscle weakness with a low lean muscle mass of 45 percent, a restrictive pulmonary defect and mild left ventricular systolic dysfunction," the authors wrote. Five days after receiving the CRISPR gene therapy, his cardiac function worsened, which might have been myocarditis; the next day he experienced "sudden acute respiratory distress [before he] progressed to cardiopulmonary arrest and was emergently placed on extracorporeal membrane oxygenation."
Eight days post-dose, he died from multiple organs failing and severe neurological injury, the researchers said.
After an autopsy, they said the patient's death was from a virus used to deliver the therapy rather than CRISPR itself, stating that there were minimal traces of the gene-editing enzyme in his body and the therapy had not yet been activated.
"Dose determination will remain a challenge for custom-designed (adeno-associated virus)-mediated therapies," the researchers wrote in conclusion.