The team from Oregon Health & Science Institute in Portland delivered the CRISPR components directly into the eye of a patient with a rare, inherited form of blindness.
'We believe that the ability to edit inside the body is going to open entire new areas of medicine and lead to a whole new class of therapies for diseases that are not treatable any other way', Dr Charles Albright, chief scientific officer of Editas Medicine, Cambridge, Massachusetts, one of two pharmaceutical companies developing the treatment told NPR.
This is not the first attempt at editing the genome directly in the human body. In 2019, US biotech firm Sangamo Therapeutics announced they had successfully inserted a corrective gene into the DNA of two patients with Hunter Syndrome, using zinc-finger nucleases (see BioNews 986).
However, this latest trial marks the first time that CRISPR has been used directly within a patient.
The team were attempting to cut out a mutation in the CEP290 gene that causes a condition called Leber congenital amaurosis (LCA), the most common cause of inherited childhood blindness. The mutation affects the function of light-sensitive cells called photoreceptors in the retina. Due to the large size of the CEP20 gene, it is not possible to use standard gene therapy approaches to replace the faulty gene with a functional copy.
The treatment consisted of an hour-long surgery, in which doctors dripped three drops of fluid containing the CRISPR components beneath the retina of one eye. It is hoped to be a permanent, one-time treatment.
It may take up to a month to know whether the treatment has been successful. If so, the team aim to treat a total of 18 patients, both children and adults, to understand how many cells they need to fix to restore vision.
Other researchers are optimistic about the potential of the study. Dr Jean Bennett, an expert in genome editing at the University of Pennsylvania called the approach 'exciting', telling AP, 'We need technology that will be able to deal with problems like these large genes'.
Dr Eric Pierce, director at the Inherited Retinal Disorders Service at Massachusetts Eye and Ear, told NPR that the approach 'opens the possibility to treat many other diseases where it's not possible to remove the cells from the body and do the treatment outside'.
'We're helping open, potentially, an era of gene-editing for therapeutic use that could have impact in many aspects of medicine,' he concluded.