The US Food and Drug Administration has placed a hold on Bluebird Bio's clinical studies of its Lenti-D gene therapy for cerebral adrenoleukodystrophy, according to MarketWatch.
A patient treated in the phase 3 study more than a year ago has developed myelodysplastic syndrome, it reports. Bluebird Bio notes in a statement that current evidence suggests "specific design features" of the lentiviral vector the treatment uses "likely contributed to this event."
According to Science, Philip Gregory, the chief scientific officer of Bluebird, said during an earnings call that researchers found by analyzing blood from the patient that lentiviral DNA had inserted into the genome at spots previously linked to MDS, suggesting the insertion drove the cells to proliferate. It adds that Gregory suggests the effect is in part due to the strong promoter included in the therapy that was meant to generate enough adrenoleukodystrophy protein to treat the condition.
MarketWatch adds that Bluebird plans to work with FDA to address the hold and still aims submit its rolling biologics license application for the treatment this year. It further says the company doesn't expect the hold to affect its other studies.